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Building my first (Princeton Reverb kit)

Discussion in 'Shock Brother's DIY Amps' started by padefjord, Mar 4, 2021.

  1. Phrygian77

    Phrygian77 Friend of Leo's Gold Supporter

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    I sometimes wonder, on another forum, in another universe unbeknownst to us...

    Edit: I imagine this was ultimately going to get me in trouble here, so ... deleted.
     
    Last edited: Mar 6, 2021
  2. padefjord

    padefjord TDPRI Member

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    A couple of pictures! I think it's starting to look like an amp. Also, I decided to call it a "Pontuston" instead of Princeton (Pontus is my first name). Painted a logo that came out a bit uneven but OK.
     

    Attached Files:

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  3. King Fan

    King Fan Poster Extraordinaire Ad Free Member

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    That looks great. Nice work.

    If you want, you can put pics inline using the 'upload a file' button, or just drag and drop the jpg into the post as you type. With work that nice, folks might like this

    upload_2021-3-9_7-33-56.jpeg

    even more than this. (Besides, I like the beer glass and langlauf photo!) :):):)

    666F83E5-C2B7-4742-9493-3E21CA94035C.jpeg
     
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  4. padefjord

    padefjord TDPRI Member

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    Cool, I didn't realize I could drag'n'drop images. Well, here's where I'm at right now. Still waiting for transformers and tubes before I can finish, but everything seems fine this far. I might have cut the heater wires a bit short, couldn't get them as pretty as I've seen in other peoples builds. As you can see, I decided to put in a power jack instead of using a fixed cable. I just don't like fixed cables.

    Thinking about a phase inverter grid stopper resistor. The kit doesn't have it, I haven't decided if I should leave it out, put a fixed one in (470k as recommended by robrob) or use a pot in the ground switch hole.


    IMG_0879.jpg
     
  5. King Fan

    King Fan Poster Extraordinaire Ad Free Member

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    Nice. I like custom face plates that still look Fender-ish.

    For the PI grid stopper, the fact they don't come in the kit means nothing pro or con. Good kits repro the original schematic. No need to add it now; it's the easiest thing in the world to add after you've got to know the amp's stock sound. I used a simple 470K, since I don't like *too* many dials to set, and found it was great. But if you didn't like the effect, you could omit it again with one minute's work, or replace it with a pot to vary the effect.
     
  6. padefjord

    padefjord TDPRI Member

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    So today the transformers and tubes finally arrived! I rewired the power jack and switch to make it more tidy and put the last parts in place.

    IMG_0918.jpg

    Did a few measurements with the rectifier and preamp tubes installed, everything seems pretty close to where it should be. Tomorrow I'll plug in a speaker and try it together with my son, who's almost as excited as I am.

    IMG_0919.jpg
     
  7. Pick_n_Strum

    Pick_n_Strum Tele-Meister

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    Excellent build!

    Another vote for a 12" speaker here. I personally love the EVM12L with the Princeton. It's fantastic!

    If you do end up redoing the heater wires, I like to get them twisted really tight - in addition to helping reduce hum, they just look really nice that way. My preferred method is to put them in a drill chuck and slowly operate the drill until I'm happy.

    Excited to hear how you like the sound of it!
     
  8. padefjord

    padefjord TDPRI Member

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    A short update - it doesn't work... I get weird noises, trying to understand what's happening and why. Sounds a bit like feedback, even without a guitar connected.
     
  9. Lowerleftcoast

    Lowerleftcoast Friend of Leo's

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    If the output transformer does not have the correct polarity the NFB will have PFB creating a squeal. Swap the brown and blue wires on the power tubes pin3 or the green black wires on the output jack. Do not swap both the brown/blue and the green/black
     
  10. padefjord

    padefjord TDPRI Member

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    Thanks! I got the same tip from the place where I bought the kit and now it works!
     
  11. King Fan

    King Fan Poster Extraordinaire Ad Free Member

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    Wow, nice. Good advice, taken very quickly and effectively.
     
  12. padefjord

    padefjord TDPRI Member

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    All I'm concerned about now is a pretty loud pop when turning the amp off. Is that normal or should I check some capacitors?
     
  13. Uncle Daddy

    Uncle Daddy Tele-Afflicted

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    It's normal, but can be overcome with an X-capacitor wired across the main switch.
     
  14. Uncle Daddy

    Uncle Daddy Tele-Afflicted

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    You can see the X-cap on the PRRI schematic here, marked C17. I normally fit them straight onto the main switch, on the transformer side bridging the hot and neutral.

    x-cap.JPG

    One of these should do it-
    https://www.ebay.co.uk/itm/2-x-ECQU...608483&hash=item34388b64ec:g:8ccAAOSwhtpf35uK
     
  15. padefjord

    padefjord TDPRI Member

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    Thanks! I might do that.

    I'm still waiting for the cab - but I did get a 10" celestion gold. Have been trying the amp through my Atomic Reactor FR which is an active monitor but can be used as a passive speaker cab. It's a bit bassy, probably because it's a full range cab, but I'm loving it anyway. The tremolo is so nice!
     
  16. padefjord

    padefjord TDPRI Member

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    The cab is finished but not here yet. Will post pictures when it arrives! I did put an X-cap in on the main switch, works great. Today I also changed the .01uf tremolo speed capacitor to a .022uf - made the range perfect in my opinion.
     
  17. Uncle Daddy

    Uncle Daddy Tele-Afflicted

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    How do you like the depth of the trem? I'm doing a PR build right now, and changed the 1meg depth resistor for a 330r. Not tried it out yet, but my previous build is stock and the trem is a bit weak, especially when compared with my Brownface Deluxe, which has throb that would make a bride blush!
     
  18. padefjord

    padefjord TDPRI Member

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    I think the stock value is fine - not crazy deep but certainly enough for me.
     
  19. Greg70

    Greg70 Tele-Meister

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    I just finished my Mojotone PR build last week. I did a build thread here on this forum.

    I built mine using the 10" Jensen speaker that Mojotone provides with the kit. With the amp volume on 5, bass on 10, and treble on 8, it will shake the practice bedroom a bit, and that's in a basement with a concrete floor. I have a Marshall half stack in the same room and the little Princeton has almost as much low end.

    The trem on mine works fantastic and is too deep on 10, which is how it should be. But remember that the bias wiggle trem depends on how the bias is set. I'm currently running around 65% dissipation so that may be why it trems so good.

    @padefjord what kit did you get?
     
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  20. padefjord

    padefjord TDPRI Member

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