So now that I have my Beta Bass squared away, of course my Beta Lead head decides to cause some trouble.
This is a weird issue - happens only when I have the guitar plugged into the MIDDLE input. With channel B or "both" selected via the footswitch, if I turn the "drive" up past 6 on channel B with the level up past 5, I get a really loud low-range feedback, like perhaps there's some oscillation going on. I thought maybe it was just normal feedback, but it happens with the guitar's volume set to 0.
It only happens with an instrument plugged in - if I just plug a cable in by itself, I don't get the feedback.
And I should mention that I don't get the feedback if I just plug the guitar straight into the B input. I can turn the drive all the way up with no problems.
Perhaps related - with the cable plugged into the middle input and just channel B selected, the volume is slightly louder than when plugged just into the B input.
Anyone have any ideas what might be causing this? Maybe there's some kind of feedback loop happening in the middle input or something??