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Plexi Micro Build

Discussion in 'Shock Brother's DIY Amps' started by Bitsleftover, Feb 27, 2020.

  1. Bitsleftover

    Bitsleftover Tele-Meister

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    [​IMG]


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  2. Pick_n_Strum

    Pick_n_Strum Tele-Meister

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    Awesome thread and beautiful craftsmanship! Curious, where do you get the turret boards with holes? For my next build, I'd like to make my own board to up my DIY game. This seems like a good way to get into it.
     
  3. Bitsleftover

    Bitsleftover Tele-Meister

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    Thank you. I’m in the uk so options are a little limited compared to you guys on your side of the pond.
    I got these from Tube-Town in Germany and I’m very happy with the quality. It cuts vey easily with a hacksaw and the turrets peen over easily.
    Modulous amplification in the uk sells something very similar.


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  4. Preacher

    Preacher Friend of Leo's

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    This looks great!!
     
  5. DanceCanse

    DanceCanse TDPRI Member

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    I love this idea. I’ve built a few Fender clones, but have been dragging my feet on trying a Marshall because I can’t decide between these three models. Combining all three circuits on switches sounds perfect! Any chance you could share your layout?

    Your cab looks fantastic too BTW. Very inspiring work.
     
  6. Bitsleftover

    Bitsleftover Tele-Meister

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    Hi, Thank you.
    I don’t have the skills to produce the kind of layout diagrams and schematics others on here do, and this is very much a work in progress but I’ll let you see what I’m working to right now. [​IMG]


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  7. Bitsleftover

    Bitsleftover Tele-Meister

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    Here’s the MOSFET tremolo I’m going to add.
    I’m populating the board and hooking up the pots etc but will leave it disconnected from the rest of the circuit until the basic amp amp is up and running

    [​IMG]




    [​IMG]


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  8. Bitsleftover

    Bitsleftover Tele-Meister

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    Heater wires hooked up.

    [​IMG]


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  9. Bitsleftover

    Bitsleftover Tele-Meister

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    [​IMG]


    Reverb pot and bypass switch wiring.
    100k mix resistor and 330k from pot wiper to reverb return.


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  10. Bitsleftover

    Bitsleftover Tele-Meister

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    Reverb board and socket hook up.
    [​IMG]


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  11. Bitsleftover

    Bitsleftover Tele-Meister

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    The post on the far left will receive B+2 and the red transformer wire will hook up to the B+ once the main board is in.


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  12. Bitsleftover

    Bitsleftover Tele-Meister

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    Reverb bypass switch and mix pot. The 2 unused connections on the left of the switch will be connected once I work out the best send and return locations. [​IMG]



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  13. Bitsleftover

    Bitsleftover Tele-Meister

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    Well, In the past few weeks, the airline I work for went bust leaving me unemployed. My wedding due to take place on Saturday has been cancelled due to the Corvid19 measures. Our honeymoon in the Maldives has been cancelled. The turbo on my car seized. Oh, then on the way home from the garage I hit a pothole and shattered the alloy wheel.
    Anyway.....the upshot is, I should have some time on my hands over the next few weeks.
    Might make a little progress.


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  14. FenderLover

    FenderLover Poster Extraordinaire

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    When it rains, it pours sometimes. Still, it could be worse. Hopefully things were just postponed and life goes on until things get better.

    Cool build BTW. I like your modular approach to the trem and verb.
     
  15. Bitsleftover

    Bitsleftover Tele-Meister

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    Thanks. I figure if the trem or the reverb turn out to be a total failure I can totally remove them from the build and have the faceplate made up accordingly.
    If they’re a success however, Ill have a module design I can drop into any build.


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    Last edited: Mar 18, 2020
  16. Bitsleftover

    Bitsleftover Tele-Meister

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    I think I’m ready to power her up.
    Nervous to say the least.


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  17. Bitsleftover

    Bitsleftover Tele-Meister

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    Arghhhhhhhhhhhhhhhhhhhh!
    No fuse in the IEC mains socket! No 20mm fuses in my box.
    Grrrrrrr


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  18. Bitsleftover

    Bitsleftover Tele-Meister

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    Nailed it!
    Started up without issue.
    Hooked up all the mods.....no real issues.

    The tube rectifier is putting out around 305VDC at the B1 first filter cap.
    The diodes are putting out about 315VDC though. I might have to drop that a bit.
    All the rest of the voltages follow suit at around 5VDC higher than spec.

    The tremolo works really well. Much better than expected. I’d go as far as to say its a total success.
    I hooked it up at the junction between the normal channel volume and its 470k mix resistor. I initially had it hooked up via a switch to stop it loading down the normal channel, but the 250k RA depth pot seems to be just high enough in this application to cause any noticeable signal level reduction. So the push pull pot has gone and its always connected.

    The one-tube-reverb is ok at best. I used a DPDT switched 1meg log pot for the mix. In the off position, the reverb circuit is totally bypassed.
    In the on/min position the 100k mix resistor and the rest of the circuit is placed between the treble pot and the PI. Even at the min position there is a considerable reduction in signal level.
    I’ll have to play with this to get the signal level back up.
    I have a switched V2A cathode bypass cap wired up with the option of no bypass, 0.68 and a 25uf. Maybe that will compensate for the gain drop. Ill try it out as soon as I can make some noise.
    As far as reverb goes its very mild. In the past Ive used a 2.2meg or even a 3meg mix pot to get more wet signal in the mix but I cant find a pot with a DPDT switch built in.

    The NFB switch didn’t work. The switch itself turned out to be faulty on fit. New switch, now works a charm.

    Cathode split switch works well.

    The tonestack switch works really well. There is a very different shift between the two tonestacks.

    The post PI MV works well. I’ve hooked up an L-Pad as well though to experiment with.

    Unfortunately, I cant really turn it up to test it because every single neighbour is stuck in their apartments.

    My only initial gripe is it doesn’t seam as gainy as I was expecting. My 5F2A is a dirtier sounding amp. Having said that, Ive not tried it with the NFB switched off yet. That might make a huge difference.


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  19. Dannebrog53

    Dannebrog53 TDPRI Member

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    Very nice build, with all the other things that's happened this has got to help. Can't wait to see it with the faceplate.
     
  20. Bitsleftover

    Bitsleftover Tele-Meister

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    View from my pad tonight....
    It’s not all bad [emoji106][​IMG]


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