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Hi, all,

As many of you know, John Dyson and I are pursuing software Noise 
Reduction decoders. I'm presenting on the subject at AES in NYC on 
October 19th. Come hear Alexey Lukin of iZotope talk about single-ended 
noise reduction at 11:15 and I'll be outlining the four other ways that 
were used to optimize signal-to-noise ratio primarily in analog audio 
tape recording at 11:45. I saw Alexey's presentation in Culpeper the end 
of June and it's very interesting.

In case you're wondering, the four methods were: Equalization, New tape 
formulations, Multi-track (two tracks per channel) recording, and 
Companders (the subject of this post).

John and I have identified eight NR systems that we are considering 
turning into software emulations. Currently we have a good version of DA 
working. I do not use the tradenames in conjunction with the decoders to 
avoid confusion.

Out next step for us is to look into DB, DC, X-I, X-II, and C4. We think 
we'll have these six operational and available in 2019. The DA decoder 
(which also involved a learning curve for John and me) has been in the 
works for about a year.

DSpR and DS are much more complex beasts with less documentation and we 
are considering that for the 2020 time frame, but not guaranteeing anything.

With that said, my research has identified a total of 16 systems that 
were released over time. The additional (with their original release 
dates) are:

Ex-Ko from Hungary (1974) and JVC ANRS (1976) which appear to be close 
enough to Dolby B to use our to-be-designed DB decoder, so they are not 
an issue.

I have hardware decoders for three consumer systems: Telefunken High-Com 
(1978), Nakamichi High-Com II (licensed from Telefunken-1979), and Sanyo 
Super D (1982). In the decade that I have had these hardware decoders, I 
have never run across tapes recorded with these systems. Let me know if 
you have any that need decoding. I'd love to do them using the hardware 
decoders.

Two consumer formats that I do not have hardware decoders for are JVC 
Super ANRS (1978) and Toshiba ADRES (1982). Is there anyone who can 
decode these and, more importantly, does anyone have tapes encoded with 
these systems?

Finally, in the early days of this, Richard Burwen introduced the Burwen 
Noise Eliminator in 1971 (same year as DBX). I had one in on evaluation 
when I worked at ABC Television and we didn't see a need for it. It used 
a more aggressive compander curve and unknown equalization. While DBX is 
a 2:1 compander, Burwen was reportedly a 3:1 compander, but there may be 
a knee in it based on one paper I saw. Since this is the only 
potentially professional format that I cannot decode either in hardware 
or software, I was wondering if any archive had any recordings in this 
format and how they were planning on playing them back.

The sad part about NR systems is, in a sense, they hold your recordings 
hostage. We have suspected and known instances of tapes being 
commercially released without proper NR system decoding, including one 
instance where the producer and artist liked the brightness that came 
with not decoding the Dolby A.

Thanks, all, for any input you can provide on or off list. Since John 
and I are doing this (we hope to be able to sell some packages, to be 
honest) we want to make certain all archives' needs are met in one way 
or the other.

Cheers,

Richard


-- 
Richard L. Hess                   email: [log in to unmask]
Aurora, Ontario, Canada                             647 479 2800
http://www.richardhess.com/tape/contact.htm
Quality tape transfers -- even from hard-to-play tapes.