4 tubes, then 2 tubes, then 1 tube

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by stu2, Apr 27, 2008.

  1. stu2

    stu2 Member

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    I've seen that the mesa lonestar amps can switch from 4 output tubes to 2 then 1. I'd like to know how this works. Switching from 4 to 2 still keeps the amp operating in class AB but doesn't switching from 2 to 1 make it single ended therefore class A? Am I incorrect thinking that output impedences change switching from full power to half power as well as class A operation requiring a different type of output tranny than a push pull. Please educate me.
     
  2. booj

    booj Member

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    I saw a review on e pinions about that amp. It uses either 2 or 4 tubes from what I could tell. Intersting concept. I like the 50 watt distorted to 100 watt clean feature. That's cool.
     
  3. stu2

    stu2 Member

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    I'm not interested in the Lonestar but would love to be able to set up a twin reverb with a similar configurable power tube output scheme. I think the 1/2 power (2 x 6l6) mode would be fairly straight forward but the 1/4 power (1 x 6l6) mode might be tricky. Good idea or just a pipe dream?
     
  4. Groovey Records

    Groovey Records Member

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    bad idea

    maybe you should look at a duel SET powered amp then going to one tube could be less of a can of worms.

    I'd think twice before even dreaming about this in a TR config. Wouldn't sound like a TR. The inherrent efficiency of a AB circuit makes the power sections yield greater then the sum of its parts.

    The original Two Stroke is a good example of a duel SET amp in class A

    EnJoY ThE MuSiC
    GrooVey ReCords
     
  5. cram

    cram Member

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    Is this similar to the way marshall throws a 100 - 50w switch on the back of some amps? I also noticed that the builder at ceriatone does a "half power mod".

    In basic terms, does it take the other two (or one) power tubes out of the path?

    This is also something I wonder about, but definately lack the tech understanding in amps for researching myself.
     

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