Prosonic build?

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by schmoog, Jan 26, 2012.

  1. schmoog

    schmoog Member

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    Hey! I know these aren't exactly hot amps in these parts, but I had and foolishly sold a fender prosonic that I absolutely loved, and I've been thinking about maybe doing a build based on the prosonic. I've done a few builds before (5F6A, 5E3, JTM45), but there is a lot more information on those particular amps. Has anyone here ever looked at doing a prosonic build? The schematic looks pretty simple, and I've started working on the board layout and lead dress. Another thing that would be helpful are some gut shots of a prosonic that I can use to lay out the components. Does anybody here have anything like that that they could share?
     
  2. Ronsonic

    Ronsonic Member

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    I don't have any drawings or pics for you. But did want to say that it sounds like a very reasonable build. The channel switching is more complex than the usual DIY amp, but being all relay based isn't that complex either. Should be a great build.
     
  3. schmoog

    schmoog Member

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    That was my thought process as well. The amp itself isn't the most complex. I loved my old prosonic, and was thinking that if I were to reconfigure it for PTP, it would be a good opportunity to not only recreate, but perhaps improve on the tone somewhat.

    At this point, I can probably translate the schematic into a workable layout, but I'm really curious how zinky/fender layed out the PCB. I figure the switching should be too big an issue. I've always thought relays are actually a pretty elegant way to handle the switching.

    I was thinking of maybe doing some other mods. Perhaps global NFB with a presence and resonance controls, adding a global PPIMV, and making the master volume more of a channel volume for channel 2, etc. I've got so many ideas, it may not even be a "Prosonic build" by the time I'm done lol.
     
  4. schmoog

    schmoog Member

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    I'd also be interestedin any documentation anyone has on the fender tone-master circuit...

    Bruce Zinky's designs are really doing it for me these days.....
     
  5. Ronsonic

    Ronsonic Member

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    You might want to look at some Redplate builds too. Those do relay based channel switching on a turret board. Very nicely too ATMO.

    Like your ideas for modding the design.
     
  6. HipKitty

    HipKitty Silver Supporting Member

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    Having worked on enough Prosonics to sink a boat, the one word of advice that I can impart is to be prepared to use a significant amount of shielded wire so as to keep the noise level at a minimum. Good luck!
     
  7. schmoog

    schmoog Member

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    Noted! lol.

    Since you've worked on so many, what are your thoughts on appropriate electrolytics? I usually use Sozo mustard vintage caps, since they have such a great reputation and I've never had an issue. Do you think sozo's would work well here as well? Or perhaps I should use Mallory 150's instead?
     
  8. ziggeding

    ziggeding Member

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  9. Science Amps

    Science Amps Member

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  10. schmoog

    schmoog Member

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    that's great! Thanks!
     
  11. TweeDLX

    TweeDLX Member

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    I think you're confusing "electrolytic" caps with tone & coupling caps. Electrolytics are the big, usually polarized caps in the power supply (usually from 16uf to 220uf, and rated at 450 volts or higher), and the smaller versions used as cathode bypass caps. Sozo Vintage Mustards and Mallory 150's are used primarily for tone & coupling caps.

    I think you're better off using the Mallory caps in this build, if for no other sake than that they take up less space on the board. You'll have some tricky layout issues, and I've found Sozos to be rather over large for some applications.
     
  12. schmoog

    schmoog Member

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    You caught me! I typed that last reply rather quickly and wasn't thinking. It pays to work while your at work and not blabber about caps lol.

    My concern with mallory is that I've heard that they can be very bright, and i don't want the already over the top second channel to be overly harsh on the top end as well if that makes sense. But I've never used the mallorys, I'm just going on what people have told me. Maybe I'm wrong?
     
  13. TweeDLX

    TweeDLX Member

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    I've never noticed Mallory caps being overly bright. I use them, ETR MET's or the Sozo standards in all of my builds.
     

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