ADR Compex F760

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I dont know if it is original but its certainly old. It looks like it was installed the same time as the output transformer but no idea if its factory. With or without transformers, the adr gain staging is wierd to say the least but I should check on that resistor.

dave
 
hi again.

I know that you can still order the original manual from Audio Design.
A friend of mine did that recently and it was not to expensive.

Dennis
 
add to the transformer info:
all three units we have at work have HAUFE in and out transformers.

a complete documentation would be fine. I have a service manual at work (in german language), but it differs MUCH from the units we have (I found that out the hard way ...)
 
wow, now thats wierd. Were those units made in england? I know ADR licensed that circuit at least to helios, I wonder if at some point a third party was making them in germany?

dave
 
Rob Flinn said:
On my 3u f760rs the Gardner transformer part numbers are marked on the back of the case, where the transformers plug in.  Therefore I believe that the Gardner transformers were specified for this version

Hi everyone.

I have a bunch of the ADR rack units, and believe the Gardner transformers were the original specified standard type for my units.  I got a Gardner model number sheet with the units from the seller, with the appropriate in/out transformers indicated on the sheet.

I believe the INPUT type should be either the Gardner MU7530, or alternatively MU7550.
and OUTPUT type should be Gardner MU7524, or alternatively MU7544.

Does anybody have some available, or know where to source these?

Or is it better these days to try to track down the Sowters?
(I think the Sowter 3276 and 3497 transformers were also recommend by ADR & maybe are still available from Sowter today?)
 
IIRC Sowter has an archieve online where you can find their direct replacement for those Gardners.
My Vocal Stressor is stuffed with the Sowters you mentioned, btw and it sounds stellar  8)
 
My company is Helios Electronics Ltd.
Some years ago we were appointed by AD&R as a workshop for repairing & servicing classic AD&R audio gear.
We keep a full stock of parts including spare "A" & "B" cards,  but most important we also have our own calibration documents which includes setting up the four pré-séts
i.e.
On the "A" card
RV3 (Control Volts)
RV7 (Rectifier Balance
On the "B" card
RV1  (Rectifier Balance)
RV2 (Distortion Null)
Which are not included in the original AD&R service manual or the handwritten documents written by the personal of AD&R.
The only reason I can see why these four mystery Pré-Séts are not mentioned AD&R, is maybe because a Twin Beam scope is required which  most users will not have to hand,  and. chances are if untouched and left at factory settings,  should not give any problems unless of course if your F760/Compex was purchased second hand then you can't be sure these have not been touched by the last owner.
A good quality Twin Beam Scope will  not be cheap, for this reason we are investigating several Android & iOS (Apple) scope applications that maybe suitable for setting up these four Pre-Sets, the results will be attached to our own Calibration Documents.
Also.
The reason why some stereo units sound different and will not balance is because the two FET's on the "B" MUST be a MATCHED PAIR and most likely will have been changed over a certain period of time, which is the reason why they are mounted in sockets, so a perfectly matched pair can  easily be fitted by the owner/user as opposed to  hiring a qualified technician.
We can  supply these FET's in matched/balanced pairs from stock, as well as the documentation for the four mysterious Pré-Séts

Kind Regards
Tony
Tony Arnold (Director)
Helios Electronics Ltd
 

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