Receiver hum/buzz - NOT what you think (please help)

[Nethergoat]

I just bought an Onkyo TX-SR500 from Circuit City (display model, $230
rather than the normal retail price of $300). No real complaints so
far, it's replacing a random JVC receiver I've had for a few years -
hooray for Dolby Digital, DTS, optical inputs, etc.

There's just one thing that's kept me wondering whether or not I
should return it - whenever the receiver is on (regardless of settings
or volume), the receiver itself hums. It's a high-pitched hum that
you wouldn't notice except when you're close enough to hit the power
button, but it's still audible enough to worry me a little bit. I'm
not used to hearing receivers hum this loudly, and I was wondering if
perhaps it had something to do with its former occupation of 'display
model.'

Am I worrying unnecessarily, or should I take advantage of the 30-day
return policy before I'm forced to put the 1-yr manufacture's warranty
to the test?

[Barry Mann]

In >, on 08/05/03
at 10:54 AM, (Nethergoat) said:

>I just bought an Onkyo TX-SR500 from Circuit City (display model, $230
>rather than the normal retail price of $300). No real complaints so
>far, it's replacing a random JVC receiver I've had for a few years -
>hooray for Dolby Digital, DTS, optical inputs, etc.

>There's just one thing that's kept me wondering whether or not I
>should return it - whenever the receiver is on (regardless of settings
>or volume), the receiver itself hums. It's a high-pitched hum that
>you wouldn't notice except when you're close enough to hit the power
>button, but it's still audible enough to worry me a little bit. I'm
>not used to hearing receivers hum this loudly, and I was wondering if
>perhaps it had something to do with its former occupation of 'display
>model.'

>Am I worrying unnecessarily, or should I take advantage of the 30-day
>return policy before I'm forced to put the 1-yr manufacture's warranty
>to the test?

A certain amount of this type of hum is normal, unfortunately, we can't
hear it and give you a good opinion.

Cheap transformers tend to hum more than expensive transformers.
European transformers are generally quieter than Japanese transformers
which are quieter than American or Canadian transformers. I hate
lamination buzzes. US engineers give me that knowing glance and wry
smile that says I wouldn't be complaining about the buzz if I had any
technical smarts because everyone knows that transformers hum. European
engineers chuckle at the dumb Americans and contend that if the
engineer wants the transformer to be quiet and knows what to do, it
will be quiet. (Note that power transformers can never be absolutely
silent.)

Gently flex the chassis. If the buzz changes significantly while you
flex, take the unit back.

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