Subject: Degaussing, erasing and magnetism
Date: Tue, 27 Aug 1996 11:58:42 -0500 (CDT)
Degaussing, Erasing and Magnetism
---------------------------------
A lot of folks have asked about degaussing (erasing) media and
particularly DAT tapes, so here's some info you might find helpful.
Gauss: A unit of measurement of magnetic flux density produced by a
magnetic force (coils). Gauss is a measurement of coil strength.
Oersted: A unit of magnetic intensity of a magnetic field in a vacuum.
Oersted is a measurement applied to media. A 4mm DAT tape
has a magnetic field strength of approximately 1500 oersteds.
Coercivity: The amount of applied magnetic field (of opposite polarity)
required to reduce magnetic induction to zero. The ease or
difficulty by which magnetic media can be de-magnetized.
A 4mm DAT tape is a high coercivity tape.
So:
1.) The higher the oersted rating, the more energy needed to *properly*
demagnetize it.
2.) In order to degauss (erase) a magnetic tape, a magnetic force (gauss)
of 2 2/3 to 5 times greater than that of the media to be degaussed
must be created. In other words to demagnetize a media of a given
oersted rating, it will take 2 2/3 to 5 times the amount of energy.
3.) A 1500 oersted tape would need a magnetic field strength in the
neighborhood of at least 3000 gauss in order to *properly* erase it.
Hope this helps and thanks to David Partridge for his input.
There is a hand held DAT degausser available, with an oersted rating of
2800, that lists for $169. Please give a call at 800-321-5738 if you are
interested.
Art
* Cassette House
* e-mail:artmuns@tape.com
* DAT tape - CDR's - Cassettes
* web page http://www.tape.com/ch
* 800-321-5738 "I will use no track before its time"
(INFO FROM: DAT Digest)
==================================
Radio Shack's High Power Gauss Field is 800 oersteds.
Specs
==================================
So as you can see, degaussing DV tapes can be done with the
right equipment. Let's see...to erase a DV tape of
1700 Oersteds I need a degausser that can handle 3400 Oersteds.
Hmmm, The Radio Shack High Power Bulk Tape Eraser handles 800 Oersteds.
No wonder it didn't work.
```
# SOX audio examples
# THX-like sound
`play -q -n synth sq F2 sq C3 remix - fade 0 5 .1 norm -4 bend 0.5,2477,3 fade 0 5 0.8`
# white noise
`play -n -c1 synth whitenoise lowpass -1 120 lowpass -1 120 lowpass -1 120 gain +14`
# play keys piano asdfghj
`n=CDEFGAB;l=asdfghj;while read -n1 k;do x=$(tr $l $n<<<$k);play -qn synth pl ${x}3 fade 0 .7 & done`
# warble sound
`play -n synth sq C trim 0 4 vol 0.2 chorus 1 1 21 1 4 10 -s bend 0,2400,4 fade 0.1 4 2`
# convert bitrate
`sox "02 It's Time.flac" -b 16 -r 44.1k "02 It's Time 44100.flac"`
converts from 48000 to 44100
# Doormeten van een transistor
het testen van een transistor is vrij eenvoudig:
je zet je multimeter op het diode teken,
daarna pak je de plus pool, rode draad van je multimeter en je zet deze op de basis van de transistor,
tussen basis en emitter en tussen basis en collector meet je nu de spanning van de PN overgang,(+-0.6v)
draai de klemmen om en je mag geen spanning meten,
tussen collector en emmitter mag je nooit spanning meten
met + aan de basis heb je met een NPN te doen, met de min aan de basis heb je met een PNP te doen....
of nog makkelijker, neem er een waarvan je weet welke type het is en doe de bovenstaande test...
als je weet dat je transistor goed is kan je de versterking meten door hem correct aan te sluiten aan de drie puntjes van je multimeter, je krijg normaal maar op 1 manier een correcte waarde..
# Dolby NR
Q. What is different about the varieties of Dolby noise reduction?
By Hugh Robjohns
I never did quite understand the subtle differences between all the different variants of Dolby — A, B, C, HX and SR. Could you explain them to me? Are there any others I've missed? What are Dolby Labs doing these days? I guess they've undergone some 'reduction' themselves...
Technical Editor Hugh Robjohns replies:
**Dolby A** was the first professional noise-reduction system — launched in 1967 if memory serves — and it used four separate frequency processing bands. You can think of them crudely as bass, mid-range, treble and high treble, with the top two overlapping so that the 'hiss region' was processed more heavily than the rest. Avoiding line-up errors between encoding and decoding was crucial, so the infamous Dolby warble tone was used to identify encoded tapes and to allow accurate replay alignment. Dolby A was originally used to get respectable audio performance out of early professional video recorders, but was later adopted for multitrack recording and cinema optical soundtracks.
**Dolby B** was a very simple domestic system intended to improve the performance of compact cassette recorders. It was also used on some later domestic quarter-inch machines. Dolby B was a single-band system affecting only the high end, with very modest compansion. It had no facility, or indeed any practical need, for replay alignment.
**Dolby C** was a much more aggressive multi-band version originally intended for small-format professional video-tape systems and narrow-gauge semi-professional studio multitrack recorders. It was very sensitive to mistracking, but was unfortunately designed without any line-up tone facility to calibrate playback levels.
In the professional market, Dolby A was superseded by **Dolby SR**, which was Dolby's most sophisticated multi-band noise reduction system. This employed 10 bands altogether, some operating at fixed frequencies and others moving automatically to suit the material, and allowed the user to achieve a signal-to-noise ratio of around 90dB from analogue tape. However, although it was a very clever and effective system it arrived just a few years too late and the digital revolution effectively eclipsed it. Dolby SR used a modulated noise signal for identification and replay alignment.
Finally, **Dolby S** (one you missed off your list) was a last-ditch attempt aimed at semi-pro and domestic recorders, and was a halfway house between Dolby SR and Dolby C. It still had no built-in line-up facility, though. It was used on some semi-pro narrow-gauge multitrackers and the last of the high-end hi-fi cassette recorders.
**Dolby HX** is not a noise-reduction system at all — it is a clever system to avoid over-biasing on analogue tape machines using high-output tapes. This system was used on some high-end domestic cassette recorders and the last of the professional analogue two-track machines, such as the Studer A807. Dolby HX is a once-only process that needs no decoding. In essence, it reduces the bias level if there is a lot of high-frequency content in the audio signal, thus preventing over-biasing and the noise artefacts and frequency-response errors that go with it.
Dolby Labs still make Dolby SR and A systems for analogue multitrack and cinema applications, and I guess they are still collecting licensing revenues from the other systems when they are used on domestic cassette recorders and the like. However, most of the company's efforts these days are geared towards digital data-reduction systems, which are based entirely on the frequency-masking principles first exploited by Dolby's analogue noise-reduction systems. That is why Dolby AC3 has always been amongst the best of the data-reduction codecs for a given data rate — the company had a major head start on the rest of the field.
# BASF tape formulas
```
Type IV - metal pigment (MP) [or metal evaporated (ME) tape whose extremely thin coating rendered it poor for analogue audio recording]. TDK made the official IEC reference tape. The pigment is such a small crystal that it can oxidize extremely quickly, enough to cause spontaneous combustion or explosions at any point in the milling/coating operation unless extreme precautions are taken, such as submersion in alcohol and a nitrogen-based environment. The particles were passivated with molecules of oxygen around the metal crystal to stabilize them because early metal tapes oxidized and lost magnetic properties. There were other experiments to modify the crystals with other metallic alloys either to enhance magnetic properties or to stabilize the crystals. Metal tapes are relatively environmentally stable with the lowest amount of print-through. They generally have the highest MOL and SOL values, but also the highest noise, so in practice they exceed Type II tapes only in low print and better high frequency dynamic range. Headwear is no different from that of any other magnetic pigment.
Type III -ferric-chrome tapes. Sony made the IEC reference tape. Thicker coatings increased MOL, and the "underbiased" thin layer of chromium dioxide brought low noise. However, the disparity in bias points between the two layers meant a sagging mid-frequency sensitivity that had to be compensated by boosting record EQ to such a degree that SOL values were very poor. (This was common to double-coated tapes but far less pronounced when the optimum bias points were closer, as in BASF Superchrome tapes and TDK SA-X.) Type III tapes were never very popular and disappeared with the arrive of Type IV formulations. Headwear was the same as that for pure chrome tapes: lowest of all tapes for soft heads; higher initial wear on hard heads until the granular ferrite surface was polished, then very low with little to no gap erosion over the life of the head (except for some Sendust heads were chemical, not mechanical, erosion was observed similar to that induced by some ferric-cobalt formulations.)
