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Class A vs. Class A/B (THD specific)

Discussion in 'Amps and Cabs' started by gomez1856, Nov 22, 2005.

  1. gomez1856

    gomez1856 Member

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    I’m in the final throws of my decision to pickup a THD amp and I have a question that just occurred to me after reading reviews of both the Flexi and the Bivalve. In the Flexi review that’s hosted on THD’s site, I read this:

    “What does all of this mean for you, the player? It could very well mean that the search for your sound is finally over. While our UniValve and BiValve-30 amplifiers offer the same flexibility and choice of tubes, they do so in a Class-A circuit. While Class-A amplifiers do have a strong following due to their smooth, even character, there are many players who need, or even crave the immediacy, clarity and “punch” of a grid-biased Class-AB amplifier. “

    I just wanted to get a little bit of clarity regarding this before I make a decision. I’m hoping to gain an understanding of how this will translate into the end user’s experience (ok, so I work at a software company:D ). Although I am interested in the technical differences (even though I’ve researched and sort of get it), I’m really tying to grasp what I’ll be “giving up” (if that’s even the right phrase) or not getting in terms of feel, tone, sensitivity, etc. by going with the Bivalve instead of the Flexi.

    I’ve been of the mindset that the Bivalve would be more suited to me given the fact that I live in a Townhouse and will be doing a lot of recording and it has the built in Hotplate. But, if the above quote means that I’ll see a dramatic difference in the areas mentioned, I’ll just buy a regular Hotplate. Any help would be appreciated.

    Oh well, can I just as one more question? I’ve read that the hotplate in the Bivalve is inferior to that of a standalone. Is there any basis for this comment?

    Thanks!
    Rick
     
  2. aleclee

    aleclee TGP Tech Wrangler Staff Member

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    As a longtime software developer, I must admit to a longtime bias towards specifications and quantifiables.

    F___ that.

    If it sounds good, I don't care if it's tube, SS, Class A or Class Z. I don't even take most forumites' word for it. I'm two states away from Missouri but I'm very much in a state of "show me" . . . and clips aren't good enough: I need to experience the amp's feel, not just its timbre in a low-resolution clip.

    The differences between Class A and AB are very much a matter of chocolate vs. vanilla. You need to try 'em both and decide on your own which you like better.

    If you like the Bivalve better than the Flexi, then it's a better amp for you regardless of operating class. If you prefer the Flexi to the Bivalve, go with it.
     
  3. gomez1856

    gomez1856 Member

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    aleclee,

    I completely agree with you. I guess I wasn't clear enough, however. I'm not looking for a better or worse, The literature clearly indicated that there was a substantial difference in the feel. I'm asking someone, perhaps that has played them both, to try to describe the difference in feel, touch responsiveness.

    I've not had a chance to play them and will be ordering online.

    Again, I'm not looking for what is better, A or A/B, at all. I'm specifically trying to assess the differences between two very specific amps that I've not been able to directly compare. Not tonally, as the main reason that I like the THD's is the ability to alter the tone by swapping tubes, but in playability and feel.

    This article that I read made it sound like a BIG difference. If the Flexi is THAT much more touch resonsive, then it would push it over the edge for me. Otherwise, I'd stick with the Bivalve as my decision.

    I hope that's clear.

    Rick
     
  4. drbob1

    drbob1 Silver Supporting Member

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    I'll take a stab at it:

    Class A-harmonically rich, not as punchy, less clean overhead, often more sustain.

    Class AB-more clean overhead, more punch, fewer low level harmonics so the sound is clearer, often set up with less sustain.

    A good comparison is a Champ vs a Princeton...
     
  5. aleclee

    aleclee TGP Tech Wrangler Staff Member

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    IMO, the biggest difference is in compression. The Bivalve is somewhat squishy while the Flexi is quite fast...kinda like the Marshall amp whose name it rhymes. ;)

    I'd highly suggest trying before you can buy. There are a few THD dealers in SoCal (e.g., Mesa store in Hollywood) where you can check things out. Gasoline might be pricey but so is buying the wrong amp.
     
  6. gomez1856

    gomez1856 Member

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    Thanks guys! I guess "squishy" is what I was looking for :D


    I know Westwood Music has a Flexi, I'll doublecheck on the Bivalve.

    Thanks!


    Rick
     
  7. markp

    markp Member

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    Bi valve ;
    upper mids that are very sweet and cut though nice I just love how they blend with horns and Hamon organ.Slammed with all most any pedal is fun for the shread.
    Able to run lower power tubes or a single tube(along with hotplate)is cool.

    Flexi;
    Very differant sound and feal,Lower mids and very fat when pushed(huge)Less gooey and more natural and really lets the sound of your guitar and the sound of your fingures shine through,cleans up amazingly.

    FLEXI is my favorite amp!
     
  8. mailman

    mailman Member

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    If he doesn't chime in soon himself, PM Ed Degenaro at THDelectronics.com ...yeah, although he works for 'em, as an unquestionably accomplished guitarist, he KNOWS all the subtle differences between the Bi-Valve & Flexi and can perhaps give you a better/more truthful hands-on comparison. Although I'm currently still "closet playing" at home, I opted for the Flexi which can "cut through almost anything," should I return to playing on stage again. Most guitar-sensitive amp I've ever played!
     
  9. Tone Disciple

    Tone Disciple Gold Supporting Member

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    I really liked the Flexi better than the Bivalve' s I have tried!
     
  10. gomez1856

    gomez1856 Member

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    Thanks guys, I was hoping that Ed would catch this and chime in as well. I'm gonna have to go try the Flexi this weekend. I'm getting married in 2 weeks and can't afford to buy the wrong amp :D , as I have a feeling it'll be a bit more difficult to justify shortly.

    Thanks again everyone.

    Rick
     
  11. mailman

    mailman Member

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    OMG, Rick!!! You're getting married? Definitely go for the FLEXI-50!!! (While you still can!):eek: :D
     
  12. gomez1856

    gomez1856 Member

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    That's what I love about this place!!!! You always get the absolute best advice!!!:dude

    I think I'm going to go with the Flexi, avatar 212, and a hotplate.

    I'll swing by Westwood Music this weekend, but I'm pretty sure that's what I'll end up with.

    Thanks again everyone! And have a great holiday weekend!

    Rick
     
  13. onehandfretting

    onehandfretting Member

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    I've had a BiValve for a couple of years now, and have dabbled with the Flexi on a couple of different occasions.

    One thing you have to keep in mind when considering these two amps is the many different tubes that you can use with them, and the impact that that has on the sound and feel of each amp.

    Many people have raved about the Flexi. But I found it to be a little sterile and flat sounding. Maybe it was the tubes (stock) that were in it. I don't know. I'm not sure if it's the vintage tubes I have in my BiValve, or what, but It sound a lot better to my ears than the Flexi did.

    As for the "squish" in the Bivalve. A lot of that can be dialed out with the Attitude knob. running it counterclockwise will make it really squishy, while clockwise will really tighten it up. I usually have mine set at about 1 o'clock, to let the notes breath a little bit.

    My experience has been completely opposite to that of Markp's. Again, i guess it's the tubes...
     
  14. gomez1856

    gomez1856 Member

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    Well, I'd like to thank you all for your feedback.

    I got to swing by Westwood music and put them both through their paces and, for me, it was a no-brainer after about 30 minutes with each.


    The Flexi won hands down! I'm in the process of ordering one right now!

    I now have to sell my JEM before my fiance attacks me!!!:D


    Thanks again all and have a great holiday weekend!!

    Rick
     

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