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howdy,
i have this older classic 30 that up until now has been fairly solid. i have done a bit of work to it out of necessity. i replaced every bloody jumper wire in the thing because i got sick of them breaking. i've also modified the tone stack with some orange drops and silver mics and bypass cap on V1 in the preamp (Steve A's mods).
over the course of the past three months, the amp has progressively gotten quieter in volume and has developed a soft distortion in both the clean and distortion channels. the distortion only happens when signal is being sent to the amp. not when the amp is silent like you'd expect from deteriorating caps. this distortion also sounds kind of like an envelope filter in a way. messing around with the tone knobs while sustaining a single note creates this "wah-wah" effect. i changed out all the preamp tubes thinking that the problem could have been with the phase inverter, but no luck. i had an older quad of el84s that i tried with the exact same results thinking that, if it were the power tubes, the older set would at least sound somewhat different. i've ordered a new quad just to be on the safe side, but i wanted to pitch the problem on here to see if anyone has ever heard of such a thing. i've tried every combination of search queries into to Google only to come up empty handed. i don't think the OT would cause such a problem... but i'm at a loss on this one. hah. any input is surely appreciated.
i have this older classic 30 that up until now has been fairly solid. i have done a bit of work to it out of necessity. i replaced every bloody jumper wire in the thing because i got sick of them breaking. i've also modified the tone stack with some orange drops and silver mics and bypass cap on V1 in the preamp (Steve A's mods).
over the course of the past three months, the amp has progressively gotten quieter in volume and has developed a soft distortion in both the clean and distortion channels. the distortion only happens when signal is being sent to the amp. not when the amp is silent like you'd expect from deteriorating caps. this distortion also sounds kind of like an envelope filter in a way. messing around with the tone knobs while sustaining a single note creates this "wah-wah" effect. i changed out all the preamp tubes thinking that the problem could have been with the phase inverter, but no luck. i had an older quad of el84s that i tried with the exact same results thinking that, if it were the power tubes, the older set would at least sound somewhat different. i've ordered a new quad just to be on the safe side, but i wanted to pitch the problem on here to see if anyone has ever heard of such a thing. i've tried every combination of search queries into to Google only to come up empty handed. i don't think the OT would cause such a problem... but i'm at a loss on this one. hah. any input is surely appreciated.
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