Audio+Design F769XR vocal stressor stereo link?

Someone asked me how to stereo link two of that boxes. He told me that every box has a link switch, but he cannot find any stereo link port.
Any idea? Any schematic?

The compressor stereo switch links to the "A" (compressor side chain) board, via the A16 edge connector. It effects the compressor and the expander sidechains, but does not effect the peak limiter sidechain, which remains independant.

From looking at the service manual, and the owners manual it looks as though it shouldn't even have the switch there on the F769X-R, the manual says that the switch is for stereo units only, so I don't know what it is on this unit for. They suggest setting each channel up seperately, and then throwing the switch.

Oddly enough, my unit does have a switch, while in the manual the photo of the unit has a blank plug in the switch hole. The photo of the F760X-RS stereo unit does have the switch. It has got me thinking now that I had better pull my unit apart and see what that switch is connected to, perhaps some studio tech in the distant past has used the hole to put a switch into for some other function entirely...

So getting back to your point, if you are lucky enough to have 2 of them then it should be a simple matter to put a stereo linking connector onto the unit if you don't mind drilling the case, but I would be suspect of that switch if your units have them, because mono units look like there is not supposed to be a switch there at all, just a blanking plug. But linking the 2 sidechain amps via A16 should get you going, don't forget the instruction to set up both units seperately before linking.

Thanks for your infos. I will get this boxes a few days later for modding. Do you have that service manual in an electronic form? Is it easy to find that A16 connector?

I have most of the documents on my .mac site, try here:

http://homepage.mac.com/agenttriez/FileSharing3.html

Thanks to Niko, I will soon scan and put up the schematic there for the ADR Gemini Easy Rider also.

By the way,please let me know what you find with the switches on your units, it is a bit of a mystery...

Thanks Steve, this will help alot.
If I can take look inside I will tell you about that mystical switch.

Hey Kubi, I have posted the Gemini schematics on the same site just now... Enjoy! Niko photocopied them and posted them all the way from Germany, and I scanned them this evening.

Hey Mr. Jones,

thank you for those schematics. Do you as well have the manual for compex? (I'm looking for those for FS760).

best regards

Chris

Thanks Steve, that's great. Do you have any idea which FETs are used here please?

I do have a manual for the F760X series of Compexes, I will put it up eventually, it is a lot of scanning. The service notes and calibration and schematics are on my site, but the only part of the owners manual I have put up is the all important "Establishing the unit in the channel" section, because as amazing as this compressor is, you will get nowhere if you don't set it up as ADR instruct, so it is really important to download and laminate this page.

Basically to use the compressor, you have to set the gain with the PEAK LIMITER first, and then turn on the compressor and (if desired) turn off the limiter. Everything is referenced to the limiter. It is not at all a unit that you can just walk up to the first time and use without a cheat-sheet, but it is an awesome unit when set up correctly.

The FET's in my unit are (according to the silkscreen and schematics)
2N3819's and a 2N3820.

The FET on the C board is a 2N3819 as spec'd, the FET on the A board is also supposed to be a 2N3819, but it is a white ceramic body marked:

E231 7647

so I don't really know what this is, and the FET on the B board is scrubbed, so I can't read the markings on it, but it is supposed to be a 2N3820.

Further on the mystery stereo switch, I just pulled my Vocal Stresser to bits and traced the switch wires - the DPDT switch had 2 wires connected, one to board A16 and one to board C5, which are the compresser sidechain and the expander sidechain. There were no other wires connected to the centre poles, so obviously the switch is there ready to have the 2 leads connected from the same PCB points on a second compressor, so what you have to do is to put a pair of sockets (or a stereo socket) on the back of each unit and wire the centre terminals of the switches to them. It needs one wire for the compressor link and one for the expander. Currently, as it is wired, the switch does nothing.

Thanks Steve, it seems to be an easy job. I will report my results.

From memory there was a white wire and a white with grey stripe on the switch, so if yours have the same colors then they are probably the same. The block diagram on my site should explain it, I doubt there would be any extra components needed, but good luck.

Chriss,
If you're desperate for a Compex manual you can still get them from ADR (£15+Vat) - they contain the schematics plus not-completely-foolproof setting up instructions (however we got there in the end!). As Steve says though, you're p***ing in the wind without the manual.....Tel +44 (0) 118 984 4545 for ADR
Matt

Thanks for the info re the FETs Steve - no problem here getting hold of 2N3819!

I wish I had some kind of tester to measure the characteristics of the 3 specific FET's in the unit, it would be great to log them to make replacement matching easier in the event of failure.