Grunting 250

Posted by: Edo Engel on 27 March 2002

Hi all,

I recently noticed that my 250 is producing a quiet snore. It's hardly audible, and I have to ask people in the room to shut up in order to be able to hear it, but I'd still like to know what it is. It's a wee noise from the amp itself, not through the speakers. It's there when the amp is switched on, regardless of whether or not other apparel is operating or feeding a signal. Any experiences? Thanks a lot in advance...

Cheers,

Edo

PS The lady dates back to 1974 or something; might be useful info...

Posted on: 30 March 2002 by J.N.

I like that!

Hi Edo; it's mains distortion causing the big toroidal transformer in the 250 to physically buzz. It does not degrade sound quality in itself, but crappy mains does have an effect upon system performance.

It should vary in intensity throughout the day as the 'quality' of your supply changes.

Chances are; it's beyond your control and coming from outside your home, but some domestic appliances (electric blankets etc:) can screw things up.

IF the problem is from beyond your abode; a separate spur won't cure it. My 135's used to play a merry tune from the transformers and only stopped when the local supply company overhauled the H.T. system.

Naim are aware of the problem and now make efforts with new products to be less prone to the problem. DON'T try to isolate the transformer with some sort of compliant mounting. They've tried it and it degrades the amp's performance.

Posted on: 31 March 2002 by johno

quote:
Originally posted by Edo Engel:
It's there when the amp is switched on...

Edo,

It does beg the question how often do youswitch it off? If it is daily and you use it daily it will sound much better if left on permanently.
They will sound better after hours/days of being left on.

John

John
Shore