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When tubes die do they take out your headphones with them?

post #1 of 9
Thread Starter 

I was interested in a Schiit Lyr - but say I let the tubes COMPLETELY die because I couldn't pick up the subtle tell-tale signs that they were about to go - in that moment when they blow up will the massive shock sent down the signal chain burn the voice coil of the headphones plugged into them?

 

I know the Lyr is a hybrid - but the same question applies to all-tube amps?

 

And also, the thing with tubes is that they gradually degrade in sound quality - but your ears also become accustomed to the change in sound. So what starts off as a $5000 dollar sound quality amp could degrade into a $200 dollar quality amp within 2 years of use - and you'd NEVER KNOW!! So is that kind of wasting your money?

 

Finally, assuming 1 hour of use per day, when would YOU replace the tubes? Don't ask me to trust my ears, because, given the gradually becoming used to the degrading sound quality argument I placed above, I don't trust my ears!!

 

Is there a special proceedure to the whole process? I've heard of biasing? Is that necessary? Do you have to pay someone to do that? Or can you buy readily-biased tubes?

post #2 of 9

There's a ton of information out there on vacuum tubes from understanding how it works to winding your own transformer.

 

There are tell tale signs like noise, from either the left or right channel. You have to swap each tube to isolate the bad tube.

 

I've never read nor heard of a vacuum tube amp destroying a speaker. If a vacuum tube dies you will hear silence.

 

Biasing is important to provide the tubes with the correct current for them to operate properly and optimally.

Some amps have an auto-bias circuit, others you can do it yourself because it is very easy and there are some that is a PITA to do.

On the ones that are not easy, get a service manual, it tells you how to do it.

 

You can buy matched tubes, but not biased tubes. You can only adjust the bias once the tube is installed in the amp.

post #3 of 9

I had the tubes from my minimax die once, I think I had a bad tube to begin with. After 2-3 months of use, 1 channel started to degrade, then with a day whatever channel the tube was in wouldn't play any sound.

The tube I'm on now have been going strong for over a year with 2-4 hours of use.

 

I've heard most tubes are good around 5000 hours, but that would be on a datasheet for the tubes if you can find that. Some may last longer, some may last shorter.

post #4 of 9

No

post #5 of 9

Any fully direct coupled tube amplifier can do serious damage to headphones

or speakers. The only amplifiers i know of that meet this criteria are the

atmasphere amplifiers, there are fast blow fuses in the output lines which

usually blow fast enough if a tube shorts.

 

Many futterman amplifiers also can cause trouble.

 

Tube amps with output capacitors can also cause major damage if

the output capacitor shorts.

post #6 of 9

Some amps like the McIntosh MC275 bias is fixed at the factory and cannot be adjusted. It has a unity coupled circuit design that doesn't rely on critical power tube bias.

post #7 of 9

I had a tube go thermonuclear in my speaker amp (DIY Dynaco ST70 clone).  I heard a crackling in one speaker that got worse and worse by the second, along with the tube glowing brighter and brighter.  I shudder to think what would have happened if I had let that continue, or hadn't been around to do anything about it.  As a general rule, I try to be around whenever my amps are playing, just in case.

post #8 of 9
It depends on the circuit you're running. Ask the manufacturer what could happen in case of failure. If they can't give you a good response, then I'd recommend buying something else.
post #9 of 9

"A $5000 amp sounds like a $200 in a few years." 

 

Lol and no. Just no.

 

Some $5000 amps come out of the factory sounding like $200 amps. The ones that come out sounding good sound good pretty much forever. 

 

Tube aging has a much more significant effect in phono stages than headphone (or power) amplifiers. When you are running equalizers off of the tubes little changes make big differences, When you are just running a simple circuit things have to be really wrong to make that kind of change. 

 

 

Quote:
Originally Posted by Uncle Erik View Post

It depends on the circuit you're running. Ask the manufacturer what could happen in case of failure. If they can't give you a good response, then I'd recommend buying something else.


You should take the same method with builders of SS gear. 

 

Really the only amps that protect the headphones in the event of catastrophic failure have either output relays or output transformers. And they are still not really failure-proof. 


Edited by nikongod - 7/25/11 at 8:42am
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