Originally Posted by pp312
You're talking about 2nd harmonic distortion vs 3rd, but wouldn't that only apply when the amps were being over-driven? Surely any decent SS or tube amp would have inaudible distortion within normal limits. Even, say, a full 2% distortion in a tube amp at normal listening level wouldn't be audible (as distortion) if the distortion is even order. Or are you suggesting it's the tube's generally higher distortion that imparts the bloom people seem to love so much? I'm not interested in tube amps for practical reasons, but I am still slightly curious as to what people are hearing and why they love it so much.
I'm not talking about harmonic distortion, I'm talking about clipping and headroom.
When you approach the limit with solid state it begins to break up abruptly and the resulting sound (a square wave) is not very pleasant to listen to. It's the sound you hear when you turn a cheap radio up too loud and it sounds like a megaphone.
When you approach the limit with tube amps they have more headroom extension meaning they can handle more signal before the start to get nasty. When you use it as a pre-amp for instance with a vocal mic, it's partially acting like a soft limiter/compressor. It will still break up when driven too hard but it does it gradually and at first the effect is pleasing to the ear, like a dirty guitar amp just starting to break up into distortion, that 'bite'.
When tube clips it starts squaring up the edges of the wave form gradually, the tops start to get flatter and flatter gradually. A solid state distortion is more like lobbing the head off the waveform and giving it an instant flat top.