Category Archives: Audio

Make pipewire play bitperfect audio / Linux

If you are like me,

and have always wondered why PulseAudio had a fixed setting for sample rate,

but thought that that situation would improve when PipeWire got established,

and then learning that PipeWire STILL had a fixed sample rate?

So that everything was resampled to 48000, or whatever setting was the default?!

Fear no more.

THIS is how to make PipeWire always choose the best sample rate when playing audio. So that a 44100 Hz files will play with a 44100 sample rate, and a HiRes 96000 file will put the soundcard at 96000.

  1. open, or create, ~/.config/pipewire/pipewire.conf and put this in:
    context.properties = {
       default.clock.allowed-rates = [ 44100 48000 88200 96000 ]
    }

    if required, add extra sample rates that your files and/or your soundcard supports.
  2. That’s it! Maybe need to log out/in, or kill PipeWire, whichever you choose
  3. check the result with
    # pw-mon
    R   52   4096  96000  83,3us  16,5us  0,00  0,00    0    S32LE 2 96000 alsa_output.usb-Focusrite_Scarlett_2i2_USB-00.HiFi__hw_USB__sink
    R   72   7200  96000  41,0us  22,4us  0,00  0,00    0    F32LE 2 96000  + LibreWolf
  4. Both the hardware (Focusrite) and the program (LibreWolf) are playing audio at 96000.
  5. I found that in order for Qobuz (and probably other streaming services as well) to really play at native bit rate, LibreWolf will do the trick, NOT the ‘native’ linux flatpak client for Qobuz.
    So use the url: ‘https://play.qobuz.com/’

Fixing another Fostex R8

Today I am fixing another Fostex R8 from a customer. The problem was that the plastic capstan wheel was slipping on its axis, and the spooling motor wheels did the same. This is a common problem with these decks. The Fostex will not play and/or spool correctly then.

Fortunately, John from https://www.tascamninja.com/ makes aluminium replacements. These fit tightly on the axis and can be fastened with a screw.

aluminium capstan wheel replacement
aluminium spool wheel replacements

I also replaced the belt. Now, the deck plays and spools perfectly.

A small problem

But unfortunately, one problem remains: the arm on which the right tension roller is mounted, has got a fair amount of play, maybe caused by a blow or something.
This is causing the right tension roller to guide the tape in a skewed position. It is not a show stopper, but it is certainly not ideal for the tape path.

Calibrating a Studer B67 for a Mastering Studio

Recently I got in contact with the owner of a Mastering Studio. He owns a Studer B67 and had a problem with it regarding calibration levels. He wants to use the B67 as a ‘bounce to tape’ device to get the tape compression-effect. And there was also the problem of randomly dropping levels when calibrating.

When I got the deck I could replicate the problem with the levels. I It seemed weird to me, but I suspected that the REC AMP cards, or maybe the Power Supply was faulty.

The deck had been fully recapped and serviced before. And I can say that the person who did that did an outstanding job! No complaints whatsoever.

I spend a lot of time diagnosing the problem, measuring every aspect of the deck, checking pots, solder joints, etc. etc. whatever I could think of.
I found one shorted tantalum cap in one of the REC AMP cards, but I wasn’t sure if that was causing the problem. The card was functioning normally. I replaced the tantalums for quality elec. caps.

After a lot of testing, the problem seemed to have gone away, as I could not replicate it anymore. It could very well be that the initial tape used to test the deck with, was not performing as it should. Anyway I tested the deck with my own BASF 911 tape and I found no problem anymore.

So I continued with the second item on the list: recording the middle speed of 19 cm/s with such a high fluxivity that tape compression could be achieved easily without over-driving the input chain too much.
At the end I put the slow speed ~@320nWb/m, the middle speed ~@510 nWb/m, and the fast speed also at ~@320nWb/m, as per the customer’s wishes.

These are the frequency sweeps: 9,5 cm/s

19 cm/s:

38 cm/s:

The Studer A810

Of course.
So I just got my Studer B67, from Germany, and I was still very much enjoying it, when the opportunity arose to buy a Studer A810. I know. When it rains, it pours.

The Studer A810 came from a company that services professional studios all over the world, and has been in their possession for a number of years and was still in use regularly. So it came with a bit of assurance that it would be OK. It had been recapped and kept in good working order.

The price however, was very steep. So that price, and the fact that I had júst gotten my B67, made me hesitate to buy it. I doubted a lot, and then some more, but I finally took the plunge and did it anyway. I did it also because in 2014 I bought my Studer A80 also at a (then) high price, but that price is now a joke. It’s nothing. It is worth so much more now. And I never ever regretted the purchase.

So then it was a matter of getting the deck. It is a bridged version, which means that the deck is in a console with an overhead VU-meter bridge attached. It is a complete package, but it is also a challenge to transport. Luckily the company that I bought it from, offered to bring the package to my home in their truck. They often have to do this I suppose in their line of work, which is servicing studio equipment.

Package for you!

So a few days before Christmas 2021 a big yellow truck pulled up on my driveway and 2 guys stepped out. I was very excited as they wheeled the A810 into my garage.

We had a nice talk about it and taperecorders in general. After they had gone I wheeled the deck into the living room, because, as it was a cold damp day, the deck needed to be acclimatized before turning it on.

The first power-up

So the next day, after having spent the night in our living room, and being all warm and cozy now, I dared to turn the A810 on for the first time. You only get this feeling once! After loading a tape I plugged in a pair of headphones, as I have no equipment to hook it up to in the living room. I have a nice tape that is recorded on my Studer B67 that sounds great. The deck and the tape did not disappoint!

I played around with it and I was pleasantly surprised at the smoothness of the tape handling. I got myself familiar with the keys on the keypad and their functions. I loaded some pancakes to try out, and that too was very enjoyable.

I was a bit disappointed because there are 2 headphone connections, one in the bridge and one in the deck. The one in the bridge turned out to be mono, and the volume of the connection in the deck was way too low to be able to listen to the music at a normal level. I could of course do that upstairs, but that would have to wait a bit until we managed to get the console upstairs.

Then, I was very curious to find out about the various cards in the machine. I opened the flap, or tray or however you want to call it, at the bottom of the frontpanel with a hex key and found this:

From left to right:
MPU Unit 1.820.780.82
Tape Deck Controller 1.810.750.81
Periphery Controller 1.810.753.00

channel 1:
HF Driver 1.820.713.00
Record Amplifier 1.820.712.81
Reproduce Amplifier 1.820.710.83
Line Amplifier 1.820.714.83

channel2:
HF Driver 1.820.713.00
Record Amplifier 1.820.712.81
Reproduce Amplifier 1.820.710.83
Line Amplifier 1.820.714.83

Upstairs at Philip’s

After a couple of days, it was time to move the A810 upstairs. For that I removed the A810 from the console and transported the deck and the console separately because of the combined weight. Separate it was doable.
In my ‘studio’/’mancave’/’hobbyroom’/’repaircenter’ I could finally listen to my new Studer and appreciate the sound through my headphones at a normal level, using the MAckie 24.8 output, and over the loudspeakers (KEF) at room level. Again, it did not disappoint!

Recording

Time to do some test recordings. The recorder was calibrated on SM900 for 38 cm/s for Tape A setting. I used my FiiO K5 Pro Digital Interface to play 24/96 tracks from Yello, Steely Dan, Dire Straits, and also some other less audiophile artists.
Later I also did a test recording from my Pioneer CD player which has XLR outputs directly to my A810. I have installed the Pioneer in the 19-inch rack that is located in the console below the A810 recorder, so now it is easy to connect them for a recording.

Tinkering and maintenance

After a few weeks, after getting really comfortable with the deck I was able to reprogram some of the keys on the deck to a different function. The Studer A810 makes that possible, and now the button layout is more intuitive for me.
So I now have 2 memory slots for tape location.

A slight problem

After a few months the deck developed a problem. When it was idle, sometimes out of nowhere the clapms on the tension arms would engage and release immediately, and that clicking would occur a few times. Also, the PLL light indicating capstan speed would blink on occasion.

I contacted the seller, who has a repair business for professional studio tape gear, and he suggested to look at the connectors and the settings of the tension arms. I investigated and found nothing wrong at first sight, but I started to calibrate the left and right tension rollers nevertheless. I quickly discovered that I needed some special Studer gauges for the adjustment. These were, of course, nowhere to be found and/or very expensive to get hold of.

Fortunately, there was a close up photo of such a gauge on internet. I found the correct dimensions and adjusted the image and made my own version in a CAD-drawing program. You can print it out and use it to adjust the left and right tension arm according to the official service manual. Here it is:


You can find the file on my site, https://www.reeltoreel.nl/ in the Studer section, Documents, A810.

After adjusting the tension arms and checking and securing the connectors on the hall sensors the problem did not occur again. Oh, and I had to adjust the position of one of the sensors for it to work correctly.

Calibrating Tape B

When I got the A810, only the Tape A / 38 cm / CCIR setting had been calibrated, to SM900 @ 410 nWb/m. But I have a lot of AGFA (BASF) PER528 tape that is very good and that I would like to use. So I took the manual and started calibrating for that tape.
The Studer A810 has 2 settings: Tape A and Tape B. It has 2 EQ curves: NAB and CCIR and it has 4 speeds (9,5 – 19 – 38 – 76 cm/s). That gives a total of 224=16 possible combinations, each of which can and has to be calibrated separately.
I say that now, but it is not entirely true. Some settings are the same for NAB and CCIR, like low speeds.

Now I won’t go into the details of the complete calibration, because that would far exceed the purpose of this blog, but it involves setting the parameters into the computer instead of twisting pots like in other conventional tape machines. I will probably do a video on that in the future, so follow my Youtube channel https://www.youtube.com/@PhilipvanderMatten to be able to see that.

I also made a handy spreadsheet (or paper sheet), where you can manually enter all the data that you store into the memory during calibration, or, if you wish, read all memory data that is currently stored and fill it out on the sheet to have it handy for when that data might be lost. You can find that on my site as well, https://www.reeltoreel.nl/ in the Studer section, Documents, A810.

While I was calibrating the Studer A810, I also made a short summary of the calibration steps from the Service Manual. This is much easier to handle than all those pages from the SM. Again, you can find that on my site as well, https://www.reeltoreel.nl/ in the Studer section, Documents, A810.

Replacing eproms.

The Studer A810 is a computerized deck, that means that it has a microprocessor built in. In this model it is the Motorola 6803. A microprocessor always follows a program, which in this case is built into an EPROM chip.

It is called the firmware. This was common practise at the time (1983). When the unit is turned on, the display will show the version of the firmware. Newer firmware version were issued by Studer later in the production cycle of the A810 and they fixed small bugs and had little enhancements. The firmware version 01/88 is considered the best and latest, firmware versions that came after that were merely fixes for synchronizers (to sync the tapedeck to other decks or to SMPTE timecode).

So I wanted to upgrade my firmware from the version I had which was 13/83 (week 13 1983) to that 01/88 version. Newer EPROM chips could be obtained from sellers, to replace the chips on the MPU board (containing the microprocessor), but they were expensive and I really wanted to burn the chips myself. Also I wanted to be able to later offer this service to other deck owners. We got to help each other, right?!

So I bought an EPROM programmer, an UV-light eraser and some empty EPROM chips. I obtained the files for the new 01/88 firmware from a well known American Studer professional and successfully managed to burn my own EPROMS.
I made a video of that which you can find here:
https://youtu.be/MVfTqoUg3xM

A Fostex R8 multitrack 8tr. dolby C 38cm/s deck

So I could purchase a Fostex R8 cheap. The unit was supposed to be in a fairly good working condition, maybe a few scratches on the front. The price was that good that I could not walk away from it. Besides, I always wanted a Fostex. Just because.

