Hey all;
I've got a Carvin X100B tube amp that keeps losing volume. I've been messing with it for some time now, so I'll give you the rundown of what I know:
1. after about 10 minutes of use, the volume drops considerably (the actual time varies, but at times you can practically set your watch by it)
2. the volume drop may be gradual (i.e., over a period of a few seconds) or sudden, and is replaced with an increase in hum (but not excessively loud hum)
3. the tone stays pretty much the same (not all flabby and weak) it's just quieter
4. this problem is intermittent and sometimes a whole week will go by without any problems
5. there are 2 channels on this amp (dirty and clean) and the problem affects both
Here's what I've tried:
1. switching preamp tubes around - no effect
2. switching channels - no effect
3. resoldering most of the board - no effect
4. cleaning tube sockets - no effect
5. the amp also has a 60% power switch, which, when toggled, makes a staticy noise and usually resolves the problem. Thinking the switch might be the problem, I rewired it to be bypassed - no effect
6. changing speaker impedance switch - no effect
There may have been others, but that's about all I can think of for now. Figuring that there was an issue of supply voltage to the power tubes, I connected my meter to one of the tubes and measured the proper voltage. I left the meter attached for a long time, and the problem went away (while the meter was in the circuit). This is the only thing that has reliably solved the issue, and I've repeated it a couple of times to make sure it wasn't a fluke. I'm not sure how that might solve things, but it seems to have.
Any ideas on what to do here?
Thanks
I've got a Carvin X100B tube amp that keeps losing volume. I've been messing with it for some time now, so I'll give you the rundown of what I know:
1. after about 10 minutes of use, the volume drops considerably (the actual time varies, but at times you can practically set your watch by it)
2. the volume drop may be gradual (i.e., over a period of a few seconds) or sudden, and is replaced with an increase in hum (but not excessively loud hum)
3. the tone stays pretty much the same (not all flabby and weak) it's just quieter
4. this problem is intermittent and sometimes a whole week will go by without any problems
5. there are 2 channels on this amp (dirty and clean) and the problem affects both
Here's what I've tried:
1. switching preamp tubes around - no effect
2. switching channels - no effect
3. resoldering most of the board - no effect
4. cleaning tube sockets - no effect
5. the amp also has a 60% power switch, which, when toggled, makes a staticy noise and usually resolves the problem. Thinking the switch might be the problem, I rewired it to be bypassed - no effect
6. changing speaker impedance switch - no effect
There may have been others, but that's about all I can think of for now. Figuring that there was an issue of supply voltage to the power tubes, I connected my meter to one of the tubes and measured the proper voltage. I left the meter attached for a long time, and the problem went away (while the meter was in the circuit). This is the only thing that has reliably solved the issue, and I've repeated it a couple of times to make sure it wasn't a fluke. I'm not sure how that might solve things, but it seems to have.
Any ideas on what to do here?
Thanks