SET Asylum

RE: recommendations for an SET integrated amp

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This Post Has Been Edited by the Author

In Reply to: RE: recommendations for an SET integrated amp posted by saki70 on April 28, 2017 at 04:52:57

What Frihed89 said below.
Paralleled tubes produce greater power and simplify transformer winding somewhat. They are also harder to drive (increased Miller C), place more demands on power supply and cathode bypass design (larger C required for equivalent performance). Moreover, they introduce the variable of trying to match the two tubes as they age - no two tubes perfectly match and that situation is likely to worsen with age.
What does this mean in a practical sense? My current thoughts are:
Traditional (old school?) amplifier designs with lots of electrolytic final PS capacitance, cathode bypass capacitance, and slow-recovery power supplies would likely benefit from paralleling output tubes. The paraelling is easily implemented and additional power can mitigate some issues and the trade-offs are probably not evident. The advantages outweigh the disadvantages. Using these types of amplifies used with moderate efficiency speakers running mid-QTS drivers and soft dome tweeters, is a successful paradigm for off-the-shelf, (relatively) broad-appeal systems. They have that classic SET sound.
Paralleling output tubes in amplifier designs where power supply and cathode bypass capacitance is carefully calculated, higher quality capacitance is used, and power supplies have quick, well-damped recovery, is probably a different story. The cost of paralleling would be much greater (as would the space required) and it would impose power supply compromises. The additional power provides greater achievable volume, but I can see how paralleling would introduce sonic compromises in this type of design. For high(ish) efficiency speakers running low QTS bass and resolving compression/ AMT/ quality ribbon drivers, I'd prefer a well-designed single output tube SET.
I imagine that it is a case of horses for courses.
Sorry for the off-topic, but that is the way I see it at present.
Cheers,
91.

"Confusion of goals and perfection of means seems to characterise our age." Albert Einstein

Edits: 04/28/17 04/28/17

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