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Op amp to Discrete Conversion - Possible?

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  • Op amp to Discrete Conversion - Possible?

    Would it be possible to convert a preamp using op amps to transistors?

  • #2
    ANything is possible, but it would be highly impractical. The circuits would be nothing alike, and a whole new circuit board would be required.
    Education is what you're left with after you have forgotten what you have learned.

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    • #3
      There are some plans on the internet showing a discreet op amp made from transistors, but I'm sure it doesn't function like the real thing.

      The question is why would you want to do this? There's nothing wrong with the sound of a good op amp.
      It would be possible to describe everything scientifically, but it would make no sense; it would be without meaning, as if you described a Beethoven symphony as a variation of wave pressure. — Albert Einstein


      http://coneyislandguitars.com
      www.soundcloud.com/davidravenmoon

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      • #4
        I just mistrust IC's, that's all. I have an ART tube MP that I wanted to hot rod a bit.

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        • #5
          Originally posted by apehead View Post
          I just mistrust IC's, that's all. I have an ART tube MP that I wanted to hot rod a bit.
          Sigh.

          Would it be possible to convert a preamp using op amps to transistors?
          Absolutely yes! It will require a redesign from the sheet metal up, though; it will use more power, have higher - and more objectionable - distortion, and be dramatically more prone to drift, aging and parts tolerances.

          And why is it you trust transistors more than IC's?
          Amazing!! Who would ever have guessed that someone who villified the evil rich people would begin happily accepting their millions in speaking fees!

          Oh, wait! That sounds familiar, somehow.

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          • #6
            Because I almost always prefer the sound of an older, discrete circuit to any chip based amps I've heard.

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            • #7
              That's probably because of the circuit topology, though, not the components. What do you think op-amps are made of inside?

              I disagree with R.G. on the objectionable distortion, though. A discrete JFET preamp with no global feedback will have sweet-sounding distortion that an op-amp (either monolithic or discrete) won't.
              "Enzo, I see that you replied parasitic oscillations. Is that a hypothesis? Or is that your amazing metal band I should check out?"

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              • #8
                Originally posted by apehead View Post
                I just mistrust IC's, that's all.
                IC op amps are made of transistors... they are pretty much made the exact same way. An op amp is a small multi transistor circuit, all in one package. That's why it's an "integrated circuit."

                Originally posted by apehead View Post
                I have an ART tube MP that I wanted to hot rod a bit.
                it's not going to be hotrodding it. Swapping IC's for better ones would be though.
                It would be possible to describe everything scientifically, but it would make no sense; it would be without meaning, as if you described a Beethoven symphony as a variation of wave pressure. — Albert Einstein


                http://coneyislandguitars.com
                www.soundcloud.com/davidravenmoon

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                • #9
                  Originally posted by R.G. View Post
                  Sigh.


                  Absolutely yes! It will require a redesign from the sheet metal up, though; it will use more power, have higher - and more objectionable - distortion, and be dramatically more prone to drift, aging and parts tolerances.

                  And why is it you trust transistors more than IC's?
                  a light coat of this is reported to cure op amps (and most everything else) of their non-musical character:
                  http://www.trt-wonder.com/page10.html

                  he goes on for pages (the spray can is $100) and includes a description of an "infinitely blind" experiment which makes Clever Hans sound like particle physics...

                  they sell caps too
                  http://www.trt-wonder.com/page20.html

                  things did sound better when I was a kid...before all that loud music took its toll on my ears.
                  Last edited by tedmich; 10-01-2009, 06:11 AM.

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                  • #10
                    For all the work you're looking at investing in this, why not think about tube op-amps?
                    Attached Files

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                    • #11
                      Hey! The original Philbrick units. Those are a favorite of Bob Pease at National.
                      Education is what you're left with after you have forgotten what you have learned.

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                      • #12
                        The generalization that discrete sounds better than opamps is entirely unfounded. I've seen, heard and repaired crappy-sounding discrete designs, and wonderful-sounding opamp designs e.g Music Man.

                        Sure, you can do a wholesale rebuild on anything, but all you'll be able to use is the chassis and possibly the power transformer, because the circuit board will have to be designed from the ground up.
                        John R. Frondelli
                        dBm Pro Audio Services, New York, NY

                        "Mediocre is the new 'Good' "

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                        • #13
                          Irregular, but enthusiastic reader of Pease Porridge.

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                          • #14
                            His troubleshooting analog circuits book is a personal favorite - I learn something new every time I read it.
                            Education is what you're left with after you have forgotten what you have learned.

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                            • #15
                              wow, I can't believe that Bob was laid off by NSC in March - sign of the times. I bet NSC hired outside "consultants" to make that brilliant decision

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