Just got a marshall Haze stack a monthish ago. One day I was trying out a pedal a buddy gave me decided to remove it and play straight in to the amp because I heard this weird crackling noise. Turned amp off unplugged plugged back in and nothing. Called a dealer than does repairs drive it down there (1.5hr drive) blew a preamp tube. Not sure why.

two days ago I plugged in my digitech rp255 to hear how it sounds through the amp(the distortions on it suck IMO) anyway while flipping through the presets to hear how they sound some presets were really loud and the next not so much. Then I heard the ccrakling again I thought maybe at first I had a bad cable to again I turn off the amp go straight in turn it on and...nothing.
Pretty sure I blew another preamp tube. The repair guy said last time that maybe the voltage coming from the regulater is too high and considered turning it down.

Is this my fault? What is causing this?
Are you getting your service through your Marshall warranty? Because if it's happened with two different pedal the problem is the amp and Marshall should be figuring out what the problem is.
Yeah it was warranty the first time I would expect the same this time. I'll have to have a chat with the tech and see what he says, I really do not want this hassle again.
I have to ask, why wouldn't the tech just check the plate voltage?

If it's blowing preamp tubes like that, it's a problem with the amp, not you. A preamp tube should last at the very least two years. I assume both the dead tubes were in the same position?

I recommend you call Marshall. Let them know you bought one of their amps, it's defective, and you're just sure that a serious, professional amplifier company like them doesn't want a bad amp floating around to tarnish their reputation.

Do not say it sarcastically.
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the distortions on it suck IMO

IMO, the distortions are great.
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I have no experience with these amps but I know many British-based amp companies make their amps with a voltage selector switch on the back. 120 for US, 100(?) for UK. Does your amp have one and if so, is it set to the proper voltage?
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aeolian seventh- I cant answer that question but I will call the tech tomorrow and maybe marshall, I do not know yet which preamp tube blew.

kutless999- by all means reccommend some settings to me I would like to use the RP maybe I am missing something

Rockxwl- there is no switch on the back of the head unless it is inside
If its happened 2 times id be asking for a replacment amp prob demanding one!
**** fixing the one you have now over and over again thats a hassle!
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Last edited by slipknot_420 at Jun 28, 2011,
Quote by rockxwl
I have no experience with these amps but I know many British-based amp companies make their amps with a voltage selector switch on the back. 120 for US, 100(?) for UK. Does your amp have one and if so, is it set to the proper voltage?

The wrong mains voltage will not cause this problem.
Quote by joe_k
The wrong mains voltage will not cause this problem.

Wrong. If the tube was blowing due to over voltage incorrect mains selection could be the issue. It doesn't seem to be the case here though. If you had a 100 Vac transformer with 120 Vac on it your voltages could be 20% higher. If you ran at 280 at 100 this would probably lead to killing a tube.

TS, take it back and ask for a replacement amp if it is under warranty. And don't be a dick about it at first, most companies are a lot more helpful if you arent an ass. If they refuse then you can get tough with them.
Quote by kutless999
IMO, the distortions are great.

Guess what? The thread is about preamp tubes exploding, not about the tone of the amp or pedal. Also, the distortions on the RP255 are mediocre at best. What a useless response.

TS: You need to pester Marshall, and maybe try to get a replacement at this point. I'm sure that the tech you brought the amp to last time just put in a new tube, which of course didn't fix the problem at all.

Next time you take it in, make sure you tell the tech that the pre-amp tube is blowing everytime you try a pedal...that way they look at the amp, and not just the tube.
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Last edited by SLonergan at Jun 28, 2011,
What voltage regulator? Sounds like your guy doesn't know much about tube amps.
It could very well be too much voltage could be on the plate of the tube but the fact that he said voltage regulator would make me very suspicious of his knowledge. I'd find another tech to look at it.
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I'm sure the tech is competent. I may not have described his words accurately.
I have used an mxr zw44 with the amp and no issues. I'll be inquiring today