Buzzing from Naim NAP250 (Olive) -- from amp not speakers. Thoughts?

[lennyw]

Hi all,
An acquaintance in Russia is having trouble with his "new" NAP250 (he bought it recently). It is buzzing, apparently from the left hand side. To clarify, it is not that it is producing a buzzing from the speakers, but that the amp itself is buzzing. He recorded it and I've uploaded it here (you may need to turn the volume up a tad):

I have owned a 180 in the past, and although I would say that it hummed (when one puts ones ear against it), it was never like this. Apparently he can hear it from 2-3m away, and it does it all the time that it's switched on.

I understand from what he's written that he could return it (which is what I would probably suggest to him), but before he does, I said that I would ask in the Pink Fish ocean to see if anyone has any thoughts.

 

[stackowax]

Could be wrong but most likely explanation is noise on the mains is making the transformer buzz. It is intermittent or all of the time?

 

[Pete MB&D]

Sounds normal for a Naim amp/toroidal transformer, you should hear mine when they all get going.
Its noise on the mains supply doing it nothing to worry about.

Pete

 

[lennyw]

Thanks for the replies.

It is intermittent or all of the time?

All the time, regardless of what else is switched on or not.

So, would it be worth him investing in some kind of mains conditioning?

 

[Linn Naim]

A dedicated power supply should fix it?

Chris N

 

[lennyw]

Do you mean HiCap etc?

 

[slammel]

Sounds similar to my 250, though the hum on mine varies during the day depending on how bad the mains is, eg. it gets especially bad when my next door neighbour puts the kettle on.. it's something you get used to. I guess if the mains is really bad then the buzz would be constant.

I don't think Chris means a Hicap, more likely a dedicated spur. Don't know if it would help though.

Stefan

 

[Linn Naim]

Sounds similar to my 250, though the hum on mine varies during the day depending on how bad the mains is, eg. it gets especially bad when my next door neighbour puts the kettle on.. it's something you get used to. I guess if the mains is really bad then the buzz would be constant.

I don't think Chris means a Hicap, more likely a dedicated spur. Don't know if it would help though.

Stefan

Sorry I meant to have said a dedicated Mains Spur from the mains disribution box.

 

[lennyw]

Thanks all for your help. Have passed on the comments.
Lenny

 

[337alant]

It could also be DC on your mains in which case you would need a filter to block that

SQ posted this before and said it worked in his system with a similar problem
http://sjostromaudio.com/pages/index.php/hifi-projects/109-dct02-the-dc-trap-high-end-style

Alan

 

[PaulMB]

I'm not technically very competent, but I have heard that amps can buzz if the PSU caps need replacing.