120w valve amplifier.

[Diabolical Artificer]

Thanks for the explanation Mark. I'm familiar with gain structure from using a mixing desk. AFAIK the procedure with one is to get the highest signal on each channel you can (for best signal to noise) without clipping the output. The "volume controls" IE faders work differently on recording gear, EG the fader is at full gain (ok not full but just about) then you turn it down rather than up on a domestic amp. My monitor amplifier in the "studio" is set to full gain (ish) and I control the input going to it from the desk. you can't do that with normal domestic gear hence my query. I'm familiar with the tricks amp makers use with the volume pot; the car analogy's a good one.

Started to fettle the power supply yesterday on the big amplifier. I had already decoupled the front end, so I decoupled the PS too with an RC filter, on the HT plus end. Still getting to grips with the AC side of things for example the fact that the HT is a low Z path due to the big smoothing caps. Didn't get far as we had a power cut here due the wind, but the last test yesterday resulted in a clean 60w OP. Now the OP sine is distorting with slight bending on the waveform. Not sure what this is. I'm familiar with clipping, Xover distortion, 2nd harmonic content and a few others but not this one. I wish someone would bring out a "interpreting scope signal's" book.

Anyhoo, heading in the right direction, onwards and upwards, Andy.