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Looking to build my first amp kit...any advice?

Discussion in 'Shock Brother's DIY Amps' started by aFewGoodTaters, Oct 28, 2020.

  1. aFewGoodTaters

    aFewGoodTaters TDPRI Member

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    As the title states, I've been kicking around the idea of building an amp kit. I've worked on my own guitar electronics for years, and have successfully built a few pedals...now I'm looking to take the next step. I'd like to start with a Princeton Reverb kit which I realize isn't the easiest but also doesn't seem overly complex either (I enjoy a good challenge).

    I'm wondering if any of the more experienced builders can provide a first timer some advice for a successful build. Anything from a recommended kit (StewMac vs Mojo Tone vs something else?) to tools (I have the basics for building) to things to watch out for, etc. I would need a kit that comes with step by step instructions as I can't read schematics....if you have any advice on resources to learn basic schematics and specifically how to translate them to a layout I would be much appreciative.

    I'm likely going to order my kit later this week and will post my build progress in this thread. Thanks in advance!
     
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  2. drew1d

    drew1d Tele-Meister Silver Supporter

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    I have built a few amps, but only simple ones. First and foremost, I would make sure you review discharging the capacitors so you are safe. (Bigger the amp, bigger the shock...) And second, I invested in a quality soldering iron with a large tip. (PACE ADS200, easy swapable tips) I feel you need a big tip for turret board stuff. Eyelet board not as much. And true point to point less so.
     
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  3. tubegeek

    tubegeek Friend of Leo's

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    @theprofessor put up a VERY complete and detailed thread on that type of build, I'd highly recommend you seek it out.

    Also: Princeton Reverb builders seem to be VERY happy with their finished amps, I think you can rightfully expect a good outcome from that choice.

    As always, @robrob (Rob Robinette)'s web pages are an outstanding resource and that amp is well documented there, including some options branching from it.

    I think it's fair to say @theprofessor found it was fruitful to draw on multiple sources for advice and inspiration - his thread distills a lot of resources into a final overall plan that worked out well and is very thoroughly detailed.
     
  4. D'tar

    D'tar Friend of Leo's

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    https://robrobinette.com/Reading_Tube_Amp_Schematics.htm

    Start here with Robs site. Thanks 1000000X @robrob !!! More than enough free information to get you hooked into a lifetime of amp tubery!

    start a thread and post pictures every step of the way. Surely we all have something to comment about everything!!!;)
     
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  5. harpdog

    harpdog Tele-Meister Silver Supporter

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    I chose MojoTone for my first...hasn’t arrived yet. Their instructions seem great and detailed and they are priced better than StewMac. Weber is priced great but lacks instructions.

    BTW if you go MojoTone, communicate with them if you want your cabinet customized....for an extra 50$ or so I got the tolex and grill cloth I wanted.
     
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  6. Boreas

    Boreas Tele-Afflicted Silver Supporter

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    Good luck with the kit!

    I would like to do something similar, but I only want to build the Princeton Reverb chassis, then put it in a custom 2x10 or 2x12 cabinet. So I don't want to spend the $$ on a cabinet and speaker I don't want. Are there any kits out there where you don't have to buy the cabinet/speaker?
     
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  7. Boreas

    Boreas Tele-Afflicted Silver Supporter

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    Are there companies other than MojoTone that will allow you to build just the chassis without cabinet and speaker?
     
    Last edited: Oct 28, 2020
  8. VintageSG

    VintageSG Friend of Leo's Ad Free Member

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    Circuit diagrams are like maps of the Underground. At first glance, they're mysterious and tricky to understand. Break down each section. Print out your schematic and after each and every component, joint or wire is completed, double check it and highlight it with a highlighter pen. Put a tick next to polarised components when you're certain you've got them in correctly. Meter regularly. Tick off the component on the bill of materials as you use it, or highlight it.
    Check twice.

    Don't skimp on your soldering iron. Don't use lead-free solder. It sucks sausages on the banks of the Styx.

    Reading component values is a useful skill, but back it up with a meter reading too. Colour vision may not be all it was, and if your lights have an odd CRI value, resistor values can be misleading.

    Point-to-point, turrets and eyelet are easier than PCB for beginners. PCB traces can bite the unwary on the behind if the soldering technique is a little off.

    Make a voltage chart!

    Meter everything and check your work twice before moving to the next component.

    As for kits, I don't know what you have over there. We're spoiled over here with Ampmaker, Tube-Town and Musikding among others. Amp building is fun, interesting, and highly addictive. Build head units, buy shelving and have one or two top-notch cabinets. Combo amps take up too much space.

    Don't zap yourself. It can frickin' hurt!
     
  9. aFewGoodTaters

    aFewGoodTaters TDPRI Member

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    I have researched capacitor discharging and plan to buy a snuffer stick from StewMac. I'll admit that the risk with filter caps has been the thing that has prevented me from trying this before. As far as the soldering station, I have a 40W Weller - it's an entry model but it has served me well so far. I have an assortment of tips - would the ST4 be sufficient for some of the larger surface work?

    Thanks for this, I will be looking into this later today!

    Thank you! That link is EXACTLY what I've been looking for but haven't found! I have some reading to do now.

