I have a question concerning profiling certain amps that use the power amp to create their sound, the VOX AC30 being one example, the Matchless DC30 being another.
Both these amps rely on significant power amp distortion to create their signature sounds do they not? However, the KPA manual specifically states that the power amp should not be allowed to distort during the profiling process. That being the case, how can the KPA create an accurate profile of these amps?
Thanks.
This is not what the manual states.
It says a combination of pre and power amp distortion should be avoided.
The amps you mention do not have a preamp distortion, so no problem.
@ Christoph - Do you believe this limitation will be lifted in due course?
I've had some good experience at profiling poweramp distortion on my amp in class A mode, but it took longer to refine for some reason than when I've been profiling just preamp distortion.
This is not what the manual states.
It says a combination of pre and power amp distortion should be avoided.
The amps you mention do not have a preamp distortion, so no problem.
Sorry, I incorrectly stated what the manual says. I was however under the impression that these amps did create some preamp distortion in the pentode preamp, but apparently that's not the case. The question is therefore moot. I guess it's those class A EL84s with no NFB that are making the magic. 
I built a class A EL84 push pull amp with no NFB using a simple 12AX7 phase inverter (a direct rip off of the VOX AC10 circuit) and it sounds pretty good when it's cranked. At least I think it's Class A. It may be Class A/B.
Thanks. 
