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Hey, new to the forums, not new to gear and recording. So i built an SSL comp clone using audio kitchen PCB's and THAT 2180 pre trimmed VCA's. Long story short I had some DIP sockets laying around that were 9 pins long so i used those for the VCA's. in some fit or whatever (prolly being to tired) I put the left and right VCA's in backwards and 1 pin that means pin one on the VCA went to nothing, pin 2 was connected to pin 8 on the PCB, pin 3 VCA was at pin 7 PCB etc etc. .I replaced all 3 VCA's and i now have audio passing through. Bypass works and i have some control over the level via threshold and make up gain knobs, but no compression, no meter movement. is it possible I fried the TL074 and or the 072? Im usually prett good at assembling things, but Nto so good at electronic trouble shooting when it comes to more complex circuits such as these. Though if explained, Ill prolly understand. Its late, and I'm frustrated, lol.

Oh and the audio is distorted unless i got the levels fairly low. Something I think may have been unhapy with the VCA's in wrong, I dont understand exactly the flow of the schematic and where the audio goes in and out vs the control voltage. if i spent hours with the schematic i may get it, but some help would be greatly appreciated.


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Boswell Thu, 06/16/2011 - 05:44

I did not know that Audio Kitchen produced a kit for an SSL compressor, and I can't see anything about it on their rustic web site. Without a schematic, it's not easy to say what the mis-connected conditions were, but there's a good chance that the transresistance amplifier following the VCA got damaged as well.

I would not want you to post the schematic in a public place, but if you were to scan it and upload the scan to YouSendIt followed by posting the download link to my Private Message box here at Recording.Org, I could take a look and get a better idea. I'll delete it after use.

In bypass mode, does the unit pass full-scale level signals?

autocomman Thu, 06/16/2011 - 09:29

The clone isnt a secret, there are schematics everywhere, so ill post the link to one of the designers pages with the schematic right on the page. Its all open source DIY. From what I gather audio kitchen among others made PCB's, not kits. There were files also to mask ur own PCB as its only a 2 sided pcb. But all i got was the boards, and more searching found a 3 year old outa date parts list, etc etc...its been a challenge to get this all together as it seems to be yesterdays news, hah. But ya. It will pass full scale audio in bypass no problem. Can u take a look at the page below and tell me what u think? thanks!

[[url=http://[/URL]="…"]SSL Clone construction page[/]="…"]SSL Clone construction page[/]


Boswell Mon, 06/20/2011 - 03:47

Since it passes audio OK in bypass, you should concentrate on the sidechain, but, as Link said, you will have to do some debugging work if you want to get a handle on this. You will need a signal generator (the phones output of a PC can be persuaded to work as one when running a suitable program) and a multimeter, or, better, an oscilloscope. Once you have this set up with a 1KHz sinewave running through the compressor, we can give you some pointers as to what should happen and what you should see at various parts of the circuit.