Mcintosh 250 Transformer Hum Normal

I had not noticed till today as it was very quiet here, I notice a slight hun from the unit, Nothing from the speakers.

Again I do not recall it but I had never had it on in a very quiet room and you have to be very very close (like right next to it) it could be that i just have very good hearing in that frequency range ;-)

If this is not normal what could cause it? The unit does not run warm and sounds great.
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Im sending it back, discussion closed...
Just wanted to clear this up. This was a Ebay purchased, seller dealer offered 30 day returns.

Dont care what transformer is in it or not ,nor about my ac here.

Have plenty of audio stuff here and have the common sence to know when something is not right and there is a issue.

Have been reading on this issue and it does happen for many different reasons.

Transformer being loose on the base, inside of the transformer loosening up and have read re- shellacking it, having it rebuilt or replaced, or something electronic wise is going south.

I did not buy this as a project , this was supposedy checked prior to the listing and the seller offered a 30 day return for faulty item.

Had they not been states away I would of ran it over and had them repair it if it was possible.

This is not the issue, there is someyhing wrong with it perood and its going back.

Its a beautiful piece but there is something wrong and for what I paid I would expect it to be working %100.

Thanks again for the thoughts and again consider this issue closed.

  • Just from a Google search

  • a lamination, winding or clamping screw in the transformer has come loose. Screws can be tightened, and you could maybe re-dip the transformer in magic lacquer.

  • the quiescent load on the transformer has increased, making it hum more (e.g. capacitor going bad, diode failing)

There are other things that can cause transformer hum, though. Within the amplifier, it may be that the transformer is running at a higher load than usual due to leaky caps or messed up biasing on the output transistors. Outside the amp, if the mains has a moderate DC bias or excessive noise, you can get hum and chatter. /u/kasonc, have you changed any heavy equipment, light dimmers, or wiring in your home recently?