Power Reduction in Astoria is Constant Current Sink?

[johanvg]

I did some backtracing on my Astoria Custom because I was interested in the Power Reduction section. This one works really good and is not the usual suspect of doing this. So what I found out is that the Phase Inverter uses CCS or Constant Current Sink in his cathode bias delivered by a MOSFET. Pulling the power reduction will change the bias and thus the operation of the phase inverter. Maybe other people can chime in on this.

[surfnorthwest]

This topic may be of some help to you.

viewtopic.php?f=81&t=19692&p=175526&hil ... on#p175526

[johanvg]

Thanks, that is the post that made me interested in the subject. I am pretty sure this is based on CCS which is rarely used in guitar amps but known in hifi amps. Maybe someone can confirm this and the reason why we don't see it in guitar amps.