toneseeker74
New member
I have been slowly tweaking the values of caps and resistors on my YBA-1. My primary goals were to reduce the tubby bass overall, make channel 1 clearer, and bring the EQ of channel 2 down from super bright to more of an upper midrange emphasis. I have succeeded on all accounts, but along the way I have introduced a propensity for the amp to feedback even with nothing plugged in. This happens about 70% of the times I use the amp. I probed around the amp with a wooden chopstick while on hoping to fix any lead dress issues. This didn't help. Tapping on each tube or any part of the chassis will amplify the tapping. Same with plugging a cord in or removing it from an input jack. Sometimes I get a loudish pop when I turn the power, not standby, switch off. I switched around various known good preamp tubes. Still no luck. I am wondering if I damaged a solder joint on pin 1 of the first 12AX7 because this is where I connected to ground each time I drained the filter caps.
Help, please!
Help, please!