"Headroom" - what is it?

[vernplum]

I've been reading a lot of tube amp reviews recently since I'm looking to buy one.

They always talk about 'headroom' when playing the clean channel. Is this to do with how hard i can play before I experience distortion? Can someone give me an amp-guru's insight into this and how it relates to different tubes, etc.?

 

[mikemann]

Yeah, you actually got the idea right. It's the amount of gain you can pump before the amp will distort or 'clip', this is in balance to master volume setting.

Where in tube amps, there is inherent 'distortion' of signal anyway, but to the guitarist, these are what we call the desirable harmonics. Which contribute to the warmness of the sound.

But to the hifi buff, it's also similar, he wants all the desirable harmonics produced but what he don't want is any clipping at all.

For bluesy warm drive of tube distortion, this is the smooth clipping of the signal produced by the tubes being overdriven.