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Valve amps turned up too high?

K

klingklang

pfm Member
I have a hypothetical question. What would be the consequences, if any, if someone were to turn up the volume of a valve amp very high? Is there likely to be any damage caused to any part of the amplifier?

Thanks!
 
klingklang said:
I have a hypothetical question. What would be the consequences, if any, if someone were to turn up the volume of a valve amp very high? Is there likely to be any damage caused to any part of the amplifier?

Thanks!
Click to expand...

Hmmm, potentially the output transformers. I think you'd have to be giving them a real good kicking though.
 
A correctly designed amp driving the correct load and being driven within range you should be OK although if prolonged at maximum output could burn out. Remember that at one time all PA and guitar amps were built with valves. Certainly the case when I had my band as a kid.

Any damage is more likely to be to the speakers particularly if the early stages of the amp were to be over driven making the output stages clip. This will most likely blow the tweeters.

Cheers,

DV
 
See Jimi Hendrix, The Who, Led Zeppelin etc tc. Valve amps go very loud fine! No guitarist on anything but a beer budget would use anything else IME.

PS As I understand it getting the impedance wrong is more likely to destabalise or damage an amp than driving it loud as the output transformer is basically an interface between the output tubes and the speaker, i.e. get it wrong and the tubes are no longer operating within design parameters.
 
Depends on the amplifier and how much over it`s limits it is being driven.
In the case of smallish class A amplifiers (Quad, Leak etc) they cannot be driven to damage since neither the load nor input level will affect the average current through the valve.

In the case of large class AB or B amplifiers it might be possible to overdrive the unit to the point where the output valves flash over but this would be way beyond any vaguely acceptable sound from the speakers, even assuming they were rated to take the power. Continued operation would certainly cause damage if the valves were flashing over.

It is unlikely that the output transformers would be damaged unless the load was disconnected in which case the amplifier could become unstable and oscillate at high frequency - the resultant high voltage generated could cause insulation breakdown in the transformer. So long as some sort of load is connected this is unlikely to happen.

Valves are generally very tolerant of short term overloads so it would have to be some serious stupidity to cause damage.
 
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