From james_eaton@btopenworld.com Fri Nov 09 10:53:00 2001
Subject:Re: More on warm valve (tube) sound...long rambling post

--- In CloneWheel@y..., "Steven Hayes" wrote:

> The reason you did not hear much sound
> difference. Is because the amp you used was a Class AB. These amps
were used
> for guitar or pa use. The reason our preamp works so well is a
result of the
> Class A configuration.

Steve, thanks for clarifying! From what you're saying, I therefore
assume that the AO-28 uses class-A sections. So...looking at the AO-
28 circuit diagram:

percussion v5, v7: class-A, class-B

vibrato recovery: v2,v3 class-A, class-A

Pre-amp: v1,1/2 v4, 1/2v4,v3 class-A, class-A, class-A, class-A

In other words there is class-A all over the place in an AO-28 and
whilst the Pro-3T simulates the push-pull output stage on the power
amplifier in the Leslie, it doesn't simulate the many class-A stages
in the pre-amp, hence the need for a class-A stage on a clone rig to
provide the right tone.

On a related point, I heard that the XB-3A had a 12AX7 in the
console. Does this operate in class-A mode to simulate the pre-amp ?

James