So, before I really start, I realize that this amp has somewhat of a blah reputation. I picked it up at a Music Go Round (love these stores, visit one if you have the chance) after hearing the quite pleasant clean channel of the amp, realizing that I may have to seriously tweak the dirty channel(s) to achieve something reasonable (at worst, I'd end up with a great clean platform for pedals).
The first thing I noticed once I got the amp home and cranked the master a bit was a serious disparity in the available volumes of the clean and dirty channels. The amp was also very bass heavy and not really articulate at all with any level of gain.
So the first thing I did was order a new preamp tube in the hopes it would be at least a marginal improvement. For you tube aficionados, I put a Genalex Gold Lion B759 12ax7 in replacing what appeared the original generic tube Marshall shipped the amp with in 2006. The disparity in channel volumes improved quite a bit and the gain was much clearer and vastly more pleasant to the ear.
Next came finding a new speaker. I tried and failed to find any specific information on the stock celestion (a G12 100avt), but after looking over that speaker and listening to it, I believe it's either directly related to or is the 'Hot 100' model on celestion's website (and to be blunt, I hate it). I wanted something that would easily handle the stated 100 watts the AVT puts out with ample headroom. After watching many videos (one of which was a fantastic high powered speaker comparison done by Zilla Cabs) and reading many reviews I settled on ordering an OverTonez Audio Thick Boy. A derivative of an EVM12L that has some JBL D120 thrown into the mix (multiple folks on forums made this comparison, I have no knowledge of/experience with the D120). After sourcing some slightly longer #10 bolts from my local hardware store I had the giant speaker installed, the amps back plate back on and it was time for noise. Glorious! Much more controlled low end, flatter mids and a sweet high end. Great note separation without being thin.
Now the amp is really fun! It has a very 1980's rock/metal voice and has some pretty reasonable effects on board for adding some subtle textures. One other fun thing I discovered is that there's more clean volume available if the effects loop is used with just a patch cable (the level is controlled with a push-push switch between the jacks and a knob on the front panel). My only real gripe is that there's only a shared EQ section for OD1 and OD2. OD1 is a bit thin sounding when the EQ is adjusted for OD2 (which yields the richest gain).
I know I've been long winded and probably waxed a little too poetic, I just don't have any friends who are gear nerds to tell all this to. I hope the day finds you all well.
