Is it true that a 100 watt Marshall played real low will be class A until it gets...

Discussion in 'Amps and Cabs' started by EADGBE, Aug 2, 2006.


  1. EADGBE

    EADGBE Member

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    cranked and then it becomes class A/B?
     
  2. conundrum

    conundrum Member

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    Operating classes are determined at the "cranked" point, so no, it's AB.
     
  3. sws1

    sws1 Member

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    To confuse things, if they determined the class at 'low volume', then technically it might be considered AB2, since half the wave form is produced by each of the tubes.

    Note that all your favorite "class A" amps are not class A, but in fact AB2. (AC30, Dr Zs, Mesa, etc.)
     
  4. Jerrod

    Jerrod Silver Supporting Member

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    Of course, there's always the question of why it matters!
     
  5. petemin

    petemin Supporting Member

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    or why you would play a 100 watt marshall real low?????
     
  6. TieDyedDevil

    TieDyedDevil Member

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    That's not what AB2 means.

    The "2" portion means that the output tubes are drawing grid current during a portion of the cycle. Hardly any MI amps (the big SVT might be an exception) run AB2.

    AB1 is commonly abbreviated to AB.
     
  7. Roccaforte Amps

    Roccaforte Amps Member

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    Actually, there are more than a few class AB2 guitar amplifiers.
     
  8. TieDyedDevil

    TieDyedDevil Member

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    OK, now I'm curious...

    My understanding is that it takes a pair of cathode-follower stages after the PI (or something else that can source tens off milliamps) to source the grid current that it would take to run the outputs AB2. The typical 100K (or even 47K) plate resistors on a PI won't hack it...

    So... besides the SVT bass amp, what are a few of these guitar amps that run AB2?
     
  9. sws1

    sws1 Member

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  10. TieDyedDevil

    TieDyedDevil Member

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    :jo Right.
     
  11. TaronKeim

    TaronKeim Member

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    EXACTLY!

    -TJK
     
  12. John Phillips

    John Phillips Member

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    Because they have one of the best clean sounds of any amp.
     
  13. nashvillesteve

    nashvillesteve Member

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    I'm sure that's the sweet spot, right?:p

    Heck a Twin Reverb set to 2 or 3 is beyond playing a small room and a big amp like that will never open up unless you're in a stadium! I just like to turn amps up some...

    SO.... if my Dr. Z is not Class A, and not Class AB2, is it regular A/B? Class Z? Class A/B/Y? Confused & Stupid!
     
  14. clothwiring

    clothwiring Supporting Member

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    I can play my 1/2 stack 2555 Jubilee at room volume. I can actually practice at home with it with out disturbing anyone. But then again, when I put it on the front porch and crank it...well that's a different story. The valleys echo with it. :)
     
  15. cameron

    cameron Member

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    There are also single-ended class A amps with more than one tube in series. Some of the small Gibson combos of the late 50s are classic examples of that design.
     
  16. steve10358

    steve10358 Supporting Member

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    100 watt Super Lead + Variac + Hot Plate + knobs on 10 = Heaven.
     
  17. Nitefly182

    Nitefly182 Member

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    variac AND a hot plate? I thought they served the same basic purpose?
     
  18. Jerrod

    Jerrod Silver Supporting Member

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    Like a brake pedal and a clutch serve the same purpose?
     
  19. Nitefly182

    Nitefly182 Member

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    No, the clutch brings an engine in or out of gear while the brake stops the car. Can you explain?
     
  20. Jerrod

    Jerrod Silver Supporting Member

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    they'll both slow the car down, but they do it completely differently, no?
     

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