Discrete DOD250: Ge transistor and final tweak woes...

[brad]

Ok, sorry for posting this schematic again after posting it in the Discrete OA Forum, but I'm going to have limited online access shortly so I'd thought I'd get as much input as possible before hand...

The circuit sounds great as it stands imho, but there are two sticking points I'd be interested in hearing opinions about:

1) I'm trying out AC125 germaniums for the PNP transistors and just want to make sure I understand biasing correctly, because the gain is substantially lower than the 2N5087s.  I'm using a 10K trimmer on the collectors and setting voltages where the emitter sits between 1v to 1.5v above the collector and just slightly above the base.  That's the type of bias needed for a PNP, right?  The emitters are reading at about the 2v mark.

Does it mean my transistors are byassed correctly when I'm getting those sort of relationships?  (I'm going by what's said in the GEO biasing article).

2) Are there any value tweaks I should make to accomodate for the discrete OA?  It's been suggested that I should try a 100K-0.1uF to ground-100K network in the feedback loop, but I can't hear much of a difference!  Same goes for lowering the input resistor value.

Anyway, thanks for any advice.  I know just enough to get circuits working, but not enough to make sure it's running optimally!