Buzzing in my amp

[Counterstriker]

my H&K blues master has this buzz whenever it's on, It's like a low vibration, I took the top off and plugged it in (against the warnings on the side) to see if I could see anything vibrating but I couldn't.. What could this be?

[JonnyBoy]

To be honest brother, so many different things could be wrong Its hard to say. Sometimes it setting close to other gear or computer, the guitar buffer being too close to the amp, dirty electricity, on and on. Try it out a few places around the house, then try it at other places out side the house. You may find that EMF;s are hard to rid around town.

[squire758]

dont run it and just get it checked out, its not that much to at least find out whats up. In my line of work the fatal thought is always "maybe I can make it home"

[waldo041]

don't know so need to ask, are there tubes in that preamp?

peace,
waldo

[Counterstriker]

Yes two, I changed them when I first got the amp a few months back.

[waldo041]

if you have the old ones you might want to try and see which one is going bad by swapping them individually.

peace,
waldo

[mijknahs]

I've just recently been getting a bad sound out of my Fender Twin. At first I thought is was a problem with one of my speakers going bad. I've isolated it to the Fender because it doesn't happen at all with the SMS (the poweramp and speakers remaining constant). It also happens with using the Fender as a preamp (into the McIntosh) or with the Fender power tube section. So it must be in the preamp section (I would guess).

The problem happens only with certain frequencies (the C note in particular). It needs to be fairly loud and it gets a weird kind of distortion resonance that comes and goes during the peak of the note. Also it abruptly stops as the note fades. It doesn't fade out with the note. It stops and then the note continues to fade. I noticed this during a gig not long ago and I was lucky to have the SMS as backup right there ready to go.

Can a bad preamp tube sound like this? It's not like a microphonic ring and it's not like a clipping sound either. It comes and goes during the note and only on certain notes. Anyone had a similar experience?