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Catastrophic Tube Failure - How common is it?

wildshoetwt

Member
Messages
831
I run a Fender Quad Reverb nearly cranked with varying degrees of attenuation most of the time. What are my chances of ruining my amp?
 

PurpleJesus

Moderation is key
Staff member
Messages
8,682
Tube failure or ruining the amp, as in, frying the transformers? Separate things. If your tubes are biased properly at the right voltages they should last, but running it wide open all the time will reduce tube life overall. Like driving a car as hard as possible will wear out the tires quicker than just cruising.
 

Vibroluxman

Member
Messages
2,103
I've had one tube blow and take out a screen resistor in 12 years of using tube amps. One other time of a power tube going wrong, no damage to the amp. A few pre-amp tubes have gone but nothing serious.
 

67super

Member
Messages
1,503
Been playing for 40 years and until the last year I never had a power tube failure damage an amp. In the last 6 months I had power tube failures take out a screen resistor and a power dropping resistor.
 

wildshoetwt

Member
Messages
831
Been playing for 40 years and until the last year I never had a power tube failure damage an amp. In the last 6 months I had power tube failures take out a screen resistor and a power dropping resistor.
Any warning signs that you're gonna watch for in the future?
 

stevel

Member
Messages
15,164
Knock wood, I've not had anything "catastrophic" in my whole life. I've had tubes go bad over time - and usually this happens gradually over an extended period of time to the point where it just finally gets annoying enough to make me go through the trouble of re-tubing the amp (which I usually do all at once).

I have re-tubed amps completely before joining a new band or when I know it hasn't been serviced for a while.

The only thing I can really remember is being at a gig when my Super Reverb had a power tube dying and the amp just kept getting quieter and quieter as the gig went on - I kept turning up and turning up but ultimately everything was on 10 and there was no sound. Barely made it through the gig.

You were posting before about replacing your Quad Reverb - I don't believe you said you were using an attenuator then but it wasn't running at the volume it "should be".

My advice to you would be, get a backup amp that will work for what you need. Never a bad idea. Plenty of good suggestions in the other thread.

I think it was suggested in the other thread too that you get that amp looked at by a competent tech - and if it wasn't suggested I'm suggesting it now.

If you haven't had it worked on in a while or don't know when it was last worked on, you need to have it serviced.
 

Rick Lee

Member
Messages
11,180
Happened to me last night, had about 30 hrs on the power tubes. Happened to me twice in two weeks about six mos. ago, never once before that.
 

wildshoetwt

Member
Messages
831
Knock wood, I've not had anything "catastrophic" in my whole life. I've had tubes go bad over time - and usually this happens gradually over an extended period of time to the point where it just finally gets annoying enough to make me go through the trouble of re-tubing the amp (which I usually do all at once).

I have re-tubed amps completely before joining a new band or when I know it hasn't been serviced for a while.

The only thing I can really remember is being at a gig when my Super Reverb had a power tube dying and the amp just kept getting quieter and quieter as the gig went on - I kept turning up and turning up but ultimately everything was on 10 and there was no sound. Barely made it through the gig.

You were posting before about replacing your Quad Reverb - I don't believe you said you were using an attenuator then but it wasn't running at the volume it "should be".

My advice to you would be, get a backup amp that will work for what you need. Never a bad idea. Plenty of good suggestions in the other thread.

I think it was suggested in the other thread too that you get that amp looked at by a competent tech - and if it wasn't suggested I'm suggesting it now.

If you haven't had it worked on in a while or don't know when it was last worked on, you need to have it serviced.
Well the QR actually got completely destroyed in a car accident. I just want to make sure when I get a new amp that I'm not doing things to it I shouldn't, I really abused that QR and learned that amp repairs are expensive. Now I just learned that using an attenuator can increase your risk of catastrophic tube failure, so I'm just trying to find out how common it is and how it can be avoided. Whatever I end up getting I will take it to an amp tech and get new tubes to begin with. BTW Thank you for your music theory series, it continues to challenge and help me.
 

Bluesful

Silver Supporting Member
Messages
42,078
So many variables.............

