push-pull vs. single-ended overdrive?

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by Free, Feb 8, 2008.


  1. Free

    Free Member

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    Could you guys please elaborate on this quote? I know of single-ended amps that have similar break-up characteristics as Class A push-pull or even Class A/B push-pull overdrive tones, so what am I missing here? Thanks for your help:

    "Typically, a push-pull class A amplifier will clip rather symmetrically, while a single-ended class A amplifier usually clips asymmetrically, most often rounded on one side while hard-clipped on the other. While both amps are indeed true class A amplifiers, their tones are dramatically different."
     
  2. skylabfilmpop

    skylabfilmpop Member

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    Single ended amps do have a hairyness to them that non single ended class A and AB do not. Looking for a recording amp recently and considering the field of low output amps from vintage champ types. My biggest beef with single ended amps, especially the hi dollar champ clones is that they lack additional preamp stages that to me seem to manage the envelope of the note. The only exception I have found after listening to Fargen, tophat, bad Cat, Reeves, Carr, tweed champs, Gibson GA5, Blackfaced champs, and the THD Univalve is the Groove tubes Soul O Single. Actually sounds and feels like a big amp and has a more tweed deluxe/Bassman/Marshall style front end. Now with an el 34 it puts out 10 watts and I thought to myself, if I am going ten watts I may as well go for somthing in the tweed deluxe range and picked up a Divided by 13 CJ11 instead. NO regrets, a killer amp that youy can actually play at home. Visit the Angela Instruments site and read the "super Single Ended" amp project notes. There are some explanations and mods for single ended hairiness there.
     
  3. Free

    Free Member

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    Thanks, Skylabfilmpop. Great response. I will certainly check out the Angela Instruments single-end info too...

    -Mike
     
  4. Free

    Free Member

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    Forgot to mention - that Mini-plex claims to duplicate Marshall Plexi-type tones, while it is single-ended 8 watt mode (and parallel 12 watt mode). Did you play that one? Thanks.
     
  5. porterburst

    porterburst Supporting Member

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  6. redtoploader

    redtoploader Member

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    The reason they sound different is that the push pull amps cancel even order harmonics due to 'summing' of opposite waveforms in the output transformer. Even order harmonics created in the preamp stages will be amplified though.

    As a result, single ended amps often have a certain wooliness to them.
     

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