Sonic atributes ultralinear vs tetrode vs pentode

Atmasphere, I really appreciate someone with your knowledge and experience answering the thread. However, the sound characteristics of Ultra-linear you describe, I unfortunately have never heard. The sound always seems compressed and hard, smaller sound stage and just not very appealling when compared to the triode mode that most amps offer in tandem with the ultra-linear mode. Thanks

Atmasphere, "Ultralinear allows the tubes to approach triode linearity, while retaining most of the power that Tetrodes (or Pentodes) otherwise make."

Unfortunately, in audio like life, there is no free lunch. In reality, ultralinear splits the difference between triode and tetrode/pentode, as opposed to offering "most" of both. Historically, folks have described it as offering the best of both worlds. As it's the textbook definition of a compromise, I'm currently of the mind that like so many other compromises, it's also offering the worst of both worlds.

At any rate, how many high-end audio amplifiers actually feature true tetrode/pentode operation? From what I see, the number these days is very small. Ultralinear rules the day (past 50 years?), with triode coming in a distant second.

Trelja, obviously we see things very differently :)

I've done a lot of work over the years with ultralinear amps (quite a lot of those were Dynaco amps)! There is no way I would say they rule the day, I would put ultralinear as a distant second to real triodes.

With regards to your prior paragraphs, I think we are pretty much saying the same thing.

One way I use to deal with the linearity issues that allow me to get the amp to work better is to cross-couple the cathode circuits around the output of the transformer. In this way I get greater linearity, with lower output impedance, and that is what has allowed me to run zero feedback to the driver section. IMO that is how you get the amplifier to be low distortion and listenable at the same time; if you use feedback the amplifier will pick up a harder edge.

Atmasphere, you've done nothing to address my refutation of your quote regarding Ultralinear operation giving "most of" what both triode and pentode offer.

As I initially said, the subject at hand represents yet another case of simply splitting the difference between two endpoints, as opposed to getting more out of something than what you put in. The world just doesn't work any way other than that.

If you compare an amplifier running in the three modes, if triode put out 20 wpc, UL would do 40, and pentode 60. Those figures work out in the absolute linear, proportional, and expected manner. In other words, again, your assertion, "while retaining most of the power that Tetrodes (or Pentodes) otherwise make" is untrue. "Ultralinear allows the tubes to approach triode linearity" would not be an incorrect statement in and of itself. But in the context of your position inferring it goes beyond the proportional and expected distance, it is.

"Rule the day" means sales/volume...

OK- here's my text:

Ultralinear allows the tubes to approach triode linearity, while retaining most of the power that Tetrodes (or Pentodes) otherwise make.

here's your assertion:

If you compare an amplifier running in the three modes, if triode put out 20 wpc, UL would do 40, and pentode 60. Those figures work out in the absolute linear, proportional, and expected manner

If we take 60 watts as being 100% of power, 40 watts is then 2/3 of that, or 'most of the power' as I stated above. I don't see that being significantly different from your position. Some hairs are in danger of getting really thin here.