Overview

This deck is squeezing 8 audio tracks onto a standard 1/4 inch tape. To put that into perspective, normal home audio deck use 4 tracks (2 -> and 2 <-) and the professional world uses just 2 tracks onto that same width of tape. So the tracks are super small. To compensate for the loss of fidelity and the added tape hiss the speed at which the tape runs is fixed at 38 cm/s or 15 IPS (cassettedecks run at 4,75 cm/s). Also, the deck has Dolby C. Dolby C comes from the cassette world, it is an enhanced version of the omnipresent dolby B and it works quite well on this deck. But I’m getting ahead of myself.

The deck, being one of the very latest generation of tape deck being made, is heavily computerized. Not for the calibration electronics, like the Studer A810 and all Studer models beyond that, but in the controls. There are a LOT of possibilities and functions that I have not even tried tried yet.
When the deck is turned on, the display shows a scrolling text of ‘FOSTEX’.

First impressions

When I got the deck I first cleaned the outside. I like to work on a clean deck. This one was not dirty, but sometimes you can get a lot of dirt off decks you collect. After that, I cleaned the heads and the tape path in general. I noticed the very plasticy rollers and the flimsy arms. Also, the roller covers were coming of way too easy. Hmmm, not so good.

I put a tape on and the deck played. So far, so good. Rewind, fast forward, no problem. The capstan was noisy however. I played around with it and decided to try recording. I was NOT disappointed with the sound quality. I was surprised how well it sounded on playback. I tried several channels and it seemed ok. The dolby C noise reduction really took away tape hiss in quiet passages and in between tracks. Just like on cassette decks.

Capstan wheel

After a while I noticed that the tape speed was dropping a little. It was ok after a while, but just after hitting PLAY it was not good.
And after a little more testing, the tape was not moving at all anymore. Even pressing the pinchroller to the capstan did not work. I noticed the capstan was not spinning anymore. When in STOP, the capstan would slowly start spinning again. Only to come to a quick stop once I pressed PLAY. But I could hear the capstan motor spinning constantly. Weird.
I had already ordered a new capstan belt, as is almost always necessary when old rubber belts are involved, so once that had arrived I put it on. But, unfortunately, that was not a solution. I found out that the wheel attached to the capstan motor shaft was slipping. It is a simple plastic wheel that had come loose from the shaft, probably because it had worked itself loose after being clamped on in the past. But now the wheel was just stationary and the shaft of the motor was spinning because of too much room inside. (blowfly pun intended)

Tascamninja to the rescue

I tried to glue the wheel to the shaft a couple of times using instant glue and some stuff that had worked great in the bathroom glueing shelves, but after a short while the wheel came loose again. I had to bite the bullet and order a replacement wheel made out of metal from the website https://www.tascamninja.com/.
I could not play any tape, or do some more tinkering while waiting for the arrival of the metal wheel, because the slippage was such that the capstan did not move at all anymore.
It arrived in about 2 weeks time, and as soon as I put it on, the tape speed was super reliable and super constant. Very happy with this solution!

recapping audio cards

I did do something in the meantime however. I recapped some of the audio boards. Although this deck is one of the last reel to reel decks to be made, it still has 40 year old capacitors in it, so the cards could use some fresh ones. But first, I had to get these cards out. Noone on the internet that I found managed to get them out, or, at least, did not mentioned it at all. Also the manual and the Service Manual had no mention of this removal. I was beginning to suspect that maybe they weren’t supposed to be removed.

But, eventually I managed to pry them out. They are just on connectors on a backplane, so definately supposed to be removed..

Knowing that I had to recap 8 boards, I made a document to use as a Quick Reference Guide with some handy info on the location of the caps and their value, the location of the pots for calibration, and the complete summary of the calibration procedure. I made it along the way as I worked on the deck.
The document is available at my site at: https://www.reeltoreel.nl/Fostex R8/
You can find the latest version there.

After recapping I started to go through the calibration procedure. It is very labour intensive, doing everything 8 times, but the 0-locate-and-auto-play function of the Fostex is a very handy feature. But then I found an even better feature: you can repeat a section of the calibration tape endlessly. To achieve that, do the following:
– press CLR
– type timecode of beginning, like 0000 and press STO and then the number of the position slot you wish, like 1
– press CLR
– type timecode of end of the fragment, like 29 and press STO and then the number of the position slot you wish, like 2
– press CLR
– type ‘1-2’ and STO. display shows 2-1.
– make sure you play the section and the deck will automatically repeat the section.
I type this from memory so I hope this is correct 🙂

Testing after calibrating

I tested the sound quality when I was done and it sounds very good!

This is a sample from playing the calibration tape. But recording a sweep to 18kHz resulted in an equally straight frequency responce! (I forgot to take screenshots)

I recorded a youtube video where you can listen to a sample. You can find it here:
https://youtu.be/W2jRQmiAHzQ

TO BE CONTINUED

DCC Quick Reference Guide to recording

Start new recording (completely overwriting a DCC tape)

To initialize a new or used tape.

DCC600:
-bulk erase your tape (if applicable)
-rewind to beginning of side A
-press APPEND
-the deck will now do its magic and write a LEAD-IN and put itself in REC PAUSE
-check levels on meters and adjust recording level (analog input only)
-press REC/MUTE to start the recording

DCC730:
-bulk erase your tape (if applicable)
-select side A
-press REWIND (|<<)
-press SELECT/PAUSE
-the deck will now do its magic and write a LEAD-IN and put itself in REC PAUSE
-press SELECT/PAUSE for the correct source, and check for the correct levels on an analogue source (press TIME 3x)
-press RECORD to start the recording

DCC951:
-bulk erase your tape (if applicable)
-select side A
-press REWIND (|<<)
-press REC SELECT/PAUSE
-the deck will now do its magic and write a LEAD-IN and put itself in REC PAUSE
-press REC SELECT/PAUSE for the correct source, and check for the correct levels on an analogue source (press TIME 3x)
-press RECORD to start the recording

Start New Side Marker(730/951), Next Mark(600) (with rewind), also called ‘Dual Album Format’ or ‘Start New Side’

This marker makes the tape switch from A to B and then REWIND to the beginning of side B.
Track numbering starts with track 1 again on side B (independent track numbering per side).

DCC600:
-press REC PAUSE
-press MARK WRITE (NEXT MARK is written and tape spools to beginning of side B (A to B) and writes LEAD-IN MARK)
-continue the recording by pressing REC/MUTE

Bonus – to make tape rewind to beginning of tape after the last music track finishes playing on side B:
-during recording, after last track on side B has finished, press REC PAUSE
-press MARK WRITE (B to A)
-Tape winds neatly to beginning of side A.

DCC730/951:
When in REC PAUSE mode or in STOP mode, press EDIT key and select START NEW SIDE and press RECORD to actually edit the tape. The START NEW SIDE marker is written on side A and the tape will spool to the beginning of side B (starts again with track1!) and write a LEAD-IN.

Reverse Marker (no rewind), also called ‘Single Album Format’ or ‘Continue B’

This marker makes the tape switch from A to B immediately but does NOT REWIND to the beginning of side B.
Side B is marked immediately with the next track number (continuous track numbering).

DCC600:
-press REC PAUSE
-press SIDE A/B (REVERSE MARK is written). Tape switches to side B and enters PAUSE mode
-continue the recording by pressing REC/MUTE.

DCC730/951:
-when in REC PAUSE mode or in STOP mode:
-press EDIT key and select CONTINUE B
-press RECORD to actually edit the tape.

Split, Connect or Renumber tracks (DCC730), START MARK, MARK ERASE or Renumber (DCC600)

DCC600:

  • When in PLAY or RECORD, press MARK WRITE to write a START MARK.
  • When in PLAY, press MARK ERASE right before the marker to be deleted.
  • To renumber, press RENUMBER.

DCC730:
When in STOP mode, press EDIT key en select SPLIT TRACK, CONNECT TRACKS or RENUMBER DCC. Press RECORD to actually edit the tape.

Make recording from CD to fit side A and side B

CD911:
press EDIT, EDIT and select tape length with |<< and >>| keys (or type length with number keys) and press EDIT.
The display will show the number of tracks for side A and the time.

How to record from various sources on a Philips FW68

Philips FW68 DCC Mini HiFi System

When recording a DCC on this cute little Philips set, there are some questions and challenges.
There are three little preset buttons on the FW68 that let you do CD -> ACC, DCC -> ACC and CD -> DCC recording. But what if you want to do something else?

You can record from ACC -> DCC, and also from TUNER -> DCC or TUNER -> ACC, but you can not use one of those three little preset buttons for recording.

How to do this:
Suppose you want to record from ACC -> DCC.
-put the ACC and an empty DCC in the machine
-rewind the DCC
-press REC PAUSE on the DCC part
-RECORD is shown in the display, the DCC player starts writing the LEAD IN etc., just wait a while until that is finished
-press PLAY on the analog deck and PLAY on the DCC deck
-A recording will be made from ACC to DCC.

The same procedure for recording from TUNER or AUX to ACC or DCC:
-press REC PAUSE on the tapedeck
-press TUNER or AUX
-and press PLAY on the tapedeck.
This works with the analog and the digital cassette deck.

Make a CD fit on sides of a DCC for recording.
-prepare the CD and DCC (or ACC)
-press EDIT on the CD | C-60 appears
-press NEXT to select the correct tape lenght
-press EDIT to confirm
-press CD -> TAPE or CD -> DCC to start the recording.
Pressing PROG REVIEW to show time.

You’re welcome.

P.S.1: ACC stands for: Analog Compact Cassette, the old, well-known compact cassette in contrast to the Digital Compact Cassette.
P.S.2: The DCC side can playback DCC and ACC (though NOT recommended), but can only record DCC. The ACC deck can record and playback ACC’s only.

Another Studer Tapedeck Has Finally Arrived! The Studer B67 Mark II

So, I got myself another Studer. This is the Studer B67 Mark II. It is in very nice condition. The model was introduced by Willy in 1975, and it is the first model that came out after the famous A80 (that I also have, which was introduced in 1970) and it is more compactly build. It has been in production until 1989. There have been 18 version of this model produced throughout the years. It was very popular with the BBC who bought a lot of units.

It is quite a heavyweight with 35 kg. I really like to handle it with two persons 😂. I have the Mark II version with the VU meters built-in.

The B67 MK2 offers the following additional features:

  1. Easier access to the tape heads for better marking and cleaning
  2. Improved editing: The tape tension sensors are mechanically blocked in stop mode, at the same time the brake moment is automatically reduced.
  3. Tape lifter defeat in wind mode. Both push buttons “fast forward” and ”rewind” must be pressed simultaneously in order to activate the ”defeat“ function. After this initial activation, one push button (< or >) must be constantly pressed to maintain the defeat function. This is not possible from
    the remote control.
  4. Spacing of the spooling motors has been increased. This allows the use of 282mm (11.1 inch) spools or up to 1000m (3281 ft) of tape.
  5. Tape tension adjustments are accessible from top (front, next to audio adjustments).
  6. Drop out of record mode when pressing play.
  7. Dump editing mode (spooling motor off) is improved: counter stops automatically (jumper selectable); motor off can be activated in all modes.
  8. Reproduce amplifiers have an additional filter which rolls off frequencies above 20 kHz. This results in a better noise figure.
  9. The timer roller mass has been reduced and the roller is equipped with a ball bearing.
  10. The audio basis board has been completely modified. The positions of the stabilizer and of the pilot amplifier have been changed. Most wire harnesses are of plug-in type and the connectors are easily accessible on the right—hand side of the basis board.
    Connectors are provided for: VU meter panel (2 CH or mono), mono/stereo switch, safe/ready switch, monitor amplifier, pilot tone connection.
  11. The power cable to the mains switch is soldered onto the logic board. A coded connection is provided at the power supply.
  12. The recorder has been modified according to the IEC recommendations.