The theory is that the NOS stuff was better built and will last longer.
 

zenas

Member
Messages
8,872
I rember seeing the Quad Reverb was in a car accident. Chassis and transformers aren't salvageable ?
At any rate if you're using that amp with an attenuator maybe a smaller amp would suit you better?
 

wildshoetwt

Member
Messages
831
I rember seeing the Quad Reverb was in a car accident. Chassis and transformers aren't salvageable ?
At any rate if you're using that amp with an attenuator maybe a smaller amp would suit you better?
The chassis no, the transformers probably (I don't know what a transformer is but I'm betting they are those large metal things?), but I already threw it all away...the actual electronics board was completely destroyed, cracked, crushed, etc

Smaller amp just isn't the ticket for me, I've never tried one that felt tight, open, uncompressed, responsive, etc. d
 

RayBarbeeMusic

Gold Supporting Member
Messages
4,872
As a tech I see catastrophic power tube failure routinely. The question then is whether it just takes the fuse or screen grids with it, or the OT, or the PT. I've seen all those situations more than a few times.

Power tubes are not light bulbs. Don't leave them in until they fail. You wont like what happens.
 

wildshoetwt

Member
Messages
831
As a tech I see catastrophic power tube failure routinely. The question then is whether it just takes the fuse or screen grids with it, or the OT, or the PT. I've seen all those situations more than a few times.

Power tubes are not light bulbs. Don't leave them in until they fail. You wont like what happens.
what are some signs of fading power tubes?
 

ledzep618

Member
Messages
4,751
I don't think I've ever had a catastrophic failure. I've had tubes for but I've never had them take other components out. Amps are meant to be cranked
 
Messages
630
Amps are meant to be cranked
I agree that this is what rock and blues musisicians in the early ages of the genres did but I respectfully disagree that guitar amps were designed that way. In the 50s and 60s everybody wanted the amps to be cleaner so that they could fill bigger and bigger venues from the stage without FOH support. The instrument amps were not intended to be distorted - manufacturers were thinking that once distortion appeared the musician would back off the volume until it disappeared. Of course we know by hindsight that this notion was wrong as the musicians routinely ignored the distortion, and ultimately wanted more of it :).

Cheers Stephan
 

InkStained

Member
Messages
4,009
I agree that this is what rock and blues musisicians in the early ages of the genres did but I respectfully disagree that guitar amps were designed that way. In the 50s and 60s everybody wanted the amps to be cleaner so that they could fill bigger and bigger venues from the stage without FOH support. The instrument amps were not intended to be distorted - manufacturers were thinking that once distortion appeared the musician would back off the volume until it disappeared. Of course we know by hindsight that this notion was wrong as the musicians routinely ignored the distortion, and ultimately wanted more of it :).

Cheers Stephan
It's hard to believe, but there was a time when amp manufacturers used to boast that their products were "distortion-free."

Thank gawd they were often wrong.

See old amp catalogs if you don't believe me, or any of the excellent books by Ritchie Fliegler, Aspen Pittman or a number of others.
 

Boomstick

Member
Messages
313
I had a '69 Marshall Major before and I cranked it up and melted a tube right into the socket. There were no warning signs, the amp stopped working... and then the smell. Granted this was because it's a Marshall Major and cranked they can put something like 1800 volts through the tubes (ask Richie Blackmore about the risk of this).

what are some signs of fading power tubes?
In a Fender (or most normal amps), your tone might start to suffer and maybe the tubes will go microphonic so you'll hear some feedback or squealing like sounds time to time, which is a sign the tubes are old and past their good life. If you do manage to melt the tube into the amp though, you probably won't get any warning signs.
 

Blue Strat

Member
Messages
30,241
As a tech I see catastrophic power tube failure routinely. The question then is whether it just takes the fuse or screen grids with it, or the OT, or the PT. I've seen all those situations more than a few times.

Power tubes are not light bulbs. Don't leave them in until they fail. You wont like what happens.
I don't think fuse or screen grid resistors qualify as "catastrophic". Transformer failure is another story.
 






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