Type II - chromium dioxide or ferric-cobalt pigment. BASF made all Type II reference tapes, despite what TDK claimed in its misleading advertising. These tapes used either DuPont's invention of chromium dioxide (manufactured only by DuPont of BASF because of the enormous expense in heat/pressure reactors required to form the particle) or ferric oxides enhanced by the addition of magnetic cobalt to the crystal structure. Chrome was the first Type II tape, but Sony's exclusive distribution deal with DuPont forced other Japanese tape manufacturers to find an alternative in ferric-cobalt (an Agfa-Gevaert invention that they were never able to stabilize properly until the Japanese figured how to do it.) Chrome had the lowest noise because of its perfect particle size and near perfect uniformity that allowed easy distribution in dispersions and excellent alignment under orientation magnets in coaters, but the first chromes also broke in milling and were susceptible to high print-through. Ferric-cobalts allowed higher packing densities that increased tape sensitivity at the lower frequencies--a compatibility point that the Japanese used as a "quality" issue against chrome tapes--and allowed higher MOL values. The tapes, however, suffered from higher noise levels, which actually increased over time as delta noise, and from magnetostrictive effects that reduced high frequency signals under pressure from the capstan/pinch roller combination. Chrome suffered from neither and actually had its noise level decrease over time--along with output--so the dynamic range stayed the same while Dolby noise reduction tracking was compromised a bit--with a slight loss in accuracy but a pleasant increase in treble response. BASF redesigned its milling operations to reduce print-through to levels equal to or better than ferric-cobalt tapes and improved MOL and SOL values with new particles and finally, the introduction of ferric-cobalt oxides with chrome for the "Chrome Extra" formulations. The same improvements were made to the double-coated Superchromes and Chrome Maxima tapes. TDK, frustrated by chrome's claims to be the "world's quietest tape," introduced double-coated SA-X with a very fine ferric-cobalt particle coated on top of the standard SA formulation. This lowered noise levels about a decibel or so below that of pure chrome tapes (before delta noise set it) but brought the curse of increased print-through due to the presence of para-magnetic particles among the finely milled top layer particles. All producers of ferric-cobalt tapes made improvements to formulations that slowly increased output levels with few compromises to dynamic range. BASF itself introduced a ferric-cobalt tape in a heat-resistant housing for car stereo use because chrome's low Curie point meant that signals could be lost if the tape were subjected to high levels of heat. (This worked to chrome's advantage when used in highs-speed TMD thermal magnetic video duplication.) Barium ferrite was an alternative pigment considered for audio but seldom used except for some video applications. Despite the nasty headwear scare used to dissuade people from using chrome tape, there is little difference in the amount of wear induced by any Type II tape that is properly calendered and finished. (All lubricant, emulsifiers, static reducers, and fungicides are in the magnetic dispersion. They are not added later in the manufacturing process.) There were some Type II metal tapes in the market to offer metal recording for older tape decks without Type IV settings, but the lower MOL and SOL values along with the very high noise levels and inability to be erased eventually killed these interlopers. The best ferric-cobalts and chromes easily outperformed these metal pigment products. Chrome tapes had their greatest day in audio duplication because BASF encouraged duplicators to use a playback EQ of 120 microseconds and back off the record pre-emphasis to improve SOL values by almost 5 decibels. (The 70-microsecond EQ setting came about when no one expected Dolby NR to become standard. Had the engineers known Dolby would be so successful, they would have left playback EQ the same for Type II tapes as for Type I. Chrome/Dolby NR/70 microseconds were all introduced at the same time to reduce tape hiss--but any two of the three options would have been sufficient. All 3 at the same time was overkill.)
Type I - ferric oxide, cobalt-modified ferric oxide. BASF made the official reference tape. These are the first and most common tapes. The range of quality levels is greatest in this class because the oxides can vary so much and because reject computer tape designed for digital signals, not audio, sometimes made its way into cheaper brands. Some of the best Type I tapes could offer low frequency signal-to-noise ratios that matched or slightly exceeded Type II and IV tapes, but their high frequency performance was never as good because of the lower coercivity of the oxides. These tapes, with their less sophisticated particles, tend to be the most environmentally stable over time as long as the binder formulations are stable. (Polyurethane binder breakdown is a plague among ferric reel-to-reel formulations from Ampex and Agfa; acid ooze is more common in cassette binder failures.) Headwear varies among tapes only because of different levels of quality in finishing the tapes: the better quality of tapes have no problem. Some ferric-cobalt Type I tapes have shown some chemical erosion on some Sendust heads, but one could argue whether it is the fault of the tape or the head design. In general, headwear is not a problem. (As a topic, headwear is a fascinating topic, rife with misinformation and rumors.)
---------------------
DIN Type II Reference Tape C 401 R BASF 100% pure chrome
IEC Type II Reference Tape S 4592A BASF 100% pure chrome
IEC Type II Reference Tape U 564 W (replaced S 4592 A in October, 1987, in the IEC meeting in Prague)
Magnetic Media Information Services, Volume XIII, No. 5 (August 20, 1993) discusses the technical work of Dr. Manfred Ohlinger, BASF's chief of pigment development. Dr. Ohlinger discussed work on CK60/XH, a chrome pigment with a coercivity beyond 1000 oersteds. He had already produce CK/75/230X with a value of 900 oe. and CK57/200X with a value of 670 oe. BASF was in full development of advanced pure chrome pigments for new 3480 cartridges and other media.
BASF had been producing pure chromium dioxide pigments in a huge reactor in Ludwigshaven, Germany, since the late 1960s. In 1995 the oxide lineup included:
CK 40-14 for audio tape
CN 43-11 for high performance, single-coat audio tapes
CK 37-11 for the lower coating of high performance chrome audio tapes. This pigment was designed for non-cross-linked binders.
CK 48-21 was for the upper layer in cross-linked dispersions. These oxides were used in Chrome Super and Chrome Maxima tapes. The tapes were identical and differed only in the housing and the tighter specs for Chrome Maxima. Most Chrome Super performed exactly the same as Chrome Maxima.
CK 50-21 was pure chrome used in VHS, S-VHS, TMD, and DCC formulations. (BASF made the only DCC tape. It was the tape in TDK and every other DCC cassette made.)
There were CC variations of these pigments. They differed in that oxygen molecules were attached to the crystal surface to prevent degradation to hexavalent chrome in the presence of water.
BASF used 100% pure chrome formulations for its EE reel-to-reel tape and for Loop Bin Master 920 and 921 used in the duplication industry before digital bins arrived. The only "hybrid" chrome/cobalt audio formulations appeared with the introduction in 1993/94 of "Chrome Plus" duplicator tape that had a small percentage of cobalt-ferric pigment added to raise AT315/MOL315. Its AT315 was 2-3 dB better than competing chrome tapes. Chrome Plus was also used in Chrome Extra audio cassettes from that point forward.
In 1992 world-wide production of magnetic powder by weight was 11% for chromium dioxide, 55% for co-fe, 32% for standard ferric, and 2% for metal powder. This total includes all applications: audio, video, computer data.
In 1994 BASF used a high-performance plastic that could withstand 95 degrees C. (203 degrees F.) without deformation. This plastic was used in the sonically welded Reference Maxima series. The tape was BASF ferric-cobalt because the heat resistance of the plastic would be wasted on a tape that had a much lower Curie point. (It was chrome's low Curie point that made it the only choice for thermal duplication--TMD--that was used for high-speed video tape duplication.) BASF kept Chrome Maxima and Chrome Super in the cassette lineup as 100% pure chromium dioxide tapes and the 85/15 Chrome Extra as its first and only hybrid chrome audio tape.
As for "audiophile" opinions, I remember reading a discussion in The Absolute Sound condemning the process. It was obvious that the writer, an editor at the magazine, had little idea of magnetic recording. If you want an audiophile journalist's perspective on high-speed duplication, you would have to turn to John Borwick or Angus MacKenzie's work in British publications.