This is the 2 track halftrack with butterfly heads. 3 Speeds (9,5 – 19 – 38 cm/s).

I got it from Germany. It came very well crated.

It has been one and a half year in the making before the deal could be finalized, because of all kinds of circumstances, including COVID-19 related stuff. But, it is finally here and I am really happy with it. I got it from a guy who has his own studio, and the guy (as I will call him) had already recapped the deck and replaced all suspicious parts throughout the machine (power supply etc.) and replaced bad parts (pinch roller) and adjusted and replaced the brakes.

He also, as a service, has calibrated the B67 perfectly for my preferred tape – AGFA/BASF PER528.

Everything is nicely organized in insertable cards.

There are a lot of possibilities in this deck. The tape path and the tape handling are super smooth.

And it sounds wonderful! The guy I bought the Studer from supplied a tape that was recorded in his studio and that tape sounds very, very good.
I have put the Studer B67 in a trolley now to be able to play pancakes.

It is a very nice, and very welcome addition the the family!

Here’s the video:

Treating old DCC tapes for the first time

When you receive one or more DCC tapes of unknown origin, you have to assume that they have not been used for a very long time. This means that you will have to treat them in a certain way, even before putting them in a deck or playing them.

Why, you ask? Because the tape has been sitting still in its shell for a long time in the position that it is in now. It has become deformed at the place where it is guided along the heads. And even worse, there is a sticky residu that has formed on the back of the tape where there are two internal felt pads inside the cassette. I am not talking about the felt that is opposite the head. These felts are inside and can not be seen, unless you break open the case, and this can not be undone.
These two felt pads have started to ‘leak’ a sticky oily substance onto the backside of the tape in the place where they touch the tape. That sticky bit will prevent the player form playing beyond that point, because well, let’s say it slips and cannot continue. It will either stop or go to the other side continuously. Until you fix this, the tape will be unplayable.

So now you know why you will always have to resist the urge to play them right away to hear what is on them, and follow this procedure.

The steps.

  1. So you will have to carefully pull the tape out. Be careful not to crease or rumple the tape, because that will surely create a dropout on that spot. To be able to do that first you must get the protective aluminium slider out of the way. Open it manually and place the wood part of a cotton swab into the round hole that has just opened up. It will fit almost perfectly and it will hold the slider open.
  2. Then, carefully pull out a length of tape of about 30 cm or more, making sure that you get tape from both reels. I use a pair of bent tweezers for that. Lay the tape flat on a white clean soft surface, like a piece of paper, with the shiny side down. The shiny side is the side that the DCC head touches, where the magnetic information is. But the gunk is on the backside. Lay the tape so that you are now looking at the matte back coated side. You may need to use some tools to hold the tape in place, I use two erasers, they are heavy and soft enough to hold the tape down.
  3. Now, and this is hard, look for some sticky residu. It will be hard to see, I use a desktop light and/or a handheld flashlight to find them. These patterns may also repeat at a ~10cm interval, so look up and down the length of the tape that you have pulled out the casing.
    I tried to make a picture:
  4. Once you are able to see the problem area clearly, take a cotton swab and put some alcohol 96% on it and gently rub the backside of the tape. Do it gently as not to crease the tape. Rub very carefully but firmly up and down the length of the tape. Once you have done this a few times, you will get the hang of it. Make sure all the gunk is gone. Let the alcohol on the tape dry for a minute and check again and repeat if necessary.
  5. Once you are satisfied with the result, you should see an even back-coated surface with no spots on it, and you can carefully manually rewind the tape into the housing using a pencil or the end of the cotton swab or as I do with the tweezers. After the tape has been carefully stored back into it’s shell, only then you can remove the wooden stick and close the lid, not sooner.
  6. The tape has been cleaned, but the third felt pad (yes the one opposite the head) needs your attention now.
    I can not explain it better then Ralf did in this video: https://youtu.be/m3DcMtor_Ck

Now you understand why it is vital to not wind DCC tape when you first handle them and not put them in a deck first, because the deck will spool the tape a bit and after that you will have a hard time finding the greasy spots.

The 2 felt pads will of course still continue to shed oil a little bit, so always rewind tape after use. You will never know when you are gonna use it again, could be years from now.

See also my older post: https://www.reeltoreel.nl/blog/?p=779

A New Member of the Family: Otari MX-55 N-M

So, the inevitable has happened……….again.

I have bought myself another piece of studio equipment to live next to my Studer. I got myself an Otari MX-55N-M

This one I discovered in Belgium. Yes, down there. It came originally from a guy with a small studio who sold all his stuff, but I got it from someone who bought some records from that guy and got the Otari as a side catch.

Getting it from Belgium required a road trip. In about 2,5 hours we were there, it was actually not too far across the border. The place was a 2nd hand vinyl shop with a lot of records, but it had CD’s and DVD’s too. Oh, and comic-books, like Suske en Wiske.
The Otari was all dusty and just a little bit dirty, but not much. I brought a test tape that I had recorded with my Studer, as this is also a 2-track studio machine. I loaded the tape, plugged in my headphones and after fiddling with the knobs (how to put this thing in playback mode, and how to get signal from it) I got some sound from it and boy, did it sound good! Within a few minutes I knew that the sale was going to be made. I just had to do a quick check for any defects that I could find and if they would be a showstopper. I could not find any.

So then came the problem of transport. My car has a loading space with a flat floor that is 70 cm high and 100 cm wide. But the machine is with a cart and wheels and a meter bridge, as you can see from the pictures. We measured the Otari and thought: well, I may fit just laying on it’s back. And it did. So I didn’t have to dismantle the meterbridge or take the machine from the cart. That was good.

After we got home I cleaned it up. From beneath the layer of dust came a beautiful and almost pristine looking deck that has no marks on it of prior use. I started to play with it and explore it’s possibilities.

  • the deck is tilt-able in various positions.
  • it has a selection switch for 2 standards: NAB and IEC.
  • it has another 3-way switch for selection of the reference fluxivity. I found that mine is calibrated to the following setting:
    • LOW – 250 nWb/m
    • MED – 320 nWb/m
    • HIGH – I don’t know, I haven’t got a calibration tape in that range. It will probably be around 510 nWb/m.
  • high and low speed is now set to 19 & 38, but can be adjusted to 9,5 and 19.
  • has a built-in oscillator with test tones of 0,1-1-10 kHz for bias calibration.
  • reel size is selectable for LEFT and RIGHT reel separately.
  • Slack tape can be picked up by pressing STOP.
  • in- and outputs are fully XLR and +4dBu.
  • the speed is adjustable from veeeerrryyy sllllooowww to very fast.
  • Startup is very quick, 1-2 cm at 38 cm/s and its up to speed.
  • Digital tape counter hms with goto and 3 memory positions.
  • Recording and playback levels are adjustable at Standard Reference Level (SRL) or user controlled with a knob.
  • Tapedump function, where the takeup reel is switched off so the tape is dumped.
  • Button for listening (cue-ing) while spooling.

This is what I found so far. It came with a remote control with 10 meter cable, 2 Otari NAB adapters (which are very well built), and 2 aluminium reels.

I noticed that the left tape roller is making more noise than I would have liked, but it works ok and someday I will replace it. The heads are ok.

I am very fond of the smooth tape transport and the overall robustness of the machine. This Otari really is meant for heavy duty studio use.

I have not measured anything except for the fluxivity levels yet, but I expect the results like wow/flutter, distortion, frequency response etc. etc. will be very good. This will make a nice younger brother to the Studer.

Oh and by the way………..

I am looking for the manual, service manual and schematics for this MX-55 N-M.
I have found manuals for other models of the MX-55 family, but not specifically for the N-M. 

I found some manuals online, but they only contained the first two chapters.

So, if anyone know of these manuals, either in printed or electronic form, I would be happy to get hold of one. Please leave a message in the comment section.

Philips EL6021 elektrodynamische microfoon

Recently I got a Philips EL6021 mic:

It has the following specs:

Since the cable that came with it was unbalanced and noisy, making the mic rather useless, I decided to rewire the cable to make it balanced so I could connect it to my Mackie 24.8 mixer.

Some reverse engineering led to this diagram:

The connector can be fitted in each of three positions, giving the microphone 3 different impedances. See the side of the connector on the mic for the details.
It is absolutely noiseless now and it has a surprisingly good audio quality!
If you have any questions or remarks, please do not hesitate to ask me.

PM2505 electr VAΩ meter Philips transistor list

This is the transistor list inside the PM2505:

BC548 2x
BF256A 3x
BC549C 2x
BC558 1x
BC559 1X

In case you need to replace them 🙂

I replaced almost all of them in an effort to fix my multimeter. It did not function anymore. When I turned on the meter, the needle would go straight into the far right corner and do nothing, whatever the dial or switches setting.

After replacing the transistors and 2 caps that are on the board, I assembled it and when I wanted to test it I found out that one of the small metal balls that operate the function switch Volt-Ampère-Ohm had come loose and was freely inside the case. This is not good of course.

So I secured it in the correct place, the function switch is working as it should and the meter is also functioning perfectly! Happyhappyhappy!

Latest acquisition: AGFA Bezugsband 9,5 DIN 45513

Just a quick post about my latest acquisition: an AGFA Bezugsband 9,5 DIN 45513.

Some pictures here:

I think it was made in 1967, which is a good construction year 🙂

I came with some documentation, which I will post here for reference and archival:

Funny the documentation mentions 250 pico Weber per millimeter track width, where nowadays we use NanoWeber per meter.

Also, much use is made of time constants like 3180 µs, which corresponds with 50 Hz.

The tape appears to be in very, very good condition.

DCC digital compact cassette tape length identification

Sometimes, for instance when there is a sticker on top of the text that says whether it is a DCC90, DCC75 or DCC60, you have to guess the tape length.

Not anymore. I have created this diagram that show you just how long the tape is by looking at the casing (backside):

Handy!

It is really silly, some brands (hello BASF!) mention the length of the tape only once on the casing, and that is exactly where normally a title sticker would be placed. By looking at the diagram, you will no longer have to guess. The black circles in the drawing are holes in the casing.

DCC90 would mean 45 minutes on side A, and 45 minutes on side B, totalling 90 minutes. In practice, there will always be a few extra minutes of tape in the cassette. This goes for all the formats.

DCC75 is a bit strange, it was also not used in normal analog compact cassettes, but it would gave you 2 times 37 1/2 minutes. Not quite sure what the reasoning behind that was.

DCC60 is 2 times 30 minutes.

Have fun with it!

Walhalla Symfonie PvdM

In the early 1980’s Dutch public radio featured a program called ‘Walhalla Symfonie’. It was described as ‘an acoustical listening trip’ (translation).

The program duration was one hour, broadcasted late in the evening. Only 34 (+4) were ever made. It basically was music, sounds, quotes, experiences etc. all put together into a one hour composition. It had a strong influence of electronic music. And every one of them had a theme. The series also had a leader tune, created on a synthesizer.

I remember some of them from my childhood. It was an exciting experience to listen in the dark (sunday evening 23:00) with your headphones on to this broadcast on the radio. Recently I found all of them on the internet, downloaded them and I again enjoyed listening to them. They have a unique atmosphere to them.

