Working on a power amp schematic

[mort]

This is what I have so far. I've been following this schematic as a basic skeleton, and will try and figure out what value caps and resistors will be needed to go with the tube types I have on hand.

Also, I'm a little unclear as to where the power amp begins and the preamp ends. For now I'm just drawing out the PA and need a little guidance on how to get from the input to the rest of the PA circuit.

Besides the gap between the input and amp, is there anything that looks out of place so far?



btw, It's not a huge concern how this thing sounds. It's more a matter of trying to stretch my understanding of tube amp circuitry. I've got the beginnings of it physical built on a plank of plywood with easy to access terminal strips and octal bases with screw terminals. Purely experimental.

[mort]

Here it is a little more filled in. Not sure where to go with the sleeve connection on the jack, and not sure if there are unnecessary parts showing for just a PA, but I think I'm pretty close.

I'm not sure what that inverter tube is gonna be. I have on hand 12ax7, 12au7, 12at7, and 12bh7a.

[g1]

Your resistors R3,4,&5 are actually part of the phase splitter circuit (6SC7). Usually the phase splitter circuit is included in the "power amp".
Think of trying to design something as a "power amp" that can be used as a stand alone unit with some other preamp. It needs the phase splitter and a cap. to block any DC from getting into the phase splitter.
For example, in a AB763 Deluxe, the power amp would include the .001 feeding the phase splitter and everything after it.

[J M Fahey]

Please build a tried and true circuit, before trying to design.

[g1]

Sorry about that, using terms like "everything after" doesn't translate well, here's what I meant:

[mort]

Please build a tried and true circuit, before trying to design.

I've built several. Just trying to see what I can learn here. Thanks for the vote of confidence though.

[mort]

Sorry about that, using terms like "everything after" doesn't translate well, here's what I meant:
[ATTACH=CONFIG]25161[/ATTACH]

So you're saying I need a .1 uF cap in series between the input and the plate, and then a 1M resistor from the plate to ground?

[g1]

Sorry, I didn't see your version 1.2 drawing when I first posted. It looks much more complete.

[loudthud]

There is an error in the way the rectifier tube is connected. The 6.3V goes to pins 2 and 7, and the output is taken from the cathode on pin 8. You are operating the 6X4 very close to it's maximum heater to cathode voltage rating (450V).

[mort]

nice catch on the heater

[mort]

Corrections.

[mort]

Should the high voltage be going to pins 3 and 5 on the rectifier instead of 4 and 6?

[g1]

Should the high voltage be going to pins 3 and 5 on the rectifier instead of 4 and 6?

Yes

[Randall]

So you're saying I need a .1 uF cap in series between the input and the plate, and then a 1M resistor from the plate to ground?

Mort, I'm trying to learn here as well, but surely you didn't mean what you said? ^

While we're at it, how about grid and screen resistors for the outputs?

[g1]

Mort, I'm trying to learn here as well, but surely you didn't mean what you said? ^
While we're at it, how about grid and screen resistors for the outputs?

I think where he said plate he meant grid.
Good point about the grid and screen resistors, they do not exist in the 5C3 deluxe he was basing this on, but should be included in any design.