6G2 Princeton DIY Layout

Discussion in 'Shock Brother's DIY Amps' started by 82LesPaul, Apr 3, 2019.

  1. King Fan

    King Fan Friend of Leo's

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    Sorry, Paul, missed this, but since the thread ain't dead...

    The 6G2 is *delightfully different* from the PR. To start with, no big mid scoop, and less tone stack loss.

    In '60s terms it's less of a Mod, more of a Rocker. Rumble at Brighton next weekend!

    The trem isn't all *that* different, but it does seem more organic / hypnotic, maybe in part because it isn't scooped, and maybe because those tone/volume factors allow you to bias the 6G2 a littler cooler for more trem.

    Brown is often described as halfway between tweed and BF. I've built all three, though, and I'd say that description isn't wrong but also isn't very helpful. In UK terms, if tweed is, I dunno, Liverpool, and blackface is London, then brown is Leeds. In US terms, if tweed is Memphis and blackface L.A., then brown is Muscle Shoals. *That* sort of 'halfway between.' :)
     
    Last edited: Jul 17, 2019
  2. Haellgren

    Haellgren TDPRI Member

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    Is there a possibility to get a hi res version on email?
     
  3. jtcnj

    jtcnj Tele-Holic

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    cool thread.
    I forgot all about DIYLC.
    Another on the long list of things I make post it note reminders for but never have time to follow up on.

    My 6G2 is my 4th build.
    I learned a ton from it as going in I understood more than each time previously.
    Same pattern after each build, but this was special.

    then I dont have my head in this for months at a time and I forget a lot.
    Still haven't built the head cab for it yet.
     
  4. Haellgren

    Haellgren TDPRI Member

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    After obtaining the .diy file I made some modifications to suite my coming build.. Can someone confirm that the bias board wiring is correct? Other changes where the grounding bus and switch for both hot and neutral.
     

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  5. King Fan

    King Fan Friend of Leo's

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    The bias board looks good. Can you tell us about your single ground bus? Are the input jacks going to be isolated from the chassis?


    Sent from my iPad using Tapatalk
     
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  6. Haellgren

    Haellgren TDPRI Member

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    No, because Im changing it to the original spec. :D
    This is my first scratch build, and I always thought that all grounds are equal. Today I learned they are not :) I will change the ground bus and separate it between b2 + and b3 +.
     
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  7. Haellgren

    Haellgren TDPRI Member

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    Better this way?
    I changed power cord colours and PT wiring after transformers I'll be using.
    Also added a Artificial CT for the heaters, since the 290CAX has none.
    Redid the power switch and ground bus.
    [​IMG]
     
    Last edited: Aug 10, 2019
  8. King Fan

    King Fan Friend of Leo's

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    Good stuff. You've done a ton of work and produced very tidy results.

    I've only checked a few areas, but if I'm right here are some other items to consider.

    Check Rob's drawing of the protection diodes. Pins 3 and 5 are inactive, so are used as tie points for the HT wires, with the diodes feeding active pins 4 and 6.

    protection_diodes.png

    The switch image is ambiguous; folks might think one pole linked hot to neutral and the other linked the two PT primaries. I might take out that center line and just draw switch schematics in the box. For example, I I don't know which switch you'll use, but a standard Carling DPST has the ins and outs grouped at opposite ends:

    upload_2019-8-11_8-37-29.png

    Minor items:
    1. It isn't fun or easy to solder effectively to the back of pots, so many people ground that 27K bias pot tail resistor with a wire to the power amp ground bolt.
    2. Many folks building 6G2s and 5F11s seem to find that resistor actually needs to be in the range of 17-24K to get the right span of bias adjustment. Mine was 20K in the end. Soldering to the pot will make changing values harder, too.
    3. Many builds still do it, but EU *and* UL standards suggest you not use a PT bolt for the green safety earth from your household mains, since PT bolts can loosen over time. It's easy to drill a hole in the side wall of the chassis and put a totally separate bolt there, with starred washer and keps nut.
    4. For the same reason, it isn't ideal to use PT bolts for the power amp ground either. I did it on my 6G2, but if I were doing it again, I'd try to drill a separate hole up between the PT, bias board, and main board, even though space is limited.
    5. Many people find the standard cap values in the trem array don't allow for nice slow trem. Easy fix: instead of .02 / .01 / .01, you just go .02 / .02 / .01.

