C201 can be replaced by a 10uF Wima type, no problem.

Just look where it comes from... the signal comes from C200 which is a 10uF cap.  😕

It makes no sense, when the first cap is a 10uf to use a bigger second 22uf, the signal does not become stronger or different.

 So the same size is good enough :)

The BC9500 preamp board circuit appears quite similar to that of the BM7000. The workshop article you had on modifying the preamp got me thinking about doing something similar to the BC9500 board. Looking at the diagram above, with the OPAmp replaced with OPA2134, could C204, 205 and 211 be replaced with a wire link? I see also that in your BM7000 mod you removed Diodes D200, 201, 202 and 203 but not quite sure reason for this.

BM7000 and BC9500 are very similar from the design. C204 can be replaced by a wire bridge, the others not.

Check and measure the dc offset across these caps. If it is less than 10mV, try to replace them by wire.

Also check, these chips are working internaly with some volts dc offset. So it is important, which cap you replace and which not, these chips are hard to get.

The diodes are not necessary, because i removed the in/out plug. So there is no possibility to get overvoltage into the amp.

Hi,

Today I have started the overhaul :-). Do I have to consider any PIN numbers on the OPA2134UA? I cannot find any sign on the chip showing a certain direction.

THX