Tube sound versus measurements

edmiller9999 · Jan 15, 2011

Hi guys. I've been reading (and changing) tubes lately. I have read more subjective stuff about tubes, especially preamp tubes, but ZERO empirical evidence, measurement, voltages, etc. Why is there all of this fluffy, blurry and opinionated stuff about how tubes sound, yet not a single person or website (that I've found) manages to give us some solid electronic facts? It seems like it would make sense to establish a relationship of certain tube measurements to a related sound.

Am I nutzz?

c.t.d-nicke · Jan 15, 2011

edmiller9999 said:
Am I nutzz?

Yes, you probably are... but in a good way.

nicke

MrMarkIII · Jan 15, 2011

Going "by the numbers" leads nowhere. It's the same thing as guys who insist that if they can't turn their bass knob above 3 without it sounding flubby, then surely something must be "wrong". No, it just means they are trying to dial in their sound with their eyes, not their ears.

stokes · Jan 15, 2011

There are many tube manuals that give the numbers you are looking for,but they really have no relationship to how a tube will sound.You can have two RCA 12AX7's that both have the same gm and current rating say,and still sound a bit different in a given circuit.Now if you take a,lets say,RCA AX7 and a Tung-sol AX7 that have the same gm and current readings they will most likely have a difference in tone as wide as night and day.Add to that the fact that tone is such a subjective matter,and you can see the "numbers" mean very little.

crane · Jan 15, 2011

stokes +1

94Tremoverb · Jan 16, 2011

+1

Electronics engineering types have been telling us (correctly) for decades that on paper, there is no difference sound-wise between tubes and transistors in a gain stage! Let alone between different tubes of the same type. You can do all the measurements you like and you will find some differences between tubes but nothing that would explain the tone differences.

It's not that the engineers are wrong or that your ears are, it's that it's two completely different types of measurement. Instrumentation is very good at measuring some things and useless at others. Ears are very good at some (different) things and useless at others.

For example, you cannot hear differences in phase between non-harmonically-related signals at all, but it's instantly obvious on an oscilloscope screen. Equally - and I'm sure this has happened to you - your ears/brain will instantly pick out the sound of your own name across the buzz of conversation in a room... and there's no instrument (not even if you record it and analyze the waveform) that can do that. Nuances of tone in tubes are closer to the second example than the first.