Converting Push-pull Amp To S.e.t.

Discussion in 'Audio Hardware' started by d.r.cook, Mar 17, 2005.

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  1. d.r.cook

    d.r.cook Senior Member Thread Starter

    Wasn't really aware it was an option, but it turns out the conrad-johnson cav-50 I bought a few months ago can be converted from push-pull to S.E.T. I take it the reproduction is improved, but at a sacrifice of roughly half the power?

    Questions: In general and/or specifically to this amp, would you recommend doing this?
    What's the cost, generally?
    Is it easily done and could someone be recommended?

    thanks for any input.


    doug
     
  2. YaQuin

    YaQuin Formerly Blue Moon

    Location:
    Madison, WI
    You will probably lose significant wattage by converting a push-pull to a S.E.T. You may gain more midrange clarity however.

    If you have speakers with low sensitivity (i.e. need a lot of power to drive) the consider a very powerful SET like wavac...if you can afford it...
     
  3. Mick Jones

    Mick Jones Senior Member

    Are you sure about this? I wouldn't have thought that a 45 watts per channel ultralinear push-pull integrated amplifier could easily be converted to SET operation. Do you perhaps mean that it can be converted from ultralinear to operating in triode mode?
     
  4. boead

    boead New Member

    Yeah, I believe its push-pull ultralinear at like 45wps and 20wps in triode mode not single ended.

    I always like triode better but 20 watts is fairly low. Still its four or five times more then mine ;)
     
  5. Drew

    Drew Senior Member

    Location:
    Grand Junction, CO
    An EL34 can be converted to triode mode with a few mods and that will change the sound, but its still not a real triode. I wouldn't do it. Buy a real 300B or 2A3 amp and some efficient speakers.
     
  6. Steve Hoffman

    Steve Hoffman Your host Your Host

    I had the big CJ (manufacture's loan) that was wired in triode. I thought it was too thin sounding. The midrange was lost in a wash of "detal" that I really didn't like.

    REMEMBER: Converting to "Triode" mode is NOT the same thing as having a SET amp! For that you need a tube that is actually a triode, like a 300B. Otherwise, there really is no point IMO. An EL-34 is a fine tube but a triode it is not.
     
  7. boead

    boead New Member

    They call it pesto-triode? EL34 and EL84 can be wired in Class-A single Ended Triode mode, tube rectified with self biasing circuit. My SET is like that. It uses one EL84 per channel, 6922 input tube, 5V4 tube rectified with hand wound irons. It s rated at 5 wps, but its realistically just 2 watts or less.

    I just heard an MV60 (http://www.conradjohnson.com/It_just_sounds_right/current-products.html) in my buddies living room on audition and it was very fat sounding and had a nicely rolled off top end. That is sort of the ‘signature sound’ of a Conrad Johnson tube amp. Soft and warm! In triode it was faster, more dynamic and a little brighter.
     
  8. boead

    boead New Member

  9. Drew

    Drew Senior Member

    Location:
    Grand Junction, CO
    I've heard 6550's wired as single ended triode and singled ended ultralinear pentode. Actually liked the single ended pentode more in that case.

    http://audionotekits.espyderweb.net/kit2.html

    Any pentode can be wired as a triode with a 100 ohm resistor from the screen grid to the plate. And triodes can be wired into push pull circuits. What was the original posters question? ;)
     
  10. d.r.cook

    d.r.cook Senior Member Thread Starter

    I think my questions have been answered--thanks! I like the sound I have, so I think I'll stick with it. The spkrs are sonus-faber home concertos.

    Next time out (if there is one), maybe a true SET.

    doug
     
  11. NOSValves

    NOSValves New Member

    Location:
    Burton, Michigan
    Many PP tube amps can be convert to SE or SET by pulling one tube and re-biasing the remaining tube. But its hardly a optimized rendition of true SET or even SE design. The transformers and circuit are not optimized for the change. Even when strapping a pentode or ultra linear PP amps output tubes for triode operation isn't giving you the real optimized sound these tubes can give you when run in strapped triode mode. Many parts of the amplifiers front end would have to be optimized for this operation.

    Craig
     
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