matta

ADR Compex F760
« on: June 17, 2006, 05:32:00 AM »
Hey Guys,

I was able to pick up and old ADR F760 Compex Compressor Limiter (without the Gate section) from a local studio for a song (Under $100USD), one channel is not working and the second has a distortion.

I decided I would be worth giving it an overhaul to restore it. It seems the lytics are original and the unit came out mid 1970... so it is in need of one.

It is a FET based stereo compressor limiter, which was later replaced by the Compex, which included an Expander.

It is built like a tank and the wiring is amazing, not to mention quality pots from Radiohm (a love hate relationship for some) and ELMA switches, with 2 Sifam meters and all discrete.

The design is quite brilliant using a series of plug in cards, including a plug in 'simple' PSU, and the compressor split over 2 cards and a third mating/edge connector card.

I thought I'd post some pics.

Front Panel:




Inside Shot:




Inside Close Up:




Compressor and PSU Boards:


 

Compressor Boards A:



Compressor Board B:




Mating/Edge Connecter boards:



They don't make them like they used to.

Cheers

Matt
Matt Allison
www.matt-allison.com

Quote
We are not going to start thinking of ways to get an octopus to commit a crime, cause that just has failure written all over it – Earl J Hickey


radiance

ADR Compex F760
« Reply #1 on: June 17, 2006, 06:10:00 AM »
Looks very well build, and for $100 a real bargain if you ask me.
So how you're going to proceed? Replace all the lytics and see if it works?
"Knowing that you are dreaming, however, does not automatically guarantee full rationality.
Then again, being awake doesn't ensure good thinking, either." -  Lynne Levitan

matta

ADR Compex F760
« Reply #2 on: June 17, 2006, 08:48:53 AM »
Quote
Looks very well build, and for $100 a real bargain if you ask me.
So how you're going to proceed? Replace all the lytics and see if it works?


Well it will be a start. I think the unit should be recapped anyway seeing how old it is. There are no visible signs of burns, or shorts, and the PSU which should be putting out +24VDC on 2 rails is giving me around +22.6VDC after rectification.

I've found the schematics and marked out all the Electrolytics, and will compare the schematic values with my card values and then replace them all and power up and see.

The FET's are socketed and the sockets it showing signs of corrosion, so will prob sub it out as well.

The unit powered up fine and the meters seems to track, so hopefully a recap and recalibration is all that is needed, if not, troubleshooting begins  :green:

At $100 it was a STEAL! The guy has had it sitting around in storage for a few years, so was glad to se it go I think.

I've seen working compexes go for over $1,500USD on Ebay and around 800 Euro's, not that I plan on selling it, but it makes me feel good about the buy.

Matt
Matt Allison
www.matt-allison.com

Quote
We are not going to start thinking of ways to get an octopus to commit a crime, cause that just has failure written all over it – Earl J Hickey

matta

ADR Compex F760
« Reply #3 on: June 17, 2006, 11:31:18 AM »
Hey Roger,

Yip, going to stick with Axials. I can get all the values I need in the Vishay BCC 021ASM series, not the cheapest, but wanting to restore with some quality caps.

I've just checked the boards against the schematic, a few deviations have been made I see, like 2 of the 8uF caps on the Schematic being 15uF on the boards, but I think it is because they use around 10 15uF's on the boards anyways.

Will order from Farnell, so will take about 2 weeks to proceed,  in the meantime I'll recap the PSU.

Cheers

Matt
Matt Allison
www.matt-allison.com

Quote
We are not going to start thinking of ways to get an octopus to commit a crime, cause that just has failure written all over it – Earl J Hickey

ADR Compex F760
« Reply #4 on: June 17, 2006, 12:05:12 PM »
I've got the exact same box but with the input output trafos mounted by the xlrs.  great piece and works fine I got it for about 1000 us from a place in london some years back.  good luck with the project, looks like a steal.
A

mattmoogus

ADR Compex F760
« Reply #5 on: June 18, 2006, 10:36:56 AM »
Hey Matt,

Youve probably already checked this but I thought Id mention...the vocal stressors we have (same era by the looks) were wired unbalanced, pin 3 hot.  So when you plugged them into a modern unbalanced input youd get no sound.  How are yours wired?



[email protected]
...btw I work for Joe :-)

matta

ADR Compex F760
« Reply #6 on: June 18, 2006, 03:27:40 PM »
Hey Matt,

Funny you should mention that  :green:

When I first tried the unit I wired it up modern standard of Pin3 Cold, Pin2 Hot.

After I found the schematics and mapped all the caps and values I THEN discovered a block diagram document with the I/O config, Hah hah! After wiring her up some new cables and testing her, she works!

Channel 1 had some really noisy pots which I was worried was DC leakage, but they turned out to be dirty. I popped in some Servisol, worked it into the pots and now she is a good as new.