    Does MojoTone allow you to customize the baffle and speaker size? I've always liked the idea of a Princeton with a 12" speaker.
     
  10. tubegeek

    tubegeek Friend of Leo's

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    @aFewGoodTaters no need to buy a stick from stewmac - a chopstick, an alligator clip, a few inches of wire, a resistor of pretty much any value between 1K and 100K, some electrical tape. Buy that stuff instead and you'll even get an order of General Tso's chicken in the bargain!

    Save your money for faceplates and transformers.
     
  11. aFewGoodTaters

    aFewGoodTaters TDPRI Member

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    Thank you for the advice. I put some of this into practice with my pedal builds (reading component values, continuity metering, etc.). Each build I learned a bit and improved with the next.

    Thanks for the tip. My tech showed me his DIY discharge stick which looked a bit like you are describing above. Maybe I'll grab some takeout Chinese tonight and get started on my own. ;)
     
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  12. theprofessor

    theprofessor Poster Extraordinaire

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    You can totally do this. I know that at the beginning it is intimidating. And you do need to be careful and have lots of respect for high voltages. BUT: the community of support here is wonderful. Folks will pitch in and help at every step of the way, because they know what they are doing and they love amps. People are very generous with their time on this site. I am no pro and have a lot to learn. But I do love Princeton Reverbs and have built a couple (and am building another with a friend now). Happy to be one of those who pitches in when you start your build thread.

    A few things:
    (1) Mojotone does have good kits, and it's so easy that it might be the best place to start. I'd do a few things differently, but it's hard to avoid the fact that Mojotone gives you good quality parts at a great price
    (2) Once you get your parts and check them all, start a build thread.
    (3) In your build thread, include lots of high-resolution photos. That will help others out a lot as they assist.
    (4) Have fun with the build! It doesn't last forever, and despite the excitement of completing the build, you'll also miss the process when it's done.

    If you're interested, I think this is the thread that @tubegeek is referring to:

    https://www.tdpri.com/threads/finally-princeton-reverb.1017499/
     
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  13. Mark the Moose

    Mark the Moose Tele-Holic

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    Mojotone has quality kits with quality components and a nice, big, color layout. For dead simple, start with a champ or tweed Princeton. Only a little more complicated, 5f11 is still a good first build. I would save blackface and British builds for a second round if you find the first build a fun and satisfying way of spending your free time and money.
     
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  14. Treehouse

    Treehouse Tele-Meister

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    Yes indeed. There are a number of options for including/excluding Cabinets, speaker, tubes, etc.
     
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  15. Boreas

    Boreas Tele-Afflicted Silver Supporter

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    Thanks! Any other companies that allow for this? I do a lot with StewMac, but they don't offer the option. I don't know whose kit is better, but I like MT's instructions!
     
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  16. printer2

    printer2 Poster Extraordinaire

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    Know Ohm's Law and voltage drops/current dividing in series/parallel circuits. U
     
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  17. loopfinding

    loopfinding Tele-Holic

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    When the amp is on, one hand ALWAYS behind your back or in your pocket. The other one needs a chopstick or other non conductive thing to poke around. And make sure it’s pretty long. You don’t want the back of your hand to brush up against anything like I have done. Don’t get cavalier with alligator clips. Don’t work on it while barefoot. Don’t be so cocksure to work on it without a meter nearby.

    Always unplug the power and discharge the filter caps when messing around when it’s off. Check with a meter before you stick your hands in there. 9 times out of 10 they will drain pretty quickly...but sometimes they don’t. Not usually lethal but they can sting you.

    Also a good idea - have someone else at home when you work on the amp. Should something go wrong, someone can get you help right away. Tell them to not even look at the damn thing should you step away from it with the chassis out.
     
    Last edited: Oct 28, 2020
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  18. aFewGoodTaters

    aFewGoodTaters TDPRI Member

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    Thanks for the words of encouragement, tips, and a link to your thread. I've glanced at it already and I'm looking forward to reading it more closely later. I'll be sure to start a new thread when the kit arrives so you all can see progress and provide feedback!

    It seems MojoTone has been getting some good responses so I'm leaning ordering through them. I've thought about starting with a 5f1, or Tweed Deluxe clone, but I've always wanted a handwired Princeton and figured I'd dive in. I realize it may be a bit more challenging.

    I'm vaguely familiar with Ohm's Law but I'll admit that some of this stuff goes over my head a bit. I'd really like to learn more about this subject though.

    Thanks, I understand that safety is always first and have read up on amp safety. It's the main reason why I haven't tried something like this before, and have never had the courage to work on / mod my own amps. Once I get experience with safely discharging the caps I'll feel more confident, but I will practice these safety measures for sure!
     
  19. printer2

    printer2 Poster Extraordinaire

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    https://www.allaboutcircuits.com/textbook/direct-current/chpt-5/simple-series-circuits/

    Ohm's law is not hard (V = I * R), series voltages have to add up to the supply voltage. In parallel circuits all the current through the circuits have to add up to the current supplied to the circuit. A little practice gets you there. It really helps in troubleshooting, if you don;t know these basics then you are just guessing. Once you get the hang of dc AC is just a hop skip and a jump away.
     
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  20. skradlee

    skradlee TDPRI Member

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    I have been wanting to build one of the MOD 102s.
     
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