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View Full Version : Marantz SR-4200 buzz



sburrell
26-07-2011, 23:07
Hi,

I'm getting a consistent low-pitch buzz from my Marantz amp - about roughly the same pitch as a bumble bee. It's not through the speakers, but directly from the amp itself.

What could this be?

HighFidelityGuy
27-07-2011, 14:14
It's usually the transformer that buzzes. Has the buzz been there ever since you got the amp or is it a new "feature"? Also, is the buzz very consistent or does it fluctuate slightly through the day?

Some trannies buzz more than others but if it's a feature of the tranny then it should be a consistent buzz that's been there all the time. If it's new or if it fluctuates then it could be caused by a slight DC offset on your mains input. This can be removed by a DC blocker. These can be made quite easily with a couple of diodes and capacitors. Or they can be bought commercially. :)

EDIT: There's a link to a thread about DC blockers in my signature below...

Ali Tait
27-07-2011, 16:07
Simon, the transformer may have worked loose and be rattling. If you're not confident having a look yourself, bring it over and I'll have a look for you.

sburrell
30-07-2011, 17:35
Hey,

I've been listening more carefully. I think the sound only appears after the amp's been on for a while. I only notice it when I'm watching late at night (when the house is quiet) and the amp's been on more or less all day.

Does that still suggest the transformer? There's no fluctuation at all in the pitch, which I guess rules out DC offset - right?

Thanks guys.

HighFidelityGuy
30-07-2011, 17:57
Hey,

I've been listening more carefully. I think the sound only appears after the amp's been on for a while. I only notice it when I'm watching late at night (when the house is quiet) and the amp's been on more or less all day.

Does that still suggest the transformer? There's no fluctuation at all in the pitch, which I guess rules out DC offset - right?

Thanks guys.

Hmm, it could still be a number of things. I don't think DC offset would cause a change in pitch, more like a change in volume.

Based on what you've said I first check the amp isn't getting too hot. Then as Ali suggested check that the tranny is still securely bolted down. Also check it has some kind of washer between it and the chassis to dampen vibration. This could have gone hard over time, so a new washer may be needed.

If that doesn't help then I'd try a DC blocker. Good luck. :)

StanleyB
01-08-2011, 10:47
Sounds like the mains transformer. There are ways of finding out for sure, but since it is a relatively dangerous procedure if you do it the way I learnt how to, I suggest that you get it down to Ali and let him check it out.

Reid Malenfant
01-08-2011, 19:05
Yes it sounds like loose laminations once things are warming up ;) Normally if it's a standard EI transformer core they are just bolted up tight & possibly dipped in varnish & then baked. Often this isn't the case though, it might be as easy as tightening a few bolts :)

No guarantees though but it could be that simple...

Unless you know what you are doing, do nothing :cool:

sburrell
06-08-2011, 08:10
Thanks guys for the advice. I guess I'll take Ali up on his offer. Ali, I'll PM you to arrange a time. :)