[nwmatt]

i have a 3bsst2 that is about 6 years old and i am hearing a mechanical hum that is audible from about 2 feet , is this normal ?any ideas what might be the cause?

[Mag]

No, my amps are silent can't here them at all and they are on.
Had a hum years ago when connected to an av/receiver. Had to move input selector to input that was not being used.

[techguy0192]

Have you tried disconnecting all cables?  This will let you know if the amp is truly the source of the hum. 

[Elizabeth]

I beleve the op is saying the noise is a MECHANICAL HUM from the chassis of the amplifier.
This could be due to DC on the AC line.. or a loose transformer. Being a toroid type this isn't loose laminations. but could be the entire transformer, being not solidly bolted down vibrating.
Generally toriod are held by a single bolt through the middle. Tightening it should solve the issue. The bolt may even be sticking out the bottom of the amp.
It should be way more than finger tight, but not super tight! I am sure there is an actual torque spec. Usually the transformer is on a little antivibration pad anyway..

If you are not wanting to tighten this yourself, your dealer should be able to do it under Bryston warranty. They certainly should have someone able to check it under warranty

[Ola_S]

As Elizabeth said, one of the reasons could be DC on the mains (I have the same problem). Try a DC-filter to rule out the DC-option.

[David C]

Ola
What DC filter do you recommend ?

[nwmatt]

i tightened the transformers and that seem to do the trick !
 thanks all

[Elizabeth]

Great news!!