I....Must...Build...a....JTM45...

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by DAB, Jul 18, 2006.


  1. DAB

    DAB Member

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    In the past 2 weeks I have developed an unresisting urge to build a DIY JTM45 (head or combo haven't decided). I have been reading up and right now it looks like the Metropoulis kit. Ceriatone looks interesting as well but I am not yet comfortable about the component list. May be other kits I don't know about yet.

    Problem is I have never even built so much as a stompbox much less an amp. I have done some soldering (probably incorrectly) putting together cords and cables for studio use. I am a fairly quick study.

    Am I crazy? :crazy:NUTS:crazy (in regards to building my own amp).

    I would appreciate any and all advice on the right kit as well as things to know and watch out for.

    I have searched the forum and read as much as I can but i still feel I need you guys to jump in and educate me.

    Thanks in advance for your advice and guidance.

    Dave
     
  2. r9player

    r9player Silver Supporting Member

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    well doing a JTM project is a lot of money to start out with .. so make sure you don't mind 'wasting' the money if things don't work out too well.
    Besides that it is fun but requires good dexterity and patience.
     
  3. BBQLS1

    BBQLS1 Member

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    I built an amp recently, it was my first, 18 watt Lite IIb. I'll be building a few more. The most complicated solder job I did before that was pickup installs. Check out 18watt.com, lots of good folks there.


    Edit: You might want to check out an 18 watt. Those 45's are pretty loud.
     
  4. SteveStrat

    SteveStrat Member

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    You ain't crazy at all. I'm gonna build one of George's '68 Super Leads this winter. I can't friggen wait!!

    I would probably be looking at building a JTM too if I didn't already have a nice '66 Bassman that fills that mid-gain need already.

    Post some pictures when you get going on it.

    Steve
     
  5. wilder

    wilder Supporting Member

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    I've never built a Metro kit, but I order a lot of parts from them. The documentation is supposed to be very good. The support on the forum seems very helpful as well. You are the one who knows if you can do it or not. There's nothing wrong with being ambitious, if you get in over your head you can always send it to George (at Metroamp) and pay him to finish it. I've built three amps at this point and it's very satisfying, but I have no idea how anyone makes any money at it! Too time consuming.
     
  6. DAB

    DAB Member

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    Thanks for the great feedback.

    I did look at the Weber kits and read some of the threads about them on TGP. Seemed like some of the components needed to be replaced. I passed based on that point.

    I did consider an 18 watt and I have been looking at the 18watt forum. Its just that the JTM45 is kind of my dream tone. I am not a huge fan of EL84 amps (thought I confess I haven't owned one but played through a couple).

    I have a reissue Bassman which I like but it doesn't get the thick creamy distortion like the JTM45 (I know the circuits are basically the same but my Bassman has beautiful cleans but not the JTM45-like distortion)

    Great point on the "if you get into trouble send it to George". I guess it's like when you build something from wood. If you screw up a piece of wood you just get another one. If its bad enough you call in a carpenter.

    Thanks for the encouragement. Nothing ventured...Nothing gained as they say.

    Any tips on the technical side of building an amp? After you finished your first one what would you have done differently?

    thanks again.....keep it coming.

    Dave
     
  7. V846

    V846 Member

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  8. DAB

    DAB Member

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  9. KLB

    KLB Member

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    Great idea, Dave. Keep me posted on your progress!

    #1 Rule: Don't touch a live chassis with both hands because if you get shocked, the current will flow through your body very efficiently.

    - Ken
     
  10. da-boogieman

    da-boogieman Member

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    I'm in the middle of a Metro JTM-45 build right now. I've built a number of amps (not Metro) so I'm comfortable with it, but George's instructions and forum look to me to be exactly what the first timer needs. Really a bunch of nice and knowledgeable folks who are able to avoid the normal net-egos we encounter so often. It sounds like you are doing thorough research (as did I) and if you decide to go with Metro, I think George will take good care of you. I'm impressed with the kit quality and George is a really nice guy.

    On kit building tips...George's forums are top notch. There is a JTM45 group on Yahoo and things like the 18W forum where you can pick up some great tips. As someone already posted, leave plenty of wire length so you have room to twist and dress your leads:AOK Don't get too fancy with bundling and grouping wires for looks; good point to point avoids noise coupling by isolating noisy and sensitive signals. Build slow and enjoy the process. It's not a race and it's time you'll look back upon with fond memories for years to come. Do work you'll be proud of;)

    Brad
     
  11. Blauserk

    Blauserk Silver Supporting Member

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    The kit may make this more doable for a first-timer. I built an 18-watter from scratch (not a kit--did it solely based on a schematic and parts I sourced myself). But I gave up on doing the JTM-45 midway through. I built the circuit board no problem, but when I took a look at the old-style Radiospares output transformer and the enormous number of leads out of it, it was so puzzling that I just shelved the project. (The birth of two children didn't help because it absorbed my free time to noodle over such things.) But the kit may make it more doable. Do a bit of practice soldering first, and always double-check what you're doing before you put the soldering iron to the work. But building an amp is enormously satisfying. Just take extreme care not to juice yourself--not a pleasant experience, I know firsthand.
     
