Class AB Push-Pull - diyAudio
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Old 16th November 2011, 03:24 PM   #1
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Default Class AB Push-Pull

  1. I read that Class AB Push-Pull sounds less muddy than Class A? Will a Class A Push-Pull sound as good or does also have similar disadvantages in sound quality?
  2. Also why would they sound any better?
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Old 16th November 2011, 03:41 PM   #2
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There's little difference, class A is usually supposed to sound slightly 'better', but it all depends on the relative designs - but you don't want class A for anything high power.
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Old 20th November 2011, 07:09 PM   #3
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Quote:
Originally Posted by Aurvandil View Post
  1. I read that Class AB Push-Pull sounds less muddy than Class A? Will a Class A Push-Pull sound as good or does also have similar disadvantages in sound quality?
  2. Also why would they sound any better?
I believe the advantage of class A is that the tubes don't go into cut-off so there is no crossover distortion.
Single ended class A will not cancel 2nd order harmonics created in the output stage so there is less harmonic distortion. Maybe that is why people say class A is more "muddy" or "warm".
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Old 20th November 2011, 07:10 PM   #4
AndrewT is offline AndrewT  Scotland
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SS or Vacuum?
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Old 20th November 2011, 08:12 PM   #5
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SS or Vacuum?
Do you ever use class AB on valves?.
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Old 20th November 2011, 08:17 PM   #6
AndrewT is offline AndrewT  Scotland
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Yes, valve ClassAB comes in two versions.

My KEL80 is a ClassAB valve power amp. It is a parallel push pull (ppp)
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Old 20th November 2011, 08:48 PM   #7
tinitus is offline tinitus  Europe
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Quote:
Originally Posted by Nigel Goodwin View Post
Do you ever use class AB on valves?.
I thought instrument pushpull tubeamps were classAB

and only the very small single ended guitar tubeamps would be classA
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Old 20th November 2011, 08:59 PM   #8
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Originally Posted by tinitus View Post
I thought instrument pushpull tubeamps were classAB

and only the very small single ended guitar tubeamps would be classA
Not true, there are some boutique guys that use class A push pull like Allesandro. He gets 10 watts from two EL84's.
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Old 20th November 2011, 09:29 PM   #9
tinitus is offline tinitus  Europe
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ok, but with EL84 PP, it could have more than just 10watt peak effect, no?
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Old 20th November 2011, 09:39 PM   #10
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Class A p-p amps do not have the dynamics that a AB amp would have. You do not get power supply sag with Class A. You can also get more dynamics due to the voltage on the screens changing. Class AB can also get pushed to the point where you get crossover distortion which also brightens up the sound. Also Class AB amps tend to run higher voltages than a Class A amp. This also can brighten up the sound. Mind you how all the parts of the amp has to be thought of as working as a whole. An AB amp can also end up sounding harsh rather than open if things are overdone. I see no reason a Class A amp needs to sound muddy, just choices the designer took if it does.
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