Amplifier with 2SC2238/2SA968 & 2SC2565/2SA1095

[Massilia]

Hi,

I have made my amplifiers using 2SC2565/2SA1095 Sanken parts for the output stages, and 2SC2238/2SA968 for the drivers. It was 18 years ago, for my tri-amplified system.
Up to 2 X 250WRms, AB-class.

For information the input stage is a cascoded differential pair using the SSM2210 matched bipolars, the second stage is a differential pair using the 2SA872A loaded by a cascoded current mirror.

Very good performances measured, high PSRR, open loop gain constant up to 20kHz.

Today I have to repair a unit.
What can I use for the following devices, as updated/improved versions:
2SA968
2SC2238
2SA1095
2SC2565

Thanks in advance

Regards

Bruno

 

[Capt Grogg]

these are Toshiba not Sanken, how many are bad?

 

[Massilia]

I believed 2SC2565 and 2SA1095 were Sanken parts but maybe I am wrong.

A driver pair 2SC2238/2SA968 (by Toshiba, indeed!) is broken.
I haven't tested yet the power stage 2SC2565/2SA1095.

Probably the SSM2210 and the 2SA972s are OK.

I saw some links saying an improved version of the 2SC2238/2SA968 should be the 2SC5171/2SA1930, but it exhibits a lower SOA (which would be a problem in my 2X 250W Rms amp, 2X68V supplied)
I found the 2SC4793/2SA1837 as a replacement with the same SOA and similar parameters, so I bought several pairs on ebay.

If the 2SC2565 and 2SA1095 power transistors are dead, it is again possible to find them as new parts on internet; but if improved versions exist I would be interesting in.

Thanks,

Regards

Bruno

 

[Bensen]

Very good performances measured, high PSRR, open loop gain constant up to 20kHz.

Bruno

Sounds interesting! Do you maybe have a schematic?

Greets