New Project - Bassman Lite Octal

[Phil_S]

No, I think you understood. Just learned a new axiom, "don't expect the screen voltage to be lower than the plate voltage at idle in a fixed bias amp." Sound right?

It depends on how you construct the B+ ladder. Remember, screens don't draw much current and neither does the preamp. You need a fairly large resistor value to cause a drop at idle. In my recent experiment with this donor amp I'm working on, 20K dropped 80V...well it's cathode biased, but you get the idea.

[Phil_S]

Maybe this just sunk in....if cathode biased, then plate voltage isn't the spec to look at. If Va-Vk = 450-40 = 410, then 410 is the number. I'm talking about the tubes. I need 6L6GC for 500V, or I can use 6L6GB for 400V. I might get by with GB?

[ampfab]

If you want a TMB type tone stack, but don't want to use an odd pot, you may consider installing a 2 or 3 way switch in place of the mid pot. This way you could select 2 or 3 mid settings. Maybe a 6k resistor for a scoupped tone, 10k for a bit more mid and a 20k for max mid, or what ever to taste. I've done this in spots that don't have room for an additional pot, but didnt want to give up control of mids. You could use an existing hole from one of your pots.

[matt h]

(deleted)