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Peavey Studio Pro 50 Board/Component Layout

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  • Peavey Studio Pro 50 Board/Component Layout

    For my first post, I looked for an Introductions or New Memeber topic, however I did not find one. I will leave some info here, but if there is such a topic please direct me to it.

    I am a 40 year Peavey amplifier user. I have an A.A.A. in Electronics Engingeering, a B.S. in Electrical Engineering, and I maintain and repair my own amps. I am not an amp technician, so there are times it will be me, a schematic, a DMM, a signal generator, and an oscilloscope sorting things out. But so far I have been successful in my endeavors. My formal education included no tube theory or applications, only solid state devices, passive components, and a lot of digital devices and systems. My tube and related knowledge is from books I have read, my experiences, and info gleaned from helpful people on the Internet. It is weird but I am quicker resolving my tube amp issues than my solid state amp issues. Probably because my solid state amps never seem to have issues to begin with. In the past 30+ years I can recall replacing a rectifier diode in a solid state amplifier. I like to say, owning a solid state amp is like owning a clock radio, and owning a tube amp is like owning an automobile.

    I have also worked on friends' amplifiers, which brings me to this post. I am helping a friend who has a Peavey Studio Pro 50 with a Saturation issue. As you increase the Saturation, the distortion becomes fizzy/muddy, not the usual Saturation distortion. He has the schematic, but no board/component layout. We could trace the components out on the board, but that is going to be inefficient.

    I contacted Peavey a week ago, but they are still on limited staffing due the pandemic, and I am confident priorities are different until they get back to normal levels.

    I have searched here, but could not find one or did not have to necessary search terms. Does anyone have a Studio Pro 50 Board/Component Layout you can share? You can email it to me, if you do not want to post it here.

    I truly appreciate any assistance.

  • #2
    Hi James and welcome to our Forum.

    Unfortunately, finding a component diagram for the older Studio Pro 40, 50, and 60 will be challenging. I have the SP 60 and could not find one. But I will keep looking for you (and me).

    Peavey_Studiopro_50_Schematic.pdf

    Tom
    It's not just an amp, it's an adventure!

    Comment


    • #3
      Thank you for the warm welcome Tom.

      I was optimistic that the conponent diagram would not be hard to find, but I appreciate you setting my expectations at a realistic level. If Peavey has it, I will post it here when I receive it from them. In the interim, we will start tracing our way through the board. At minimum, we will record the component locations we do identify and I will post that.

      All the best,
      JP

      Comment


      • #4
        Welcome to the forum James.
        I'm attaching the schematic to aid further discussion.
        From your statement I'm assuming you are familiar with the sound of the Peavey 'Saturation' circuit. Just double checking as I would probably be inclined to describe it as kind of fizzy/muddy myself.
        Attached Files
        Originally posted by Enzo
        I have a sign in my shop that says, "Never think up reasons not to check something."


        Comment


        • #5
          These are the Studio Pro versions I have with layouts.

          Studio Pro 40.pdf
          Studio Pro 60.pdf
          Studio Pro 110.pdf
          Studio Pro 112.pdf
          STUDIO_PRO.pdf
          Just found Studio Pro 50
          STUDIO_PRO_50.pdf
          Attached Files
          Last edited by dmeek; 09-17-2022, 11:31 PM.

          Comment


          • #6
            I think that wraps up anything I requested, and much more g1 and dmeek. You forum members are the best, and if I can ever return the favor I will. I will continue to stop by, so reach out if you think I can offer anything to assist!

            Comment


            • #7
              Man, you are the best! Probably why the guy who pulled my butt out of the fire so many times in the past hung out here. I cannot thank all of you enough! But if there is anything I can ever do to help, please reah out!

              Comment


              • #8
                Originally posted by g1 View Post
                Welcome to the forum James.
                I'm attaching the schematic to aid further discussion.
                From your statement I'm assuming you are familiar with the sound of the Peavey 'Saturation' circuit. Just double checking as I would probably be inclined to describe it as kind of fizzy/muddy myself.
                Well, distortion is always subjecruve, but this is much harsher than usual. I am an 80's guy, so not too much, but more than '59s or Seths bring to the table. I am still working on what my firend considers enough, but he is is a solid resourxe and we will get him there.

                Best,
                JP

                Comment


                • #9
                  Peavey "Saturation" was never something to write home about, and in my view suffered from trying to do many jobs with the same tool, at the same time, in this case a single OpAmp.

                  Compromises are inevitable and that shows.

                  Poor U1a is forced to, simultaneously:

                  * provide input stage gain

                  * make that gain variable using R12 as two separate pots: left half controls stage gain, right half attenuates, combined with R10.
                  Grounded center tap separates them.

                  * work as a distortion pedal with a twist: R9a controls gain/distortion, R9b is more subtle,controls "how much" do clipping diodes CR5/CR6 are allowed to clip

                  * preamp stage has its own clipping diodes CR3/CR4, independent from the Saturation ones (WTF?)

                  * large value C4 (usual would be from 100pF to 1000pF at most) in parallel with gain/distortion pot R9a murders highs at higher settings.

                  * unfiltered clipped distortion goes straight to next stage, which to boot has a Bright control.

                  That explains apparently contradictory descriptions, it IS buzzy at low/mid levels, muddy at high distortion.

                  Maybe there is a sweet spot where everything balances out nicely.

                  In a nutshell,a separate distortion pedal will do that better, since it has just *one* task.
                  Even a humble ultra simple MXR Distortion+ , go figure.

                  There is an old saying:jack of all trades, master of none.
                  Juan Manuel Fahey

                  Comment


                  • #10
                    Thanks for ^, J M Fahey . My friend seems confident that the distortion has become unpleasant. I ended up with a concussion and have not made any progress, but I am back at it today. Whatever I find I will report back.

                    Comment


                    • #11
                      Hi, i was looking for the schematics of this great amp and i found this forum, so i registered, thanks for the blueprints, i wanted to know the values of some resistors that became coal near the left top corner of the board, and reading the schematic i noticed the output section has a grounding error, and is in all the vversions 40, 60 110, 112. Is it me or maybe i dont know how this could be a suitable conection for the speaker. Can anyone explain please?? Do you noticed the emmiters of the big BJT's are conected to gnd?!
                      Thanks in advice

                      Comment


                      • #12
                        Originally posted by keyboarder61 View Post
                        i noticed the output section has a grounding error, and is in all the vversions 40, 60 110, 112. Is it me or maybe i dont know how this could be a suitable conection for the speaker. Can anyone explain please?? Do you noticed the emmiters of the big BJT's are conected to gnd?!
                        This is not an error but a different type of design, sometimes called 'flying rails' or a few other names.
                        Where we normally see the output (emitters of power transistors) is grounded. Where the power supply main rails are normally grounded, we disconnect from ground and connect to the speaker. Follow the line from the center-tap of the power transformer secondary and you will see it does not go to ground, but is labelled 'output'.

                        Originally posted by Enzo
                        I have a sign in my shop that says, "Never think up reasons not to check something."


                        Comment


                        • #13
                          thanks for the data, ive seen the connection you say, thought that was the error, is always better to ask,

                          Comment

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