Hi all! I am a new owner of an 18 watt TMB model. I bought it used after only testing it a medium to low volume for a few minutes before paying and walking away with it. So, when I got it home I very anxiously removed my 800 from my 4x12 and sat my (sort of new) head on top, made sure the speaker resistance was set, plugged it into the cab, powered it up, let it warm up, plugged my guitar into it, checked levels and switched the standby to on position. So far so good!
Low volume gave me a beautiful and bright clean sound... awesome! Time for some crunch I says! When I turned it up and played with the EQ I got some really great tones but in the background there is this weird pulsing electrical type of noise almost like there was a flanger in the background. The low frequencies began to come out pretty muddy and made this sound more predominant too. I then rolled back the bass on the eq and brought up the treble some. Still there, still muddy when I pound out an E chord. I swapped the mesa preamp tubes for the sovteks from my Marshall to see how that would sound. At first I enjoyed a crisper sound but again when I cranked her up a bit along came that weird oscillating sound again. I tried to ignore and tried to get that buyer's remorse feeling out of my head and jammed away for a while. Next thing I know the volume starts to drop until I can hardly hear the thing!
Now I'm worried. Switch it off, switch it back on, same thing. I unplug everything and stared in the back like it would fix something. I plug everything back in, power up, plug in and the volume is back but the weird noise is still persisting. Even when I'm not playing there is a pulsing sound and I forgot to mention that it also picks up a radio station. So, I have turned it off and come here to see if anyone has had a similar problem or might know what is causing this. Also does anyone have a pdf copy of the schematic so if/when I have to bring this to my amp guy he will have something to go by? I don't know how close this circuit is to the Marshall 18 watt amps so I don't want to tell him to use it.
Thanks!