Musicians Roadhouse

Hi all,

I just got a used Andertons CS JTM145.
However I just noticed a strong buzz, that intensifies as I increase the loudness control and is stronger on the high input.
It seems to get higher when I increase the treble or the loudness 1.

I have replaced the ecc83 valves but did not fix anything. I don't have an ecc82 yet, but will try swapping that one two.

Is that buzz normal? What could cause it if its not the valves?

I would appreciate any advice you can share.

Thanks

Power tubes pairs that are more than 8Ma apart in idle current can get very noisy. It sounds like 60htz line hum. I always assume when buying a used amp that a full retube is on the menu. But that might not be the culprit but it wouldn't hurt to have a known good set of tubes in there. Grounding issues can cause large amounts of unwanted noise problems. Considering also that you state the noise increases when changing the input there could be a bad solder/wire connection at the input jacks. Are you confident working around circuits that can have potentially lethal voltages present?

Just to try and eliminate the easy things, is it possible just moving the amp away from a potential noise source would help?

I work on my amps on a kitchen counter and that one spot in my house picks up a strange high pitched ringing (unknown source). I was pulling my hair out...until I just moved the amp.

Also, is there any hum/buzz with volume on 0? As mentioned, the fact that the volume control affects the noise could indicate it's something very early in the preamp.

What 'note' is the buzz? Try to find the note on your guitar. If it's very near a 2nd fret/5th string B note then that is 60Hz (in the US) and would generally indicate filament-induced hum (this is usually not buzzy/raspy). If it's double that (120Hz) then it could indicate a filtering issue.

Thanks for the replies guys.

I have now changed all the tubes and the problem persists.
I've also tried a different location and cables. Still the same.

Spiderwars, yes there is some buzz at 0 volume. It is not 60hz.

At this point I assume there is a problem with the loudness 1 pot so I should take it to a technician.

Starting to regret buying this one. Never had any problem with my other 1 watts.