I'm helping a friend out with some upgrades on his pair of Classe DR-8 amps, which he has been using bridged as mono blocks for many years.
The input board of each amp has four opamps, however Classe went out of their way to remove the model numbers of them (see the attached photo).
My Classe CA-300 uses two dual opamps on the input board, so I'm assuming these CA-8's are single opamps. The schematic I was able to find online doesn't show the input board at all, and the service department at B&W (who now support old Classe products since the original Classe design and support teams were lost with company closure) don't have any documentation as to what opamps were used.
Does anyone here have a suggestion what these opamps might be? Based on the age of the amp there are probably better parts to use, but I don't want to mess with anything blind. Thanks in advance.
The input board of each amp has four opamps, however Classe went out of their way to remove the model numbers of them (see the attached photo).
My Classe CA-300 uses two dual opamps on the input board, so I'm assuming these CA-8's are single opamps. The schematic I was able to find online doesn't show the input board at all, and the service department at B&W (who now support old Classe products since the original Classe design and support teams were lost with company closure) don't have any documentation as to what opamps were used.
Does anyone here have a suggestion what these opamps might be? Based on the age of the amp there are probably better parts to use, but I don't want to mess with anything blind. Thanks in advance.
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Don't assume they are single opamps. That input board is a balanced to single ended convertor and one amp may (probably is) a dual. Check the power pins. They are different for dual and single opamps.
FYI most likely NE5532 and NE5534
FYI most likely NE5532 and NE5534
To find if they are single or dual opamp you can simply trace the power supply pins of the chips since they differ between single and dual opamp. Just check typical datasheet of single and dual opamp.
However, depending on their use in the application it can be tricky to change them if, for example, the opamp is the front end part of a more complex circuit with overall feedback where frequency stability may be changed.....
there are also voltage and current feedback opamps.
Better to have the complete schematics to evaluate their use before changing them if they work....
Fab
However, depending on their use in the application it can be tricky to change them if, for example, the opamp is the front end part of a more complex circuit with overall feedback where frequency stability may be changed.....
there are also voltage and current feedback opamps.
Better to have the complete schematics to evaluate their use before changing them if they work....
Fab
Have you looked at the DR-10 schematics, they may shed some light on the subject.
Here’s a link to the manual http://bwgroupsupport.com/downloads/techmanuals/classe/DR-10-Model 10-TM.pdf
Here’s a link to the manual http://bwgroupsupport.com/downloads/techmanuals/classe/DR-10-Model 10-TM.pdf
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Am guessing that they are not overly fast devices, since they are in sockets and not soldered in place.
While you are tracing the power pins, maybe you can see the hat voltage they are using?
I would also place my bets on the ne5532 as well...
While you are tracing the power pins, maybe you can see the hat voltage they are using?
I would also place my bets on the ne5532 as well...
From this manual on sheet 4 of 5 it looks like ic1 is dual opamp and ic2 is single.
Fab
Thanks guys. I don't have the amps on hand right now, but now I have some things to look at when my friend brings them over.
