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How hard can you drive a tube amp?

D

Devo-lution

Jun 24, 2009
535
4
#1
A few days ago, I had a chat with the bass guy of our local guitar shop.

We talked gear and he seemed utterly appalled that I sometimes drive my tube amp quite far (far= volume 7, gain 8). He was absolutely sure that I'm going to break my amp if I continue on doing this.

So, bogus or should I really be careful not to drive it too hard?

p.s. I am aware that driving a tube amp makes your power tubes etc. work harder so they'll have to be replaced more often. Not too big a deal for me since there are only six valves in the amp and I am prepared to replace them every now and then.

p.p.s. volume 7 and gain 8 seems like a really extreme setting, but my amp can stay clean on relatively high settings. 7 and 8 would be overdrive, but no all out distortion or fuzztones. In a mix it can still sound clean-ish.
 
#4
Depends on the amp. Tubes will naturally wear out faster but overall the greater concerns are that power transformer designed to be from the cheaper side may overheat due to greater power draw and that may cause them to fail due to insulation melting or just thermal fuse blowing due to exceeding the safe temperature limits. Additionally, an output overdriven to a reactive load (read=loudspeaker) will cause flyback voltage sparks in some amps, which may toast up clamp diodes (subsequently blowing a fuse) or - even worse - punch through the insulation of the OT windings or perhaps arc through a badly designed circuit board. The heat from greater power draw and losses will decrease the life expectancy of some components like electrolytic capacitors and the increased ripple in the B+ circuit will cause ill effects to main filter caps.

Some amps are designed more generously to tolerate such effects while some amps are not. So, yes: amps can die because of excessive cranking. Not all will but it's not a far-fetched idea either. Devices like attenuators will enhance the effect because they make cranking so much easier on ears.
 
#5
dukeisdog said:
What amp do you have?
Click to expand...

FAD four 100

Belgian made bass amp, so the chance that any of you know it is pretty slim.

My local tech did a maintenance check on it after I bought it second hand and he told me the following:

circuit is a bit bassman 110-inspired... PCB-board... good components in general (mostly European and US components, but he saw one or two Chinese switches or something like that)

Contacted the builder as well: It was some kind of prototype (he's a long time guitar amp builder... this is one of his first bass amps). Handwired and built around 2009/2010.

Also... This amp is a not very hot headed. It doesn't really get super hot. I can easily touch the metal components after a cranked gig. On the contrary, my guitar player's vox is always red hot after gigging.
 
#6
Devo-lution said:
FAD four 100

Belgian made bass amp, so the chance that any of you know it is pretty slim.

My local tech did a maintenance check on it after I bought it second hand and he told me the following:

circuit is a bit bassman 110-inspired... PCB-board... good components in general (mostly European and US components, but he saw one or two Chinese switches or something like that)

Contacted the builder as well: It was some kind of prototype (he's a long time guitar amp builder... this is one of his first bass amps). Handwired and built around 2009/2010.

Also... This amp is a not very hot headed. It doesn't really get super hot. I can easily touch the metal components after a cranked gig. On the contrary, my guitar player's vox is always red hot after gigging.
Click to expand...
$

I would not worry about it. The numbers on the knobs means nothing. Does it sound good? Is it clean sound. As long as it is producing clean sound you are not over driving it. If it would be bad a old VOX ac30 or an old bassman would not have a very long life as the are always cranked up loud. Thats why they sound that good. They prodeuce a natural power amp distortion.

Jocke........
 
#7
vij said:
$

I would not worry about it. The numbers on the knobs means nothing. Does it sound good? Is it clean sound. As long as it is producing clean sound you are not over driving it. If it would be bad a old VOX ac30 or an old bassman would not have a very long life as the are always cranked up loud. Thats why they sound that good. They prodeuce a natural power amp distortion.

Jocke........
Click to expand...

It's overdriving, but still pleasing to the ear. I can still play mellow love songs if I don't dig in too hard :hiding:.

And about the cab thing... It can take a punch. It's a 1x15 but it's rated power is over 500 watt RMS and I never heard the speaker farting.

[Invalid or Expired Link Removed] (the amp's specs)
 
#8
Depends on the amp and which tubes.



If it's the pre-amp section, I wouldn't worry too much as long as you get a tone you like and the cab can handle it.


If it's the power-amp section ... probably not a good idea. A little overdrive in the power section might sound good but too much can hurt both the amp and speakers. In a spectacular way.
 

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