"Eiron" wrote in message
...
Hi experts,

How much DC offset would you consider acceptable in a power amp?
What can you do on a rainy Sunday afternoon? I was poking around
inside
an old Rotel RA-970BX amp. It works OK except that the DC offset is
about 100mv and 50mv on the two channels, which seems rather high to
me.
There is no adjustment, except for bias current, so any tweaking
would
probably have to be adjusting the current in one of the long-tailed
pairs
by swapping resistors.

--

Have you tried adjusting the bias to see if you makes any difference?

If you Google 'schematic RA970BX' you will get copious information
including the service manual which includes how to set the bias. I
suspect it will correct it.

You should ideally be aiming for 10mV or less offset.



--
Woody

harrogate3 at ntlworld dot com