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stereo amps

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  • stereo amps

    Cruising around the web looking for guitar amp info, I would come across many schematics for tube stereo amps and click out of them because I was not interested
    at the time, now I am, and cannot find what I am looking for. If anyone knows where
    I can find a 50 watt class A monoblock or 50 watt per stereo audio amp schematic I would
    apreciate very much if they could point me to a link.

    Thank you so much,


  • #2
    Are you going to build a poweramp based on one of these schematics?


    • #3
      May I suggest a Google search for "Dynaco Stereo 70"
      "Enzo, I see that you replied parasitic oscillations. Is that a hypothesis? Or is that your amazing metal band I should check out?"


      • #4
        stereo amp

        First let me thank you guys for responding, I really appreciate any help and or
        suggestions. Yes, I want to build a power amp for a friend but he is looking to
        have class A dual mono power amps to drive his phono setup and says he
        wants around 50 watts to destroy his ears with (seems like way more than needed)
        but he is paying for the parts and they are his ears to destroy so...

        I have the full documentation and manual for the ST 70 but I think (unless I am wrong
        in which case I can convert) that the ST70 is a push pull amp?

        I guess mono or stereo isn't an issue as long as it's class A and 50 watts thereabouts
        so if I am wrong about the ST70 being a pushpull class ab or if anyone has a 50 watt
        class A schematic that is fairly straight forward (for a first timer to hifi) and sounds good
        please let me know.

        Oh, and I am sorry for taking so much time to respond but my computer was down
        for the last few days, which is cool because now I have a better box.

        Thanks so much,



        • #5
          As far as I know the ST70 is push-pull Class-AB, but biased as hot as possible so it's well down the road to Class-A. That's probably why it only gets 35w out of a pair of EL34s.

          Note that push-pull amps can be either Class-A or Class-AB. Single-ended audio amps can only be Class-A. PP Class-A isn't somehow worse than SE Class-A: it actually gives lower harmonic distortion than SE. If you're looking for a lot of Class-A power (and 50W is considered a lot in Class-A) then push-pull would probably be better since it can give the same performance with a smaller and cheaper OT.
          "Enzo, I see that you replied parasitic oscillations. Is that a hypothesis? Or is that your amazing metal band I should check out?"


          • #6
            And single ended amps do not cancel p/s hum, while p-p amps do.
            Education is what you're left with after you have forgotten what you have learned.


            • #7
              stereo amps

              Thanks guys, to me the ST70 looks like a straight forward build and
              there are many good reviews around the web in regards to it's
              performance, I will see if my bud wants to give it a try.

              My computer keeps freezing up so I will most likely have to send
              it back to the tech, I will be off line for who knows how long
              this time, better box, but just as ephemeral as the rest.