```
# DCC tape
Quote:
`The tape formulations supplied by manufactures was actually from video tape stock rather than cassette stock, i.e. mostly chromium tapes but cobalt doped ferric formulations were also available at the least in the early days of DCC, for archival purposes the ferric formulations have a longer lifetimes despite the lower price, this use of video tape stock explains why metal tape playback is not officially supported in the DCC standard. A few chromium audio cassette formulations are very similar to video tape formulations so that it's theoretically possible to force some audio cassettes to work in a DCC recorder by modifying the enclosure and tape pad (if you need to seriously over-bias a chrome tape to make it sound right on an analogue recorder, chances are that it's video stock), but no audio cassette ferric formulations are similar to the video type ferric formulations that DCC expects.`
It's hard to make sense out of what the author is writing, partly because of poor grammar and punctuation, partly because of misinformation. DCC was NOT video tape "stock." It was audio base film coated with CK 50-21 pure chrome pigment, which was also used for VHS, S-VHS, and TMD video formulations in different dispersions and different processing. TDK, Panasonic, and other Japanese tape manufacturers didn't bother with producing ferric-cobalt DCC tape. They bought pancakes from BASF because they wanted a hand in the DCC jar just in case consumer demand picked up, but they didn't want to invest too much in risky development. (BASF initially did the same with DAT. We sourced the first BASF DAT tape. Tape manufacturers were being cautious at the time because there were too many formats to develop all of them and too many losses from the VHS consumer market.)
The sentence fragment starting with "for archival purposes...." makes no sense to me. The same is true regarding metal tape playback. The author is probably British judging from the language used, so I don't know where he or she got the information.
# Lagers
# identificatie
Kogellagers zijn in verregaande mate gestandaardiseerd. Nummercodes identificeren een specifiek type kogellager. Meestal is op het kogellager de nummercode gestanst. C-aanduidingen zeggen iets over de speling van de binnenring t.o.v. de buitenring binnen het lager.
C3 is de meest voorkomende variant. Dit is een lager dat gelijk is aan zijn C0 genummerde broertje met uitzondering van de speling, die is dus groter. Men heeft ook nog C1 die heeft een veel kleinere speling dan C0 (de standaardmaat) en C2 met een kleiner speling dan C0, maar iets groter dan C1. Verder is er naast de genoemde C3 ook nog een C4 en C5, die hebben een nog grotere speling.
**In volgorde van speling beginnende bij de strakste zijn de codes: C1, C2, C0, C3, C4 en C5.**
Bij inline-skates is de Amerikaanse onderverdeling ABEC standaard. De schaal loopt van ABEC 1 tot ABEC 9 (de nauwkeurigste lagers).
# coderingen
Overzicht codering toevoegingen inzake afdichting & speling
| **SKF**
| **FAG**
| **NTN**
| **SNR**
| **NKE**
| **Koyo**
| **NSK**
| **Nachi**
|
| **1-zijdige metaal-afdichting**
| Z
| Z
| Z
| Z
| Z
| Z
| Z
| Z
|
| **1-zijdige rubber-afdichting**
| RS1/RSH
| RSR
| LU
| E
| RSR/RS2
| RS
| DU
| Z
|
| **2-zijdige metaal-afdichting**
| 2Z
| 2Z
| ZZ
| ZZ
| 2Z
| ZZ
| ZZ
| ZZ/ZZE
|
| **2-zijdige rubber-afdichting**
| 2RS1/2RSH
| 2RSR/C-2HRS
| LLU
| EE
| 2RSR/2RS2
| 2RS
| DDU
| 2SNL/2NSE
|
| **speling groter dan normaal**
| C3
| C3
| C3
| J30
| C3
| C3
| C3
| C3
|
| **speling groter dan C3**
| C4
| C4
| C4
| C4
| C4
| C4
| C4
| C4
|
| **speling kleiner dan normaal**
| C2
| C2
| C2
| C2
| C2
| C2
| C2
| C2
|
| | | | | | | | |
Tot slot nog een paar opmerkingen.
- Lagers waarbij geen toevoeging is vermeld, hebben geen afdichting daar bij de toepassing rekening gehouden word met de (constante) smering van het lager;
- Lagers die een 2Z afdichting hebben zijn stofdicht en hebben een hoger maximaal toerental dan de rubber afgedichte varianten;
- Lagers die een 2RS1 afdichting hebben zijn spatwaterdicht. Dit betekent overigens geenszins dat deze lagers waterdicht zijn!;
- RVS lagers worden aangeduid met een S en W voor de codering van het lager. Bijvoorbeeld SKF W6004 2RSH of ECO S6004 2RS
# tabel
In onderstaande tabel staan de meest gangbare coderingen voor kogellagers, m.u.v. spanring kogellagers,spindellagers en vierpunts-kogellagers. Doordat de lagerfabrikanten niet allemaal dezelfde lageraanduidingen gebruiken, kan het zijn dat er voor een bepaalde eigenschap verschillende afkortingen bestaan.
| **SKF**
| **FAG**
| **NTN**
| | |
| 2RS12RSH
| 2RSRC-2HRS
| LLU
| :
| spatwaterdichte slepende afdichting van rubber met wapening van staalplaat aan beide zijdes van het lager
|
| 2RSL
| | | :
| wrijvingsarme variant van 2RS1
|
| 2RZ
| | | :
| wrijvingsarme variant van 2RS1
|
| 2Z
| 2Z
| ZZ
| :
| geperst stalen beschermplaatje (stofafdichting) aan beide zijdes van het lager
|
| A
| | | :
| hoek is 30 graden (1-rijig hoekcontactkogellager)
|
| A
| | | :
| geen vulopeningen + hoek is 30 graden (SKF 2-rijige hoekcontactkogellager)
|
| B
| B
| B
| :
| hoek is 40 graden (1-rijig hoekcontact kogellager)
|
| B
| | :
| hoek is 25 graden (FAG 2-rijige hoekcontactkogellager)
|
| C2
| C2
| C2
| :
| radiale speling kleiner dan normaal
|
| C2
| | | :
| axiale speling kleiner dan CB (2-rijige hoekcontactkogellager)
|
| C3
| C3
| C3
| :
| radiale speling groter dan normaal
|
| C3
| | | :
| axiale speling groter dan CB (2-rijige hoekcontactkogellager)
|
| C4
| | | :
| radiale speling groter dan C3
|
| C5
| | | :
| radiale speling groter dan C4
|
| CA
| | | :
| lager voor gepaarde montage, bij O- of X-opstelling is de axiale speling in ongemonteerde toestand kleiner dan CB
|
| CB
| UA
| | :
| lager voor gepaarde montage, bij O- of X-opstelling is de axiale speling in ongemonteerde toestand normaal
|
| CB
| | | :
| speciale axiale speling (2-rijige hoekcontactkogellager)
|
| CC
| | | :
| lager voor gepaarde montage, bij O- of X-opstelling is de axiale speling in ongemonteerde toestand groter dan CB
|
| D
| DA
| | :
| gedeelde binnenring (2-rijige hoekcontactkogellager)
|
| DB
| DB
| | :
| 2 gepaarde kogellagers in O-opstelling
|
| DF
| DF
| | :
| 2 gepaarde kogellagers in X-opstelling
|
| DT
| DT
| | :
| 2 gepaarde kogellagers in tandem-opstelling
|
| E
| | | :
| geoptimaliseerde inwendige constructie hoekcontactkogellagers
|
| F
| | | :
| massief stalen vensterkooi hoekcontact kogellager
|
| GA
| UL
| | :
| lager gepaarde montage; bij O- en X-opstelling is er in ongemonteerde toestand een lichte voorspanning
|
| GB
| | | :
| lager gepaarde montage; bij O- en X-opstelling is er in ongemonteerde toestand een matige voorspanning
|
| GC
| | | :
| lager gepaarde montage; bij O- en X-opstelling is er in ongemonteerde toestand een zware voorspanning
|
| UO
| BG
| :
| lager gepaarde montage; bij O- en X-opstelling is in ongemonteerde toestand spelingsvrij
|
| J
| JP
| J
| :
| geperste kooi van staal, op de kogels gecenteerd
|
| J1
| | | :
| idem J (2-rijige hoekcontactkogellager)
|
| K
| K
| | :
| Conische boring
|
| M
| M / MP
| L1
| :
| messing kooi op kogels gecenteerd
|
| MA
| MA
| | :
| messing kooi op buitenring gecenteerd
|
| MB
| | | :
| messing kooi op binnenring gecenteerd
|
| N
| | | :
| borgringgroef in de buitenring
|
| N1
| | | :
| 1 borggroef op zijvlak buitenring
|
| NR
| | | :
| borgringgroef in de buitenring + borgring
|
| P
| | | :
| kooi van glasvezelversterkte polyamide bij hoekcontact kogellagers
|
| P5
| | | :
| maat- en loopnauwkeurigheid ISO 5
|
| P52
| | | :
| P5 + C2
|
| P6
| | | :
| maat- en loopnauwkeurigheid ISO 6
|
| P62
| | | :
| P6 + C2
|
| P63
| | | :
| P6 + C3
|
| PH
| | | :
| kooi van glasvezelversterkte polyether-etherketone (PEEK) bij hoekcontact kogellagers
|
| RS1/RSH
| RSR
| LU
| :
| spatwaterdichte slepende afdichting van rubber met wapening van staalplaat aan een zijde van het lager
|
| RSL
| | | :
| wrijvingsarme variant van RS1
|
| RZ
| | | :
| wrijvingsarme variant van RS1
|
| TH
| | | :
| kooi van vezelversterkte fenolhars op kogels gecentreerd
|
| TN
| | | :
| kooi van polyamide op kogels gecentreerd
|
| TN9
| TVP/TVH
| | :
| kooi van glasvezelversterkte polyamide op kogels gecentreerd
|
| TNH
| | | :
| kooi van glasvezelversterkte polyether-etherketone (PEEK) op kogels gecentreerd
|
| Y
| Y
| | :
| geperste kooi van messing, op de kogels gecenteerd
|
| Z
| Z
| | :
| geperst stalen beschermplaatje (stofafdichting) aan een zijde van het lager
|
| | | | |
Voorbeelden:
1. SKF 6005 2RSH = groefkogellagers met spatwaterdichte slepende afdichting van rubber met wapening van staalplaat aan beide zijdes van het lager;
2. FAG 3202B 2RSR TVH = 2-rijige hoekcontactkogellager met een hoek van 25 graden, kooi van glasvezelversterkte polyamide op kogels gecentreerd en spatwaterdichte afdichting;
# uitleg
Deze codering is officieel als volgt:
**voorvoegsel** - hoofdnummer - volgcode\_A volgcode\_B volgcode\_C / volgcode\_D1 t/m D6
Je ziet dat deze codering vrij ingewikkeld is. Immers: niet altijd wordt het voorvoegsel of worden de volgcodes allemaal gegeven.Het is dus ook goed mogelijk dat alleen het hoofdnummer en volgcode B wordt gegeven.
