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Analog Devices 111 Discrete Op Amp
Old 26th January 2009
  #1
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ulysses's Avatar
 
🎧 15 years
Analog Devices 111 Discrete Op Amp

Anybody seen one of these before? I found it inside my CBS Labs 710 Automatic Loudness Controller. It looks like this unit was built in about 1968, around the time Melcor was introducing the op amp to the studio world. It has the same footprint and it looks like it has the same pin-out as the Melcor and API amps (including the Trim pin).
I thought this was interesting. I'd love to hear what anybody knows about the early history of this form factor, which came first, who first used this layout, etc.
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Analog Devices 111 Discrete Op Amp-img_3389.jpg  
Old 4th March 2009
  #2
Here for the gear
 
🎧 10 years
Ulysses,
I just received a CBS Labs 710 Automatic Loudness Controller from an old timer who I asked about any vintage compressor/limiters that he might have. I have not had a chance to do any real testing with it yet. If you have any opinions to share or any more info on this unit please keep me in the loop.........I am all ears.

BTW I may have the original manual that came with the unit coming my way. If you are interested in a copy let me know. I would be happy to copy it.

Iggy
Old 5th March 2009 | Show parent
  #3
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ulysses's Avatar
 
🎧 15 years
Great to hear, Iggy, thanks.
I haven't actually listened to the 710 yet. It sat on a shelf, then it needed some cleanup, and then I didn't find the time. But I will. I expect it to be pretty cool. The opto element is interesting - an incandescent lamp and an LDR in one integrated package. I was able to change the LDR from essentially open circuit to something like 80 ohms by applying a half-dead 9V battery to the lamp terminals. Seems like you could get a wide range of compression with something like that. The sidechain in the 710 is another story. Seems needlessly complex. All this frequency-dependent detector nonsense that all gets summed into a single gain control element. But I would love to see a full schematic so I can see exactly what it does, and think about maybe tinkering with it a bit. I have a photocopy of a little manual that doesn't include a schematic. I've drawn out the schematic of the audio board, and I know the power supply pretty well because it's the same as in the Volumax, but the entire sidechain is kind of a mess that I haven't really dug into. I probably won't unless I get a schematic. So yeah, if you get that manual I'd love a copy. I should probably operate the thing and evaluate it a bit before I yank out the AD111 and replace it with something a little more common (so that I can fiddle with the AD111 elsehow).
Old 5th March 2009 | Show parent
  #4
Lives for gear
 
🎧 15 years
A lot of that is radio oriented level holding stuff. Long term averaging that set's and holds a threshold plus the normal attack and release stuff.
Old 6th March 2009 | Show parent
  #5
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ulysses's Avatar
 
🎧 15 years
Yeah, that's why I'm thinking a lot of it could be bypassed. This opto shouldn't need anything more than a little amplifier driving the bulb with audio to turn it into something vaguely LA3a.
Old 14th April 2009 | Show parent
  #6
Here for the gear
 
🎧 10 years
Justin,

I was able to get ahold of the owners manual for my 710. I scanned it and have a PDF copy for you. It is the full manual with schematic. The PDF File is 4mb let me know the address that you would like it sent to.

Iggy
Old 14th April 2009 | Show parent
  #7
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ulysses's Avatar
 
🎧 15 years
Thanks, Iggy. If you click my company link below, you'll find yourself on a Roll Music page with an e-mail link at the bottom.

Cheers!
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