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

[David Anderson]

The output transformer of the AO-28 is set up to act as a phase  
inverter; the secondary is center-tapped.

DAA

On Jul 13, 2007, at 12:39 PM, Bruce Barnes wrote:

> 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!