Stel je voor dat je een lager **DIN625 6201Z** hebt. Wat voor lager heb je dan? Dat is de vraag die we hier gaan beantwoorden.Aan het eind van deze faq kan jij dit decoderen. Dus lees snel verder.
# Voorvoegsel
Het voorvoegsel wordt zelden genoemd. Daarom zal ik die hier niet bespreken.
# Hoofdnummer
Veel voorkomende lagers zijn hieronder te vinden, met hun maten.Alle lagers zijn in Z, ZZ, RS en RS2 verkrijgbaar.De maten zijn in **millimeters** weergeven.
| **Code**
| **d**Diameter binnen
| **D**Diameter buiten
| **B**Hoogte
|
| 6000
| 10
| 26
| 8
|
| 6200
| 10
| 30
| 9
|
| 6300
| 10
| 35
| 11
|
| 6001
| 12
| 28
| 8
|
| 6201
| 12
| 32
| 10
|
| 6301
| 12
| 37
| 12
|
| 6002
| 15
| 32
| 9
|
| 6202
| 15
| 35
| 11
|
| 6302
| 15
| 42
| 13
|
| 6003
| 17
| 35
| 10
|
| 6203
| 17
| 40
| 12
|
| 6303
| 17
| 47
| 14
|
| | | |
De hoofdcode uit het voorbeeld is **6201**. We gaan dit als eerste decoderen.De hoofdcode bestaat uit cijfers en is gerelateerd aan het soort lagers en de grootte ervan.Het eerste cijfer geeft het soort lagers weer. In het voorbeeld is dat dus een **6**.
| **code**
| **verklaring**
|
| 0
| Dubbelrijig hoekcontact lagers
|
| 1
| Zelfinstellend kogellagers
|
| 2
| Tonlagers
|
| 3
| Kegellagers
|
| 4
| Tweerijig groef kogellagers
|
| 5
| Axiale kogellagers
|
| 6
| Groef kogellagers
|
| 7
| Hoekcontact lagers
|
| 8
| Axiale cilinder lagers
|
| N
| cilinderlagers
|
| |
Het lager in het voorbeeld is dus een **Groef kogellager**. Dit het meest 'gewone' kogellager wat wij kennen. Dus een gewoon lager.
De rest van de cijfers van de hoofdcode geven de maatvoering aan.
## Volgcode's A t/m D
De volgcode's A t/m C worden door een spatie gescheiden.Meestal is er maar een van de 3 code's aanwezig. Indien er een volgcode C is aangegeven, is er nooit een volgcode D opgegeven.
# Volgcode A
De volgcode A geeft informatie over het **inwendige** van het lager.Dit zal niet vaak voorkomen.
| **code**
| **verklaring**
|
| A
| Speciaal ontwerp voor speciale toepassing
|
| A
| Contacthoek 30 Graden bij hoekcontact lagers
|
| B
| Contacthoek 40 graden bij hoekcontact lagers
|
| B
| Contacthoek kleiner dan 17 graden bij kegel lagers
|
| C
| Contacthoek 15 graden bij hoekcontact lagers
|
| C
| Contacthoek 20 graden bij kegel lagers
|
| CA
| Contacthoek 20 graden bij hoekcontact lagers
|
| D
| Contacthoek 28 graden en 30 minuten voor kegel lagers
|
| DJ
| Contacthoek 28 graden en 48 minuten en 39 seconden voor kegel lagers
|
| E
| Contacthoek 35 graden bij hoekcontact lagers
|
| J
| Bepaalde maten van een kegellager voldoen aan de ISO standaard
|
| |
# Volgcode B
Deze volgcode B geeft aan hoe de **afdichting** is bij het lager.
| **code**
| **verklaring**
|
| (geen code)
| het lager is aan beide kanten open
|
| RS / RS1 / RSH
| het lager is aan een zijde spatwater dicht dmv 1 rubberen afdichtring
|
| 2RS / 2RS1 / 2RSH
| het lager is aan twee zijden spatwaterdicht dmv 2 rubberen afdichtringen
|
| RSL
| het lager is aan een zijde spatwaterdicht met extra lage wrijving
|
| 2RSL
| het lager is aan twee zijden spatwaterdicht met extra lage wrijving
|
| Z
| het lager is aan een zijde stofdicht dmv 1 metalen plaatje
|
| 2Z = ZZ
| het lager is aan twee zijden stofdicht dmv 2 metalen plaatjes
|
| |
Het lager in het voorbeeld heeft bij volgcode B een **Z**. Dit geeft dus aan dat dit lager aan 1 kant is dichtgemaakt met een metalen plaatje.
# Volgcode C
Deze volgcode C geeft informatie over de **kooiconstructie**. Dus over de 2 stalen ringen waarin de kogel draaien.
| **code**
| **verklaring**
|
| (geen code)
| standaard: massief ijzeren kooi
|
| F
| Massieve ijzeren kooi
|
| J
| Geperste plaatstalen kooi
|
| L
| Massieve lichtmetalen kooi
|
| M
| Massieve messing kooi
|
| P
| Met glasvezel versterkte polyamide kooi
|
| Y
| Geperste kooi ven messing plaat
|
| |
# Volgcode D
Achter het **/** teken staan de kenmerken t.a.v. materiaal,hittebehandeling, nauwkeurigheid,extra speling, smering e.d..
| **code**
| **categorie**
| **verklaring**
|
| P0
| Nauwkeurigheid
| klasse 0 van de ISO tolerantie-klassen = ABEC 1
|
| P2
| Nauwkeurigheid
| klasse 0 van de ISO tolerantie-klassen = ABEC 9
|
| P4
| Nauwkeurigheid
| klasse 0 van de ISO tolerantie-klassen = ABEC 7
|
| P5
| Nauwkeurigheid
| klasse 0 van de ISO tolerantie-klassen = ABEC 5
|
| P6
| Nauwkeurigheid
| klasse 0 van de ISO tolerantie-klassen = ABEC 3
|
| C1
| Extra speling
| Krappere speling dan bij C2
|
| C2
| Extra speling
| Krappere speling dan bij C3
|
| C3
| Extra speling
| Speling normaal
|
| C4
| Extra speling
| Ruimere speling dan bij C3
|
| C5
| Extra speling
| Ruimere speling dan bij C4
|
| | |
# Het voorbeeld uitgelegd
Het voorbeeld wat is gaf was een DIN625 6201Z. We gaan nu kijken wat dat betekent:
| DIN625
| Duitse Industrie Norm 625
| Dit betekent dat het een kogellager is
|
| 6201
| Hoofdnummer
| Dit geeft de afmetingen aan: 12mm binnendiameter; 32mm buitendiameter en 10mm dikte
|
| Z
| Volgcode B
| Dit geeft aan dat het lager aan 1 kant stofdicht is met een metalen plaatje
|
| | |
# Quadroponic or DTS surround sound
1. REDIRECT [Quadrophonic or DTS surround sound](https://www.reeltoreel.nl/bookstack/books/mediawiki-import/page/quadrophonic-or-dts-surround-sound)
# Play audacity over network
# How to play Audacity over network using pulseaudio sound server
If you use pulse-audio as sound server, you can use module-native-protocol-tcp to accept tcp connection from your remote machine.
