Ordered a ValveStorm JTM45 for Bluesbreaker 2x12

Discussion in 'Building the Classics' started by Rotorcraft230, Mar 10, 2020.

  1. Rotorcraft230

    Rotorcraft230 Active Member Premium Member

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    Well I just ordered a JTM45 from ValveStorm and can’t wait to get started. This will be my second build, the first was a “HIWATT clone” from Trinity Amps”Ordered a Trinity Triwatt to build”. Still trying to get ordering info from Merren and Marstrand, haven’t decided on which to use probably gonna depend on availability. And as far as the cab looking to go with SourMash 2x12 combo. Anyone use this cab with the ValveStorm JTM45 kit. We really want to use Alnico speakers but they are expensive probably gonna go with Greenbacks for the time being. Well that’s about it for now stay tuned for the build.

    Mark
     
  2. MarshallDog

    MarshallDog Well-Known Member Premium Member

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    Make sure you post lots of pics of this build! How long do you think it will take?

    I’ve always wanted to build an amp but just never have gotten around to it.
     
  3. Rotorcraft230

    Rotorcraft230 Active Member Premium Member

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    This is gonna be fun I can assure you there will be many pictures. You can check out my other build

    “Orederd a Trinity Triwatt kit to build”.

    There are lots of pics this build will be the same quality if not a little better from what I have learned.
    How do I post a link to another thread?
    Mark
     
  4. MarshallDog

    MarshallDog Well-Known Member Premium Member

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    Just go to the Thread, highlight and copy the url address and then past it is the Post!
     
  5. Rotorcraft230

    Rotorcraft230 Active Member Premium Member

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  6. Rotorcraft230

    Rotorcraft230 Active Member Premium Member

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    Thanks MarshallDog

    Edit. The Triwatt I’m guessing took 50-60 hrs. This one I’m guessing 1/2 the time, seems to be Less complex. I work on helicopters so I tend to pay lots of attention to the details.
     
    Last edited: Mar 11, 2020
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  7. Chris-in-LA

    Chris-in-LA Well-Known Member

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    I just emailed Merren, told him what I wanted and asked what it would cost with shipping. He got back to me pretty quickly. It took about 3 weeks to get the finished product I think.
     
  8. neikeel

    neikeel Well-Known Member

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    I built a similar creation a few years ago. Metro JTM45 to original specs with GEC KT66s, mustards but Xicon resistors and a Mercury OT. Installed in a TAD (German supplied Mojo) 2x12 with Celestion Gold speakers (pics on Metro site somewhere).

    It was quite much cleaner than I wanted at normal volumes. Worked quite well as a pedal platform. The cab was very heavy. I would typically let our keys player run through it as it never really sounded great for guitar on its own and lugging that big and heavy a cab around was a pain (easier to wheel a 4x12 and separate head around.
    In the end I cracked and sold the cab. The speakers are safely in a cupboard waiting for a good home (they are too nice to sell).
    The head was reworked with a Metro -103OT and some Piher resistors. The OT made it a much sweeter amp with smooth natural break up and crunch. When I needed ££ for something else I sold it to a studio for decent price. I would happily have another but my original '65 fills that space now and I see no need to change.
    The Merren OT is excellent too. I guess you are saving $ by using Marstran PT and choke with a Merren OT?
    Personally I would look at one of the 2x12 that are more compact (like the ones used for 18w. I have one for my 18w Trem (the JTM45 will fit). Much more portable and with an open back sounds very good. I am using T1220 Ceramic celestions in mine as they are less efficient than the alnicos and you can turn the amp up closer to the sweet spot.
     
  9. Rotorcraft230

    Rotorcraft230 Active Member Premium Member

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    I haven’t decided on which transformers to use either Merren or Marstrand. Depending on availability, but I want them to be the same Merren PT & OT or Marstrand PT & OT. ValveStorm sells you a Mercury choke which I bought.

    I see Meteramp sells PT and OT as well. Anyone use those?

    Not really trying to save money I just want the best sound but it has to be KT66 OT.
     
  10. Exojam

    Exojam Well-Known Member

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    Why not ClassicTone transformers?
     
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  11. Rotorcraft230

    Rotorcraft230 Active Member Premium Member

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    That is an option but I’ve read They have too much B+ voltage.
     
  12. Gene Ballzz

    Gene Ballzz Well-Known Member

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    The weight and size could be kept down by going for a single 12" combo cabinet.
    Just Sayin'
    Gene
     
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  13. Gene Ballzz

    Gene Ballzz Well-Known Member

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    I've used several and they are fairly consistent at .5% to 1.5% over spec. It has not been a problem.

    Just My $.02,
    Gene
     
  14. neikeel

    neikeel Well-Known Member

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    What choke?
    The metro and a Marstran Iron are very similar. Go on price and availability.
    Merren s stuff is very good but I get better response/price etc from Brian Wallace at Marstran. My 45/100 with his iron is spot on for tone as is my 50w plexi. :2c:
     
  15. Rotorcraft230

    Rotorcraft230 Active Member Premium Member

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    I see classic tone offers a PT with 690v and 625v. I’d I was to use classic tone PT which voltage would I USA?
    Edit not USA, use
     
  16. Rotorcraft230

    Rotorcraft230 Active Member Premium Member

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    The choke is Valvestorm supplied mercury magnetics . I really want Marstrand but I can’t get an answer back from them. Did “contact us” twice
     
  17. neikeel

    neikeel Well-Known Member

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    If you are going for Jtm45 with GZ34 rectifier you want 350-0-350 secondary for 450v dc on the plates of your GEC KT66s. ;)
     
  18. Rotorcraft230

    Rotorcraft230 Active Member Premium Member

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    Now I’m confused. If classic tone is 690 or 625 secondaries how do you get to 350?
     
  19. Rotorcraft230

    Rotorcraft230 Active Member Premium Member

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    Dumb question I’ll sure.!!!!!!!
     
  20. neikeel

    neikeel Well-Known Member

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    The HT is the volts either side of a centre tap. 350-0-350. So 700v if you measure between the start and finish of both windings. You write it that as it tells you how the rectifier will work. Some PTs don’t have s centre tap (eg Hiwatt Partridges and they have a bridge rectifier for the requisite voltage). Your centre tapped PT will use a two phase rectifier like a GZ34 valve or a couple of diodes with no ground.
     
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