Broadcast Audio Processor History

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mediatechnology
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Broadcast Audio Processor History

Post by mediatechnology »

Barry Mishkind's website has an interesting history of Broadcast Audio Processors

Part 1 "The Audio Prism Story," by Glen Clark: http://www.thebdr.net/articles/audio/pr ... oPrism.pdf

Part 2 "The Era of Multiband Processing," by Jim Somich with Barry Mishkind: http://www.thebdr.net/articles/audio/pr ... -hist2.pdf

Part 3 "Digital Processing Starts Making Noise," by Jim Somich with Barry Mishkind: http://www.thebdr.net/articles/audio/pr ... -hist3.pdf

Part 4 "WCRB and the Classical Music Wars," by Grady Moates http://www.thebdr.net/articles/audio/pr ... lAudio.pdf

I found some interesting quotes in these articles
You see, there is a lot more magic in the Audio Prism than Glen talked about in his article last month. His control voltage side-chain is a work of art: there are four comparator “trip points,” creating five operational “level windows” for
the audio: [1] too low to do anything with, so do not do anything 'cause it is probably noise, [2] high enough to probably be useful program material, but not high enough to be competitive, so bring it up, [3] right where it needs to be, [4] too high, so bring it down, and [5] way too high, grab it quickly and YANK it down – but release it quickly when the momentary overload has passed. Most other processors of the day only had [2] and [4] worked out, so Glen‟s side-chain was already perfect for classical music.
Another magical thing about the Audio Prism is the musical way that attack and release times were controlled. Up until the Audio Prism, time constants were quite variable, because they were usually derived directly from the peak level of the audio envelope. Glen‟s approach was different – all of the bands in an Audio Prism used the same attack and release time constants. Also the timing was developed with current sources/sinks driving capacitors, for a very smooth, musical gain change.
brianroth
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Re: Broadcast Audio Processor History

Post by brianroth »

Interesting articles! Back in the early 1980's I was involved with the British company Audio+Design (best known for their Compex and Vocal Stresser dynamics boxes). I wrote this ad:

brianroth.com/library/audio+design/a+d-transdynamic1981.pdf

A friend of mine was Chief Engineer for the top rated local rock station at the time, and he installed one of the systems ahead of I-don't-recall-what in his audio chain. But, Lloyd used six (!) Compex channels (3 bands per on-air channel) which provided a TON of adjustability.

http://brianroth.com/library/audio+design/compex.pdf

Bri
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mediatechnology
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Re: Broadcast Audio Processor History

Post by mediatechnology »

Wow. I used to have a Compex.

I think I still have the manual. ADR made some nice stuff...
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Re: Broadcast Audio Processor History

Post by brianroth »

There is other Kewl Stuff in the "processing" section of Barry Mishkind's website...particularly Part 1 of the processing history which goes back into Ye Olde Tymes:

http://www.thebdr.net/articles/audio/proc/index.html

I never knew the ancient GE units actually used the audio to modulate an RF carrier which was then clipped, then demodulated!


Bri
Professional audio and video systems design/installation/maintenance.
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brianroth
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Re: Broadcast Audio Processor History

Post by brianroth »

mediatechnology wrote:Wow. I used to have a Compex.

I think I still have the manual. ADR made some nice stuff...
I have some random scans of A+D docs posted here:

http://brianroth.com/library/audio+design/

Includes several magazine ads that I wrote (we "re-branded" ADR as A+D back in those days) as well as some schematics. I still have a bunch of un-scanned A+D tech info in my file cabinets.

Also a pic of my great friend Nigel Branwell when he was obviously quite young...he was the director of USA operations back in the early 1980's. Nigel went on to work extensively with the marketing of Ambisonics microphones. Alas, he passed away 10 or 15 years ago.

Oops...looks like I accidentally hijacked this thread! <g>


Bri
Professional audio and video systems design/installation/maintenance.
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