In the following example, I use an ssh tunnel to forward the audio request from remote machine to the local one.
On the local machine, do something like:
`$ pactl load-module module-native-protocol-tcp auth-ip-acl=127.0.0.1`
`$ ssh -XC -R 9999:127.0.0.1:4713 pvdm@192.168.1.1`
then on remote machine you can use:
`$ paplay -s 127.0.0.1:9999 soundfile.wav`
`$ padsp -s 127.0.0.1:9999 audacity`
ADDED I discovered that auth-ip-acl does not accept localhost as a valid parameter, you have to use 127.0.0.1 (or whatever your machine uses localhost address).
# Check soundcard settings: bitrate
To check settings
# Which sound cards are installed, and what number are they?
`> cat /proc/asound/cards`
`0 [NVidia ]: HDA-Intel - HDA NVidia`
` HDA NVidia at 0xfc080000 irq 69`
`1 [Generic ]: HDA-Intel - HD-Audio Generic`
` HD-Audio Generic at 0xfc500000 irq 72`
`2 [USB ]: USB-Audio - Scarlett 2i2 USB`
` Focusrite Scarlett 2i2 USB at usb-0000:30:00.4-2.3, high speed`
`3 [Pro ]: USB-Audio - FiiO K5 Pro`
` GuangZhou FiiO Electronics Co.,Ltd FiiO K5 Pro at usb-0000:30:00.4-1, high spee`
# Focusrite Scarlett 2i2
```
> cat /proc/asound/card2/stream0
Focusrite Scarlett 2i2 USB at usb-0000:30:00.4-2.3, high speed : USB Audio
Playback:
Status: Stop
Interface 1
Altset 1
Format: S32_LE
Channels: 2
Endpoint: 0x01 (1 OUT) (SYNC)
Rates: 44100, 48000, 88200, 96000, 176400, 192000
Data packet interval: 125 us
Bits: 24
Channel map: FL FR
Capture:
Status: Running
Interface = 2
Altset = 1
Packet Size = 200
Momentary freq = 192000 Hz (0x18.0000)
Interface 2
Altset 1
Format: S32_LE
Channels: 2
Endpoint: 0x82 (2 IN) (ASYNC)
Rates: 44100, 48000, 88200, 96000, 176400, 192000
Data packet interval: 125 us
Bits: 24
Channel map: FL FR
```
# UCA202:
`# cat /proc/asound/CODEC/pcm0p/sub0/hw_params`
`# cat /proc/asound/card0/codec#0 `
```
access: MMAP_INTERLEAVED
format: S16_LE
subformat: STD
channels: 2 <-------- will be 4 for iO4
rate: 48000 (48000/1) <------ this changes with the input audio file
period_size: 44100
buffer_size: 88200
```
# FiiO
48kHz and below: BLUE
48kHz and above: YELLOW
DSD: GREEN
`# cat /proc/asound/card0/stream0 | grep Momentary`
or
`# cat /proc/asound/card1/stream0 | grep Momentary`
```
Momentary freq = 44095 Hz (0x5.8308)
```
\- - - -
`# cat /proc/asound/card0/stream0 `
`# cat /proc/asound/card0/pcm0p/sub0/hw_params`
```
GuangZhou FiiO Electronics Co.,Ltd FiiO K5 Pro at usb-0000:00:12.2-3, high spee : USB Audio
Playback:
Status: Running
Interface = 1
Altset = 2
Packet Size = 36
Momentary freq = 44095 Hz (0x5.8308)
Feedback Format = 16.16
Interface 1
Altset 1
Format: S32_LE
Channels: 2
Endpoint: 1 OUT (ASYNC)
Rates: 44100, 48000, 88200, 96000, 176400, 192000, 352800, 384000, 705600, 768000
Data packet interval: 125 us
Interface 1
Altset 2
Format: S16_LE
Channels: 2
Endpoint: 1 OUT (ASYNC)
Rates: 44100, 48000, 88200, 96000, 176400, 192000, 352800, 384000, 705600, 768000
Data packet interval: 125 us
Interface 1
Altset 3
Format: SPECIAL
Channels: 2
Endpoint: 1 OUT (ASYNC)
Rates: 44100, 48000, 88200, 96000, 176400, 192000, 352800, 384000, 705600, 768000
Data packet interval: 125 us
```
# FiiO via S/PDIF
`# cat /proc/asound/card1/pcm1p/sub0/hw_params`
```
access: MMAP_INTERLEAVED
format: S32_LE
subformat: STD
channels: 2
rate: 48000 (48000/1)
period_size: 1024
buffer_size: 32768
```
# Cm6631a
```
The latest product upgrades, increase optical output! ! !
This product USB direct power supply,
Input: USB input, print port and Android interface, input easily linked computer or mobile phone
Output: output optical! Coaxial! Linear audio! Headphone output!
Easily drive 300 European and American headphones
A finished board, finished machine optional! Black or silver white shell! CNC high-precision machining, pure aluminum chassis structure, 6631 combined with multiple version optimization and improvement, sound sophistication beyond XMOS, Naiting, not irritable! Small exquisite children! !
Each board test OK delivery, using anti-static packaging .Windows10 automatic identification, you need to drive can contact me
Support coaxial SPDIF '''output'''
Support I2S output can be external decoder
Internal includes ES9023 own decoded audio output
Can connect mobile OTG, recommended player download address http://www.hiby.cd/
Compatible more stable. By professional PCB full posts, precision parts design. All posts using active low temperature
Support millet box, the other boxes are not all tested, compatible with Apple, PC Computer WindowXP / 7/8/10
Float crystal vibration, high-quality optical fiber to ensure 192K transmission performance.
Support 24bit / 44.1K, 48K, 88.2K, 96K, 176.4K, 192K,
Usb audio input and up to 32BIT 192K audio input onboard three Panasonic gold capacitors, high-precision active crystal oscillator, the latest version of the optimized wiring, better indicators!
Output 1: Audio Input with ES9023 High-Precision Decode IC with Internal Drive Circuit High Thrust
Output 2: I2S output, can be connected to other DA devices
Output 3: SPDIF output! That is a coaxial output and optical output
Brand Name:Olive Leaf
D/A Converter:CM6631A
Model Number: Sound Card USB to I2S
DSD Sampling Frequencies:None
Outputs:RCA,3.5 mm
Material:Metal
PCM Word Length:24-bit,32-bit
PCM Sampling Frequencies:192 kHz
USB Compatibility:IOS,Windows 8,Windows 10,Windows 7
Inputs:USB Type-B,USB Type-A
Bluetooth:No
Type:Portable
```
# BASF Cassette history
This page is taken from the forum at tapeheads.net.
It is reproduced here with the sole purpose to show the pictures in an easy way. The text is exactly the same.
The original thread is located at: [https://www.tapeheads.net/showthread.php?t=31379](https://www.tapeheads.net/showthread.php?t=31379)
---
There are six basic categories of BASF true chrome tapes for compact cassettes:
# chromdioxid SM 1971-80 are **singe layer** true chromes, with magnetial properties according to DIN reference tape C401R.
1971-74: [http://www.vintagecassettes.com/basf/basf\_files/image5036.jpg](http://www.vintagecassettes.com/basf/basf_files/image5036.jpg)
1974-76: [http://www.vintagecassettes.com/basf/basf\_files/image5098.jpg](http://www.vintagecassettes.com/basf/basf_files/image5098.jpg)
1976-77: [http://www.vintagecassettes.com/basf/basf\_files/image5175.jpg](http://www.vintagecassettes.com/basf/basf_files/image5175.jpg)
1977-80: [http://www.vintagecassettes.com/basf/basf\_files/image5187.jpg](http://www.vintagecassettes.com/basf/basf_files/image5187.jpg)
(77-79 without "hifi stereo cassette" badge, 79-80 with "hifi stereo cassette")
# chromdioxid super SM 1977-80 are **double layer** true chromes with off-standard magnetical properties, still close to C401R, but higher sensitivity and a non-linear frequency range on DIN-aligned recorders:
1977-80: [http://www.vintagecassettes.com/basf/basf\_files/image5189.jpg](http://www.vintagecassettes.com/basf/basf_files/image5189.jpg)
(77-79 without "hifi stereo cassette" badge, 79-80 with "hifi stereo cassette")
# chromdioxid II SM and Cr Extra II 1980-ca 1993 were **single layer**true chromes, with magnetial properties according to IEC II reference tape S4592A.
