[Eeyore]

Sander deWaal wrote:

"Bob H." said:

A DC-blocking cap at the input?
Not likely.

It's between the high cut filter and the input to the amp stage, and
it's definatley a signal cap.

My comment was directed at Graham, he asked if the cap was somewhere
in the feedback loop.

That could only be possible, if the feedback resistor from the base of
the inverting input of the differential pair is connected to ground
with a cap.
IMO, that's not a harmful place ;-)

It's potentially as equally harmful as the input cap actually.


Looking throught the tone control section, I see another 33uf cap if
the tone controls are bypassed, a 220u if not. Also, a 10u after the
volume pot to the stage prior to the tone controls. So I guess there
are at least 3 caps in the signal stage.

The reason for the 100 uF being that large, is that in effect, all
caps are in series, with some resistors and pots inbetween.
This gives several different corner frequencies.

If someone cares to offer me the working voltages at those point and the input
impedances I can easily work out if the use of zero-bias electrolytics is
'harmful' or not.

Graham