Explaining the mysteries of amp biasing

[jonkay1]

How to bias, that is, the mechanics of biasing is pretty straight forward.
The mystery is how do you arrive at the correct measurements? Some people say to bias a tube hot for better sound. Others say to bias it cold for better sound. Others don't consider the sound at all, but are going on some book learned notion of how bias is to be set. If you go to any forum about biasing, all they talk about are plate voltages and amperages. They seem to never discuss the sound they are trying to achieve, but don't we bias an amp because we want it to sound better? Would someone please grant me enlightenment? Thanks in advance.

[sjhusting]

Here, read this: http://www.tube-town.net/diy/bias-setup-e.pdf

If you bias too cold, you get 'crossover distortion' which sounds bad. If you bias too hot, the tube is dissipating more heat -> shorter life. What sounds 'best' is up to you. I set to 70% by the meter; then tweak by ear; then measure to make sure I'm within reasonable bounds.

steven

[celeste]

You bias for what sounds best for you, you also have to respect the dissipation limits of the tube, respect that and bias is open all the way down to cut off, what ever sounds best to you, or who ever you are biasing the amp for. Remember, the more dissipation, the shorter the life of the tube, the bias vs. tube life curve is exponential.