Originally Posted by SilverEars
I hear a lot about tube providing warmth. Does tube typically provide stronger low end? This is what I read, that SS amps are thin sounding.
Also, the tube distortion is 2nd harmonics? Or 3rd. How do these harmonics affect how we perceive the sound? Some say it's desired. What does that do to the signal and in the result the sound?
What are the benefits to tube amps?
No tubes don't typically provide stronger low end. Quite the contrary. They generally need either a capacitor or a transformer at the output and are often a few db down at the very low end.
Distortion spectrum is a matter of the topology used in the amplifier. For some reasons, the single-ended topology is most common in hifi products, especially headphones related. This topology gives a dominant H2. But you also encounter amps using push-pull, where H3 dominates, giving a perceived more dynamic sound. As most tube amps don't use feedback or very little (not enough open loop gain in most simple topologies), distortion is mostly made of the first harmonics, which the brain doesn't object to too strongly.
The benefits to tube amps... depends. No, really, it depends a lot on the topology/tubes used and what you're after. One can easily taylor the sound. Main reason we still have tube amps is that we can. Since they're naturally quite linear, it's also easier to get decent sound from tubes with simple topologies. Transistors and jfet require more thinking.