08-25-2014, 06:29 AM
These ampegs typically have no grid stoppers. You might be hearing blocking distortion.
with the volume knob at 10 - there is no grid resistance on the following tube stage in this circuit other than the impedance of the previous stage. You might find it has less of that frying sound if you back it down the slightest bit, and won't loose much distortion.
You might also be hitting the first tube very hard and causing it to flex in it's grid bias significantly - especially with a boss pedal that has a buffered signal when the pedal is on or off. This might be added to the frying sound, in addition to the nature of all that high end and the amp at 10. And it may be that if there is significant blocking distortion, any OD the pedal is producing might be negligable.
First try turning the volume knob down just a tiny little bit, then a bit more, see how that compares. Then, if it makes little to no difference in regard to the frying sound, try plugging straight into the amp and see what that does.
Adding grid resistors is doable and might be an improvement on the sound of these amps when run so hard for better driven sound, but not sure if you are handy and know how to work these things safely.
Otherwise, I suppose it could be the tubes, but probably not the power filter caps.
I suppose it's possible you have a leaky coupling cap...I reccomend replacing them all anyhow--because, why not(?) here, and they're not 30-40 year lifespan parts, nor do they have vintage value as being stock, and mainly it saves time and headache since they'll inevitably drift and leak and blow one by one over the years and cause issues, and replacing them all with new quality parts is far easier and safer than testing them all to find out which leak and which don't...but that is far easier if you're handy.
In this case, you are running the amp pretty hard, why not pull two tubes and change the output impedance? You'll save two tubes that are being driven hard as it is, instead of four, even if you only get -3db less volume. You don't need headroom unless you are playing live with it cranked to 10 - which should be loud enough for, say, Royal Albert Hall. Otherwise, 2 power tubes running at or near full out is more than plenty loud for most people. If it seems quiet, something might be very wrong.
with the volume knob at 10 - there is no grid resistance on the following tube stage in this circuit other than the impedance of the previous stage. You might find it has less of that frying sound if you back it down the slightest bit, and won't loose much distortion.
You might also be hitting the first tube very hard and causing it to flex in it's grid bias significantly - especially with a boss pedal that has a buffered signal when the pedal is on or off. This might be added to the frying sound, in addition to the nature of all that high end and the amp at 10. And it may be that if there is significant blocking distortion, any OD the pedal is producing might be negligable.
First try turning the volume knob down just a tiny little bit, then a bit more, see how that compares. Then, if it makes little to no difference in regard to the frying sound, try plugging straight into the amp and see what that does.
Adding grid resistors is doable and might be an improvement on the sound of these amps when run so hard for better driven sound, but not sure if you are handy and know how to work these things safely.
Otherwise, I suppose it could be the tubes, but probably not the power filter caps.
I suppose it's possible you have a leaky coupling cap...I reccomend replacing them all anyhow--because, why not(?) here, and they're not 30-40 year lifespan parts, nor do they have vintage value as being stock, and mainly it saves time and headache since they'll inevitably drift and leak and blow one by one over the years and cause issues, and replacing them all with new quality parts is far easier and safer than testing them all to find out which leak and which don't...but that is far easier if you're handy.
In this case, you are running the amp pretty hard, why not pull two tubes and change the output impedance? You'll save two tubes that are being driven hard as it is, instead of four, even if you only get -3db less volume. You don't need headroom unless you are playing live with it cranked to 10 - which should be loud enough for, say, Royal Albert Hall. Otherwise, 2 power tubes running at or near full out is more than plenty loud for most people. If it seems quiet, something might be very wrong.