• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Big SET amps: how to make them „lively“

Have asked a friend of mine with several decades of experience in tube amp building (but mostly pentode and tetrode stuff plus a few 2A3, 300B etc) to assemble a SET 211 for me.

Have looked for some first hand experience with the schematic I have in mind, dating back to 1971.
https://www.diyaudio.com/community/threads/uesugi-211-vintage-1971.400065/

I can’t say many SE or PP amps with bigger triodes have impressed me over the last 3 decades or so, other than the beauty of timbres. I found these usually lacking dynamics and liveliness (besides other frequent shortfalls).

I’m wondering what’s the secret of a good lively, rythmic SET amp, especially with larger triodes such as 211, 845, 805 etc. Leaving aside the output transformer and other component quality considerations.

Have tried to identify some patterns and correlations with the degree of sophistication of the power supply (the simpler the better as opposed to multistage PI filtering sections etc) but I read nothing conclusive so far.

Any views?
 
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Choosing the appropriate amplifier is the second step, precedes it the "best" loudspeaker searching.

Finding the "perfect" (to each his own) speaker a painful and long search (and mainly costly) .... and maybe very disappointing to realize, that this a picky goods: using it with different amplifiers the result may average, good, phenomenal ... but most of the time it's frustrating.

If you find "tube friendly" speaker, the next barrier is the sensitivity.
The wrong amp-speaker pairing gives "liveliness", the power and sensitivity imbalance mostly cause insufficient PRaT (Pace, Rhythm, and Timing).

So choosing SET is always problematic, but without matured sound reproduction line (speaker and it's environment) maybe "shot in the dark".
 
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elac310,

You said:
"I can’t say many SE or PP amps with bigger triodes have impressed me over the last 3 decades or so, other than the beauty of timbres. I found these usually lacking dynamics and liveliness (besides other frequent shortfalls)."

Are you talking about amplifiers in Someone Else's system(s)?
. . . Or, are you talking about the same amplifiers in Your system?
. . . Or Both their system(s) And Your system?

How can you leave out the discussion of the output transformer?
Only with OTL can you leave out that discussion (and I will not ever own an OTL, and I do not want to).

The power supplies are another important discussion.

Loudspeakers, theirs and/or yours; Room, theirs or yours.

Every music recording playback is a complete System, starting with the musical performer, the microphone, etc.
On and On . . .
System concept is paramount.

This thread may have to split into 2 or 3 different threads, or could just stay as one thread.
 
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I built a number of GM70 based power amplifiers for friends while others built copies on their own. No one has ever complained about a lack of good dynamics in these amps. My recipe; fixed bias output stage, IT transformer coupled high current driver using a high transconductance triode usually also fixed bias. Low impedance power supply (SIC rectifiers and CLCLC filter for the HV, separate supply for the driver). Higher voltage transmitter triodes generally have high rps and will have similar output impedance and load interactions through their output transformer as lower voltage DHTs into lower impedance transformers. What they will give you is higher power, and less distortion at modest power levels.
 
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