Walked into Jansen last Saturday after U2 and tried out the Tweaker next to the Rebel 30 combo. I enjoyed the clean channel of the Rebel, and the 'verb, but didn't pay too much attention to the drive channel, and it was out of my price range anyway
The Tweaker is an interesting gizmo - 15W of 6V6 powered goodness, 3 EQ modes (Fender, Marshall, Vox), 3 band EQ, and a buttload of other mini-switches. Despite its clean looking layout it also boasts an effects loop hidden away underneath as well as an additional speaker out, and a worldwide voltage selector.
On paper, it's extremely versatile, and being cathode biased essentially seems to mean that you can shove any powertube in that'll fit, which could be cool for experimentation purposes down the line.
Housed in a classy looking little cab, with a basket-weave front and curly white script which look suspiciously Bogner-esque, it packs a single 12" Celestion G12H30.
So... heaps of cool features, but what does it sound like?
First thing on my mind was, how much gain does it have, and how well does it clean up?
Winding the gain all the way up in the Marshall (Brit) mode yielded a very familiar midrange girth and fatness with my LP. You won't get high-gain shred levels out of this, but it will do a decent "boosted 800" type of sound, complete with pinch harmonics flying. Doesn't quite have the low-end thump of a big amp, and is a tad looser due to the semi-open back cab, but that's where one of the extra switches comes in - flick the "Deep/Tight" switch onto Tight and it cuts out a little of the lows going into the preamp, giving you a tighter low end. Next move is to use the "Modern/Vintage" switch - putting it into Modern mode then bumps up your lows and and highs to make them more "present" at the end of the chain. This mode has been compared to a Marshall 18 watter, but I wouldn't know.
Rolling back the guitar volume will give you decent dirty-ish cleans, but the decreased headroom due to 15Wness means you won't get sparkling cleans by simply rolling back. That's okay.
Putting the amp into Fender (USA) mode, and winding the gain down and master up, with the mids pulled back yielded a crisp, blackface-inspired clean. Flicking on the Bright switch got it further into that territory, with cleans comparable to the HRD I had recently, but at sane volume levels. That said, it can get pretty loud and pretty treble-ear-kill too. Winding up the gain in this mode gave a bright, crunchy overdrive.
Up next was Vox (AC) mode. With middling levels of gain in this mode, and with the Bright switch on, there was a definite AC vibe with the slightly rounded out, chimey highs, and that distinctive, kinda "boxy" tone. I have no idea how close it comes to a real AC15/30, but for me the feel was definitely there. Could happily have bashed out big open chords on this all day long. Very touch responsive and still sounded big on single notes struck with authority. Had a quick squiz this morning running the M13 into it and pushing it with the M13's overdrive, sounded great! This is my favourite mode so far, and I'll probably be trying this out at my next practice/gig to see how it goes with a band.
All in all, I'm stoked with this amp. Great price from Jansen, showed up the very next morning, and looks cool as!
There you have it, a slightly uneven review of the Tweaker.
Damn, now I have to do some work...
.. If he treats his women like he treats his gear he should change his name to jonah-ed (though I'm as yet unconvinced that anyone other than Unique could sustain a committed relationship while maintaining that kind of revolving door approach to gear)...then again, maybe not Jonah...ed usually sells his old stuff before buying new! 
the man has no shame. 