    Are you going to start a separate build thread? Your layout is perfect at this point in this existing thread, but as you go forward you may get more input from a new thread.
     
  9. King Fan

    King Fan Friend of Leo's

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    And just in case you thought I'm being critical... just the opposite. I've been putting off drawing out my 6G2 as built, but I'm gonna PM you to see if you'd share your nice DIYLC file. It would save me tons and tons of time and effort.
     
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  10. RatBug

    RatBug Tele-Meister

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    Here is a link I made to 82LesPaul's DIY file. It should get you started.

    https://www.tdpri.com/threads/6g2-princeton-diy-file.966302/
     
  11. Haellgren

    Haellgren TDPRI Member

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    Thank you!! I've read your build thread (and almost every other 6g2 build on the net). I'll take your advice and change my layout accordingly :)

    I'm starting my own build, but I have a 10 day vacation and a move to do before. I'll hopefully start in early September if I have time.
     
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  12. RatBug

    RatBug Tele-Meister

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    +1 Here

    I've got a large majority of the parts here but I'm afraid to start it till I'm sure I have everything right.

    This thread has me worried.
     
  13. Haellgren

    Haellgren TDPRI Member

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    Common sense, a good layout and a multi-meter goes a long way! I was afraid when plugging my first Princeton into the wall, but going slow and double checking everything is important.
     
  14. RatBug

    RatBug Tele-Meister

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    Thank you for the tips.

    Just to be clear though, I do this kind of stuff everyday as part of my job so following a schematic is fine for me which is why this seemed like an easy project.

    The part that has me worried is all the artful parts ya'll are doing, the mods and tweaks, should I go with a Cap can or three 30 uF caps, or wait... Why is that guy using two 30 uF caps and a 20 uF cap, and that other guy is using three 20 uF caps.

    uhg!
     
  15. King Fan

    King Fan Friend of Leo's

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    Don't worry, be happy. Research and reading are the funnest, cheapest parts of an amp build. They can last as long as you want, whereas the build itself always goes too fast no matter how slow you go; and, no one was ever electrocuted, or worse, disappointed by their tone or their playing, during the research phase. :)

    I was gonna mention the filter caps to @Haellgren -- but I was already hitting him with a lot of other non-vital info. Short version: despite the schematic, Fender actually built most if not all 6G2s with a 20 / 20 / 20 cap can. That's the amp that people rave about. But you get a small advantage in noise reduction by going a bit bigger on the first cap, so I ended up at 30 / 22 / 22 just because I could. These small details, or where you anchor a ground bolt, aren't gonna really effect the sound of your amp. Lots of modern builds go 30/30/30 and some go 20/20/20 -- 10 uF doesn't make or break anything.

    Where'd I get this info, these opinions? I was guilty of a vague, wandering thread about 6G2 filter caps when I was planning mine. Lots of smart folks chimed in, and eventually I made a choice. If you want to see what they said, you can read that thread here.

    Here's what makes a difference in your amp. Speakers. PT voltages and B+, to some extent. OT (but it's hard to go wrong with vintage spec). And did I mention speakers? The 6G2 is a beautiful simple machine. Concentrate on a safe build that works, and enjoy the research and then the build all the more.
     
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  16. King Fan

    King Fan Friend of Leo's

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    Thanks for that. If it helps anyone down the road, to use, as you say there, don't read the code, just download to your computer. It'll show up as a .xml file, but delete the .xml suffix (leaving the .diy suffix) and it'll open in DIYLC. Seems timely to renew my thanks to 82LesPaul, who got this thread and these great drawings rolling. :)
     
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  17. RatBug

    RatBug Tele-Meister

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    Just as you said... All the research, reading, searching, learning is part of the fun. I did a search here for every thread with "6G2" in the title and I read, and took notes. I still don't have a solid picture yet though.

    I'll start my own thread when I have a list of concise questions to ask.
     
  18. Kalev

    Kalev TDPRI Member

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    Hi,

    It’s my first post, but can I ask a question
    What transformer are you using (OT) ?

    BR
    Kalev
     
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  19. King Fan

    King Fan Friend of Leo's

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    Hi Kalev. Not sure what everyone here is using, but it looks like a couple of us used the ClassicTone 40-18045, and Haeligren's layout shows Hammond 1750E.
     
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  20. RatBug

    RatBug Tele-Meister

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    I went with the Hammond 1750E but only because it seemed to be popular here, not because I know any better.
     
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