Problem with my Mark IV!

Soooo, I just got a Mark IV shipped to me today and I just got home from jamming on it for like 2 hours and something is definitely wrong and I was hoping I could get some help? When I play in lead channel it sounds VERY thin. When I play in lead channel + EQ it sounds even worse. Its almost like the power is cut by over half. But what's weird is that it sounds decent when playing heavy chunky rhythms, but if I play a single note on the low E (say 8th fret) using the neck pickup, it sounds absolutely HORRIBLE... VERY VERY thin, it almost sounds like I didnt even play a note even though the volume is up. The guy I bought it from said that it has new tubes. Not sure what it is, I am unfamiliar w/ Mesa's. Anyone?

Oh, and the power tubes are the 2 6L6's in the middle and the 2 EL34's on the outsid. If that matters at all...

I run the FX Loop like this: Return in the mono jack, Send in the send. FX loop switching, and the auto rhythms in the middle. I don't use any of the satellite send/eq's. Should I?
Running pentode, simulclass, and mid-gain.


Thanks!

OK, so I think I've isolated the problem... it's the bass knob for the lead channel! If I go any higher than ~7 on the bass, the low notes (drop C) literally become unplayable. Absolutely no note comes through... It's just a flabby sound of crap. Is this common? I think something might bewrong with the knob because it's really stiff. The other knobs on the head, I can move easily but this bass knob is very stiff... like something inside is restricting it's movement. Is that a problem?

If I put the bass to 10 and use my neck pickup (EMG-85) to play a single note on the low C... oh my. Sounds like the worst sound anyone would ever hear hahaha

High gain on mark series amps usually don't have a bass setting more than 4. Try putting the bass on 3, and make the graphic eq in a v shape.

I realize you may not be a petrucci fan, but try his settings for high gain and see if it sounds high gain. I don't think the knob should be that hard to turn, regardless.

http://johnpetrucci.com/gear2.htm

JMMP said:

High gain on mark series amps usually don't have a bass setting more than 4. Try putting the bass on 3, and make the graphic eq in a v shape.

I realize you may not be a petrucci fan, but try his settings for high gain and see if it sounds high gain. I don't think the knob should be that hard to turn, regardless.

http://johnpetrucci.com/gear2.htm

Click to expand...

Yeah, I got a few settings from the internet and tried them out... it sounds a lot better. Freaked me out last night when the bass was at 8 and it sounded like total ****. Thought i just bought a broken amp

Well, I just got back from practice and I've got some pretty good tones dialed in. Once you figure em out, this amp screams. However, I couldn't find any settings that made the lead channel sound that great without the EQ. Engaging the EQ just makes everything sound sooo good. Does anyone ever use the lead channel without the EQ?