JKMV12
Well-known member
Fortunately this doesn't seem to be that severe (though sounds can be deceiving). Here is the issue:
Just today my speakers started producing a low-mid level "thump" noise. Both speakers produce it (i can feel the vibration on both cones). The volume controls have no effect on it. I have both of them all the way down and it still happens. It happens at irregular intervals; they are 1-10 seconds apart. It seems like the longer the interval...the louder the next thump. The presence and density knobs seem to change the tone of the thump (i.e. more bass or more treble). The guitar is not plugged in at all. The only thing attached to the amp is power.
My first guess would be a capacitor somewhere because it sounds like a pulse of energy being released. So a capacitor that can't hold its charge anymore?
I took the chassis out to check the inside but i found nothing obvious. I powered it up without the guitar in and didn't notice any arcing or abnormalities while in operation. I did find that the V1 tube was a little microphonic (no squeal...just a loud ring when its tapped. it goes away but is more pronounce than the other tubes). I got a good tube in there but it still makes the "thump" or "pop" like i described. Any suggestions/ideas?
Thanks,
John
Just today my speakers started producing a low-mid level "thump" noise. Both speakers produce it (i can feel the vibration on both cones). The volume controls have no effect on it. I have both of them all the way down and it still happens. It happens at irregular intervals; they are 1-10 seconds apart. It seems like the longer the interval...the louder the next thump. The presence and density knobs seem to change the tone of the thump (i.e. more bass or more treble). The guitar is not plugged in at all. The only thing attached to the amp is power.
My first guess would be a capacitor somewhere because it sounds like a pulse of energy being released. So a capacitor that can't hold its charge anymore?
I took the chassis out to check the inside but i found nothing obvious. I powered it up without the guitar in and didn't notice any arcing or abnormalities while in operation. I did find that the V1 tube was a little microphonic (no squeal...just a loud ring when its tapped. it goes away but is more pronounce than the other tubes). I got a good tube in there but it still makes the "thump" or "pop" like i described. Any suggestions/ideas?
Thanks,
John