#1
I currently have a dead preamp tube in my amp, so my question is can I still play it while I wait for the replacement to arrive. Could any Damage be done to my amp? I have 3 good tubes left while I wait for the new ones to arrive.
#2
no, you cannot play it.
yes, you can do damage to your amp.

oh yeah, always have a spare of every tube in your amp handy.
#3
Different preamkp tubes control different things. For example, youll probably have one for your clean channel and one for dirty channel, one for reverb, one for effetcs loop, etc, etc..

I don't think you can damage your amp by playing like that (as this is a way to test for bad preamp tubes in the first place), but youll probably lose some functionality, like in my amp if I pull the tube responsible for the clean channel, i cant use the clean channel as simple as that.

Maybe someone has more info on this but I bealive this is how it should work.

EDIT: some of the tubes are vital, others i dont think so much. Figure out which one's which.
#4
I just have a mesa boogie subway rocket with a rythm lead, and contour channel and they all seem to work. I suppose I'll just stay off of it for a few weeks and wait for the tubes to come in. Don't really wanna mess anything up. *Sigh*
#5
How do you know the tube is dead? Did it lose it's vacuum? Is it white inside the glass?
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#6
three questions:

1) what amp is it?
2) what tube is it?
3) how do you know it's bad?
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#7
I have a Mesa Boogie Subway Rocket with 4 12AX7 tubes. I know Its bad because when I turn the amp on it doesn't glow like the other ones. Its the very last one in the series. Definative answers would be greatly appreciated. I need something to keep me going until I get the new ones.
Last edited by ubtguitarist at Mar 8, 2009,
#8
Quote by ubtguitarist
I have a Mesa Boogie Subway Rocket with 4 12AX7 tubes. I know Its bad because when I turn the amp on it doesn't glow like the other ones. Its the very last one in the series. Definative answers would be greatly appreciated. I need something to keep me going until I get the new ones.
Preamp tubes don't have to glow to be working properly. The last preamp tube is the phase invertor which is notorious for not glowing. Your amp is fine.
MARSHALL JVM 210H
PEAVEY JSX
KRANK 412
MESA 412
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#9
I just looked at it and saw that some of the pins aren't connected to the inside of the tubes. Is this normal? I suppose it probably is fine though. The guy who sold it to me told me that he hasn't changed the tubes once since he got the amp 8 years ago. I figured they're probably prone to breaking sometime soon.

EDIT: Never mind I do think its working. Well its too late, I already ordered the new tubes. I suppose I'll hold on to them until my tubes start dying then.
Last edited by ubtguitarist at Mar 8, 2009,
#10
There is absolutely no harm in swapping out the preamp tube(s) when you get new ones. But, if your amp turns on and plays and sounds normal, then nothing is wrong.
You immediately hear something is wrong when a preamp tube is not functioning.
MARSHALL JVM 210H
PEAVEY JSX
KRANK 412
MESA 412
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#11
^Yeah, especially the phase inverter. If the PI was dead I'd think you'd have zero sound.
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#12
Thanks Bro. Damn I was gonna get a new pedal but spent my money on tubes instead. Oh well, Nothing wrong with some new tubes. This is my first tube amp, so I really didn't know too much about them. Just another quick question. I heard the power tubes are usually the first to fail. If these are fine, I suppose the pre amp tubes still have a lot of time left in them right? Unless under special circumstances I suppose.
#13
Preamp tubes can last for years. Sometimes new ones fail quickly though, right out of the box. But generally speaking, they have very long life spans and don't degrade nearly as fast as power tubes.
MARSHALL JVM 210H
PEAVEY JSX
KRANK 412
MESA 412
FENDER STRATS
DIMARZIO
CELESTION
#14
^+1 NOS preamp tubes could outlast an amp.
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#15
oh really? Damn I really think I'm going to cancel My order on tubes then. I probably spent 60 bucks on preamp tubes and 20 bucks on power tubes. I've heard people say that the tubes lasted only one year if you played them frequently. I figured they meant preamp tubes as well. I suppose I'll hold off on the tubes for a while. All this worrying over nothing.
#16
You can hold off on your order, but I recommend having at least one spare preamp tube on hand for emergencies.
MARSHALL JVM 210H
PEAVEY JSX
KRANK 412
MESA 412
FENDER STRATS
DIMARZIO
CELESTION