This triggered me to make one myself. So here is my attempt to make a Walhalla Symfonie!
It is much shorter, around 20 minutes. And it has a different feel than the originals had, mine is less experimental, less far out there, more mainstream. But I think that it is agreeable to listen to as a listening experience. So, if you have 20 minutes to spare, take a listen and let me know what you think! (quality headphones and a relaxed listening environment are strongly advised)

fixing DCC audio cassette tape

A box of DCC tapes

I have lying around a box with +/- 50 used DCC tapes that I purchased a while ago. DCC is the Digital Compact Cassette, invented by Philips. I have gone through them all, I listened to some of the tracks on each tape and sorted which ones I wanted to keep because of what was recorded on it. But most of them could be recorded over.

history

In my youth I had the privilege to experience the evolution of the compact cassette (CC), also a Philips invention btw. It had just made its way from dictafoon-like devices to the hifi/consumer audio market. And I witnessed its rise to a high end audio device (Nakamichi et al.). I have lots of CC tapes, probably my entire youth is recorded on those.

Then, in 1992, DCC came. But by that time, I had lost interest in recording music, or audio as a whole for that matter. So I never really noticed at that time. Also the Sony Mini-disc and DAT recorders went completely past me.

But when I rediscovered my audio hobby around 2010, I got very interested in these three now obsolete recording techniques. And fortunately you can get these devices rather cheap these days.

My Philips DCC600

I have all three devices now.

DCC surprised me in a very positive way. I got the same, familiar feeling playing cassettes that I had back then and that I had gotten used to. Also the deck that I got feels very solid and tape handling is direct. The DCC cassettes themselves feel very, very well thought about. Even the casing and the jewel box is outstanding well designed, even more so the prerecorded tapes.
On top of that, you get CD like audio quality. I say CD like, but I dare you to hear a difference. I was very, very impressed with the whole concept. In hindsight I wish I had used it back then.

squeaking

I noticed when I went through the lot of old tapes however, that some of the DCC tapes were making a squeaking sound when they were played. And some of those would not play at all. The deck, just kept clicking, the drive mechanism reversing a few times, before finally giving up. So I thought that these were bad tapes, or maybe they had some shedding or sticky tape or whatever and that they could not be relied upon. I was resolved to throw them away.
It was clear that it was the tapes that were the problem and not the deck, because most of the tapes would play perfectly and the problem ones would not.
I did some research into cleaning the head of the deck, but found out that this was not a trivial task, and that the fragile head could easily get damaged. The general conclusion was that you don’t clean it, unless it is absolutely necessary because all tapes play bad and it is clearly visibly dirty. So I didn’t.

forum

I researched some more and came across a post on a Dutch forum dedicated to Philips equipment. You can find the post here:

http://www.mfbfreaks.com/forum/viewtopic.php?f=5&t=10492

although I think you need to register first. And it is in dutch 🙂

gunk

It is described there that there are actually 2 problems: the squeaking and stuck tape. The squeaking problem is related to two pieces of felt that are inside the DCC cassette, not visible from the outside. There is also a third piece of felt, this is the familiar one that presses the tape on the head. The 2 problematic felts are located near the left and right rollers located inside the cassette:

These felt pads leave behind a greasy spot on the backside of the tape when the tape is not used for a long time. The deck has trouble running the tape past these spots and finally gives up. This spot is somewhat greasy, but also a bit sticky. This can be observed by pulling the tape somewhat from the cassette and checking the backside. It is not necessary to open the tape casing for this.

In order to do that, you must pull back the sliding cover and pull the tape out very, very gently with a small tool and make sure that you do not damage or crinkle the tape. You can see the gunk if you look very carefully. Let light shine on the surface. Make sure that the tape is at the problem spot when you stopped the deck and pulled the tape out, from BOTH reels.
It was impossible to make a good photo of this, so you will have to look for this yourself.

cleaning

In order to clean the tape, make sure you gently use some non residu cleaner, like IPA or alcohol or videospray cleaner 90 or whatever fits you, and gently rub the problem spot using a cotton swab. Hold the tape down while you swab, careful not to damage or wrinkle the tape. That happens so easily! Remember it’s the backside of the tape.

After that, let the tape dry for a moment, simply wind the tape back inside the housing and play the tape. Voila! It’s working again!

squeaking

For the squeaking problem: I fixed this by cleaning the felt located opposite the head as well. It won’t get completely clean, but just try to clean it as much as possible. I did it with a cotton swab with IPA. Just rub it a lot and also twist the cotton swab over the surface of the felt. Let the felt dry, this will take some minutes, and wind the take back inside.

After that, the squeaking was gone.

more tips

  • Always rewind the tape completely before you unload and store it for a longer period. The (clear) leader tape, that’s what the felt presses against when the tape is rewound, doesn’t seem to have as much problem with the grease.
  • Also don’t demagnetize the head! Never! It will ruin it forever. The head does not require demagnetization.
  • Never ever use a cleaning cassette. The head is way too fragile and it will ruin it forever.
  • If you absolutely have to clean the head, use alcohol or IPA . Preferably with natural chamois leather, but a cotton swab will work as well.
    Update: since I wrote this article, I *have* cleaned the heads of my DCC decks. Several times. No problem. Just use a cotton swab with IPA and be very gentle. I have taken out the mechanism however. See also my video:
  • Avoid playing normal (analog) compact cassettes in a DCC player. Normal cassettes are not as clean as DCC cassettes because they have no tapeprotection and will make the head and the drive mechanism dirty. But most of all the tape formulas used in the analogue tapes are not as good as in the DCC and will shed oxide on the head. Better safe than sorry!
  • See an other post of mine https://www.reeltoreel.nl/blog/?p=809 where I explain the tape length identification marks on the DCC cassette.

All info and the picture of the open DCC cassette are from the forum mentioned.

See also my new post here:

https://www.reeltoreel.nl/blog/?p=949

Dolby 363 rack with model 350 cards

recording

Since I was very young I was intrigued by recording studios and the equipment therein. Can you tell?? (cue Studer A80 blog entry). A few years ago I had the opportunity to visit the famous Wisseloord studios here in Holland and needless to say that that was a thrilling experience. I am intrigued by the recording process, and mainly the tape part. But recording techniques in general have my interest. Like how to record a solo acoustic guitar, or how to record a symphonic orchestra. And as pure as possible. In order to do that, in the old days, you need a tape recorder, and there lies the base of my fascination.

tape hiss

Tape has a very nasty flaw: it introduces tape hiss into the signal. Tape hiss is clearly noticeable when you play around with consumer decks, giving a nasty hiss in quiet sections when you replay your recordings. This wasn’t so much of a problem when recording from LP or FM radio, which has a background noise that would make the tape hiss less noticeable. It became a bigger problem since CDs came around and the source of the recordings were becoming quieter or even dead silent.

If you wanted to minimize the tape hiss, you had to resort to quieter, and more expensive tape. You had to use the more high-end decks, and have them calibrated properly to that tape. Thorough maintenance became even more important.

studio – multitrack

If you thought that you had a problem with tape hiss at home, imagine the problem professional recording studios had with it. They have to conform to the very highest of standards because they are at the very beginning of the audio path, a path that would result eventually with you playing the record or CD at home. So they want to introduce as little noise (in general) to the signal as possible. Adding to the problem was the fact that multi-track recorders had 16, 24 or 32 tracks that all brought their hiss to the final 2 channel stereo end-mix.
Without proper noise reduction, even in the most expensive studio with the high end tapemachines and studiotape running at high speed the end result would suffer quite substantially from tape hiss.

noise gate

To circumvent this problem, studios often reverted to using devices like noise gates. When the audio level of a track would drop below a certain level, the noise gate would kick in and mute the channel on playback. This was of course done so that the downmix to 2 tracks would be more silent in the quiet parts. There is an interesting article on the use of Kepexes used by Alan Parsons on Dark Side of the Moon by Pink Floyd:

I remember extensive use of Kepex noise gates. I think part of the sound is these Kepex gates. They had a certain sound rather similar to tape compression. We were not just using them to reduce tape noise, they had a sound as well.

Read the article here: http://daily.redbullmusicacademy.com/2015/11/interview-alan-parsons

Dolby A

But, toward the end of the 60’s a new technology came around. Invented by Ray Dolby, Dolby (“A”, as it was later renamed) promised a reduction in tape noise level of around 10-15 dB. It was targeted at the professional market, and it was also used in the recording of optical sound on films for motion pictures, improving the audio quality significant.
In music studios it was an instant hit. Much of the music of the 70’s would not sound so great on CD’s as we know it now if Dolby A would not have been around.
The card that enables Dolby A for the 363 is the Cat 450 card.

Dolby SR

Without going too much into the history of Dolby, (you can look that up on Wikipedia for yourself) suffice to say that in 1986 Dolby introduced its best performing professional noise reduction system to date: Dolby SR.
Dolby SR stands for Spectral Recording, and it utilizes different techniques to achieve an increase in dynamic range of 25 dB. Professional tests conducted using a studio environment (link) concluded that a recording made with Dolby SR was indistinguishable from a digital recording.
So, my fascination with professional tape recording equipment would not be complete without some noise reduction and/or compression units. I purchased a Dolby Model 363 rack with 2 Cat 350 modules.
There is also a combined Dolby A/SR card, that is the Cat 300 card.

The test

My intention was to test these out with my Studer A80. But, as I was preparing some test material, I found out that my A80 was actually too silent and my source material too noisy to test this properly. I had a vocal track that was almost super silent as far as noise is concerned.
So I took out my most ‘noisy’ deck, which I think is my Teac A3440, and recorded some vocal track on it. With, and without Dolby SR.
To be fair, this was a quick and dirty test, and in no way this was an exhaustive test. I tried to find a noisy tape as well. I found that using the SR unit I was able to push the A3440 to a level where it was rivaling a CD as far as noise and dynamic level was concerned. You have to hear it to believe it.

Measuring (baselining) with my new National Distortion Meter

I like measuring. So I bought a National Distortion Meter. It is the VP-7701a.

This device is capable of measuring the distortion of an sine audio signal. And can be useful to calibrate vintage audio equipment.

Baselining

To be able to make any meaningful measurements, I need to do some baselining, meaning that I want to measure the distortion when the device is not measuring anything at all. If that makes any sense to you. It does to me anyway 😀
When the base distortion levels are extremely low, I can measure devices and discard the base distortion. But when the base distortion levels are significant, then I would have to subtract these levels from the measurement each time I do a measurement. Which I do not want, because it is a hassle.

So in order to do that I need a pure sine wave for input. The device does not provide that, at least not one that is available to the user. The device measures the distortion by subtracting its own sine waveform from the one that is being measured, and the result should be zero. But only if the supplied waveform is 100% equal to the internal sine waveform. My search for a matching waveform therefor brought me to 3 sources:

  • a pure sinewave provided by my soundcard from the computer, created in audacity
  • a test CD made for this purpose which I bought 20 odd years ago
  • a test CD that I created myself with pure sine waves created by audacity and burned to a CD

This is the test CD that I once (’90-s) bought:

It has all kinds of tests on it: frequency sweep, fase checks etc and also sine wave tones across the audio spectrum.

Result

This is the result of my base line tests:

The results show that both my soundcard and the commercial testCD are useless for my measurements. The CD that I made myself is a lot better. It performed marginally better on my Technics SL-P777than on my Philips DVD 963SA player (SACD). The result is such that I think that the base distortion is low enough to not take it into account when I start to measure real equipment. So I will be using this CD as my source for sine waves.

One side note: my CD is recorded at 0dB level, so the player outputs 2,5V which is rather high. I may have to make a second CD where the levels are lower, like -10 or -20 dB.

Cleaning contacts in audio equipment

file_342_9To clean contacts in audio equipment, I do the following:

  1. clean the contact with Kontakt 60
    this will dissolve the corrosion and is slightly acidic. Follow up with 2 & 3.
  2. clean the contact with Kontakt WL or IPA
    this will rinse the contact clean and evaporate completely
  3. protect the contact with Kontakt 61
    this will put a protective layer on the contacts to prevent corrosion and wear so that you won’t have to do this again next year 🙂

For potentiometers don’t use 60, this will erode the internals. Use Kontakt 390 or Kontakt Tuner(600). Tuner works very well.

