Dangers of tubes?
Jul 2, 2008 at 3:27 PM Post #16 of 27

Uncle Erik

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Quote:

Originally Posted by Penchum /img/forum/go_quote.gif
Tubes in old radios do fail and take stuff with them. Nothing like this happens with new tube headphone amps today. If it did, it would be a MAJOR topic here at HeadFi, and we all know it. It just isn't probable that a tube will explode or melt down in one of today's modern tube headphone amps.

No one should be afraid of new tube headphone amps.



Failures might not be catastrophic, but they do happen. A friend of mine's amp recently blew an output tube (newer amp) which took down a few things with it. Didn't start a fire or anything, but he caught it right away and cut the power. If he hadn't been there, no one knows what may have happened.

This gear is not without risk. If you're running chips at 16V, not that big of a deal if something going wrong. If you're running 300V and something goes wrong, there's more that can happen. If a tube failure causes something to short, that can lead to other problems.

I agree that this gear is mostly reliable, but my problem is with those who think they can leave gear on 24/7.

It really isn't safe. These circuits are about the same as they were 60 years ago, and we're using the same tubes.
 
Jul 2, 2008 at 3:42 PM Post #17 of 27

Enthusia

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I agree with most of the logical posts here. If you think you can leave your tube amp on 24/7 without supervision then your nuts, but if you use your equipment wisely and take care of them then these events will most likely never happen.
 
Jul 2, 2008 at 4:26 PM Post #18 of 27

regal

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If you have an OTL tube amp (no output transformer) there is always risk of shock. If the output capacitor fails as a short you send high voltage to your headphones/ears. In the old days people would not use OTL amps on headphones for this reason. Some designs that include a simple cathode follower are safer than totem pole arrangements. It is a good idea to change your output capacitors every few years and make sure your amp is well ventilated.
 
Jul 2, 2008 at 5:31 PM Post #19 of 27

TimJo

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My brother was a DJ in the 70's and I remember him talking about how the engineer at the station would replace the transmitting tubes after they hit a certain number of hours. Just for fun, the engineer built something so he could take an old tube and crank up the voltage (to the heater I guess) until the tube would explode. They would do this in one room, with the tube in another room, and watch it explode looking through a window between the two rooms.
tongue.gif


I guess he wasn't worried about thorium poisoning...
confused.gif
 
Jul 2, 2008 at 6:17 PM Post #20 of 27

Skylab

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The biggest danger in a tube amp is renegade tube rolling
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Jul 2, 2008 at 6:34 PM Post #21 of 27

jamato8

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Grow up with tubes and you understand them. When new to you as the automobile was to horse and carriage users, there is mystery and over hyped speculation. Sure there can be trouble as with most anything from a ladder to a toothpick. I work with voltages from 720 volts down. It is all knowing what you are doing and just educating yourself rather than taking as gospel what someone may say. When people ask me for advice I try and help but always keep on searching. I love tubes and SS is ok to. :^)

Yeah, like above, just because the pins are the same doesn't mean you can pop it in. Know what you are doing and this just takes some effort on finding out the answers but know that there is a lot of misinformation out their.
 
Jul 2, 2008 at 7:05 PM Post #22 of 27

SleepyOne

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I think you know when it is time to replace your tubes - it just sounds flat. Used to use tube pre/power amp, don't feel it is dangerous at all.

The real danger is tube rolling - very damaging to your wallet! Also there is real risk that the resulting sound is not necessary better, just different (better at something but worst at other). If you get it right it can be magical but you could also get it wrong, a bit like a day at the casino.... Luckily forums like this helps minimised the risk.
 
Jul 2, 2008 at 8:21 PM Post #23 of 27

nor_spoon

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Quote:

Originally Posted by regal /img/forum/go_quote.gif
If you have an OTL tube amp (no output transformer) there is always risk of shock. If the output capacitor fails as a short you send high voltage to your headphones/ears. In the old days people would not use OTL amps on headphones for this reason. Some designs that include a simple cathode follower are safer than totem pole arrangements. It is a good idea to change your output capacitors every few years and make sure your amp is well ventilated.


Ouch, shock through headphones and ears. That is nasty. Hope my incoming OTL amp is not going to fail
eek.gif
 
Jul 2, 2008 at 8:57 PM Post #24 of 27

Penchum

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Quote:

Originally Posted by Uncle Erik /img/forum/go_quote.gif
Failures might not be catastrophic, but they do happen. A friend of mine's amp recently blew an output tube (newer amp) which took down a few things with it. Didn't start a fire or anything, but he caught it right away and cut the power. If he hadn't been there, no one knows what may have happened.

This gear is not without risk. If you're running chips at 16V, not that big of a deal if something going wrong. If you're running 300V and something goes wrong, there's more that can happen. If a tube failure causes something to short, that can lead to other problems.

I agree that this gear is mostly reliable, but my problem is with those who think they can leave gear on 24/7. It really isn't safe. These circuits are about the same as they were 60 years ago, and we're using the same tubes.



I agree with this and you've made it clearer for others to understand it. I don't know of anyone running their tube amps 24/7, but if someone is, they should take the warning like it as meant for them specifically. For the normal "0-4 hour then I turn it off" listener, the chances of a real problem are just not probable.

Max listening sessions of 8 hours, always a cool down to room temperature before starting another 8 hour listening session, and otherwise turned off, will extend the life of your nice tube amp.
 
Jul 2, 2008 at 9:03 PM Post #25 of 27

Penchum

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Quote:

Originally Posted by nor_spoon /img/forum/go_quote.gif
Ouch, shock through headphones and ears. That is nasty. Hope my incoming OTL amp is not going to fail
eek.gif



It sure would be nasty, but highly unlikely to ever happen in the first place.
smily_headphones1.gif
 
Jul 4, 2008 at 2:26 AM Post #26 of 27

pabbi1

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Quote:

Originally Posted by Uncle Erik /img/forum/go_quote.gif
The biggest risk is tube accumulation. Once you get hooked, more and more show up. I don't understand it.


 
Jul 4, 2008 at 2:56 AM Post #27 of 27

Dept_of_Alchemy

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If you have pets or small children then glowing tubes could be a concern as it could hurt them. As far as reliability is concerned as long as the amp comes with a fuse and is properly grounded the chances of a fire I would say is minimal, I have heard of poor quality tubes 'flashing' and spiking and damaging headphones but those kind of things are isolated incidents and are generally well documented around here.

- DoA
 

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