AB763 preamp question ?

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by crunchman, Mar 15, 2015.

  1. crunchman

    crunchman Member

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    Does the aforementioned preamp produce distortion when pushed with a clean boost ? I have never owned one so I do not know, I would think and have thought that ALL preamps do but thats not true...Thanks.
     
  2. xtian

    xtian Member

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    Yes. It's not easy to get distortion out of the first triode without a boost, but with one you can get some very nice string articulation and grind and will compliment your single coils.
     
  3. crunchman

    crunchman Member

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  4. dani_boy79

    dani_boy79 Member

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    would an Electo Harmonix LPB-1 do the deed and push the first stage into overdrive?
     
  5. crunchman

    crunchman Member

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    Surely, these are commonly used to increase preamp gain.
     
  6. smolder

    smolder Gold Supporting Member

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    That the theory behind how I lower volume of that circuit with humbuckers without loosing the tone I've got.
     
  7. pdf64

    pdf64 Member

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    It depends on the guitar.
    I think it's unlikely that it would (to any useful degree) with regular single coils, especially if plugging straight into the LPB1, which would load the PUs rather.
     
  8. crunchman

    crunchman Member

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    Last edited: Mar 16, 2015
  9. Baxtercat

    Baxtercat Member

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    Yep, that's why they invented these boosts. Drive the amp input with a bigger signal for overdrive/saturation.
    Pretty much what we did in the early '70s w/ Fender amps.

    [​IMG]
     
  10. Prattacaster

    Prattacaster Member

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    It takes about 1.5 to 2 volts AC to get appreciable distortion at the output of the first stage with a 1Khz signal. Since a guitar has varying frequencies and amplitude this figure is a little inaccurate but is a good guideline.

    Most preamps can produce much more signal gain, as they are designed to output line level signals into lower impedances. Many overdrive pedals wont get you 2vac without a significant amount of distortion created by the pedal itself. A good clean boost should get you pretty close.
     
  11. xtian

    xtian Member

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    So when a boost pedal says 26dB of boost, how does that translate to a multiplier for voltage? Like, 1v p-p input, 26dB gain, equals ?v p-p output?
     
  12. xtian

    xtian Member

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