Hi every body! Let say that I have an audio power amp (EL34) in push-pull. I can set amp in triode, pentode or ultra-linear mode...

1. What is the best sounding mode (in order from very good to good)?
2. What is the more powerfull mode again in order??

Lot of web pages talk about these modes, but I can not found comparison between them.

Thank you!!
J-F

Hi J-F

This a question for the audio guys. I can tell you wired as pentodes you will have the greatest output. Triode less power but more linear.

Norm

:Hi every body! Let say that I have an audio power amp (EL34) in push-pull. I can set amp in triode, pentode or ultra-linear mode...
:
:1. What is the best sounding mode (in order from very good to good)?
:2. What is the more powerfull mode again in order??
:
:Lot of web pages talk about these modes, but I can not found comparison between them.
:
:Thank you!!
:J-F

Hi J-F

I have a Dynaco ST-70 wired in "triode", it is a very easy modification to make and you can always return to stock configuration if you don't like it. The Dynaco uses EL34. The power output is less but isn't really a factor if you have efficient speakers. It gives a very smooth and rich sound but the midrange might seem a attenuated. Try it and see what you think.

:I have a Dynaco ST-70 wired in "triode", it is a very easy modification to make and you can always return to stock configuration if you don't like it. The Dynaco uses EL34. The power output is less but isn't really a factor if you have efficient speakers. It gives a very smooth and rich sound but the midrange might seem a attenuated. Try it and see what you think.

I have a chassis and output transformer to a Dynaco. Don't they come stock wired in Ultra Linear? Great amps by the way!

-Zach Omega

:Hi every body! Let say that I have an audio power amp (EL34) in push-pull. I can set amp in triode, pentode or ultra-linear mode...
:
:1. What is the best sounding mode (in order from very good to good)?

Well that depends on what you consider good. Ultra Linear is going to be very linear as the name suggests. In that event, it will be more true to how the sound should be.
Trioded pentodes always sound sort of warm because they are actually tetrodes (suppressor grid is still working). They also have a lot higher capacitance than when pentoded because the screen grid is no longer shielding it. Still, it is much more linear than a pentode.
Pentodes have a powerful sound. Whatever one you happen to like is the best sounding though.

:2. What is the more powerfull mode again in order??

Pentode is most powerful.
Ultra Linear is a compromise between max power and max linearity.
Triode is lowest in power.

:Trioded pentodes always sound sort of warm because they are actually tetrodes (suppressor grid is still working). They also have a lot higher capacitance than when pentoded because the screen grid is no longer shielding it.

How does this "higher capacitance" give a warmer sound?
-anon

:
::Trioded pentodes always sound sort of warm because they are actually tetrodes (suppressor grid is still working). They also have a lot higher capacitance than when pentoded because the screen grid is no longer shielding it.
:
:How does this "higher capacitance" give a warmer sound?
:-anon

It rolls off more of the high end giving the appearance of a more dull or "warm" sound.

-Zach Omega