1980-82: [http://www.vintagecassettes.com/basf/basf\_files/image5245.jpg](http://www.vintagecassettes.com/basf/basf_files/image5245.jpg)
1982-85: [http://www.vintagecassettes.com/basf/basf\_files/image5304.jpg](http://www.vintagecassettes.com/basf/basf_files/image5304.jpg)
1985-87: [http://www.vintagecassettes.com/basf/basf\_files/image5327.jpg](http://www.vintagecassettes.com/basf/basf_files/image5327.jpg)
1987-89: [http://www.vintagecassettes.com/basf/basf\_files/image5347.jpg](http://www.vintagecassettes.com/basf/basf_files/image5347.jpg)
1989-91: [http://www.vintagecassettes.com/basf/basf\_files/image5367.jpg](http://www.vintagecassettes.com/basf/basf_files/image5367.jpg)
1991-93: [http://www.vintagecassettes.com/basf/basf\_files/image5387.jpg](http://www.vintagecassettes.com/basf/basf_files/image5387.jpg)
1993-95: [http://www.vintagecassettes.com/basf/basf\_files/image5417.jpg](http://www.vintagecassettes.com/basf/basf_files/image5417.jpg)
# Cr Super II 1980-ca 1995, as well as Cr Maxima II 1982-ca 1994/95 are **double layer** true chromes with off-standard magnetical properties, still close to S4592A, but higher sensitivity and a non-linear frequency range on IEC-aligned recorders:
S 1980-81: [http://www.vintagecassettes.com/basf/basf\_files/image5246.jpg](http://www.vintagecassettes.com/basf/basf_files/image5246.jpg)
S 1981-82: [http://www.vintagecassettes.com/basf/basf\_files/image5279.jpg](http://www.vintagecassettes.com/basf/basf_files/image5279.jpg)
S 1982-84: [http://www.vintagecassettes.com/basf/basf\_files/image5309.jpg](http://www.vintagecassettes.com/basf/basf_files/image5309.jpg)
S 1984-85: [http://www.vintagecassettes.com/basf/basf\_files/image5318.jpg](http://www.vintagecassettes.com/basf/basf_files/image5318.jpg)
S 1985-87: [http://www.vintagecassettes.com/basf/basf\_files/image5329.jpg](http://www.vintagecassettes.com/basf/basf_files/image5329.jpg)
S 1987-89: [http://www.vintagecassettes.com/basf/basf\_files/image5350.jpg](http://www.vintagecassettes.com/basf/basf_files/image5350.jpg)
S 1989-91: [http://www.vintagecassettes.com/basf/basf\_files/image5370.jpg](http://www.vintagecassettes.com/basf/basf_files/image5370.jpg)
S 1991-93: [http://www.vintagecassettes.com/basf/basf\_files/image5390.jpg](http://www.vintagecassettes.com/basf/basf_files/image5390.jpg)
S 1993-95: [http://www.vintagecassettes.com/basf/basf\_files/image5420.jpg](http://www.vintagecassettes.com/basf/basf_files/image5420.jpg)
M 1982-85: [http://www.vintagecassettes.com/basf/basf\_files/image5310.jpg](http://www.vintagecassettes.com/basf/basf_files/image5310.jpg)
M 1985-87: [http://www.vintagecassettes.com/basf/basf\_files/image5332.jpg](http://www.vintagecassettes.com/basf/basf_files/image5332.jpg)
M 1987-88: [http://www.vintagecassettes.com/basf/basf\_files/image5352.jpg](http://www.vintagecassettes.com/basf/basf_files/image5352.jpg)
M 1988-91: [http://www.vintagecassettes.com/basf/basf\_files/image5372.jpg](http://www.vintagecassettes.com/basf/basf_files/image5372.jpg)
M 1991-93: [http://www.vintagecassettes.com/basf/basf\_files/image5392.jpg](http://www.vintagecassettes.com/basf/basf_files/image5392.jpg)
M 1993-95: [http://www.vintagecassettes.com/basf/basf\_files/image5422.jpg](http://www.vintagecassettes.com/basf/basf_files/image5422.jpg)
The last examples of the 1993-95 line-up had already the next generation of tape described below.
# CE II 1995 until the end: "**single-layer** chrome/ferric cobalt mix (85%/15%)"
(quoted from Wilhelm) with higher sensitivity compared to the older models, magnetical properties close to IEC II reference tape U564W
[http://www.vintagecassettes.com/basf/basf\_files/image5437.jpg](http://www.vintagecassettes.com/basf/basf_files/image5437.jpg)
# CS II and CM II 1995 until the end (plus some 1994 Chrome Maxima II):
**Double layer** tape, the lower layer being the same mixture of ferric cobalt and chrome as in the CE II, and the upper layer pure chrome. Frequency response nearly as flat as a single layer tape, magnetical properties close to IEC II reference tape U564W
[http://www.vintagecassettes.com/basf/basf\_files/image5440.jpg](http://www.vintagecassettes.com/basf/basf_files/image5440.jpg)
[http://www.vintagecassettes.com/basf/basf\_files/image5442.jpg](http://www.vintagecassettes.com/basf/basf_files/image5442.jpg)
With the last series of CS II during the Emtec era, I am not sure what tape they used.
All four Maxima Design Editions had the contemporary Chrome Maxima tape.
All budget chrome cassettes with different names, such as Chrome Standard II, ReCorD II, Sound (Level) II, the 353 Cr II Live as well as the Disney series and other printed shell promotional cassettes had one of the **single layer** chrome tapes, either the old Chrome Extra II or the new CE II formulation.
# The Chrome II Super \_Quality\_ was specially made for Lidl discounter stores
Despite having the "Super" shell, I am not sure whether they had single layer CE II or double layer CS II tape inside:
1995-97: [http://www.vintagecassettes.com/basf/basf\_files/image5484.jpg](http://www.vintagecassettes.com/basf/basf_files/image5484.jpg)
1997-2002: [http://www.shizaudio.ru/audio/data/media/109/BASF-EMTEC\_Chrome\_Super\_Quality\_II\_C90.jpg](http://www.shizaudio.ru/audio/data/media/109/BASF-EMTEC_Chrome_Super_Quality_II_C90.jpg)
# 24bit vs 16bit, the myth exploded!
It seems to me that there is a lot of misunderstanding regarding what bit depth is and how it works in digital audio. This misunderstanding exists not only in the consumer and audiophile worlds but also in some education establishments and even some professionals. This misunderstanding comes from supposition of how digital audio works rather than how it actually works. It's easy to see in a photograph the difference between a low bit depth image and one with a higher bit depth, so it's logical to suppose that higher bit depths in audio also means better quality. This supposition is further enforced by the fact that the term 'resolution' is often applied to bit depth and obviously more resolution means higher quality. So 24bit is Hi-Rez audio and 24bit contains more data, therefore higher resolution and better quality. All completely logical supposition but I'm afraid this supposition is not entirely in line with the actual facts of how digital audio works. I'll try to explain:
When recording, an Analogue to Digital Converter (ADC) reads the incoming analogue waveform and measures it so many times a second (1\*). In the case of CD there are 44,100 measurements made per second (the sampling frequency). These measurements are stored in the digital domain in the form of computer bits. The more bits we use, the more accurately we can measure the analogue waveform. This is because each bit can only store two values (0 or 1), to get more values we do the same with bits as we do in normal counting. IE. Once we get to 9, we have to add another column (the tens column) and we can keep adding columns add infinitum for 100s, 1000s, 10000s, etc. The exact same is true for bits but because we only have two values per bit (rather than 10) we need more columns, each column (or additional bit) doubles the number of vaules we have available. IE. 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024 .... If these numbers appear a little familiar it is because all computer technology is based on bits so these numbers crop up all over the place. In the case of 16bit we have roughly 65,000 different values available. The problem is that an analogue waveform is constantly varying. No matter how many times a second we measure the waveform or how many bits we use to store the measurement, there are always going to be errors. These errors in quantifying the value of a constantly changing waveform are called quantisation errors. Quantisation errors are bad, they cause distortion in the waveform when we convert back to analogue and listen to it.
