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First Non Kit Amp build - JTM45 Micro (Bassman Micro)

Discussion in 'Shock Brother's DIY Amps' started by D_Hallett, Jan 20, 2021.

  1. D_Hallett

    D_Hallett TDPRI Member

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    Hello,

    First post here. I'm currently working on a JTM45 Micro based on Rob's Bassman Micro design with the 12AX7 in V1. The cab is nearly complete, I jest have to finish the Tolex (ran out of glue!). It's a 2x10 cab with greenbacks. Pictures to follow shortly. Here's a shot of the board at the moment
    [​IMG]Board01 by Derek Hallett, on Flickr
    and back
    [​IMG]Board02 by Derek Hallett, on Flickr
    If anything seems a miss, let me know!

    Derek
     
  2. dan40

    dan40 Friend of Leo's

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    Welcome to the forum! Your board looks nice and tidy. Just make sure all of the jumpers are correct and soldered well before installing the board. Trying to troubleshoot an issue with those after the build can be a pain. I do most of my jumpers on top of the board these days for that very reason.
     
  3. D_Hallett

    D_Hallett TDPRI Member

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    Thanks! I'll make sure to double check them before mounting the board.

    Derek
     
  4. gigante

    gigante Tele-Meister

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    Welcome!
     
  5. robrob

    robrob Poster Extraordinaire Ad Free Member

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    Welcome D, your board looks good I don't see any problems.
     
  6. willholt92

    willholt92 Tele-Meister

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    Subscribed.

    I have a similar project on the go at the moment but in a head and cab (once I finish my house renovations)
    Looking forward to seeing your cab.
     
  7. D_Hallett

    D_Hallett TDPRI Member

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    Hello all,

    Thanks for the kind words. My glue arrived and I got to finishing the cab. It's a Marshall 1974 style combo cab - 2x10. Finger joined Birch ply. Bluesbreaker grill cloth, white piping, gold cord, ect - I went the full 9 on trying to give it a Marshall aesthetic. The greenbacks have been mounted but not wired up (I also have to get 3 more washers). The back top panel hasn't been added yet as I have to figure out the chassis mounting holes. I'm very pleased how it turned out.
    [​IMG]Cab01 by Derek Hallett, on Flickr
    [​IMG]Cab02 by Derek Hallett, on Flickr
    [​IMG]Cab03 by Derek Hallett, on Flickr
     
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  8. willholt92

    willholt92 Tele-Meister

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    That cab looks awesome, beautifully done.

    Can I ask where you got the gold piping from for the insets on top? I've been trying to source some for my head and cab and can only seem to find the gold string type in the clear outer sheath.
     
  9. D_Hallett

    D_Hallett TDPRI Member

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    willholt92 likes this.
  10. D_Hallett

    D_Hallett TDPRI Member

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    Hello,

    As previously mentioned, I'm going for a Marshall aesthetic. This includes using Cliff Jacks in place of the regular Switchcraft jacks I would normally use. The problem is that I wasn't familiar with how they worked, and after doing some searching and trying to wrap my head around it, I think I figured it out? I was hoping that you guys could check and let me know if I got it or if I'm way off base. These are all going off of Robrob's Bassman Micro plans. First, the input
    [​IMG]Input01 by Derek Hallett, on Flickr
    Next, the FX Loop
    [​IMG]FXLoop01 by Derek Hallett, on Flickr
    lastly, the speaker connections
    [​IMG]Output01 by Derek Hallett, on Flickr
    I'm sorry if it's been gone over previously, but being a visual learner, I needed to draw it out rather than just read about it. Thanks!

    Derek
     
    willholt92 likes this.
  11. Bitsleftover

    Bitsleftover Tele-Holic

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    Hi Will. Tube-town do it. They call it “Trim Strip Gold” and its about 1.5 euro per meter.
    Sol-Sound in the UK do it also. They call it “Marshall Gold/Green String”. A bit more expensive but less postage i imagine.
    Cheers
    Mick
     
    willholt92 likes this.
  12. Bitsleftover

    Bitsleftover Tele-Holic

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    That cab is stunning!
     
    D_Hallett likes this.
  13. willholt92

    willholt92 Tele-Meister

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    Ah perfect, thanks mate.
     
  14. dankilling

    dankilling Tele-Afflicted Silver Supporter

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    Love that cab- is the upper panel separate from the speaker baffle, or is it all one piece?
     
    D_Hallett likes this.
  15. D_Hallett

    D_Hallett TDPRI Member

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    Thanks @dankilling. The way I did the speaker baffle was to first cut a piece that filled the entire opening. I then cut the holes for the speakers, and attached the grill cloth spacers. That all gets painted black, and then I attached the grill cloth. I then cut a separate piece of wood for the valance, covered it in black tolex, and stapled the white piping to one of the long sides, which acts as the bottom and buts up against the grill cloth. The valance is then attached to the main baffle board with screws. There are those who would glue the valance on, but it would be incredibly difficult to change or replace the grill cloth in the future. The last step is to staple the white piping around the completed baffle.
    So long story short, its multiple pieces:lol:
    There's plans for a 1974 style combo cab floating around the internet. It's what I followed.
    I think the valance piece and the grill cloth spacers are supposed to be 1/4", but I made mine 1/2" so I could have more space to staple the grill cloth. You just have to make sure that you have enough room in the cab for the extra space, which should be no problem - it's only 1/4" more.

    Derek
     
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  16. D_Hallett

    D_Hallett TDPRI Member

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    Got everything wired up - next step is the amp start up procedure. I ended up going with Switchcraft type jacks for the FX loop and the outputs. For the output I thought that since one ones really going top see them, the style didn't really matter. For the FX loop, it was just my own stupid mistake. When I was doing the layout, I didn't leave enough room between the pots. It's still pretty tight with the jack I have in there now, but they work much better. Lesson learned! Also pictured is my DIY amp cradle - really nice to have and made wiring that much easier.
    [​IMG]
    [​IMG]
    you can see my homemade faceplate - not the greatest, but it will do for now.
    [​IMG]
    [​IMG]
    Caught a mistake while wiring - I had my artificial center tap resistors both going to lug 2 in V4, not lug 3
    [​IMG]
    Also put this together this morning
    [​IMG]
    If you see any issues, let me know

    Derek
     
    King Fan and tubedood like this.
  17. D'tar

    D'tar Friend of Leo's

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    Fantastic build. Beatiful cab and great soldering. Well done!
     
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  18. robrob

    robrob Poster Extraordinaire Ad Free Member

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    You're missing a ground jumper between the first filter cap and the cathode resistor, unless it's under the board.
     
  19. D_Hallett

    D_Hallett TDPRI Member

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    @robrob - do you mean this one?
    [​IMG]
     
  20. robrob

    robrob Poster Extraordinaire Ad Free Member

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    Yes.
     
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