RB-1090 Buzzing trafo/s

[geeza]

Hello Everybody after 3yrs of absence (shame on me)

Two years ago I've bought second hand RB-1090. Great engine for my TwoPointFive's. I've noticed a mechanical buzz coming out from the chassis. It's not so loud but its predecessor in my set-up (RB-1070) was completely silent.
Does anyone were faced the problem? Any ideas to resolve this?
I will be thankful for suggestions.

rgds.

[Glen B]

Two possiblities are a loose transformer mounting bolt or direct current (DC) offset on the AC power line. Possible sources of power line DC offset are ceiling fan speed controllers, halogen lights, light dimmers, other appliances with speed or temperature controls.

[Isaac]

This might help.

http://www.psaudio.com/ps/products/detail/humbuster-iii?cat=power

[Glen B]

The OP really needs to try removing possible sources of hum, before spending $300.00 that may not be necessary. He needs to check for a loose transformer and tighten up the mounting bolt if its loose. If that's not the problem, the next step would be to check for sources of DC/excessive harmonic distortion by turning off or unplugging any suspect items as described above, or shutting off all circuit breakers. Only if none of those work, should the next step be to try a noise filter.

[SkyDover]

My RB-1090 gave me some hum/buzz in 3 different homes and I always blamed Rotel for it, never could get the issue solved, even though Rotel did do a great job trying to help me. I just dealt with it over the years but then I moved into a new home with a home theater room that had a dedicated plug for the amp to assure no hum issues. For the first time the Rotel RB-1090 is dead silent. If I plug the amp into another non dedicated plug through out the house, there is hum/buzz. So it's likely that it's something in the house. I never figured out what was the cause in any of the homes I've been in.

I thought it might be the smoke detectors but turning them off at the fuse box, there is still hum/buzz. The house doesn't have any dimmers or florescents.

Now I realize it wasn't Rotel's fault!!

[windshear]

Another thing not to overlook is the line voltage. I have seen it with my RMB1095. Your electrical supply is not always at the rated voltage and sometimes when it goes higher the transformer can hum. My supply should be 220V but i have seen it go as high as 240V and this caused my transformer to emit a low hum. It certainly took me a while to realise what was going on.

[Glen B]

I thought it might be the smoke detectors but turning them off at the fuse box, there is still hum/buzz. The house doesn't have any dimmers or fluorescents.

The source of DC could have been a neighbor whose house is connected to the same power company transformer as yours. Any device other than a light dimmer or fluorescent light, that employs a diode in series with the power line to regulate voltage/speed/temperature can cause DC.

[MICHAEL STRO]

I had the same buzz problem it drove me crazy. I ran a ground wire from each piece of equipment to the ground lug on my power conditioner buzz went away.

[madmac]

I would suspect grounding as well. Also what Glen B said about the presence of voltage regulators (ie: dimmers). Not a good idea at all to run audio/video components in ungrounded power recepticals EVER. Surge protectors are voided and do not work using ungrounded recepticals either.