Dual single ended amp?

[Bergheim]

Okay, bear with me now..

I'm thinking of building something outside the usual single ended and push-pull output stage topology, namely a "dual single ended" power stage.
Efficiency and weight saving are obviously not on the priority list here.
Anyway, I imagine it like this: A conventional phase splitter feeds two single ended power tubes, each with their own OT. Each secondary is connected to its own speaker output, wiring the two so that they are in phase.
I believe this will produce an interesting sound, since one tube will be in cutoff while the other one is going into grid overdrive. Mixing different speakers/cabs will also be very easy since it requires either two cabs or one cab with two (or more) speakers wired separately.

Any reasons this won't work the way I'm thinking?

[roberto]

So you want to build two single ended feedback-less class B tube amps?

[Phil_S]

I believe I've seen this in stereo hi-fi. I don't think it is a new idea, but in hi-fi, one channel is left and the other is right. I'm guessing there is no splitter. Dual input - dual output.

I expect you'll get about 25% efficiency. So, it will be a power hog, but not as loud as the power requirement might suggest.

[Bergheim]

So you want to build two single ended feedback-less class B tube amps?

Not quite sure I understand the class B part, but essentially two power stages/amps, yes.
Let's use the LTP as an example.
Tube 1 is fed from the inverting side and tube 2 is fed from the non-inverting side. Since the PI produces a full wave signal at both sides, both tubes will operate in class A, until clipping at least, as far as I know. Both tubes are cathode biased at 100% like normal.
I haven't thought about nfb yet, but I suppose it can get tricky since there is two separate secondaries.. If it's taken from speaker jack 1, it will not correct the distortion produced in tube 2, correct?

Anyway, the idea is to kind of emulate the effect of playing through two amps at once. Naturally the difference won't be as dramatic since there is only one preamp signal, but I think the imbalance in the PI along with further imbalance in each power tube and small differences in the OTs might produce some of the holy mojo 3d magic that so many are dreaming of On the other hand, the effect might be too small to tell, at least in a live situation. Would be cool if it worked though.

[Bergheim]

I believe I've seen this in stereo hi-fi. I don't think it is a new idea, but in hi-fi, one channel is left and the other is right. I'm guessing there is no splitter. Dual input - dual output.

I expect you'll get about 25% efficiency. So, it will be a power hog, but not as loud as the power requirement might suggest.

Single input into differently voiced preamps in parallel followed by a blend control would be the prefect way to fully implement the "single but parallel" idea In case the preamp signals are out of phase, the second input in the ltp can be used for one of them.

[wpaulvogel]

My thoughts are that it will be class A until overdriven and then transition into class AB. The NFB taken from one of the output transformers is fed back into the tail of the LTP and will influence both outputs just as it does with a single push pull output transformer.