Rivera Rake: Intermittent Tube

[ronster]

One of the power tubes in my Rake doesn't always glow. I've switched the positions, and it's the same tube (not socket) each time. I just had it checked out and rebiased a month ago, tech said the tubes were like new.

What would make a tube work sometimes (for weeks), then suddenly not?

Can I damage the amp by running it like this?

[VaughnC]

What do you mean by "glow"? All tubes have a filament that glows an orange color but sometimes, depending on the design of the tube, it can be difficult to see.

If you're talking about a blue glow, that's not what determines whether or not a tube is working. Some tubes will exhibit a blue glow and some won't, even of the exact same type. Electrons colliding with residual gas and/or the glass envelope itself are the usual causes of the blue glow.

However, if your amp has a typical push/pull output stage and one tube wasen't working, you would hear distortion when you try to play clean. It won't hurt anything to run an amp this way but is sure wouldn't sound very good for clean sounds.

[ronster]

Thanks VaughnC,

I was able to get this answered over in the Amps & Cabs section. - definitely a flawed tube.

Now I have to break down and buy a bias tool so I can re-tube without running to the tech each time...