[nick2282]

i think i asked this a long time ago but i forgot. what would happen if you took one of the power tubes out of your amp and tried to play? would there be any harm. im just wondering because a lot of nicer amps have the option to cut off 1 or more power tubes to drive it at a lower volume, would this be the same as just taking one out? if not, is it possible to add the feature of cutting out a power tube into your amp.

[Ax]

i think Ryan (Building429_Boy) does this with his Carvin..

[tht00]

Originally Posted by nick2282

i think i asked this a long time ago but i forgot. what would happen if you took one of the power tubes out of your amp and tried to play? would there be any harm. im just wondering because a lot of nicer amps have the option to cut off 1 or more power tubes to drive it at a lower volume, would this be the same as just taking one out? if not, is it possible to add the feature of cutting out a power tube into your amp.

It completely depends on the design of the amp.

[thesteve]

FWIW, I don't know of any amps that have the option to cut only one power tube out.

Most amps that have a 1/2 power feature cut one pair of power tubes. This is because these amps are running in Class A/B push-pull configuration. In this mode, you need two tubes to complete the "push" and the "pull" aspects of the circuit. You can pull one tube, but I've read that the result is less than desireable.

On many tube amps that run a 4x6L6 configuration, you can pull the two inner or two outer tubes to cut the wattage in half. From what I understand, this causes a negligible loss of volume, but a noticeable loss of headroom. I recall reading that this also causes a change in impedance on some amps. I can't remember what direction this occurs in though. I don't know if the two-tube pull can be performed on 4xEL84 configured amps. I don't know why it wouldn't be possible, I just can't recall reading about it.