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why so many gain stages in the preamp?

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  • why so many gain stages in the preamp?

    The effects send/recv stages are not for gain?

    http://el34world.com/charts/Schemati...lead%20_60.pdf
    The only good solid state amp is a dead solid state amp. Unless it sounds really good, then its OK.

  • #2
    Not really, no.

    The output of V2b goes into a 20/1 voltage divider to feed the SEND jack.

    The return stage is mis-drawn. Obviously the return jack and 1 meg resistort connect to the grid of the tube, not the cathode. The 1k resistor is the cathode resistor. I also think the 100k plate resistor on V3b belongs on V3a. V3b plate conects directly to B+. That stage is a cathode follower to drive the tone stack with its low impedance.

    The gain of V3a stage is to boost the lkine level FX return back up to tube levels for the rest of the journey through the amp.

    Note the 2/3 voltage divider going into the grid of V2a.
    Education is what you're left with after you have forgotten what you have learned.

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    • #3
      V2b - the stage before the send - absolutely IS for gain/distortion. That makes 3 gain stages for the low input and 4 for the high (normal?!) input. The grounded-grid and the CF after the return are for impedance matching and signal recovery. So V3a is for gain, technically, but only because so much was thrown away by the 4.7k/(100k+4.7k) divider at the send. Not distortion.

      edit: Enzo beat me to the punch! Also, in my ignorance I assumed a grounded-grid stage was a THING
      If it still won't get loud enough, it's probably broken. - Steve Conner
      If the thing works, stop fixing it. - Enzo
      We need more chaos in music, in art... I'm here to make it. - Justin Thomas
      MANY things in human experience can be easily differentiated, yet *impossible* to express as a measurement. - Juan Fahey

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      • #4
        There are gain stages, but they are not simply adding up. That 2/3 divider knocks the signal back down some before continuing. Some amps are like that, they boost a signal only to cut it in half after the stage, so six gain stages is not so much to pile up a huge gain score, but more for tone shaping through all the stages. Guys can replace all that with a couple 12AX7 stages and say "see, I got the same gain with les tubes", but then it just sounds like a Fender.
        Education is what you're left with after you have forgotten what you have learned.

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        • #5
          Thanks everyone! (big learning curve Im climbing). So the Soldano amps are a more 'marshall crunch' sounding kind of amp? Ive never heard one, will try to find a youtube sound clip, but you know how good those are.
          The only good solid state amp is a dead solid state amp. Unless it sounds really good, then its OK.

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          • #6
            Enzo, thanks for the note on the plate resistor re v3a v3b. Why wouldn't there be resistors on the plates for both v3a and v3b?
            The only good solid state amp is a dead solid state amp. Unless it sounds really good, then its OK.

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            • #7
              Because it is a cathode follower. Sorry, because V3B is a cathode follower.
              Education is what you're left with after you have forgotten what you have learned.

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