Price paid: $ 1100
Purchased from: ebay
Features: The THD Bivalve is one the very few TRUE Class 'A' guitar amplifiers you will run across. Many other manufacturers boast class a circuitry only to deliver cathode biased class a/b circuits. This is the real deal.
Features... 1 channel, 2 inputs: high and low, high is significantly grittier and louder. I have read that the 'low' channel just goes through the input tube and the 'high' channel uses the input and driver tubes, don't know for sure though. For knobs you have volume, treble, bass, attitube(aka mids). Only 1 master volume makes for loud amp, the attenuator(see below) doesn't count imo. Mids switch for a mids boost, and a 'light bulb' switch for noise reduction, resulting in less errant noise evidently. Mine never worked. Also featured on the front plate is a switch to activate/bypass a knob that controls an onboard hotplate attenuator(not impressed); and another switch to toggle between a high or low plate voltage(lower voltages for el84 or 6V6's). AND that's NOT ALL!
Turn this amp around and you'll see a fistful of fuses, a series effects loop, a line/passive out with volume knob, and 2 speaker outs with switchable impedance from 4 to 16 ohms. You can also run quite an array of power tubes and [of course] preamp tubes. You can even mix and match power tubes and get converters for el84's. This amp running on 2 el84's(via yellow jackets) makes 5 watts! You can even just run 1 of those tubes for 2.5 watts! Oh my. If you think that is alot of features then I would have to agree with you. In fact this has more robust features than just about any amp I have seen under 50 watts.
this is a very serious amp, it's loaded with the good and useful features you may want, but can still act like a simple little tone machine that is just as happy taking pedals in the front as it is taking em in the effects loop.
I am a little displeased in that I feel this amp needs to become too loud to start sounding good, I am not talking about overdriving the power section into saturation either, I mean just the good clean tone you expect out of this amp is achieved at quite high volumes and using the built in hotplate suck quite a bit of tone imo. // 10
Sound: I usually use a american std Ash strat HSS with handwound pups, with some pedals using a Orange ppc212 with a couple weber speakers. This is a great stand alone amp, but I feel it's real strength is helping blend tone. Using this amp in conjunction with another amp with complimentary tone can achieve a very robust sound. I find this amp to be quite adaptable if you can get to perform at a low enough volume.
I really love how sensitive this amp is to tube selection in that you can give your amp more headroom with some kt88's or get a dirty old amp feel with a 5 watt el84 amp, or mix a 6V6 with a 6L6 just to get a strange take on a fenderish tone. You can also cool the preamp section with a 12at-7 or get some ecc803 for a woodier mids sound. Quite scultable with no biasing.
while this amp is great, but a little loud, I must say it is also somewhat challenging as well. This is not an amp you just walk up to and get an 'easy' tone out of; this is an amp that rewards intricate, dynamic and complex play with a depth that is only truly accessible to someone who is talented enough to coax an endless array usable tones from the amp but is also knowledgable enough to know what those tones are. In other words this is a tone freak's amp. // 8
Reliability & Durability: Seems pretty robust and sturdy I have no worries of any imminent failure. Tech supports seems capable and reliable as well, only heard good things. I did get one of THD's amp bags for this amp, the zipper broke pretty quick and I got pretty ticked with how much the bag cost. Doesn't really reflect on the amp though // 9
Impression: I own tons of gear and have been playing over a dozen years, this doesn't rank as one of my favorite amps but I have come to recognize it incredibly strong tonal abilities and is used when better tone is desired. I don't really know of any other amps that deliver all the bivalve delivers and is a powerful Tool for an amp arsenal.
If lost or stolen I would probably say I am gonna get another one but I wouldn't. It's strange, this amp is killer, it blows me out the water in it's conventional uses but I don't find it a totally necessary piece of equipment.
I love the amps range and features but my one gripe would be that the attenuator is supposed to act/be like a better master volume knob and I feel it fails miserably and would just much rather have a master volume. // 9