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
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
