Just got a jvm210h head and playing it in high gain mode is well, difficult. I bought it for this gain channel so its not like its "too much" ha. Gains at about 6 on the red mode, but whenever i try to use any mids it just screams with terrible feedback. And even without mids my guitar has to be volumed down pretty low to make it sound decent. Is any of this to be exepected? Maybe a blown speaker? What do you all think. Ampw as purchased used but everything seems to line up fine otherwise...
My first suspicion would be a microphonic preamp tube. Try swapping a few out, see if that helps?
That's not always what microphonic tubes sound like. I would at least try tapping them with a pencil with the amp on to see if the sound comes through the speakers, but ideally you should still get at least one good 12AX7 to rule out the most obvious issue.
Roc8995Sounds like a plan i'll try it out in the morning when I can turn up to an audible volume again and update with results.