From www.ReeltoReel.nl Wiki
Jump to navigation Jump to search


No, Dolby A was developed in the 1960s for studios and Dolby B near the end of the decade as I understand it. A lot of people didn't see the need for it at first but it took off eventually and when introduced in cassette decks it made a difference with mostly lower grade ferrics as high end until Chrome tapes were introduced.

Signal to noise figures then were in the realm of 40-55 dB so with good tape and B NR you could easily top 60 in a quality deck. This is actually good because it matched well with the phonograph stages of the day.

When quieter sources and better circuits came about it became apparent that more was needed. This is likely how dbx got it's place in the market.

dbx is short for David Brownfield(?) eXpander or similar. As I recall it was introduced around 1971? The concept is brilliant and seems frightfully simple, whether it was then or not. With voltage control amplifiers (VCA) the level can be logarithmically reduced by 50% and expanded to the original 1:1, technically pushing the perceived noise floor far below that acheived by Dolby (30 dB is a good figure, can be more). When a version is applied to records the results (dbx disc) can be closer to what we'd expect from a CD. Static, deposits and wear would be the lone drawbacks, no longer a real noise factor. With a good quality of vinyl and pressing the sound can be quite nice!

I've heard that the Teac reel to reel decks with dbx actually use type II but don't quote me. I have a model 155 4-channel type I and two, soon to be three NX-40 units. Type II isn't so inferior that it won't suffice for reel recordings and type III and onward have been introduced in recent times in professional equipment.

Other offerings from the company have included limiters, single-ended expanders, routing switchers like the 200 amd 400 series and a large range of professional equipment. The current company is a part of Harman International and is mainly a professional audio equipment provider.