OK PLEEEEAAASE tell me about THD amps?

[Guitarfool]

Hey guys/gals im getting the G.A.S pains :eek: for a THD amp.. Someone i know has recommended 1 + also i have read some good reviews on this amp, can some of my more knowledgable friends please "enlighten me" on these amps.. (Univalve, Bi Valve, ect)

Are they 2 channel amps?
Do they have effects loops?
Are they sort of "real modeling tube amps"?
Do they sound good at lower volumes? (hotplate?)
How good do they really sound?

Thanks for any help that 1 can give.. Oops i just realized i did all this typing in the wrong thread area (sorry mods)..

[Stratmeister]

Hey Fool, I can fill you in on the Univalve. Great little amp, versitile, cool looking, full of features, and sounds great.

Here's the deal, you can mix and max tubes almost any way you want. By that I mean if you like 6V6 tone, plug a 6V6 in. Do the same with a 6L6, EL34, 7581, 6K6,... you get the picture. No biasing, no hassle, instant tone change. Do the same with the preamp tubes too. The only tube that you have to do something different for is a EL84, which requires use of a Yellow Jacket adapter due to the different socket size. Mine can with the YJ.

I have boxes full of old power and preamp tubes, and it's a lot of fun to just pull them out and see how they sound.

Features? Hi and low impedance inputs, labelled "Rock" and "Roll". Switchable 2, 4, 8, or 16 ohm output impedance so you can put virtually any cab on this thing. I use everything from a 1x12 to a Marshall 4x12. Line out. Single channel. Built in variable attenuator (hotplate) and bypass. Built in noise reduction and bypass. Switchable low and high plate voltage for the power tube of choice. Standby switch. Figure around 15 watts, and very loud at that. It can be surprising with a 4x12 what you can keep up with. No effects loop. No modelling whatsoever. Pure tube circuitry.

This is my "home amp" since I can switch cabs and tubes at will, and turn on the attenuator when I need to keep it down. It's a lot of fun, and certainly giggable if it's your only amp in either a club or it's miced. Currently my tone flavor of choice is a pair of Telefunken 12AX7's and a Mullard EL34 with a single 12" Celestion Greenback. Instant baby Marshall.

But I can quickly swap in a pair of RCA 12AX7's and a blackplate 6L6, plug in a Strat, and have that spankin' clean Fender sound with a EVM-12L. Instant baby Twin.

The Bivalve is the big brother of the Uni, and has two power tubes which again you can mix and match without biasing. You could even have a 6L6 and a EL34 in at the same time.

I picked up mine used, in like new condition, for $600, with about a dozen tubes the guy had bought. That's where it can get expensive if you let it, buying all shapes and sizes of tubes to try. The list of tubes you can use is huge, but that's part of the fun. You can definitely find your tone in there somewhere.

Once I bought mine I had additional offers around $500-550 but most didn't include tubes since those can be sold for extra cast. You can get great info over at http://www.univalve.net

Hope that helps... :dude:

[Tom Gross]

THD used to make an incredible amp, the Plexi, a plexi clone that looked like a tweed bassman and screamed like, well, a plexi.

They now make a new amp, the "Flexi" - which is supposed to also sound incredible, although I haven't had the pleasure of seeing or hearing one. It looks more like a Bi-Valve or UniValve tho.

Stratmeister has given an excellent write-up of the Univalve. Bear in mind that these are versitile, but in a different way than other amps. You can get many incredible sounds out of these amps, but it is about tube swapping, not channel switching. So unless you keep an oven mitt and box of tubes on stage, they are best for either one fantastic sound, home use, casual jam use, or recording.
You can set them up for a fantastic sound that cleans up with the volume knob, but it is no XTC in terms of 3 sounds with the press of a few buttons.

[Boomer]

Are they 2 channel amps?

The Univalve and Bivalve are not channel switching amps but they have two channels (or more properly two inputs with an extra gain stage in one)

Do they have effects loops?

The Bivalve has a passive loop

Are they sort of "real modeling tube amps"?

I don't think you can think of them that way. I felt that changing tubes in my Univalve really just changed the flavor of the amp but not the soul. Different power tubes change the way the amp reacted. Different preamp tubes change the amount of gain and, again, the flavor, just like putting different manufacturer tubes in any other amp. Since all the circuitry remains the same the basic tone of the amp can only change so much!

Do they sound good at lower volumes? (hotplate?)

Define "lower volumes"! At bedroom levels any attenuator will suck tone out of the sound. At gig/practice levels the Hotplate works very nicely.

How good do they really sound?

That's pretty hard to answer. If you like the sound that it produces, it's a great amp. If you don't, it's still a great amp. I know that's not a very good response but that's all I got!