Kontakt 390 is an old Philips recipe and should be an all-in-one solution. I have not used it yet.

Don’t use contactspray!

Good luck!

AEG Magnetophon AW-2

A very good acquaintance gave me some recorders recently. Among them was this beauty: The AEG Magnetophon AW-2.

aeg_1

As you can see, this recorder is from 1951 and is more than 65 years old! This particular device that I have was used in cinemas for sound reproduction. It sits in a suitcase for easy carrying around. It is quite heavy though. It uses platters and pancakes.

aeg_2

aufname und wiedergabe switch

aeg_3

on/off-volume and play/rewind switch

It is in a very reasonable condition. So far nothing seems to be broken beyond repair. My goal is to try to restore it so that it plays tapes again. I have not turned it on yet, it first needs a lot of TLC.
It appears that when used with ‘modern’ tape, this unit will nowadays produce stunning results that would exceed what would have been achieved back then.

For instance, there are three very heavy duty belts in this one motor machine. And with belt I mean like belt from a car engine. They are not in a condition to be used again, so these will have to be replaced. Also some of the electronic components, like capacitors and rectifiers are way beyond their normal operating life so they will have to go too. And then everything else that I will run into. Hopefully the tubes, there are a few, still work.

I have started to open the device up and clean it.
p1040011

p1040012

Immense belt

p1040019

fltr: erase, r/w head capstan and pinchroller

the heads:

p1040018

somewhere in this shell is the head

p1040017

erase head before cleaning

p1040022

oil’s well!

There are of course a lot of electrical components as well that need to be replaced. The first and foremost candidates are the capacitors, as there are certain types that don’t last for so long.


The device contains some paper-oil capacitors, like this one:

 

This will certainly have to be replaced before I can switch it on. I am told that ones like this will probably be ok:

The device is really beautifully made. When I ventured inside I fell in love with it more and more. But there are a few ‘minor’ issues to be resolved, like: where is this supposed to be connected?

I was told that this rectifier could go up in (probably very nasty) smoke:

So I will need to figure out how to replace it.

Fortunately I have got the electrical diagram:

Philips N4522 (twice) and another N4520: new arrivals!

I recently went on a road trip and came back with:

  • a Philips N4522 2-track. This machine is in very good condition and has recently been serviced in Germany.
  • another N4522 2-track, but this one is going to need some TLC. There are some issues with it, although none of them are serious problems. But I just like to fix it as much as possible.
  • another N4520 4 track. I already have one, but this new arrival is not recording well. This has probably something to do with the levels, but I have not looked into it yet.

So now a have a total of 4 Philips N452X machines and that looks like this:

The two on the left with the white VU meters are the 2 track stereos, and the two on the right are the 4 track stereo machines.

Wow! What speed flutter!

Why speed measurement

For some reason I got interested in the speed of my tape decks. Why, you ask? I really don’t know. I was fiddling around with my vintage Philips multimeter, which is capable of measuring the frequency of a tone, when I thought it would be cool to use that meter to measure the 1kHz tone which is a the beginning of my (generic) calibration tapes. If the tape runs too fast, the measured frequency would be over 1000Hz, and if the speed was too low, it would be under 1000Hz. Suddenly I was fascinated by the fact whether my decks were running at the exact speed or not, or if not, how much deviation it had.

Now, you have to understand that I do a lot (well, actually not that much) calibrations of decks, but I never ever calibrated the speed. I never bothered before. I never had a problem with speed before. I never had the need to adjust the speed of a deck. So whatever I measured now, it would be the ‘default’ speed, untouched.

So I loaded the test tape onto all of my decks, connected the multimeter, and did my measurements.

The results were sometimes surprising, sometimes more or less expected.

Merk/Type speed %
Akai GX77 980 98
Revox PR99 994,5 99,45
Teac X7R 995 99,5
Philips N7300 998 99,8
Teac X2000R 998 99,8
Philips N4520 1000 100
Tascam 34B 1000 100
Studer A80 1000 100
Teac A3440 1002 100,2
Teac X7 1011 101,1

And a graph says more than words, so:

What can we conclude from this?

  • The Akai GX-77 really runs too slow

  • almost all decks run within +/- 0,5% of the correct speed, which is within the DIN norm

  • only 3 decks run a EXACT the correct speed: the Philips N4520, the Tascam 34B, and the Studer A80.

    • the Philips N4520 is know for its quartz/PLL like control, so this is no surprise

    • the Tascam 34B is a professional deck, but this result still surprised me

    • the Studer A80…..well…….need I say more?

enter the wow and flutter

So that has been a very interesting experience. But then I started thinking about variations of the speed, also known as ‘wow’ and ‘flutter’.

Wow is the slow variation in speed, with a period below 6 Hz.
Flutter is the fast change in speed, with a frequency above 6 Hz.

One can experience wow then playing a record where the hole is not centered, and the speed goes up and down all the time.

Flutter is more difficult to hear because it is so fast. It can be measured however. Flutter is created by faulty mechanics: a capstan here, a roller there, dirt, bearings, the overall construction etc. It would appear that less flutter makes for a more tight and clean sound.

There is always wow and flutter. No mechanical system is without them. It is just a matter of reducing it as much as possible.

causes of W&F

what are the causes of W&F? There can be many. The capstan or axis involved might not be perfectly round. The bearing idem. The system may not be perfectly lubricated. There may be dirt on tape guides, causing jerky tape motion (on a microscopic scale). Tape may not be slit evenly. Etc. etc. etc. There really are too many to mention here.

Remember: There is always wow and flutter. No mechanical system is without it. Realize that.

measuring wow and flutter

Now there I had a problem. To measure W&F you need a special device called a ‘wow and flutter meter’. Of course, you can rely on Philips that they had such a product back in the days. They did. It is this one:

But unfortunately I don’t own one. It is on my wanted list though. They are relatively rare, and sometimes expensive. If you have one, or one like this, and you would like to sell it to me, please let me know.

software to the recue

What to do now? Fortunately I found an interesting program on the web that is supposed to measure W&F. It’s called WFGUI. Here is a screenshot of the program in action:

That looks impressive, right? It can measure DIN 45507, wow < 6Hz, and flutter >6Hz. According to the documentation provided with the program it has been tested against some real life hardware W&F meters and the results were very very comparable. Good!

Now I had a different challenge with this program, as it runs on windows, and I only have Linux. But, I soon found out that it runs perfectly fine in Wine! Yeah!

You can select between the 2 most used frequencies in calibration: 3000 and 3150 Hz. (It also shows the measured frequency for your convenience.) Then there are 3 values to take notice of:

  1. RMS (%): this shows the root mean square value in % of the current measurement
  2. Peak: this shows the current peak in % using a nice needle display
  3. maximum value of RMS and Peak in % during the last 10 seconds
  4. and it also produces a nice waveform of the current fluctuation measurement (this is NOT the input or output sinewave)

Now, this is where it gets interesting. The program has different settings so it can measure different values. It can measure:

  1. DIN (Deutsche Industrie Norm), or more specifically DIN 45507
  2. wow: measure variations between 0,3 Hz and 6 Hz
  3. flutter: measure between 6 Hz and 200 Hz

Now I will not go into too much detail here, but take it from me that the DIN norm is a sort of average between the 2nd and 3rd setting, i.e. it takes a little bit of both. If you want to know more, you can read the documentation that comes with the program, that has some nice graphs that show it all. That will explain everything. For my measurements I used all three settings (DIN, wow and flutter), and I measured all 3 values (RMS, Peak and Max RMS)

calibration tape

The problem I had is that measuring these kinds of W&F is traditionally done with a tone of either 3000 or 3150 Hz. And, more specifically, you need a special (and expensive) speed calibration tape with that tone on it recorded in a very precise manner.
Guess what, I do not own such a tape. They are quite rare actually, although you can still buy them at MRLtapes.com I presume. My regular Bezugsband (German for calibration tape) has a 1kHz tone at the beginning, but that is used foor reference level measurements.

making my own test tape (huh?)

So I thought about it a bit and I knew I was never going to buy that special speed calibration tape (>€130). What if I took my trusted tone generator and used that to record and immediately playback a 3kHz tone? Of course that would be an imperfect recording, because it would contain W&F, but wasn’t that just what I wanted to measure? And if you play back that recording on the same deck, doesn’t that give a good indication of the performance of that deck? The more I thought about it, the more sound (pun intended!) the idea seemed to be.
Doing that would mean that I could not refer to a know calibrated source anymore. But I’m not interested in those figures. I can now compare the performance of my decks between themselves, see who stands out, either way.

Some people may argue that one can not make his or her own test tape. Of course that is true. But that is not the purpose. I want to measure the W&F of a deck. I was going to use the deck itself to record a tone and play it back at the same time.
Some may argue that that is not a good way to measure W&F. I disagree. I will explain.

When you record the test tone on the DUT (device under test), it wil will be recorded with wow and flutter. That is clear. So it will be an imperfect recording. So what. That is what I want to measure, so that seems ok to me. Let’s assume that the recorded tone will contain at the maximum an amount of W&F of n. If you would examine the tape in a laboratory you would find max n W&F. The DUT obviously has a W&F value of n. So at some points in time the value would be 0 (zero), at some points in time the value would be n (the max value) and most of the times some value in between. This will vary constantly, and it will vary very quickly.
Now I play back this tape on that same deck that has that W&F reading of max n. So again, some of the time that tape will play back with no W&F, and some of the time it will play back with the maximum value of n, and most of the time some value in between. The resulting W&F will be 2*n at the most, to be exact that would occur when a piece of the tape that was recorded at that moment with n W&F value will be played back at a moment that the deck plays back with a W&F value of n.

testing

So again I dragged all my decks to the test bench and hooked them up one by one. Now reading the values from the program proved to be quite a challenge, because the readings vary a lot and change very quickly. So i took a sort of ‘observed average’ , as I would call it.

I did the measurement all at 19 cm/s, because that is the common speed all my decks have. I have noted where I used an other speed, like 38 cm/s.

 So what are the first results?

  • the kind of tape used for the test has a great influence on the end result. At first, I used an older tape and got very different (much much worse) result that when I later used a brand new tape of the same type. This was kind of shocking!
  • tape speed has a great influence on the stability as well. All deck produce much better results on 38 cm/s than on 19 cm/s. A few quick test at 9,5 cm/s were even worse.
  • I did not find any difference when using the beginning, the middle or the end of the tape, but I have not tested that on every deck. I suppose if a deck has too much or too little tension, the position on the tape would matter

After a lot of testing I had a spreadsheet full of values that were very difficult to interpret. So I made a graph out of all the numbers and this is the end result:

This may seem overwhelming and confusing at first, but it really isn’t. Let me clarify for you.

  • On the X-axis (lower) you see the three different measuring methods for each deck: DIN, wow and flutter.
  • Each deck has an corresponding line in the graph for these 3 values.
  • Lower values (lower lines) are better.
  • Legend is on the right, showing which line corresponds to which deck. It is a bit crowded but bear with me.