I'll prob go ahead and order the rest of the caps and get around to recapping her when I get a chance.

This is one REALLY nice compressor, 1176'ish in sound, so far I've just put some Acoustic Guitar through her, but enjoying the sound.

For $100 and a few hours of my time I think I scored great!

Cheers

Matt
Matt Allison
www.matt-allison.com

Quote
We are not going to start thinking of ways to get an octopus to commit a crime, cause that just has failure written all over it – Earl J Hickey

Rob Flinn

ADR Compex F760
« Reply #7 on: June 19, 2006, 05:37:18 AM »
Matt

It's worth checking if the 2 channels track well.  I have the earlier version of this unit (3U).  Both channels work but sound different, when set the same.  

Also in the 3U version the cards are mounted upright, which makes setting them up a pain unless you have extender cards.  I'm going to open mine up(when I get a chance) to compare my cards to the ones in yours, because mine have more presets than are in the manual, which has made me wary of messing with them.
regards Rob

matthias

ADR Compex F760
« Reply #8 on: June 19, 2006, 05:47:04 AM »
congratulations...  that's really a bargain...

the boards doesn't seem to be very complex..
do you think it would be worthwile to make a diy project??

how does it sound on drums?

chrissugar

ADR Compex F760
« Reply #9 on: June 19, 2006, 05:55:49 AM »
Quote from: "matthias"

the boards doesn't seem to be very complex..
do you think it would be worthwile to make a diy project??


Maybe put those boards on a scanner?  :grin:

There is only one 760 in the country and I tried to convince the owner to sell it to me but no success. So it looks like the DIY route is the way. :grin:

chrissugar
Christian Mike Sugar
        CMS-LAB


API

ADR Compex F760
« Reply #10 on: June 19, 2006, 01:55:40 PM »
I have four of the console version of this compressor.
Sounds amazing i think, great on drums and acoustic!!

Have just recapped 2 of them (with BC/philips caps like they originaly used) and is going to set them up and do a stereo match.
Sowter still makes the original transformers for them, so you can add them if you want, quite expensive though.
Will run mine unbalanced for now, maybe balance the other pair when i rack them.

Great find!!

Regards,
Dennis

soundguy

ADR Compex F760
« Reply #11 on: June 19, 2006, 02:04:02 PM »
the original had 600 inputs you can also try a 10K in there.  The gain structure in these things is so entirely f**ked that the difference between a 600 and 10K isnt subtle at all, at least not in my studio.  I have one with original transformers and one I put new 10K's in and they are different enough to keep them use specific.  The 10K inputs leave the unit a little cleaner, which in this design is definitely a plus.

I dont know if I would be very excited to do a board layout for one of these, it would be a lot of work and totally not worth the effort to bother with unless you can come up with the entire manual so you can set the thing up correctly.  The F600 btw is just the compressor, that would be the one to work on if you had to do it, save a lot of energy leaving the expander circuit out.

dave

chips are good with dip...

matta

ADR Compex F760
« Reply #12 on: June 19, 2006, 02:39:14 PM »
Quote
It's worth checking if the 2 channels track well. I have the earlier version of this unit (3U). Both channels work but sound different, when set the same.

Also in the 3U version the cards are mounted upright, which makes setting them up a pain unless you have extender cards. I'm going to open mine up(when I get a chance) to compare my cards to the ones in yours, because mine have more presets than are in the manual, which has made me wary of messing with them.


Hey Rob,

Both channels seem to track well, but the second channel seems to be around 5 dB's quieter than the first. I will need to recalibrate them when I get a chance.

Mine is the 2U version and the cards can be accessed by removing the the top and bottom panels, and placing the case sideways, you can then access from Boards A and B, MUCH easier than extender cards.

Do you use yours much?

Quote
the boards doesn't seem to be very complex..
do you think it would be worthwile to make a diy project??

how does it sound on drums?


Not tried Drums yet, for not the box has been reassembled and put away in storage, will only play with it when I complete my 2 channel Neve and the API's I'm working on... kind of like a prize at the end.

The comp boards are pretty easy, the mating board is crazy with loads of twisty traces and off board wiring... would require the whole disassembly of the unit to work out all the wires, the wiring and pin is is rather illogical...

Quote
Have just recapped 2 of them (with BC/philips caps like they originaly used) and is going to set them up and do a stereo match. Sowter still makes the original transformers for them, so you can add them if you want, quite expensive though. Will run mine unbalanced for now, maybe balance the other pair when i rack them.


Mine don't have the optional Sowters, and are unbalanced. The caps are BC/Phillips, but I think BC is not owned by Vishay, which are the caps I was speaking of earlier in my posts. I'm going to order a set and when I find some spare time I'll prob recap the unit.

