I have a "new" Fender-made Model T head, purchased recently from a local shop on closeout. I thought I'd post some impressions just as potential resource for other Model T users or to invite suggestions on how to get the most out of my rig. Here goes:
RIG
My rig consists of the Model T through a Jenkins Sound Shop "Highway 61" 2x12 cab loaded with a Weber C12B and a C12S. Together, these speakers are rated at only 60 watts, but they seem to handle the T's punishment rather well. I never max out the volume clean or distorted, but I do play loud in a band situation. I have an '01 Les Paul Standard with SD Seth Lover humbuckers and a DeArmond M77T with stock pups. Both sound great through the T.
GENERAL IMPRESSIONS
This is one loud, proud mother of an amp. It has incredible volume and presence that can get out of hand very easily if you're not careful. I use mine in a fairly basic rock quarted set-up, and it can handle all I need it to. It's only problem is that the sweet spots on the amp are just too loud for anything but big stage use. The gain channel really does not start sounding good until the master is up past 6 or so on the dial. Below this, the gain has a fizzy, unmusical character - even with upgraded tubes (see below). Once you get it cranked, however, it rocks with the best of them and all fizziness is gone. The clean channel also sounds much, much better up at "stage" volume - I would say that this starts at around 3.5 on the volume dial. This channel breaks up very musically past 4 or 5 on the dial, but it is damn loud at the break-up point.
I have a Weber MASS power attenuator on order to try to tame the beast, and I'm pretty optimistic about it. A lot of people seem to be giving good reviews of the MASS for applications just like mine with the T.
TUBES
Power Tubes
I like the stock Groove Tube re-branded Svetlana 6L6GC's that came with the amp. They seem to sound proud and strong at most volumes, and they are used and respected by many players. It's my understanding that some T's came with Sovteks instead of the Svets. I can't speak on the Sovteks. Fender advises to bias these at 30 mA per tube, which is a rather cold setting. I've warmed the bias up to 35 mA per tube, and I like the sound much more - especially with the distortion channel. I may even go up to 40 mA per tube to put the tubes on the "hot" side of things and see if I can retain some clean headroom. I've contemplated installing some JJ 6L6GC's, KT66's, or some 7581A's in place of the Svets, but I'm not sure I want to sink that much money into an area of the amp I'm already happy with.
Pre-amp Tubes
The amp came stock with all Sovtek 12ax7's in the pre-amp positions. I immediately began switching these around after getting the amp. I settled on the following scheme for the tubes:
V1 (first stage for clean and distortion channels) - JJ ECC83S from Lord Valve. The JJ's don't work well in all amps, but this one really improved the T. It has a metric ton more output than the stock Sovtek, without much more gain. The clean sounds are very balanced and the gain is strong on the distortion channel.
V2(second stage for clean channel) - JJ ECC83S from Lord Valve. See above.
V3 (second stage for gain channel) - Sovtek 5751 from Lord Valve. This cleaned up the distortion channel a lot, but it may be getting replaced for something with more gain to balance out the distortion channel a little.
V4, V5 (buffer tubes of some sort) - Stock tubes.
(Phase inverter tube - I think it's V6, but it may be V7) - Chinese 12at7 from Groove Tubes. This made a *HUGE* difference in the character of the amp. The volume and gain controls are much more usable now and do not jump from quiet to sonic storm if you breathe on them too hard.
V7 (I forget what this one's function is, but it's not a tone tube) - Stock tube.
That is all for now, but I'll probably follow-up as I think of more info. Rock on!!!