Here are the conclusions:

  • the most upper line, meaning the worst deck, is the Teac A-3440 at both speeds. This is one of my oldest decks.
  • for fun I included one turntable, my Technics SL1900. That is the blue dotted line. I found that I had a test record with a 3kHz tone on it, so I could actually do the measurement. I was surprised to see that the values produced were in the same range as the tape decks. However, unlike all decks, the wow is the worse value of the three.
  • the best deck is the Studer A80 @ 38 cm/s. Of course, Studer was famous for their mechanics and always paid special attention to the tape path. Studer used the best available bearings and even had special lubricant that had to be used.
  • a very positive measurement is the Philips N7300, the light blue line in the lower part.
  • in general, the newer decks (Philips N7300, AKAI GX-77 and Teac X-2000R) are in the better part of the graph. Maybe it is because when they were manufactured, the W&F was better under control, or it is simply because they are fewer used.
  • the ReVox PR99 (also a Studer brand), the dark blue line, is giving the A80 a run for his money.
  • the results for the dual capstan decks that I have (Teac X7, X7-R, and X2000-R) are not as I expected. Yes, they are good, but they are beaten by single capstan decks. The whole idea of the dual-capstan system is that that would eliminate (well, minimize) W&F values. I think the system fails to deliver. And on top of that, it introduces a lot of unwanted negative side effects, that are most notable after all these years when the decks age.
    The result of playing in the reverse direction were mostly comparable to the forward direction, so no real diffrerence here.

There you have it. I hope you liked my article. If you have any comments, please leave them below.

-edit  31 may 2016-

I have recently purchased a ‘real’ wow and flutter meter, the B+K Precision wow and flutter meter 1035. 
I have used this meter to check some results from the softwareprogram above, and the results fortunately match. Great!

A80@19 RMS Peak max RMS
DIN 0,0225 0,04 0,0294
wow 0,013 0,019 0,0166
flutter 0,0406 0,029 0,0484
a80@38 RMS Peak max RMS
DIN 0,0093 0,019 0,0136
wow 0,007 0,01 0,009
flutter 0,0368 0,059 0,0398

Re-capping a vintage quadraphonic amplifier: JVC MCA-V7E (quadrophonic)

JVC MCA V7E closeup

For some reason I wanted to do a recap job of my vintage quadraphonic amplifier, the JVC MCA-V7E that you see above. This unit is actually in very good shape, so the reason for me to do this is also unclear to me, really! But sometimes my ways are inscrutable.

recap

A recap job means that you replace all the old, worn out electrolytic capacitors that are >40years old with new ones, preferably audio-grade types. Electrolytic capacitors are known to dry out when they get older. And then they lose their characteristics. Worst case is that they short out, or that they start acting as a coil or as a resistor. These are all things that you do not want in your amplifier. Or in any other device, for that matter. Also, the original caps were never the same quality as the ones that you can buy today just because manufacturing, tolerance and materials have become so much better in 40 years. So in theory this should enhance the performance of the unit.

Also, it is not a question if an electolytic caps will fail, but when. So after the recap your equipment will be good for at least another 40 years, but probably a whole lot longer.

Panasonic FC series

If you are gonna do it, you want to do it good. Then you go for the audio-grade caps.

These black caps are available at sometimes crazy prices of several euros a piece, but there is a very good capacitor at a very reasonable price. So all audio enthousiasts like me that do not have a money tree in the backyard use these FC series caps, as you will probably need a good bunch of them. In this case I used around 50-60 of them, but I have not counted them exactly.  I ordered them from farnell.nl  they have the complete range of values at good prices. The only problem is the minimum order amount of 50 euros.

The works

This is what the unit looked like before I started:

before

Basically all the grey capacitors that you see here had to be replaced. This consists of the Power Supply board, the tone/preamp board, the mainamp board, and the phono board which is located on the underside

I started with the PSU (power supply). These contained some big ones.

psu_done

PSU after

psu_before

PSU before

Note the difference in size. The new ones are a lot smaller. They have the same value nevertheless. After I had done the power supply, and the amplifier still worked (!!) 🙂 I tackled the phono board.

phono_before

phono before

And then the preamp.

tone_preamp_done2

premp done

tone_pre_before

preamp before

And then the main amp:

halfway2

halfway

amplifier_print_before

before

All_done2

all done

After all the works was done, it was time to turn the power on. Exiting! Nothing exploded and no component was getting very hot, so I connected an input signal on the four inputs and turned up the volume. Channel 3 was not working. Hmmm. I remembered a problem I had when removing the large capacitor from the third channel, when the copper strip had come loose from the board. On closer examination I saw that it indeed was not making contact properly anymore, so that was easily fixed. Now the 3rd channel worked ok!
The sound from the ‘new’ amplifier is very crisp, someone called it ‘clean’. I think that is an apt description. I turned the JVC up quite a bit, and experienced no problems. So I am very happy with that.

Testing & measuring

Next up is a bit of testing and especially measuring. Because I wanted to test some new type of transistors, I have installed them in the channel 2 pre-amp. I want to see how they stack up against the original ones. I am especially interested in distortion and overall performance. If they don’t perform well, I will re-install the old ones. Maybe the amp needs to be biased as well, but I’m not sure yet.
I also turned up the calibration on the meters quite a bit, so now the needles are showing signal even at normal volume levels, that was not so before. Previously they just lingered around in the left corner doing mostly nothing.

I have provided here a simple drawing of the electrolytics on both amplifier boards for your convenience, if you should decide to do the recapping as well. Good luck!

JVC_MCA_V7E_elcolayout_mainamp

JVC_MCA_V7E_elcolayout_preamp

Another Akai: GX-77

Today I picked up a mint condition Akai GX-77

3779855926_a41e21b91b_z

This photo is from the internet; I will upload a real photo later.

The unit does not work; the two pinch rollers won’t come down all the way and the tape loader roller in the middle is stuck at the top so I will have to fix that. The middle roller is necessary for tape loading and unloading.

auto reverse

This unit is a real beauty. It is an auto-reverse deck, and is capable of playback AND recording in both directions. Therefore it has 6 heads and two capstans. The capstans are always spinning, in opposite directions and only the pinch roller associated with the current playing direction is engaged. The result of this is that switching tape direction takes only 0,4 seconds.

other features and specs

  • It has user adjustable bias through a dial on the front
  • capable of using EE tape (chrome)
  • L+R recording level knobs have a 3rd ‘master’ knob which controls both channels
  • output level is adjustable from the front
  • digital tape counter with optional backup adapter

Here are the full specs:

  • Track system: auto reverse, 4-track, 2-channel, stereo system
  • Heads: 2 x GX record, 2 x GX playback, 2 x erase
  • Motor:
    • 1x FG servo direct-current capstan motor
    • 2x direct-current reel motor
  • Reel size: up to 7 inch reel
  • Tape speeds: 3 3⁄4 7 1⁄2 ips
  • Wow and flutter: 0.03% (7 1⁄2 ips)
  • Fast forward rewinding time: About 80 seconds
  • Frequency response:
    • 25Hz to 33kHz ±3dB (19 cm/s) 
    • 25Hz to 25kHz ±3dB (9.5 cm/s)
  • Signal to Noise Ratio: 63dB
  • Total harmonic distortion: 0.5%
  • Input: 70mV (line), 2mV (DIN)
  • Output: 0.775V (line), 0.3V (DIN)
  • Dimensions: 440 x 244 x 227mm
  • Weight: 17kg
  • Power consumption: 28W

work begins

The first thing I did after opening up the unit was checking the belts. It has three: one capstan belt and two for the spooling motors. The capstan belt was ok, it was still feeling like it should, but it was probably a little stretched because it didn’t feel very tight to me. I ordered a new set which included the 2 spool motor belts for €12,-

Once I had the belts replaced, it still would not engage the middle roller. It is supposed to go up and down.

akai gx-77 with the roller stuck in top position

akai gx-77 with the roller stuck in top position

Searching on the internet I found that there is a large white gear wheel located behind the 2 flywheels which controls the up/down movement of the roller. When I manually engaged this wheel, everything worked. Tape was loading fine. But I had to help it every time. So what could cause this?

old dried out grease

The answer is: old grease. Old grease is grease that, over the course of 35+ years, has started to dry out and instead of lubricating, it starts clogging things. So I had to take the unit further apart to the point where every gear wheel is removed and cleaned.

gear

gear

akai gx-77 plunger arm dried out grease

akai gx-77 plunger arm dried out grease

This plunger arm was very slow returning to it’s default position and probably missed the next turn when the hook had to engage. So I fixed that.

Also the right flywheel (as seen from the back) has a gear on it. This was also very loose on the spindle and could be turned quite easy. I put it in a ultrasonic bath and tried to clean it with IPA. Now it moves a lot rougher.

flywheel with gear

So after almost completely removing all moving parts and cleaning and re-lubing them I carefully put the unit back together to try a cautious test. Here is the result:

As you can see the unit works smoothly now. At the moment the deck is still mostly disassembled but I will put it back together again and then start the mechanical adjustments and followed by the electrical calibration.

Akai gx-77 weer in elkaar

As you can see the beauty is put together again and is recording and playing like new. Very happy with it!

A Quadraphonic 8-track player: National Panasonic RS-845us

The JVC, my first 8-track

jvc ed-1240     IMG_20141125_161052

I possess one JVC 8-track player, the JVC ED-1240, a very nice and featureful deck.

The main reason I am interested into the 8-track world is, of course, the fact that aside from 4 track reel to reel tape, this is the only format that has discrete quadraphonic. I realise that the quality of the sound is not up to par like the Studer, or even a normal tape deck, but it will have to do 🙂

The first time I heard this 8-track deck i was very disappointed with the sound. So I found myself a challenge at hand. I have cleaned it, repaired it, refurbished the motor, changed the belt, demagnetized it, changed all the caps on the power board etc. etc. and eventually it performs quite well.teaser

tapes

I cleaned and repadded the 8-track cassettes that I have. I even found it necessary to lube the inside axis a little bit to prevent squeaking and to lower the rumbling and the mechanical noises from the cassettes while playing. The end result is quite pleasing I must say.

But there are still some issues with the player, so if anyone has the schematics, or the service manual, please contact me!

Quadraphonic 8-track

But this post is not about this deck. The JVC is just stereo. This post is about a new one I just bought. A few weeks ago I ran, quite to my surprise, into a quadraphonic 8-track player from National Panasonic, the RS-845us.

Here it can be seen on top of my JVC. At the moment the picture was taken, it was playing a quad tape as you can see by the ‘4 channel’ indicator light. In this mode there are only 2 programs, not 4 as you would find with a stereo tape.

problems ahead

But, alas, this player also came with its problems. I tested it before I bought it, and it was ok as far as I could test it at the time. Coming home, when I could test it for a longer period, I found the same issues I had with the JVC, like irregular tape speed etc. Also the sound was not as good as I was used to from the JVC.

So I did my usual fixup things, like cleaning everything, oiling etc. No good. I quickly found out that the voltage over the motor was dropping several volts at times. I suspected the power circuit board. So i tested the diodes, they were ok. I tested the caps and replaced them all nevertheless, although they were not really out of spec. Unfortunately, that did not help much. New belt. There was some improvement, yes. But still the voltage drop at times, from 12-13V all the way down to 6-7V. The motor would almost stop turning then. And it would squeak a lot.

motor fix

The solution would be to open up the motor and fix it there. That is always a bit tricky but I did it before and I therefore have some experience with the procedure. It went surprisingly well. There was some dust (powder) from the magnets and from carbon brushes. I also scraped clear the spaces between the 3 parts of the rotor (I think it’s called) so there would not be any more shortage. I reassembled a clean motor and lubricated it. When I tested it it it ran very smooth and silent. Cool! The tape speed is also a lot more constant than before. Also the sound seems to have some more punch to it. Maybe it has to do with improved tape-head contact, or with a more stable power supply to the audio board due to the changed caps.

audio fix

But I also have the capacitors ready for a complete overhaul of the audio prints. So somewhere in the next few days I hope I will find time to replace them and see if that will fix the muffled sound. I don’t expect a lot from that action, but hey, that’s what this hobby is all about.

[Update:]

Yesterday I did the recapping of one of the 2 audioprints, i.e. the print for the front channels. This is the result:

When I tested the audio after the process, I found that there was very little, if any at all, change in sound quality. I had made a ‘before’ recording so I could compare the sound.

