Audio and Design F760

[[silent:arts]]

I started to calibrate a F760 at work two years ago ...
Seamed to be an easy job, since I found the calibration manual (in german) at work too.
started to tweak the trim pots, realized too late the PCB has 3 more trimpots than the drawings / descriptions  ???

 

[hodad]

I would like to add transformers for my Compex. It´s the same as shown in the pictures above. Do I need simple 1:1 trannies for input and output?

Go here
http://www.groupdiy.com/index.php?topic=6006.0 for more info.  According to info here, some outputs were wired 150:600.  I just picked up a pair of MU7524's for the outputs--don't have any input transformers yet.

 

[matthias]

does anyone know Heinrich Keinert from Berlin ?
someone told me that he partly developed, serviced and modified a lot of ADR gear in the 70s and 80s.
If I remember right, he still services ADR gear on request.

 

[Rob Flinn]

I started to calibrate a F760 at work two years ago ...
Seamed to be an easy job, since I found the calibration manual (in german) at work too.
started to tweak the trim pots, realized too late the PCB has 3 more trimpots than the drawings / descriptions  ???

That is precisely my problem, the difference being that I worked out that it had 3 extra pots before I tried to calibrate it !!

 

[Slenderchap]

@ colin:  did you design a new pcb from the schematic? or did you copy the original pcb?

At this stage I have simply done it from the schematics.... (with a couple of obvious schematic errors corrected)....  I put the 3 PCBs on one PCB .... but they are not interconnected except for power.... so it can be treated as though it were 3 individual circuits.

The idea at the moment is to do some experimetation.... so it was done "as simply/cheaply as possible"..... all the switch resistors etc will be soldered to the switches on the front panel.

Colin
www.audiomaintenance.com

 

[sahib]

I like PCBs designed that way, placing circuit blocks individually on the PCB where possible. A lot of equipment used to be designed that way and it was a bliss to service them.

 

[Rob Flinn]

Colin,

Does your board have the 3 extra presets that nobody seems to know about included ?

 

[Slenderchap]

I would say probably not as it was done from the schematics....  but until the unit I purchased arrives I don't know.

It may be of course that by the time it is completed as a project many of the trimmers have been dumped anyway.... it is rare that a circuit needs that much "adjustment".... given the accuracy of the 7824 and 1% resistors..... but we'll see.

Colin
www.audiomaintenance.com

 

[bernbrue]

Hi,
opened my Compex to add some transformers. I took some inside fotos. Enjoy!
regards
Bernd

http://www.twin-x.com/groupdiy/albums/userpics/Compex_002.jpg

http://www.twin-x.com/groupdiy/albums/userpics/Compex_003.jpg

http://www.twin-x.com/groupdiy/albums/userpics/Compex_004.jpg

http://www.twin-x.com/groupdiy/albums/userpics/Compex_005.jpg

http://www.twin-x.com/groupdiy/albums/userpics/Compex_006.jpg

http://www.twin-x.com/groupdiy/albums/userpics/Compex_007.jpg

http://www.twin-x.com/groupdiy/albums/userpics/Compex_008.jpg

http://www.twin-x.com/groupdiy/albums/userpics/Compex_009.jpg

http://www.twin-x.com/groupdiy/albums/userpics/Compex_010.jpg

http://www.twin-x.com/groupdiy/albums/userpics/Compex_011.jpg

http://www.twin-x.com/groupdiy/albums/userpics/Compex_013.jpg

http://www.twin-x.com/groupdiy/albums/userpics/Compex_014.jpg

 

[Rob Flinn]

Are you sure you have enough resolution on those pics ? 

 

[bernbrue]

Since I started with DIY I have to wear glasses  ;D
regards
Bernd

 

[Rob Flinn]

Bernbrue

Just checking your pcb's against mine & they a not the same.
My version even has discreet voltage regulators. No 7824 in my F760X-RS

I'd be happy to take some pics, if someone can host them ??  I don't have any webspace at the moment

 

[bernbrue]

Hi,
you can upload them here
http://www.twin-x.com/groupdiy/
regards
Bernd

 

[bernbrue]

Hi,
Compex with Haufe RK 310 trannies. They do an excellent job.
regards
Bernd

 

[dustbro]

Prototype PCB will be here next week....
I think I have this one pretty well covered.

Colin

Very exciting!

 

[Rob Flinn]

Hi,
you can upload them here
http://www.twin-x.com/groupdiy/
regards
Bernd

Tried registering here, but it's not confirming by email ?  any ideas ?

 

[bernbrue]

Hi,
these pictures are from Robs unit. That´s a completely different Compex. 3RU and different frontpanel.

regards
Bernd

 

[roginator]

whell I asked about compex DIY about a year ago...and everybody told me that is toooo difficult job to do

so couse of that now I have 2 compex ( one with and one without trannies)
also I have scamp rack loaded with 5 S01 compressors....

depends what you need but all 3 models sound different..I love scamp S01 and its very close sounding to F760X RS without trannies... maybe sound even better on some aplications than compex...

also some guy at Qaudio is working on 500 format compex last 2 years

i will upload tomorrow some documentations I have on ADR F760 wich are not on DIY Factory!!!!

 

[q2audio]

Hi Guys,

I think it was a Gear Slutz post that incorrectly named me as "Qaudio"; it's actually Q2 Audio...

Yes, I've been working on a Compex reissue with support from Ian at ADR (now called "Audio Design (Reading)") for about two years. What is taking so long? Too many other things going on in my life, working a day job that sucks the life out of me, three other products in concurrent development not to mention certain parts manufacturers dropping the ball repeatedly and I don't have the time during working hours to make sure they are (were) doing their jobs. My prototype is nearly completed at this point.

My goal was to fix some of the annoying problems associated with the original design: drifting calibration, poor stereo pots, changing one switch or pot requires a major teardown of the unit... all while maintaining the original character of the unit and making it more suited to modern manufacturing (less hand wiring). I'm keeping the three circuit cards and the front panel will look nearly identical with the exception of two extra screws per channel. All components will be through-hole. I nearly had a design complete with SMD resistors everywhere but the audio path - this was a few month side trip that I was talked out of by others in the business due to the high volume necessary to make SMD worthwhile.

Tony Arnold at Helios-Electronics is working on a 500 Series "Helios" F700 which is the Compex without the "ex". I will probably not bother to do the same thing but instead concentrate on the 2U Compex and possibly the Vocal Stresser as well (if there is enough interest).

Best,

Tim

 

[Slenderchap]

Here is the actual schematics of the Compressor/Limiter/Expander/Gate (ABC boards) part of my F769 stresser.....

www.audiomaintenance.com/downloads/adr_f769_abc_boards_actual.pdf

I initally drew out the schematic using the "standard" drawings that can be downloaded from the net (AnalogRules.com).... then I went through my actual PCBs and changed the drawings to suit.... then re-checked them against the boards for errors ... so I am fairly confident that these are correct.

Colin
www.audiomaintenance.com