Sonic atributes ultralinear vs tetrode vs pentode

Do you mean "triode" vs. pentode? It would help to have more info in re: what speakers, size of room etc.
Ultralinear uses taps on the output transformer to help broaden the frequency response (bandwidth).
Triode/ Pentode refer to the number of elements inside the tube that perform the amplification.

I know what triode mode is, its a pentode or beam tetrode "strapped" in triode. There are a lot of amps that use pentodes or beam tetrodes that operate in different modes. I know what an amp "strapped in triode sounds like and Ultralinear, I have an amp that functions in tetrode mode only. Maybe I just should have asked about a amp that operates in Pentode, but I thought a comparison would be more helpful and easier to put into words.
Thanks
Mike

You won't hear so much difference between Tetrode and Pentode, but you will hear a difference between Ultralinear and the others. Ultralinear allows the tubes to approach triode linearity, while retaining most of the power that Tetrodes (or Pentodes) otherwise make.

So Ultralinear circuits make less distortion and tend to have a lower output impedance. If the designer is crafty and takes advantage of this, the result will be an amplifier that is smoother and more detailed, as removal of distortion usually has that effect. Ultralinear amps need less loop feedback in order to work, and in some cases don't need any at all. Loop feedback adds brightness to almost any amplifier, so if you can run without it you can have a more relaxed presentation.

However, not all designers will do that, so YMMV.

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.