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Power supply hum transmitted to loudspeakers

I know the issue of hum and buzz has been discussed endlessly. Is it not almost universal that all amplifiers with power transformers have some low level power supply noise that will cause minimal leakage hum, buzz, or hiss through the loudspeaker with your ear close enough and no inputs to the amp connected?
Is this considered the noise floor of the amplifier? According to Galen Carol's website, if you can't hear it through the music and your system sounds the way you want it to, this idle noise should be ignored. Any thoughts?


normie57
atmasphere's avatar
atmasphere
11,862 posts
 
have had their power supply upgraded, but still has a small amount of buzz at the loudspeakers, not audible while playing music beautifully.(with and without shorting plugs). I've learned to ignore it and realize the amplifier was meant to play music, not to necessarily be dead silent at idle.
Its worth getting to the bottom of little buzzes like this- you will notice the system sounding better. The reason is, depending on how the buzz originates, it can cause intermodulations. Its worth it to get them gone!
toddverrone's avatar
toddverrone
840 posts
 
@boxer12 i disagree about shielded power 'chords' being an absolute must.
i thought the same when i made my first batch of power cords and made them all shielded. they did, indeed, make my system quieter. after further builds with different architectures and materials, i have found that unshielded power cords can be just as quiet as shielded and can sound less compressed.  as usual, it all depends on the system.. the one caveat is that pretty much everyone agrees that digital components do best with shielded PCs.
wolf_garcia
6,714 posts
 
I had some transformer hum from a high current SS amp I use for a spare speaker system (for my deck) and a PS Audio Humbuster III completely fixed the issue. I now plug both of my amps into it although my main tube amp is quiet anyway. I demand that my system is humless and it is…I have lighting dimmers here and there and they don't bother the rig, and even my turntable is dead quiet after I put a new din plug Mogami cable on the Akito arm (Jelco or something). P.S. Audio should have kept making the humbusters…they're cool.
audiobrian
185 posts
 
I guess a good question is how much noise emanating from your loudspeaker, once your system is energized, is normal? I avoid saying acceptable as we all have different tolerances.  When we place our ears 12 inches from the tweeter or midrange driver and hear a low level, buzz, hum or hiss, with nothing audible at the listening chair, is this normal/expected? When I run tube gear I often hear a low level hiss, with solid state a low level buzz, but no more than 1-2 ft from the loudspeakers. 
normie57 OP
50 posts
 
A question for Atmashere/Ralph:(and others who care to contribute)

With your fine OTLs and the sensitive loudspeakers you often use, can you hear any noise/hiss 1-2 ft from your loudspeakers at idle? My VAC amps and my AudioNote Kit Interstage Monoblocks both have low level buzz audible 1 ft from my KEF Ref 3's, not particularly sensitive loudspeakers. This occurs when they are plugged directly into dedicated outlets or my Torus isolation transformer. Thanks!
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