Like Valvetronics

[petemoore]

  Not sure why yet, they're inexpensive and make for very sweet amp tones, even from the 8'' ceramic and SS output they come with.
  Through an 18w / TT Hempcone in grande' pinewood enclosure, downright stunning tones abound ! [Though it sometimes seems the Treble and Bass controls must be used to compensate for the "emu speaker LP filters"].
  They beat me to the implimentation [perhaps the logical conclusion or 'idea spawn'] of putting a reactive load in the preamp, I think VOX did a really amazing job in the RnD dept. following to a fine conclusion [AD__VT amps] this great concept.
  I have only played around with it for a few days, initial impressions are 'very impressive', I read the manual and understand they've thrown in reactive loading in the processing pot with this one...'Very Impressive indeed !'.
I found reactive loading/preamp relatively interesting and easy to type [vaguely] about, not so easy to just start doing.
  I'm done [for now].
  The AD15VT also provides effects.
 

[biggy boy]

I love my little  AD15VT lots of amp models and effects.
Plus it puts out some decent sound quality and volume for it's size.

[petemoore]

  A visitor from Minneapolis arrives and has 3 VT's, 2 thirty watt and a AD15VT.
  The speaker in the amp is a good bit brighter than my TT, the cabinet is reasonably sized and looks to be mostly an enclosure.
  We arrived at a misconclusion that there was a mal' in the amp, he wanted and took the speaker for another project, left the amp here, as others have before for various reasons. He was delighted when I phoned about the noise reduction 'broken amp' setting, that the amp is probably fine.
  Wedgeing a speaker jack insulator board in the back took all of 8 minutes, dense hardboard drilled, glued [I like to tighten up the end fibers left after drilling], jack tightened in it, shear down a 1'' opening from the side, leaving a 1/2'' 'tab' [where the shears don't want to cut the inside corners] with which the perfectly sized/cut/trimmed board can jam between the new tab and the tabs of the chassis edge, pinning the board very tightly in.
  Then, using a bigger cabinet, as expected, made the tone more 'roomy'.
  Having used the phone out through a tube amp for a few days before googling and reading the manual before I discovered the noise reduction 'problem', then using the SS output, I'm somewhat surprized, and must do further testing before opening wormcans.
  The best amp/rig is simple: the one you're having fun with because it's making you happy.

[teemuk]

Up to my knowledge, the Tonelab pedals are only "Valve Reactor" circuits with somekind of a reactive dummy load. The amplifiers, on the other hand, simply "mirror" the speaker load, scaled to higher impedance, to a triode push-pull stage that mimicks a typical power amp circuit. It's a very ingenious circuit because it interacts with the speaker, not with some kind of dummy load. Furthermore, the attunuator (placed in between the triode stage and the SS power amp) affects the feedback from the speaker in such way that the response does not change at various settings.

For those who are interested in more info, various patents cover the whole "Valve Reactor" circuit and schematics of Valvetronix products can be easily found with a little bit of searching.