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Do class A amps draw power even when turned off?

I have a Pathos TT integrated amp (class A). The manual said it draws 300 watts even when there is no signal running thru it. Does this mean that it is drawing 300 watts even when I have it turned off, or only when it is turned on regardless of whether or not it's playing music???

If it still draws 300 watts of power when turned off, I guess there is no harm in un-plugging it?
128x128pdreher
ghostrider45
449 posts
 
Actually, if it's truely a Class A design (Pure Class A, the power usage (in this case 300W) will be constant, irregardless of whether or not there is a signal.
herman
2,244 posts
 
.

Does this mean that it is drawing 300 watts even when I have it turned off
NO, it is consuming no power when it is turned off. The exception would be if it has a remote that is waiting for a command to turn on but that circuit would draw very little.

, or only when it is turned on regardless of whether or not it's playing music???
This is the correct answer. The power consumption does not go up when playing music. Class A amps consume the same amount of power whether they are playing music or not
zaikesman
3,017 posts
 
But class-A amps throw off the most heat when they are not passing a signal, unlike class-AB amps (in other words, no significant amount of the constant electrical power being consumed gets dissipated as sound power by the speaker when silent, so more must get dissipated as waste heat).
timrhu
2,779 posts
 
Zaikesman, that's very interesting. I'm not questioning your statement but am wondering if you can site a source for it. I've noticed this phenomenon with an amp I have that claims to run class A for first fifteen watts. I always attributed the cooler amp after playing music to the fact that the amp is sometimes running A/B. Thanks.
pdreher's avatar
pdreher OP
1,207 posts
 
Thanks for everyone's help... I can always count on the members of Audiogon to pull thru for me!
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