So I am a little disappointed about that, but I guess the 8-track format was never intended for good audio quality, At least I didn’t break it. 🙂

So while I have all the caps here to replace the rear print also, I will not do that; too much trouble for little or no result…..

Anyway the unit is reassembled now and it playing happily.

Studer A80-R

So, the inevitable has happened.
I have bought a Studer A80-R.

Studer A80

Studer A80

Studio

This is a beast. The unit is 70x60x84 cm, and is the size of a washing machine. And it weighs around 100kg. That is even heavier than a washing machine. It has wheels though. So you can roll it around.
This is the studio recorder that the artists from the seventies used to record their material on. It came in several configurations, from 1/8” (cassette tape) to 2” (24 track). Mine is the A80-R (for ‘rundfunk’ i think) 1/4” 2 track, speeds 7½ and 15 IPS (19 & 38 cm/s). Every studio in the world had one, or several. The most prominent artists that used the Studer A80 are Pink Floyd, Alan Parsons, etc.
I came in contact with someone who has access to professional studio equipment and repairs them on a regular basis, often in his spare time. Sometimes studios get rid of these machines that are in the way, and then he takes them in and repairs and refurbishes them.
I have visited him to look at the machine that I would buy and the second time I went there, the machine was all done and I took it home. Which was not a simple task. It fitted the back of my car fortunately.
After I got it home I wheeled it inside, where it would stay in the living room for the time being. It was simply impossible to get it upstairs.

Here is a short clip:

Challenges

The Studer gave me some challenges. First, the inputs and outputs are the balanced XLR type. I already have adapters to/from RCA which I used for my Revox PR99, but the problem is the line level. My other equipment is home use stuff, so it’s line level is -10dBV. The Studer, being a professional piece of equipment, uses +4dBu. This box fixes the level conversion and the physical connections.

xlr-rca lveveller
Second, the Studer was simply too heavy to carry up the stairs to the first floor where my audio room is. So it sat in the living room, happily enjoying the family life. And, between you and me, it sounds so good in the room.

Caps

Unfortunately, after a few weeks, the left motor, the supply motor, was giving problems because the tension was not there in play. Also, rewind was not possible anymore. A search on the net and my supplier both revealed that on the board 1.080.383 there are 2 transistors that control the 2 motors.P1010315

They are BC141-16 with heatsink on them. On my deck the one for the supply (left) motor was broken. I replaced him twice, but that was not the cause of the problem. The problem was elsewhere. The transistor blows as a result of that other problem.
Further investigation revealed that there could be problems with the tension potmeters that control the tape tension (the A80 has a sophisticated tension control system) or with the motor capacitors that could be faulty after 30+ years. I tested the potentiometer and I could not find anything wrong with it. So I removed and tested all the motor caps (9 pcs.) and found they were not entirely up to spec anymore.

A80 rear - motor caps

A80 rear – motor caps

I replaced them all, and installed a new BC141 just tot be sure. And so far, it works flawlessly again. Fingers crossed.

mechanical calibration

So now that all the caps were replaced, i though that the tape tension was a bit off. So i grabbed the service manual and started the mechanical calibration of the deck. This involves setting the (emergency) brakes, the tape path, the capstan pinch roller, and of course the tape tension and edit mode characteristics back to the desired specification. I have bought spring scales just for this! It was fun to do and the end result is here:

Heavyweight

So I had a Studer A80 in my living room. Now who can say that? It was always clear that it would have to be moved to the upstairs room eventually. When my brother-in-law heard about my problem, he thought it would be a challenge to get it upstairs. So one day he showed up on my doorstep. Long story short, an hour later it was done. Actually, it took almost an hour to do the preparations like attaching the rope appropriately (and carefully!), and it took just 10 seconds to go from the bottom of the stairs to the top of the stairs! So now it has reached its final destination, my “audio room”.

Testing

Being hooked up to some good sounding equipment, my trusty Technics amp and my new KEF Q700 speakers, and using my Philips SACD player as source, I made test recordings and played them back. My tape of choice was BASF 911 and SM900. The results were nothing short of spectacular! The level of OEMPF that his recorder is able to put on tape is astounding! And, those of you who are familiar with analog recording equipment will know that there is always noise (tape noise, vinyl groove noise, FM-noise, cassettes!) when working with these machines. Not so with the Studer! It is so quiet! And that is a piece of equipment that was made around 1970. Incredible.

I am still enjoying this beast. I am tempted to do the technical calibration as well to calibrate it for BASF 911 or 900, but it sounds so good already i’m not sure it would get much better, and there is always the risk of f***ing it up. So for now, i think I’m good.

A Quadraphonic Akai 1730D-SS

My new addition to the collection is already a few months old, but here is the blogpost anyway.

It is an AKAI 1730D-SS Quadraphonic tape deck that I received from the first owner.

[picture shamelessly stolen from the internet]

When picking it up I tested the deck and only 2 of the 4 channels worked. Only the REAR. Strange. And one of those 2 channels failed intermittently.  When I got home I opened up the deck and had a look at it. I put on one of the many quadraphonic tapes that came with the deck. Quickly I found out that cleaning and fixing the 2ch-4ch switch solved that problem. That was easy.

But the FRONT channels still did not work. At all. No sound, no noise, no click when the deck was powered up, no nothing. I sure hope the playback amp hasn’t died. It appeared there are 4 audioprints in the machine, see picture. At the left of the picture you see the 2 playback prints, at the right the record prints. Each print is stereo. FRONT at the top, REAR at the bottom.


[picture showing the 2 right audio prints removed from their slots]

By turning the pot on the prints I found out wich print was unresponsive (I am going to recalibrate it anyway, so that did not matter). I took it out of its slot for further inspection.



Unfortunately I could not find anything wrong with the print or the components. No burned components, fused caps, burn marks, loose contacts, nothing. I was beginning to feel that I was reaching the end of my knowledge because I have not got expert knowledge of electronics.

When I was going to put the print back into its slot, I noticed something odd about the slot. The slot is a kind of very crude ISA-style slot type, like in the first IBM PC. I saw that the plastic of the slot was broken! That caused the print to not make good contact with the pins in the slot. See the pictures.





When I carefully with my hand pressed the slot so that the print made contact, everything started working! Eureka! ‘There, I found it.’ 

Now how to fix it. Glueing was no option. I soon thought of a tight tie-wrap, that might do the trick. I pulled the tie-wrap as tight as I could. See the pictures.



Then came the next issue. The deck did not want to record at all. I soon found out that the other slots were damaged too (duh). So another set of tie-wraps to the rescue. I put tie-wraps around everything and reconnected it all.

It worked ok, but not reliable. Even when just looking at the recorderprints weird effects on the signal were noticable. First I doubted my tie-wraps, but that solution DID work reliably at the playback prints. Just to be sure I sanded the contacts on the prints and voilá: everything worked flawlessly! So I put the print in and secured them thoroughly. ‘There, I fixed it again’

This is a machine from the early seventies, that has been idle for who knows how long, and I’m surprised at the audio quality.

Now I need to demag it, and calibrate it. Then it will probably sound even better!

[edit]
Although it sounded good at first hearing, further test revealed there was noise in the left front channel ,even when it was not playing. Same on the right rear.

So I replaced the 2sc458 transistors on all the audio prints. After that, I eagerly turned on the machine.

No signal at all!

Remember that I am only doing this as a hobby, I am not a professional guy and I know very little about electronics.

Searching and searching and searching again I found out that the new transistors I had ordered, had a different pin-out than the ones that came of the print. I had put the new ones in with the same orientation as the old ones, that seemed logical but that was incorrect. :) They simply needed to be turned around, so that was relatively simple. I did not need to cross their legs.

After that it worked again, fortunately! Apparently these guys can withstand some rough handling haha. And the best part is, that the deck is silent again now, the noise is gone. I recalibrated it and it sound great!

A problematic Teac X-2000R

2014-03-31 18.59.39

Recently I obtained, for a fair price, a Teac X-2000R. It is a stereo reverse deck, with 6 heads, which means it will record also in reverse. It has dbx built-in, and it can use (chromium) EE tape. A digital counter in hours, minutes and seconds and bias fine tuning on the front panel is also provided. It has 9,5 and 19 cm/s speeds.

Dual capstan

Another prominent feature that is has, however proved to be a very problematic one. The deck is equipped with 2 capstans. This feature was introduced into the later tape deck models, almost towoards the end of the tapedeck-era, to further improve tape-head contact and wow&flutter. These assumptions are correct, and they work well when the deck is in new condition and everything is well calibrated and up to specifications.

On this deck however, things were not new and not up to specs. The dual capstan design is a challenge in itself, but things are further complicated by the fact that it has to function in reverse as well. On this unit that is accomplished by a belt that ‘travels’ across different parts of the flywheel that varies in diameter.

Problems

After the initial cleaning, optical and technical/mechanical, it soon became apparent that the tape handling was not up to par. Sometimes the tape would ‘run away’ from the heads a bit, resulting in loss of audio or worse: tape jam. Things were even worse when playing in reverse. I soon found out (through the service manual) that there were adjustments to be made to the tape tension.

Tape tension

But the increased tape tension was not the solution. When it was ok in forward play, it was bad in reverse. Or vice versa. Or it differed when loading large reels (26 cm) compared to 18 cm reels. Or it was different with different brands of tape. And that wasn’t even reproducible across sessions. And the next day it would be different again.

Solution

Of course the first thing I did was to change the belt. I have a blog of that action, but it is in dutch. So here it is, sorry only in dutch:

====== BEGIN OF DUTCH TEXT ======

Nou, de siem-snaar was snel binnen, en vanochtend was het toch regenachtig, dus aan de slag gegaan met het vervangen van de Teac X-2000R snaar.

Ik heb de uitbouw gedaan volgens de foto’s in deze thread, daar heb ik heel veel aan gehad:

http://www.audiokarma.org/forums/showthread.php?t=59729


Daar wordt behandeld een X-1000R, en die blijkt toch niet helemaal hetzelfde van binnen. Ik kwam meteen al een grote print tegen die in de weg zat, deze is er niet in een X-1000.
Hierdoor kon ik niet bij de bovenste schroeven komen van de plaat waar de capstanmotor op vast zit. De print moest dus los en daarna omhoog gelift worden, er zitten helaas te veel kabels aan vast om hem compleet uit de weg te krijgen.







Na wat kabelbomen losgeknipt te hebben, kon ik de print opbeuren en omhooghouden met een plakbandrol.





Hierna kon ik er wel goed bij.





Nog even de plaat losknippen van de motor zelf:



Er zitten alsnog wat kabels in de weg, maar die zitten gelukkig vast met connectoren. Loshalen die hap dus.





Eindelijk uitgebouwd. De 2 vliegwielen in de achtergrond:



De 2 vliegwielen verwijderen. Goed links en rechts uit elkaar houden.



Overigens viel me meteen op het grote verschil tussen de snaren: de oude is een stuk langer dan de nieuwe. Dus of de oude was wat uitgerekt, ondanks dat het rubber nog vers aanvoelde, of de nieuwe is ietsje te krap. Of allebei.

Toen heb ik alles losgehaald en schoongemaakt en opnieuw gesmeerd: de vliegwielen, de aandrukrollen en het aandruk mechanisme. Oud vet verwijderd, nieuw vet er op. 

Alles zeer grondig schoongemaakt. Vliegwielen er weer op, meteen de washers aan de voorkant weer over de capstans gedaan. Nieuwe snaar er op:



En toen alles in omgekeerde volgorde weer vast. Het was een beetje pielen om de snaar weer over de motor te krijgen, maar het ging uiteindelijk wel. Als laatste de print weer laten zakken en vastgezet.

