[HAM] AO-28 GG output voltage/phase questions

[Bruce Barnes]

Hello!
  I have some questions concerning the G-G output from the AO-28
amplifier.  What is the output voltage I should expect to see from
these terminals?  Also will the outputs be 180 degrees out of phase? I
have a JR-20 tone cabinet and I am trying to build a preamp for it
that will allow me to use it as an instrument amplifier (for guitar,
the line-out on my M-3, etc) and from looking at the schematic it
appears to be a pretty basic push-pull amplifier. My first thought was
I'll build a simple fender/marshall type phase inverter to get the
differential signal and that will be that.  However, upon inspection
of the preamplifier stage in the AO-28 I didn't find anything that
resembled a phase inverter (to me anyway) and that got me wondering
exactly what is going on in there....?  Any level of response to these
questions would be very helpful, from a simple explanation to o-scope
screenshots!


Thanks!
Bruce