birdrules

I had posted a short while back in the Amplifier forum about some issues I was having with the amp. I've been getting high pitched feedback like sounds coming out of the amp with the master volume at 2-3 o'clock and the channel volume at around 12 o'clock. On all topology settings, and using either the high or the low input jacks. I didn't realize it at the time of the original posting, but it seems it only does this when my JTV-89 is plugged in to the amp. I mute the strings with my hand, have the volume knob on the guitar all the way up, and it just feeds back at the volume listed above. This is with the modeling off. I tried 2 other Ibanez guitars, and a Jackson under the same conditions and get no feedback whatsoever. The evidence points to the JTV being the issue. Any ideas as to what could be causing this?

I was at work all day, but I managed to shoot an email to my sales engineer today. Hope to get a reply by email or phone tomorrow.

Wow, I bought my JTV-89 from there 6 weeks ago. Hate that I missed out on that.

I tapped on the tubes with a stick, and I do not hear it through the speakers. One tube does seem to be glowing noticeably brighter than the other. Not sure if that means anything.

Hello, everyone. I've had my DT50 212 for about 6 weeks now, and it's been great up to this point. For at least the last week it been sounding...not right. The sound quality has become poor, almost muddy or not very well defined. It's especially noticeable on the high gain topologies. Also, in full volume mode I usually have the main volume knob at 2 o'clock. When I turn the channel volume to 12 o'clock or higher I get a horrible squeal or feedback type sound of some sort. Does it even when I have the strings completely immobilized by my hands, in both channels and most topologies. I have very limited experience with tube amps before this one, so I'm not sure what it could be. I've tried a couple of guitars with this, my Ibanez S570, and my JTV 89 and it's the same for both. I do also have the latest firmware installed. I would record a sound clip, but I doubt my cell phone would do it justice. Thanks in advance for any help I get!