6ck4 pp amp

[Sheldon]

Turns out I have a 1.5h, 200ma choke that I had ordered some time ago by mistake. Put that in before the 100u cap with no other changes. Voltage dropped from 355 to about 348. Considerable improvement in sideband noise. This is about 1.6V into 8 ohms, at least that's what the DMM reads during the highest test signals.

Sheldon

[Sheldon]

before choke

[EC8010]

That looks a lot better. Add a reservoir (50uF?) before the choke and see the hum really drop. Does it sound better?

[Sheldon]

Originally posted by EC8010
That looks a lot better. Add a reservoir (50uF?) before the choke and see the hum really drop. Does it sound better?

I tried that. A couple volts higher, but no significant change in the spectrum. In the existing supply there is a 47uF choke, but it has 150ohms in series to ground for the CCS supply. Adding an extra 47 doesn't seem to make much difference as noted.

Sound better? I think it sounds a little clearer overall. But I haven't listened much and I don't trust my memory for a good A/B. Overall, it is a nice sounding little amp as long as it's not driven too hard. I do like that it measures better. I'm in the middle camp. I don't think zero distortion in the output necessarily makes for better sound. I can believe that a little low order harmonic distortion might be dandy, but I doubt PS distortion generally does any good for the sound.

Sheldon

edit: BTW, I'm having fun taking these measurements with RMAA. It's nice that I can plug in various tubes and see different noise and distortion patterns. Makes it easy to select tubes for that specific circuit, and the best position for a PP pair. I can even watch the changes as I fiddle with bias or balance.