First Marshall build - JTM45 content

Discussion in 'Building the Classics' started by RiverRatt, Feb 16, 2021.

  1. RiverRatt

    RiverRatt Well-Known Member VIP Member

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    For you guys who don’t know me, I lost the use of my right hand back in 2003. Shortly after that I started trying to figure out how to work on amps and play guitar. I ended up wrapping my thumb and index finger with sports tape. To work on amps, I either use the soldering iron in my good hand and loop the spool of solder on my index finger, but I found that taping the iron in my hand like I was holding a pencil. This works much better but I have to be careful and not let the iron wander.

    I started building 5F1/5F2A clones out of my vast collection of resistors and caps, and using a donor solid state combo amp. I tried building a Matchless Spitfire out of a Hammond organ amp and that didn’t turn out nearly as well as the little single ended amps. So I approached the JTM45 with some trepidation.

    The first mistake I made was getting the chassis and faceplates from China. The PT cutout was made to fit a 5F6A PT. I ended up enlarging the cutout to fit the proper Heyboer JTM45 PT. There were threaded receivers on all the preamp tube holes, and on the mounting tabs on the sides of the chassis.

    I had to deal with stuff like that all the time. Tube sockets were 90 degrees wrong, etc. I got the board from ValveStorm and ordered the small parts kit to populate it. That kept me busy for that month while I waited for the next month so I could order more parts. From there it snowballed and sucked me into the project hard. My transformer set arrived beat to hell. When I opened the box, all that was there was the OT. So, that set me back again. I just started wiring up what I could while I waited for the replacement iron.

    By the time the PT and choke arrived, I had read the build guide until I knew what everything was and what everything did. The amp went together pretty quickly after that. I had two loose grounds that were pretty easy to troubleshoot. I biased up the tubes and headed to my friend’s house where he was holding the 2x12 combo cab. First we ran the chassis on top of his 1960A cab. I was floored. It sounded sooooooo good I couldn’t believe it! I had my dream amp.

    Then we put it in the combo cab with a pair of Eminence Texas Heats. Sounded like ass. Not a good word to say about those speakers. Then one of the KT66’s lost its vacuum. I had to put some old 5881’s in it and live with that while I waited for the replacement tube. I also ordered a pair of Greenbacks from ZZounds on their payment plan. I can handle a small monthly payment much easier than buying them outright.

    Finally all the pieces came together and the beast was roaring again. I know this is old hat to most of you guys, but damn I can’t stop smiling!

    Here are some pics. The reason I mentioned the hand thing first so maybe y’all will go easy on me with the wiring job.

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    Thanks for reading this rambling story. When the roads get clear of all that ice, I’m gonna take it to my friend’s house and hopefully get some decent sound clips.
     
  2. Chris-in-LA

    Chris-in-LA Well-Known Member

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    Looks pretty good from here. I agree that these things sound great! I built 2, one Valvestorm kit with Metro iron and a Ceriatone Bluesbreaker. But, are you able to play or are you just building the amps for fun?
     
  3. mickeydg5

    mickeydg5 Well-Known Member

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    That is all shiny and new. :thumb:

    RiverRatt can play, I am sure. :yesway:
     
  4. RiverRatt

    RiverRatt Well-Known Member VIP Member

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    I can play. No fast picking, but I can easily do bluesy stuff and bang out some power chords. I am getting faster but accuracy isn’t quite there yet. I just keep trying to play the harder stuff to keep me challenged. I was getting fairly good at Superunknown by Soundgarden the other day.

    I’ve given away almost all my little amps I built. Mostly to friends who are players. I still have the last one I did, and it turned out to be my favorite. I built a 5F2A in a 1x10 Sundown combo. It has a mid boost and no NFB. At about 3/4 cranked you hit the sweet spot. I put a Celestion VT Jr. from a Marshall Origin 20 combo. It barks like a big dog.
     
  5. RiverRatt

    RiverRatt Well-Known Member VIP Member

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    This is the 5F2A. I had to put the transformers inside the chassis. Never done that before. It worked fine though.

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  6. Chris-in-LA

    Chris-in-LA Well-Known Member

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    Damn, doing custom builds. I just buy the kits, I’m too lazy to redesign things. I’ve built so many amps recently I was tempted to sell off a few just so I could build some more. It’s addicting. The 5f2 is one that I haven’t done.
     
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  7. adew1

    adew1 Active Member

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  8. _Steve

    _Steve Well-Known Member

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    Looks awesome man!
     
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  9. neikeel

    neikeel Well-Known Member

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    Great job.
    Now the problem is that given all the hassles you had with this build and it turned out well you will probably want another ‘perfect’ build!
     
  10. RiverRatt

    RiverRatt Well-Known Member VIP Member

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    LOL nah, the only thing I need to do is change out the grill cloth. It has that L shaped stain on the left side. Dude told me that it was water damage but he wasn’t the original owner so he didn’t know the back story. One friend is telling me that a build has to have something like that to distinguish it. Another friend told me that electrons don’t care. So, for now at least, it stays as-is.
     
  11. neikeel

    neikeel Well-Known Member

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    No, I was not suggesting doing anything to this, I meant plotting you next build!
     
  12. RiverRatt

    RiverRatt Well-Known Member VIP Member

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    You know, I don’t really feel compelled to build anything right now. Even though I spread this project out over months, it still cost a lot. A friend helped me get the transformers. I think I’m gonna wait at least a year before tackling another big build. I do have another small combo donor amp. So far I’ve mounted the PT and that’s it. I still haven’t figured out what I want to do with it. I’d like to build a Plexi 6V6 sometime but right now I’m just kicked back enjoying the sounds coming out of that JTM45.
     
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  13. Guitar-Rocker

    Guitar-Rocker Well-Known Member

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    Great job dude !
     
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  14. RiverRatt

    RiverRatt Well-Known Member VIP Member

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    Thanks Terry! You are being very kind. Your work is impeccable. My wiring looks like somebody threw up a plate of spaghetti.
     
  15. Richcols

    Richcols New Member

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    Looks pretty good from here.
     
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  16. RiverRatt

    RiverRatt Well-Known Member VIP Member

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    Thanks, I really appreciate all the kind works. I have had it in the combo can with two UK Greenbacks and it’s a monster of an amp. I’ve never had an old Marshall. I wish I’d done this a lifetime ago.
     
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  17. Marshall50w

    Marshall50w Well-Known Member

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    RiverRatt, I would never have the patience or knowledge for that matter to build amps. The JTM 45 looks a beauty.
     
    Last edited: Feb 24, 2021
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  18. RiverRatt

    RiverRatt Well-Known Member VIP Member

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    I just started studying schematics and finally understood what was happening in those old tweed Fenders. They aren’t very complicated at all. With a beefy enough pair of transformers, you can run just about any octal output tube. I had a 5F2A running a KT88 for a while. My all time favorite though was a 6L6G smoked glass tube. Unbelievably thick, creamy distortion. The next favorite is an old GE 6CA7.
     
  19. Marshall50w

    Marshall50w Well-Known Member

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    In my JTM45, I have a pair of GEC KT66's smoked glass from the '50's that came out of an old church organ - perhaps these tubes are truly the 'Holy Grail' lol !
     
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  20. RiverRatt

    RiverRatt Well-Known Member VIP Member

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    I don’t know, but I would love to find out :D
     

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