So far so good, what I've said until now would agree with the supposition of how digital audio works. I seem to have agreed that more bits = higher resolution. True, however, where the facts start to diverge from the supposition is in understanding the result of this higher resolution. Going back to what I said above, each time we increase the bit depth by one bit, we double the number of values we have available (EG. 4bit = 16 values, 5bit = 32 values). If we double the number of values, we halve the amount of quantisation errors. Still with me? Because now we come to the whole nub of the matter. There is in fact a perfect solution to quantisation errors which completely (100%) eliminates quantisation distortion, the process is called 'Dither' and is built into every ADC on the market.
Dither: Essentially during the conversion process a very small amount of white noise is added to the signal, this has the effect of completely randomising the quantisation errors. Randomisation in digital audio, once converted back to analogue is heard as pure white (un-correlated) noise. The result is that we have an absolutely perfect measurement of the waveform (2\*) plus some noise. In other words, by dithering, all the measurement errors have been converted to noise. (3\*).
Hopefully you're still with me, because we can now go on to precisely what happens with bit depth. Going back to the above, when we add a 'bit' of data we double the number of values available and therefore halve the number of quantisation errors. If we halve the number of quantisation errors, the result (after dithering) is a perfect waveform with halve the amount of noise. To phrase this using audio terminology, each extra bit of data moves the noise floor down by 6dB (half). We can turn this around and say that each bit of data provides 6dB of dynamic range (\*4). Therefore 16bit x 6db = 96dB. This 96dB figure defines the dynamic range of CD. (24bit x 6dB = 144dB).
So, 24bit does add more 'resolution' compared to 16bit but this added resolution doesn't mean higher quality, it just means we can encode a larger dynamic range. This is the misunderstanding made by many. There are no extra magical properties, nothing which the science does not understand or cannot measure. The only difference between 16bit and 24bit is 48dB of dynamic range (8bits x 6dB = 48dB) and nothing else. This is not a question for interpretation or opinion, it is the provable, undisputed logical mathematics which underpins the very existence of digital audio.
So, can you actually hear any benefits of the larger (48dB) dynamic range offered by 24bit? Unfortunately, no you can't. The entire dynamic range of some types of music is sometimes less than 12dB. The recordings with the largest dynamic range tend to be symphony orchestra recordings but even these virtually never have a dynamic range greater than about 60dB. All of these are well inside the 96dB range of the humble CD. What is more, modern dithering techniques (see 3 below), perceptually enhance the dynamic range of CD by moving the quantisation noise out of the frequency band where our hearing is most sensitive. This gives a percievable dynamic range for CD up to 120dB (150dB in certain frequency bands).
You have to realise that when playing back a CD, the amplifier is usually set so that the quietest sounds on the CD can just be heard above the noise floor of the listening environment (sitting room or cans). So if the average noise floor for a sitting room is say 50dB (or 30dB for cans) then the dynamic range of the CD starts at this point and is capable of 96dB (at least) above the room noise floor. If the full dynamic range of a CD was actually used (on top of the noise floor), the home listener (if they had the equipment) would almost certainly cause themselves severe pain and permanent hearing damage. If this is the case with CD, what about 24bit Hi-Rez. If we were to use the full dynamic range of 24bit and a listener had the equipment to reproduce it all, there is a fair chance, depending on age and general health, that the listener would die instantly. The most fit would probably just go into coma for a few weeks and wake up totally deaf. I'm not joking or exaggerating here, think about it, 144dB + say 50dB for the room's noise floor. But 180dB is the figure often quoted for sound pressure levels powerful enough to kill and some people have been killed by 160dB. However, this is unlikely to happen in the real world as no DACs on the market can output the 144dB dynamic range of 24bit (so they are not true 24bit converters), almost no one has a speaker system capable of 144dB dynamic range and as said before, around 60dB is the most dynamic range you will find on a commercial recording.
So, if you accept the facts, why does 24bit audio even exist, what's the point of it? There are some useful application for 24bit when recording and mixing music. In fact, when mixing it's pretty much the norm now to use 48bit resolution. The reason it's useful is due to summing artefacts, multiple processing in series and mainly headroom. In other words, 24bit is very useful when recording and mixing but pointless for playback. Remember, even a recording with 60dB dynamic range is only using 10bits of data, the other 6bits on a CD are just noise. So, the difference in the real world between 16bit and 24bit is an extra 8bits of noise.
I know that some people are going to say this is all rubbish, and that “I can easily hear the difference between a 16bit commercial recording and a 24bit Hi-Rez version”. Unfortunately, you can't, it's not that you don't have the equipment or the ears, it is not humanly possible in theory or in practice under any conditions!! Not unless you can tell the difference between white noise and white noise that is well below the noise floor of your listening environment!! If you play a 24bit recording and then the same recording in 16bit and notice a difference, it is either because something has been 'done' to the 16bit recording, some inappropriate processing used or you are hearing a difference because you expect a difference.
G
1 = Actually these days the process of AD conversion is a little more complex, using oversampling (very high sampling frequencies) and only a handful of bits. Later in the conversion process this initial sampling is 'decimated' back to the required bit depth and sample rate.
2 = The concept of the perfect measurement or of recreating a waveform perfectly may seem like marketing hype. However, in this case it is not. It is in fact the fundamental tenet of the Nyquist-Shannon Sampling Theorem on which the very existence and invention of digital audio is based. From WIKI: “In essence the theorem shows that an analog signal that has been sampled can be perfectly reconstructed from the samples”. I know there will be some who will disagree with this idea, unfortunately, disagreement is NOT an option. This theorem hasn't been invented to explain how digital audio works, it's the other way around. Digital Audio was invented from the theorem, if you don't believe the theorem then you can't believe in digital audio either!!
3 = In actual fact these days there are a number of different types of dither used during the creation of a music product. Most are still based on the original TPDFs (triangular probability density function) but some are a little more 'intelligent' and re-distribute the resulting noise to less noticeable areas of the hearing spectrum. This is called noise-shaped dither.
4 = Dynamic range, is the range of volume between the noise floor and the maximum volume.
`Source: head-fi.org`
Comments:
1. ) The Nyquist theorem does not include amplitude quantization meaning infinite resolution, so it doesn't discuss quantization effects at all.
2. ) There is no audio system in the world giving more than 20 clear bits of signal due to resistance and semiconductor noise chracteristics.
3. ) You cannot "recreate" a single thing by dithering, just make it sounding more natural to the ears, especially when using noise shaping filters for the dither signal.
4. ) It's not true ADC's do any dithering. Some of them do some lowpass filtering with noise shaping involved when delta-sigma type which happens not for the dithering purposes but for the signal itself.
5. ) You cannot increase dynamic range by dithering.
6. ) It's not dynamics killing people and affecting hearing but sound pressure with the given numbers of 140dB = pain, 160~180dB = death, respectively. You can listen to the signal with the 144dB dynamics not exceeding safe sound pressure limits, just set the volume appropriately. Sure, you won't hear the bottom of your dynamic range then.
Answers:
1. True.
2. True. Most people believe that their 24bit DAC is actually a 24bit DAC, just marketing I'm afraid.
3. True. Dithering is just a process which should be used whenever a quantisation or re-quantisation is performed, to convert quantisation errors into un-correlated noise.
4. This one is not true. All ADCs use dither. Some 24bit ADCs use self-dither, in other words because the digital noise floor is so low (-144dB) the noise generated by their own internal components is enough to dither, but one way or another, they all dither. Also, all ADCs use a low-pass brick wall filter (anti-alias filter). Noise-shaped dither is not and should never be used in an ADC or when mixing. As the recorded channels are mixed the re-distributed noise is summed and can cause problems. The only time noise-shaped dither should be applied is during the last quantisation process. This usually means when converting the 24bit master from the recording studio into 16bit for CD release.
5. Sort of true. In an absolute sense CD has 96dB dynamic range, however if we move the noise that is down at the -96dB level to areas of the hearing spectrum where we are less sensitive (for example below 60Hz or above 12kHz). This gives a perceived improvement of dynamic range for 16bit. Bob Katz, the leading expert, reckons that about 120dB is the perceived dynamic range achievable with today's dithering technology.
6. True. Though of course by turning down your amp and not hearing the quietest sounds, then you are not hearing all the detail or the whole dynamic range, so it rather defeats the whole purpose of more dynamic range (more bits) in the first place.
