ID these L-C eq cards with VP Trans-amps

Long shot, but thought I'd try. Cleaning out some shelved projects. I've looked high and low on and off for years for any info I can find on these but no luck. I've got all the available app notes for the Valley Trans-amp, have looked through the usual suspect MCI and Soundcraft docs from the late 70s/early 80s. Same deal.

It's easy enough to ID some (most?) of the pins since the Trans-amp is labelled, but with traces on the top side running under soldered components it's hard to figure all of them out with certainty.

No labeling/text anywhere on the PCB that I can see.

Any ideas? I'm starting to think these might have been some of the application demos/prototypes Paul Buff made, but it's just a guess based on lack of any docs. Before I start guessing/testing/blowing up, I thought I'd ask.

Thanks,

BT

 

b

The Transamps were pretty popular building blocks back in the early 80s. The PCB edge connectors look like something we would use/see in a console from around that time frame.

JR

Agree. That's why I went down the MCI and Soundcraft alleys. All kinds of info out there about how their consoles from that era were modded with Trans-amps.

But the trimmer-style pots have me wondering if these might be from a cart unit or something. Hope not, because if so there's even slimmer chance of finding anything out about them.

rackmonkey said:

Agree. That's why I went down the MCI and Soundcraft alleys. All kinds of info out there about how their consoles from that era were modded with Trans-amps.

But the trimmer-style pots have me wondering if these might be from a cart unit or something. Hope not, because if so there's even slimmer chance of finding anything out about them.

Click to expand...

Transamp app notes show trims for CMRR.

JR

I meant the row of trimmer style pots on the front, which appear to affect EQ settings. Trimmer style as opposed to easily changed regular knobs.

rackmonkey said:

I meant the row of trimmer style pots on the front, which appear to affect EQ settings. Trimmer style as opposed to easily changed regular knobs.

Click to expand...

Agree they look like tape machine cards, but what do you want to do with them?  Probably pull the TransAmp and transformer and build  something cool  8)

I can imagine transamp being used as a low noise head amp for a tape machine.

JR

mjrippe said:

Agree they look like tape machine cards, but what do you want to do with them?  Probably pull the TransAmp and transformer and build  something cool  8)

Click to expand...

Well, that’s the question, isn’t it? I wanted to hear what they sound like as is, though given the tiny inductors I probably shouldn’t expect that they can take much level. If that’s turns out to be the case, it’s on to plan B.

But reading past posts about the Trans-amp, i’m Not sure what to do that’s cool with them. IIRC, CJ wasn’t super impressed with what he built with them. “Clinical and boring” is what I took away from that thread.

Has anyone come up with a circuit they really like with these things?

I am kind of intrigued by using the TAs for make up gain in an inductive EQ.