[zenblaster]

I just got my first Bryston- a gorgeous 4B from 1977 that looks right out of the box. It was just at Bryston a few months ago so I am assuming everything is ok. when I power it up I am getting a  pretty good hum from one channel. what's the process to find the problem, thanks

[James Tanner]

Reverse the inputs and see if the hum stays on the same side.

james

[zenblaster]

I switched inputs and the hum stayed on the same side. If I switch the toggle to stereo (as opposed to mono) the hum is in both speakers.
By the way- this amp looks like it just came out of the box in 1977,  the original box even looks new!
thanks,
Bernie

[James Tanner]

If you disconnect the inputs and have the speakers connected does the amp hum?

james

[zenblaster]

no hum with amp on and speakers connected

[James Tanner]

Ok it sounds like it might be a bad ground on the input stage of the amplifier or a bad cable feeding that channel - please give Bryston Service a call.

james

[zenblaster]

I  found the hum- when I disconnected the cable input from my pre the hum stopped. Now I have to  properly ground the cable and I should be OK

Thanks for the quick response James