====== END OF DUTCH TEXT ======

Unfortunately this was not the solution that fixed it completely, although the situation improved a bit. Even increasing the tape tension to incredible heights (or incredible lows) did not fix it. So I went online to find a solution.

Several fora messages suggested that everything in the tape path was relevant to my problem. From tape guides, to the rubber idle rollers, to lubrication of the tension rollers, to the state of the rubber of the pinch rollers. From the tape tension to the smoothness of the tape in question. It seems that everything was related to weather the dual capstan principle would function correctly.
So I soaked the pinch rollers in detergent for one night. The rubber was much softer and grippier after that treatment. Again, a little improvement, but no permanent fix.
I switched the pinch rollers from left to right, to see if that would improve the situation. No way.
I lubricated all the moving parts, I installed the little O-rings that were required for the rollers to function correctly (expensive little buggers!). Still there was no definitive solution that worked all the time.

Meeting

In April I went to a meeting of fellow tape deck enthusiasts where there was an opportunity to work on decks. I tagged the deck along, and fortunately there was an expert who was willing to take a look at the Teac. Immediately he found one problem: I had put the tape tension way too high. We measured more than 100 gr. when 50 was required. He used a Tentelometer, a very rare instrument which he posesses. It looks like this:

After we adjusted the tension to 50 grams, the tape handling was still not good. In fact, it was worse. Then, the guy helping me thought the problem might be in the capstan motor, of which the carbon brushes would have degraded over the years resulting in less powerful drive. So, on the fly he opened the capstan motor, removed the old brushes and (he had them available) installed new ones.20140412_145008 20140412_144659After this, still no good. But I had new carbon brushes! Jeey!

At the meeting we came to the conclusion that maybe the new belt I had put in was not an original Teac spare part but a fake. So I went to an official Teac repair center and got myself an original Teac approved belt. After I installed that belt, still not any better. Grrrr.

The solution!

Eventually, as a sort of last resort, I took the Service Manual and went through all the mechanical adjustments mentioned there. Some I could do, some I couldn’t. For instance, I haven’t got a spring scale necessary to measure torque. And then, finally, after I adjusted the pinch roller pressure to a much lower value, it suddenly all seemed to come together.
When I adjusted for a very, very low pressure of the pinch rollers on the capstans, even to the extend that I could very easily stop the tape when playing, the tape would indeed run fine along the heads and reverse play was no problem. So I adjusted for a little more pressure but anyway now it works great and I haven’t got any more tape issues.

Great sound

After that, I planned to calibrate the deck. This also proved to be not as easy as I thought. The service manual mentions a lot of steps and I think I did them all 4 or 5 times. The problem was that the record calibration required EE or Chrome tape, which I did not have. Fortunately I could borrow a Maxell XLII tape from a friend.
Bu after I calibrated the deck using the EE tape, it did not sound good. The level was way too low. And when I recorded at a higher level, the amount of distortion was unbearable. Something was not right here. After advice given to me on my favorite forum, I used normal tape to do the calibration. It still wasn’t to my expectation. I’m not sure what fixed it, but I repeated the calibration procedure several times, and after that I found the recording to be very good!

EE (chrome) tape

So the deck was performing as it should, reversing as it should, handling tape as it should and now I was to test it with EE tape and with the dbx noise reduction and dynamic expander on.
The result was, well, as close tot the original sound as you can hope for. The high tones were beautiful, and the sound was quiet as a CD. Out of nowhere the music starts. This is tape technology at it’s finest. I am very happy with my new tape deck.

Installing new Ortofon 2m red cartridge in the Technics SL-1900

Yesterday I received my new cartridge: the Ortofon 2m red. It came with a brush, some screws and a little screwdriver. All in the package for €84,-

2M Red Verso hifisiteI couldn’t wait for a day off to try it so I installed it yesterday evening. I have never before installed a cartridge, and I must admit the thought of doing so was a bit daunting.

I had read a lot about installing and adjusting phono cartridges in the past few weeks so I understood the basics. I had downloaded the Technics protractor from vinylengine.com, printed it and checked the scale of the print. But now it was time to put the theory into practice.

headshell_old

My old-style head shell

I soon realized that this new cartridge wouldn’t fit in the headshell I had designated for it. This is an old style Technics head shell with one screw on the top.

Although only one screw is visible in the picture, it has an additional mounting bracket underneath that should fit the 2 screws necessary to mount normal cartridges. But my Ortofon needs to have the heads of the screws on the topside and that is not supported in this headshell.

But fortunately I have two headshells, the other one is the newer type which has the normal two screwholes at the top. Using the screws which were provided in the package I was able to quickly attach the cartridge provisionally to the headshell.

 

new style headshell

new style headshell

So that was fairly easy. Next was the task of adjusting the ‘contraption’ 😀 I took my protractor and put it on the turntable on top of a record.

I soon learned that when I moved the cartridge all the way to the front of the shell that the needle followed the ‘arc’ on the protractor perfectly. Yes!

IMG_20131219_212926

using the protractor

But when I tested the alignment of the cartridge on the two gridline patterns on the protractor, I found that it was not perfect in line. So I adjusted it very slightly to the point that it was in line on both patterns and then secured the screws. Pfew! Job done!

 

 

yes-90125

Yes – 90125

 

Then came the testing. I must admit I was a little but afraid, or better anxious. I tried it out with a record from Yes – 90125.

I put the needle down very very carefully.

I put on my headphones.

But as soon as the first tones from the song (Owner Of A Lonely Heart) were played, I relaxed. It sounded very very good!

IMG_20131219_212756

The Ortofon happily playing in my sl-1900

There is a lot of definition in the sound. There is also a lot of ‘punch’, which I like. HF tones are also ok. Bass is tight and well defined. Overall, I have never ever heard a record sound so clear. True, in the past I have not had good quality turntables. In fact, they were rubbish. But I never thought a record could sound like this. It is so close to a CD. I’m also very glad that I treated my records carefully in the past, I didn’t play them a lot (I immediately recorded them onto tape) so that I now have old, but ‘like new’ records that sound wonderful!

I continued to listen to albums from ELO, Marillion, Tchaikovsky and 12-inch’s from Chaka Khan, Unique (What I Got IS What You Need). Those were the first records I found for grabs. It was a good experience. I am pleased. In the coming evenings I will listen to some other albums.

I was surprised how quickly and how easily an inexperienced person like myself could do this task. It took me a little over an hour including the adjustments. I can recommend it to everyone.

Coming up next: cleaning the records with a LP cleaner

New arrival: Technics SL-1900 turntable

This week I picked up a Technics SL-1900 turntable

1900

Technics SL-1900 (image borrowed from internet)

I was actually looking for a more high end model, like the Technics SL-1600Mk2, SL-1700Mk2, 1800Mk2 or even an SL-5300. But, those are hard to find, and when found, are very expensive and could cost more than €200,-. I found a very inexpensive SL-1900. It still had the original Technics 270 cartridge installed. And it came with an additional 270 cartridge without a needle. So I thought ‘oh, what the heck’, and I went to get it.

I was not disappointed. Not at all. In fact, I was very impressed. For the last years I have used a Dual cs-607, so that was my reference. And although the Dual has more definition, this one is more agreeable to listen to because….well, it has less definition. It doesn’t reveal all the noises and scratches and clicks and pops from the record so much as the Dual does. Compared to the Dual it lacks highs though.

UPDATE:

Please read the next post on how I installed an Ortofon Red cartridge in this turntable. https://www.reeltoreel.nl/blog/?p=364

Some information from internet:

Description

The Technics SL-1900 is a 2-speed, direct-drive turntable with fully automatic single disc playback. A one-chip IC, incorporating 321 elements, controls motor speed for superb accuracy with servo control. The tonearm mechanism gives convenient automatic set-down, lift-off and stop. Memo-repeat control permits up to six repeated plays of the record, or continuous play. The heavy monolithic bas and isolator system protects against external vibrations. The SL-1900 comes complete with an EPC-270C-II moving magnet phono cartridge.

Some specs:

  • Brand: Technics
  • Model: SL-1900
  • Manufacturing year: 1977
  • Made in: Japan
  • Colour: Braun
  • Power: 4,5 Watt
  • Dimensions: 137 x 430 x 334mm
  • Weight: 7,2 kg
  • Original price ca.: $400,-
  • Direct Drive
  • Fully automatic operation
  • Platter: 310mm aluminium diecast
  • Speeds: 33 and 45rpm
  • Wow and flutter: 0.03% WRMS
  • Rumble: -73dB
  • Tonearm: universal, static balanced
  • Effective length: 230mm
  • Overhang: 15mm

und auf Deutsch:

Technische Daten

  • Antrieb: Direktantrieb
  • Motor: Gegenelektromotorische-Kraftfrequenz-Generator Servo Gleichstrommotor
  • Drehzahl: 33 1/3 und 45 U/min
  • Gleichlaufschwankungen: 0,03% WRMS (JIS C5521), ±0,042% bewertet Null-zu-Spitze (DIN 45507)
  • Rumpelgeräuschabstand:
    • DIN 45539A: 50 dB
    • DIN 45539B: 73 dB
  • Plattenteller: Aluminium-Spritzguss, 310 mm
  • Betriebsart: Automatisch oder manuell
  • Pitch: ±5%
  • Tonarm: Rohrarm, statisch balanciert
    • Nadelauflage: 0 – 3 g
    • effektive Achslänge: 230 mm
    • Überhang: 15 mm
    • Kröpfungswinkel: 21,5°
    • Reibung: 7mg (horizontal und vertikal)
    • Spurfehlwinkel: Innerhalb + 3 (145mm vom Mittelpunkt), + 1 (55mm von Mittelpunkt)
    • Gewichtsbereich für Tonabnehmer: 5,5 – 9,5 g
    • Gewicht des Tonarmkopfes: 9,5 g
  • Tonabnehmer: Technics EPC-270 C-II (MM)

Besondere Ausstattungen

  • Aufsetztpunkt: Einstellbar für 12″,10″ und 7″ Schallplatten
  • Memo-Repeat: wiederholtes Abspielen von ein- bis sechsmal, oder dauernd wiederholendes Abspielen einstellbar
  • Schwergewichts-design: Schweres Polymer-Unterchassis auf Viscoelastisch gedämpften Stahlfedern
  • Motor-Rotor ist direkt mit dem Plattenteller verbunden (war damals von Technics entwickelt worden)
  • Elektronisch gesteuert mit damals revolutionärem One-Chip-IC AN 630
  • hochempfindlicher Tonarm mit Kardan-Aufhängung in Präzisionszapfenlagern. Damals ebenso aussergewöhnlich.
  • Viscogedämpfte Tonarmsteuerung und Anti-skating – damals ein Novum ebenso wie die dicken, kapazitätsarmen Phonokabel.

Information about the cartidge:

Allgemein

  • Hersteller: Technics
  • Modell: EPC-270C-II
  • Baujahre: zum 1976
  • Hergestellt in:
  • Farbe:
  • Gewicht: 6,0 g
  • Neupreis ca.:

Technische Daten

  • Prinzip: MM
  • Frequenzgang: 20 – 15.000 Hz (±2 dB)
  • Kanaltrennung:
  • Kanalbalance: 2 dB (1 kHz)
  • Übersprechdämpfung: 25 dB (1 kHz), 20 dB (10 kHz)
  • Ausgansspannung:
    • 1 kHz, Höchstamplitude: 3,2 mV
    • DIN 45500: 6,4 mV
  • Abschlusswiderstand: 47 kOhm – 100 kOhm
  • Induktion:
  • Nadeltyp: Diamant elliptisch
  • Empfohlene Auflagekraft: 1,75 ±0,25 g
  • Nadelnachgiebigkeit: 12x 10^-6 cm/dyn