  12. Hacksaw

    Hacksaw Time Warped Gold Supporting Member

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    Just my perspective,

    I have done the ted weber project jtm45, there is only schematics and a rough pictures. no instuctions. no support other than a forum to ask questions. if this is your first build I would to with something that may have instructions and support of some sorts. Ted webers site states the jtm45 is a level 3 project. if you have some electrical experiance with AC and DC you can probably find your way through it. if you dont have much experiance I would get a kit with instructions. put it together, then go back with different parts as needed, or wanted. ted weber is a good kit. I am waiting for ted to open sales for the Smokin joe series so I can try one of those.

    as far as first time kit, be paitient with it. and install / wire the rectifier socket before installing the AC Jack etc.. :)
     
  13. scottlr

    scottlr Member

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    Being unemployed, I have a LOT of time on my hands. I looked at the Metro Amp website, but it is closed for maintenance or something. What is the price for an 18 watt kit? And that is just the chassis and no cabinet, right?

    If the instructions are that explicit, and plain English, I may want to have a go at it myself. I have done tolex and grill cloth a few times, so that is no problem. I have limited electrical experience, though.
     
  14. TheAmpNerd

    TheAmpNerd Member

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    +1 on this!

    Rich over at GuyTronix is a stand up guy. I think for your first build
    KISS is the order of the day. That is Keep It Simple Stupid.

    The advantages of a smaller kit like this are:

    Greater probability of success
    Shorter time frame to completion
    Work on soldering skills
    Work on trouble shooting skills -- yes even something as simple as this.
    Work on builing and construstion skills
    Low initial investment
    Replacement parts for disaster are relitively cheap

    NOTICE

    The poster said email and phone support?
    He used them for this kit which might tell you something,
    that is it might be a great kit for first timers.

    AND

    If you find you hate it after a day or two you and walk away with
    minimal loss. READ: Your wife/girlfriend/significant other/guitar playing
    buds won't bitch/complain/whine/disrespect you.

    FINALLY

    If you do a successful build you can be proud of your accomplishment
    and order the next larger kit while still being able to play something
    you built your self.

    :AOK

    Once you do that, you get sucked into this amp building thing and
    you thought buying amps/GAS was addictive...imagine buying all the
    stuff then setting out to build all your favorite amps.

    It is a good thing we all FINSH what we start out to finish
    and nobody has any spare parts or projects laying around the
    house, living room, dining room, kitchen, bench, bedroom,
    garage, bathroom, front hall way, attic, storage room, dog house,
    litter box, barn, etc.

    Did I miss any rooms? If so, please feel free to reply.

    Oh -- not that I would know about any of that either.
     
  15. scottlr

    scottlr Member

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    I don't see any tubes. Do you have to buy those yourself?
     
  16. scottlr

    scottlr Member

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    FWIW, I did the same thing when I got into fly fishing. I couldn't see spending the bucks for the great fly rods, but i wanted a really nice one. So, I built my own, from a kit, then I built 7 more from components I chose myself. After trying them all out, I kept 3 of them I really liked, and sold the others. An amp might another way to do the same thing. But, I think rod building and amp building are 2 completely different things...perhaps. There are a lot of details you need to address in rod building, but there is no electricity involved, so you can't hurt yourself, other than maybe a cut or something like that. But, I THINK i can do this, so is there any reason NOT to give it a go?
     
  17. glaswerks

    glaswerks Gold Supporting Member

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    Agreed, Ted is doing some nice chassis' that will help the project along if you decide to continue.
     
  18. TheAmpNerd

    TheAmpNerd Member

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    Scott,

    What did you build your first time out?
    A basic fiberglass rod
    A Fenwick graphite or boron blank?
    A piece of cut bamboo?

    When I built my first rod I used a two part Fenwick fiberglass blank, a cork butt, and closed graphite guides for less friction.

    I made some mistakes with it but the rod cam out fine. Infact I think
    it is stashed in a corner around here somewhere...I've caught some nice
    large mouth bass with it...here in Texas and a few trot out in northern
    CA.
    At least in rod building...

    ...actual fly fishing (at least for me) can be dangerous...

    ...pretty easy to poke and eye out on the back cast. : )

    ...that is why I wear sunglasses when fly fishing.

    AND

    ...the dog stays about 30 yard upwind!

    OR

    ...under the car!
     
  19. DAB

    DAB Member

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    Thanks Ken. I still remember when you slapped my hand away as I was about to touch the wrong thing inside my 72' Superlead. The shock factor is a little unnerving for me and I will be obnoxiously careful.

    On that topic I read somewhere that there is a mod that can bleed the filter caps when you turn the power switch off. I understand that it doesn't drain them completely right away but will take the current down to non-lethal levels very quickly.
    Anyone familiar with this mod? Is it a good idea? Any drawbacks particularly in the tone area?.

    dave
     
  20. DAB

    DAB Member

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    Thanks BlueJ.

    I wouldn't have had any idea about the wire thing. Great Tip. I think I am going to get one of those compartmentalized storage things for keeping the electronica in.
     

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