Buzzing Stopped on Marantz Amp

[JamVal]

My son gave me this PM350 ST310 combo for Christmas.

I know these are not their better gear.

The amp has had a slightly audible buzz/hum, not through the speakers, just audible from the amp itself if you are close to it, like a transformer buzz.

It hasn't bothered me as you can't hear it through the speakers.
Today I'm listening to some LP's and I noticed it stopped buzzing. Just wondering what it might have been?

 

[Watthour]

Or might still BE. Your initial analysis may be correct. Transformer cores can loosen and hum sympathetically, and this can change with temperature, load, and time. I've had several Pioneers with Bando transformers get loose, and have removed them to tighten up the lamination tie rods/fasteners. I had one that had to be stripped and varnished because of rust and the inability to tighten it enough to make it quiet.

If the noise returns when the unit is dead cold, that might be yet another sign that you suspicion was correct.

 

[JamVal]

Or might still BE. Your initial analysis may be correct. Transformer cores can loosen and hum sympathetically, and this can change with temperature, load, and time. I've had several Pioneers with Bando transformers get loose, and have removed them to tighten up the lamination tie rods/fasteners. I had one that had to be stripped and varnished because of rust and the inability to tighten it enough to make it quiet.

If the noise returns when the unit is dead cold, that might be yet another sign that you suspicion was correct.

Thanks, it has gotten warmer here, finally, we had a cold winter, and a terrible spring up until this past week.

 

[restorer-john]

The lamination buzzing on transformers can range from virtual silence to quite annoying. There are solutions that mostly work, but in the case of the PM-350, you can consider placing a washer or two under one of the 4 securing screws between the transformer and chassis. When you tighten down the transformer, you may skew it just enough to silence the buzz. Wait until it is noisy (warm) and try each corner of the T/Xformer.

The PM-350 may be small, but it is very nicely designed and uses good quality components. They are much, much better than people give them credit for. At a time when all other brands were selling STKxxx based 30-50w integrateds, your little Marantz has discrete and well designed power amp stages.

They are also as cute as a button IMO.

 

[JamVal]

Thanks John. I'll give the washers a try. I might be good for the summer, although it got unseasonably cool here today.

I like the looks of it also, it lines up well with my other components: