Will this work Se bridged type

[mozz]

Just threw this together from Fender schematics, all wiring is not shown or complete. Just looking to see if the idea is correct.

[mozz]

Going to breadboard this, fairly sure it will work. 8k/8 transformers so i will use 16 ohm speaker.

[Dave H]

Yes, I think it will work as long as you get the phase right.

[eschertron]

I see a pair of 100k resistors pulling up both the cathode and anode of your PI to B+ (unless I'm just looking at the drawing crosseyed). Just before the final coupling caps. Double check to see where they came from and if they should be removed from this design.

edit: keep us posted! I want to find out how the dueling OTs work out.

[Dave H]

I see a pair of 100k resistors pulling up both the cathode and anode of your PI to B+ (unless I'm just looking at the drawing crosseyed). Just before the final coupling caps. Double check to see where they came from and if they should be removed from this design.

Well spotted, I didn't see them. I don't think they are necessary.

[mozz]

Yeah, forgot to erase those. It was pieced together in Paint quickly. Will update. May not need one of the gain stages either. I was more concerned if it's worth spending time to breadboard it and if anyone has tried this before. Will have some sort of tone control or stack also. I have read of low freq oscillation when bridging. If I use the concertina as the V1, bad idea?

[eschertron]

If I use the concertina as the V1, bad idea?

What's the intended source? If you have a tone stack, you'll likely need a recovery stage before the PI (or use a dual-triode for LTP - either way, a whole tube). I could see a single tube - gain stage and concertina - as the whole preamp, but gain is limited so the chance the 6V6s ever reaching clip is low. With a tone stack, you'll need more signal feeding the input than a typical boost pedal can supply.

[mozz]

It's a guitar amp. Output tubes will be 6bq5 (6gk6's actually). I'll figure out the gain and tone control later but just hoping the overall topology is correct. Concertina has .9 gain? So if it's in V1 I'd be adding noise so better off with phase splitter on V2 or 3?

[Dave H]

It could be 1 x 12AX7 + 2 x 6BQ5. You don't really need the Cathodyne PI. The phase inversion could be done by the OT secondary wiring. It could either be as in the OP with the speaker 'bridged' across the outputs or one side of the speaker could be grounded. The OT secondaries are still in series across the speaker. It's just the ground connection which is moved.

[g1]

The phase inversion could be done by the OT secondary wiring.

I'm wondering about peak supply loading in this scenario? Is it worth consideration or negligible?

[Dave H]

I'm wondering about peak supply loading in this scenario? Is it worth consideration or negligible?

I'm not sure. The average power supply current would be the same. The peak current is provided by the reservoir capacitor.

[mozz]

I'm going with a PI, where or what type is yet to be decided. This is a better clearer picture of the output stage(if it will work). I would like to have separate vol and/or tone controls(if possible) but if the output stages are not identical, (such as phase problems with separate tone controls set at different positions) will it still work? I'm going to start building the power supply, then both output channels. After they work, a PI and some tone controls. My original idea was a 2-12 combo, 1 input, PI, then 2 separate SE outputs into 2 separate speakers, but i think it would not work(sound) good.

[nickb]

Yes, but why?

Bridged configurations are useful in SS amps where you want to keep the power rails low voltage and because there is no impedance matching transformer. Since you have a transformer there's just no good reason to do it. It means you have to use two expensive SE transformers which have to carry substantial DC instead of a single PP one in which the DC cancels out so making better use of the core. Aside from the novelty I'm not seeing the upside.

[mozz]

Parts are not the issue. It could be considered novelty, i consider it learning. I have 2 SE output transformers from a 6bq5 amp. I have the power transformer which powered both channels. I have 20 pieces of 6GK6 that i love to substitute for el84 just to be different. The reason to do it is because it is not being done. I want to see what it sounds like, a SE amp or a PP amp, do i get crossover distortion like a PP 6bq5 amps get, is the output wattage the same as PP or the same as PSE. If i use different value final coupling caps on each side, what does that do to the sound? What if one side is 6bq5 and other is 6v6? What if one side is fixed bias? Lots of variables.

[uneumann]

Parts are not the issue. It could be considered novelty, i consider it learning.

You may want to look at the BiValve for inspiration - it was made by THD and has 2 SE stages feeding separate primaries of the OT.
You're using 2 OTs but the idea is similar.
I don't think it has a PI.

http://www.thdelectronics.com/BiValve_Manual_080105.pdf