Quote
I dont know if I would be very excited to do a board layout for one of these, it would be a lot of work and totally not worth the effort to bother with unless you can come up with the entire manual so you can set the thing up correctly. The F600 btw is just the compressor, that would be the one to work on if you had to do it, save a lot of energy leaving the expander circuit out.


I have the entire hand written tech manual from ADR, which def. is a big help, along with the set up  manual as well, which you need to do to make this compressor make sense.

Dave my understanding is the F600 is the Limiter, not the same as the Compressor-Limiter in the 760. My unit is a F670-RS, which seems identical to the the Compex (F670X-RS) with exception of Board C, the Expander Board and associated controls.

Cheers

Matt
Matt Allison
www.matt-allison.com

Quote
We are not going to start thinking of ways to get an octopus to commit a crime, cause that just has failure written all over it – Earl J Hickey

soundguy

ADR Compex F760
« Reply #13 on: June 19, 2006, 03:02:13 PM »
omg matt, what needs to happen to get those manuals on the web or copied and in the mail???   Seems like everything that is available is only snippets.

I thought the ratios on the f600 were adjustable, but maybe not you might be right.  I had always assumed that the F600 was the mono predecessor to the unit youve got there.

dave

chips are good with dip...

cannikin

ADR Compex F760
« Reply #14 on: June 19, 2006, 03:17:35 PM »
Hey Matta,

I have the same one.. only my 2 channels are in on the Busses of my tiny Console... If you have any questions ask away.
Tube limiters..yum!

matta

ADR Compex F760
« Reply #15 on: June 19, 2006, 03:34:57 PM »
Hey David,

I've seen yours in your console... I try not to think about it cause it keeps me awake at night  :green: I caught a pic on Gearslutz a while back! What a beauty.

Dave I hear you on having everything in one place!

Here is what I have.

The Block Diagram of the ADR Compex
The Schematics for Cards A, B and C
The Set-up Docs for the Compex

All of which I got from Steve here and are up at Kev's site here: http://www.diyfactory.com/data/stevejones.htm

Then I got the handwritten tech notes for the 760S for the alignment and set-up, courtesy of Tim Farrant of Buzz Audio.

They are on his site, but I'm not sure I can link them, I'd need to ask first I think, or at least ask to host them on my site.

Cheers

Matt
Matt Allison
www.matt-allison.com

Quote
We are not going to start thinking of ways to get an octopus to commit a crime, cause that just has failure written all over it – Earl J Hickey

Rob Flinn

ADR Compex F760
« Reply #16 on: June 19, 2006, 07:26:00 PM »
Quote
Sowter still makes the original transformers for them, so you can add them if you want, quite expensive though.


Mine has gardeners transformers & ampex, both of which are the octal plug in types.

Matt
Quote
Both channels seem to track well, but the second channel seems to be around 5 dB's quieter than the first. I will need to recalibrate them when I get a chance.


This is similar to what mine is doing, but one chennel is not sounding the same as well.  They are supposed to be a bit known for needing regular calibration.

It is a pain with the cards vertical for the reasons you state.   I spoke to Mr Harley who designed these.  A very nice, helpful man.  However he couldn't remember anything about setting up my version & I've never found a proper manual for it despite several requests.  

I know everyone will ask for internal pics of mine, but I can't take any until I by a new digital camera, because a friend dropped the one I had last week & bu****ed it.
regards Rob

matta

ADR Compex F760
« Reply #17 on: June 19, 2006, 07:30:35 PM »
Hey Rob,


Quote
I know everyone will ask for internal pics of mine, but I can't take any until I by a new digital camera, because a friend dropped the one I had last week & bu****ed it.

 
Dejavue...

The pics of my ADR were the first pics I took using my new digital camera after the last one gave up the ghost after 3 years... spooky...

Matt
Matt Allison
www.matt-allison.com

Quote
We are not going to start thinking of ways to get an octopus to commit a crime, cause that just has failure written all over it – Earl J Hickey

Rob Flinn

ADR Compex F760
« Reply #18 on: June 19, 2006, 08:35:47 PM »
Matt

what camera did you buy.  I'm not sure what to get. All the new ones don't seem to use CF memory cards, which is annoying.
regards Rob

gang of elk

ADR Compex F760
« Reply #19 on: June 19, 2006, 09:52:48 PM »
Interesting, mine has original sowters, input is 10k, output 600.

Hey dave, was the 600 input in yours original you think?   The manual I have here shows input transformer spec to be 10k input.   Maybe someone put a 600 in yours, causing fussy gainstaging, as you mentioned.  I never thought of it as a problem but like I said mine has 10k input.  

On the output, when adding a transformer, the 3k3 resistor that sets gain in the line amp of the 'B' board should be removed (junction of 15uf and 47k feedback R).   The manual states that there is no degradation of signal to noise when doing this.   Probably good to check this on units that did not come w transformers but had them added later.


 

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