DBX/THAT 202 Test jig?

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pinebox

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Mar 11, 2015
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Has anyone made a stand alone test jig for these VCAs? I could sacrifice a VCA card from an SSL module but then I would need to break out a whole channel strip whenever I want to test one. Thought about making one from just the 4k SSL VCA card alone with but then I would need to mess with the logic so I was wondering if anything like this is already out there before I invest time tinkering. Thanks.
 

gyraf

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you could just make a one-channel GSSL, socketed 202 module, no sidechain VCA, ratio, timing or rectifier, check 202 by turning makeup-gain?
 

David Kulka

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I built one a while back. I don't know whether I documented it but if I can find anything I'll post it here. Basically you just need +/- 15 VDC, correct input impedance, the right CV range and scaling for the control input, and some resistors or trimmers for distortion null adjustment, IIRC. I don't think it needed an output buffer. I used color coded grabber clip leads for the 202 connections.
 
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David Kulka

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Here's a photo of my VCA tester. I'd forgotten how elaborate it is. :)

It's set up to test 200, 202, and 202C VCA's which are all a little different. The clamp at the bottom holds the VCA in place, upside down. The grabber clips connect to the pins of 202's and 202C's. For 200's I use the two Molex connectors. The pot with the dial adjusts the control voltage. I think I might have used a reverse log pot to give the range better linearity, but I'm not sure. The PCB has a buffer amp which may be on the input, to isolate the signal source and deliver a specific input impedance.

Unfortunately I don't have any documentation for it but if you have 1 or 2 specific questions I could probably answer them. Good luck with your project.
 

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Rob Flinn

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I built one a while back. I don't know whether I documented it but if I can find anything I'll post it here. Basically you just need +/- 15 VDC, correct input impedance, the right CV range and scaling for the control input, and some resistors or trimmers for distortion null adjustment, IIRC. I don't think it needed an output buffer. I used color coded grabber clip leads for the 202 connections.
Would the op amp be on the output. One normally needs an I to V convertor on the output.
 

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