# Pulseaudio settings for audiophiles
Pulseaudio is usually installed with default options to make it work with most hardware.
But settings can be tuned for better sound-quality. Adjust the following settings in your daemon.conf:
```
resample-method = soxr-vhq
avoid-resampling = yes
flat-volumes = no
high-priority = yes
realtime-scheduling = yes
default-sample-channels = 2
default-sample-rate = 96000
alternate-sample-rate = 48000
default-sample-format = float32le
```
- The two sample rate settings can be adjusted to suit your hardware configuration.
- Also the sample-format can also be u8, s16le, s16be, s24le, s24be, s24-32le, s24-32be, s32le, s32be float32le, float32be, ulaw, alaw.
- resample-method can be
```
trivial
speex-float-0
speex-float-1
speex-float-2
speex-float-3
speex-float-4
speex-float-5
speex-float-6
speex-float-7
speex-float-8
speex-float-9
speex-float-10
speex-fixed-0
speex-fixed-1
speex-fixed-2
speex-fixed-3
speex-fixed-4
speex-fixed-5
speex-fixed-6
speex-fixed-7
speex-fixed-8
speex-fixed-9
speex-fixed-10
ffmpeg
auto
copy
peaks
soxr-mq
soxr-hq
soxr-vhq
```
# SOX audio tool Quick Reference Guide
# generate file
Generate 1 second of white noise.
`sox -n output.wav synth 1 noise`
Generate a 1-second sine tone.
`sox -n output.wav synth 1 sine 440`
Generate a 10-second sine sweep file.
`sox -n output.wav synth 10 sine 0:20000`
Exponential sine sweep
`sox -n -r 44100 sine-sweep.wav synth 10 sine 5/22050`
# play
Play synthesized audio.
`play -n synth sine 440 trim 0 1 gain -12`
Play sine verbose 24 bits /=exponential
`play -V -n -b 24 -r 48000 synth 10 sine 20/20000`
`play -V -n -b 24 -r 48000 synth 10 sine 20/20000 vol -50dB`
And then ARTA:
```
Fs (Hz): 192000
FFT: 4096
Wnd: FlatTop
Avg: Peak Hold
```
# calibration tones
Play 30 tones at once, for frequency adjustment of equipment etc.
`play -r 192000 -V -n synth 300 sin 20 sin 25 sin 31.5 sin 40 sin 50 sin 63 sin 80 sin 100 sin 125 sin 160 sin 200 sin 250 sin 315 sin 400 sin 500 sin 630 sin 800 sin 1000 sin 1250 sin 1600 sin 2000 sin 2500 sin 3150 sin 4000 sin 5000 sin 6300 sin 8000 sin 10000 sin 12500 sin 16000 sin 20000 remix 1-31 1-31`
where:
192000 is the samplerate, if your card supports it
300 is number of seconds
\- This results in the following spectrum: 
If you want to generate the file yourself, use:
`sox -r 192000 -V -n "31 frequencies.flac" synth 300 sin 20 sin 25 sin 31.5 sin 40 sin 50 sin 63 sin 80 sin 100 sin 125 sin 160 sin 200 sin 250 sin 315 sin 400 sin 500 sin 630 sin 800 sin 1000 sin 1250 sin 1600 sin 2000 sin 2500 sin 3150 sin 4000 sin 5000 sin 6300 sin 8000 sine 10000 sin 12500 sin 16000 sin 20000 remix 1-31 1-31`
It will create a 300-seconds FLAC file with the 31 tones called "31 frequencies.flac"
# modify
Reduce level by 12dB
`sox speech.wav output.wav gain -12`
Crop to the first 1 second of the file.
`sox speech.wav output.wav trim 0 1`
Reverse the contents.
`sox speech.wav output.wav reverse`
Normalise the contents to 0dBFS.
`sox speech.wav output.wav norm`
Equaliser (-6dB @ 100Hz, -24dB @ 8000Hz)
`sox speech.wav output.wav bass -6 100 treble -24 8000`
Add room modelling reverb.
`sox speech.wav output.wav reverb 50 50 100`
Trim digital silence from start and end.
`sox input.wav trimmed/output.wav silence 1 0.1 0 1 0.1 0`
-
`sox infile outfile gain -n`
normalises to 0dB, and
`sox infile outfile gain -n -3`
normalises to -3dB.
# effects
chorus effect: A typical delay is around 40ms to 60ms; the modulation speed is best near 0.25Hz and the modulation depth around 2ms. For example, a single delay:
`play guitar1.wav chorus 0.7 0.9 55 0.4 0.25 2 -t`
Two delays of the original samples:
`play guitar1.wav chorus 0.6 0.9 50 0.4 0.25 2 -t 60 0.32 0.4 1.3 -s`
A fuller sounding chorus (with three additional delays):
`play guitar1.wav chorus 0.5 0.9 50 0.4 0.25 2 -t 60 0.32 0.4 2.3 -t 40 0.3 0.3 1.3 -s`
# compand
The following example might be used to make a piece of music with both quiet and loud passages suitable for listening to in a noisy environment such as a moving vehicle:
`sox asz.wav asz-car.wav compand 0.3,1 6:-70,-60,-20 -5 -90 0.2`
The transfer function (`6:-70,...') says that very soft sounds (below -70dB) will remain unchanged. This will stop the compander from boosting the volume on `silent' passages such as between movements.
However, sounds in the range -60dB to 0dB (maximum volume) will be boosted so that the 60dB dynamic range of the original music will be compressed 3-to-1 into a 20dB range, which is wide enough to enjoy the music but narrow enough to get around the road noise.
The `6:' selects 6dB soft-knee compand-ing. The -5 (dB) output gain is needed to avoid clipping (the number is inexact, and was derived by experimentation).
The -90 (dB) for the initial volume will work fine for a clip that starts with near silence, and the delay of 0.2 (seconds) has the effect of causing the compander to react a bit more quickly to sudden volume changes.
# general
\--multi-threaded | --single-threaded
` By default, SoX is `single threaded'. If the --multi-threaded option is given however then SoX`
` will process audio channels for most multi-channel effects in parallel on hyper-threading/multi-`
` core architectures. This may reduce processing time, though sometimes it may be necessary to use`
` this option in conjuction with a larger buffer size than is the default to gain any benefit from`
` multi-threaded processing (e.g. 131072; see --buffer above).`
# PipeWire Quick Reference Guide
qpwgraph
pw-top
pw-cat - Play and record media with PipeWire
pw-dump
pw-dsdplay
pw-play
pw-record
# Use METAFLAC to edit Flac Tags
Install FLAC package, then metaflac will be present.
`#root@moode:/mnt/SDCARD# metaflac --set-tag ARTIST="David Axelrod" holythursday.flac `
`#root@moode:/mnt/SDCARD# metaflac --set-tag TITLE="Holy Thursday" holythursday.flac`
`#metaflac --list my_music.flac`
# Installing audio plugins
IMPORTANT FOR VST INSTALLATIONS: If you deploy plugins as a subdirectory of your VST2 directory, the subdirectory should contain substring 'lsp-plugins'. Otherwise plugins won't find the VST2 core library. Please notice that '~' means user's home directory.
1. 1. For Linux/FreeBSD
The usual directories for LADSPA are:
` * /usr/lib/ladspa`
` * /usr/local/lib/ladspa`
` * /usr/lib64/ladspa`
` * /usr/local/lib64/ladspa`
` * ~/.ladspa`
` `
The usual directories for LV2 are:
` * /usr/lib/lv2`
` * /usr/local/lib/lv2`
` * /usr/lib64/lv2`
` * /usr/local/lib64/lv2`
` * ~/.lv2`
The usual directories for LinuxVST are:
` * /usr/lib/vst`
` * /usr/local/lib/vst`
` * /usr/lib64/vst`
` * /usr/local/lib64/vst`
` * ~/.lxvst`
` * ~/.vst`
The usual directories for JACK core library are:
` * /usr/lib`
` * /usr/local/lib`
` * /lib`
` * /usr/lib64`
` * /usr/local/lib64`
` * /lib64`
The usual directories for JACK binaries are:
` * /usr/bin`
` * /usr/local/bin`
` * /bin`
` * /usr/sbin`
` * /usr/local/sbin`
` * /sbin`
` `
The usual directories for CLAP are:
` * /usr/lib/clap`
` * /usr/local/lib/clap`
` * /usr/lib64/clap`
` * /usr/local/lib64/clap`
` * ~/.clap`