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Amplifier hum - normal?

Is it normal for amps to emit a slight humming noise from the transformer when turned on?

I never noticed it in my old integrated that I lived with for over 10 years, but that was lower power. Now I've gone from 50wpc to 120wpc... don't know if that makes a difference here though.

I mean, it's not nearly enough to bother me or even really be audible past 3 feet away... but I am curious if this is typical for amplifiers to do this.
djembeplay
tvad
9,467 posts
 
Some do and some don't.

From my experience, tranformer hum has no correlation to an amp's power rating.

It has more to do with the quality of transformer and amp design.
jeffo19
25 posts
 
I have found that higher power amps tend to have a little hum to them. Some more then others. If you can only here it from 1-2 feet in a silent room, that it pretty normal.
djembeplay OP
169 posts
 
I have a Yamaha M-40... did they use quality transformers?

It is pretty quiet... i would say you could barely hear it from 3 feet away from the chassis top in a silent room.
tvad
9,467 posts
 
I have owned several SS amps.

Bryston 4B SST - no hum whatsoever
Bryston 14B SST - no hum whatsoever
McCormack DNA-2 - no hum whatsoever
Odyssey Stratos Mono Extreme - no hum whatsoever
Belles 350A Reference - no hum whatsoever
Belles 150A Reference - hummed like a $10 hooker
Pass Labs XA-60.5 - no hum whatsoever

My history with SS amps suggests that no hum is more common than hum.
gbart
290 posts
 
I too have owned a good number of high powered solid state amps and never had any hum issues. I have had hum problems with large toroid isolation transformers. A lot of modern amps have toroids, which are more prone to humming and buzzing as a result of DC on the power line. I would look to exclude this as a possible source of mechanical hum.
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