RickyLee
Well-known member
So now I got some strange issue that I know was not present before the last week or so. It seems that if I run the amp without the footswitch plugged in, that channel 2 sounds bad and has a strange buzz noise issue. The amp defaults to channel 2 when I power up and the back channel selector switch is set at the footswitch position. Is this normal?
Another question: Is it bad to use that back rotary switch or move it out of the "footswitch" position while having the footswitch plugged in?
When I run the amp with the footswitch plugged in and that back rotary switch set at the "footswitch" position, channel 2 does not have those odd noises and buzz.
This also seems to coincide with this new problem that I have, where all channels now sound off and a bit harsh. When I strum an open E chord I have this bad breakup and harshness on my two bottom strings. The amp lost it's clarity. I tried replacing all the preamp tubes with no change. I also tried runnning 2 of the 4 6L6's, or each pair of two separately with no change.
And last night I thought I found the issue as I plugged my guitar directly into the FX loop return. At first I did not have much output, so I thought I was on my way to narrowing down the problem. I plugged the cable in and out of the return jack a few times and the power amp seemed to sound better after that. So then I plugged into the front input but there was no change in this odd sound I am having.
This bad tone and harshness came a few days after I did a couple of mods. They were the mud mods, where I snipped one leg each of the 120pF caps that were across the phase inverter plate resistors. And I snipped one leg of that .005uF cap that is in series with the 56K to Ground after the FX loop. I ended up putting a 270pF capacitor back in place of that .005uF. I had the amp sounding really good after the mods and played it for quite a bit after that with good results. Then a few days later, the next time I turned on the amp to play it, it did not sound like the same amp at all and that is when this bad sounding harshness was there.
The other thing I am curious about, is if I could have damaged that ferrite bead after the front input? That same day that I was working on it with the mud mods, I had unsoldered the wire to the front input positive and soldered in a 56K resistor at the input. I did not hear any tonal change, so I removed that resistor and soldered the wire back to the input. But the amp was working properly right after that still, so I am not sure there.
Anyone know if there is a way to test that ferrite bead? Is there a certain value of resistance reading I should see there?
Another question: Is it bad to use that back rotary switch or move it out of the "footswitch" position while having the footswitch plugged in?
When I run the amp with the footswitch plugged in and that back rotary switch set at the "footswitch" position, channel 2 does not have those odd noises and buzz.
This also seems to coincide with this new problem that I have, where all channels now sound off and a bit harsh. When I strum an open E chord I have this bad breakup and harshness on my two bottom strings. The amp lost it's clarity. I tried replacing all the preamp tubes with no change. I also tried runnning 2 of the 4 6L6's, or each pair of two separately with no change.
And last night I thought I found the issue as I plugged my guitar directly into the FX loop return. At first I did not have much output, so I thought I was on my way to narrowing down the problem. I plugged the cable in and out of the return jack a few times and the power amp seemed to sound better after that. So then I plugged into the front input but there was no change in this odd sound I am having.
This bad tone and harshness came a few days after I did a couple of mods. They were the mud mods, where I snipped one leg each of the 120pF caps that were across the phase inverter plate resistors. And I snipped one leg of that .005uF cap that is in series with the 56K to Ground after the FX loop. I ended up putting a 270pF capacitor back in place of that .005uF. I had the amp sounding really good after the mods and played it for quite a bit after that with good results. Then a few days later, the next time I turned on the amp to play it, it did not sound like the same amp at all and that is when this bad sounding harshness was there.
The other thing I am curious about, is if I could have damaged that ferrite bead after the front input? That same day that I was working on it with the mud mods, I had unsoldered the wire to the front input positive and soldered in a 56K resistor at the input. I did not hear any tonal change, so I removed that resistor and soldered the wire back to the input. But the amp was working properly right after that still, so I am not sure there.
Anyone know if there is a way to test that ferrite bead? Is there a certain value of resistance reading I should see there?
