Marshall bluesbreaker update to JTM45

Discussion in 'Amps and Cabs' started by ToneMasting, Dec 24, 2009.


  1. ToneMasting

    ToneMasting Member

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    Hey fellas,
    I am having serious thoughts about purchasing a Marshall JTM45 head and 4x12 greenback cab.
    Im using a 50W BB (bluesbreaker) RI from 91 these days, and a few things bother me about it.
    First of all it wont really break up unless I turn it waaAAay up (!) and beeing a 50W amp it blows everyones head off.
    Secondly it seems to get a little tonally "thin" when I'm playing classic rock as ACDC/Hendrix and that sort.
    Dont get me wrong, I love my BB and I'm nok thinking about getting rid of it.

    Would a 30W JTM45 break up earlier and does the head'n'cab JTM45 setup give a better bass response for rock?

    If anyone has an opinion please help!
     
  2. DICKIE C

    DICKIE C Member

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    The Bluesbreaker is a JTM-45, just in combo form.
     
  3. DICKIE C

    DICKIE C Member

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    Yeah, you're right. Forgot about that! :messedup
     
  4. ToneMasting

    ToneMasting Member

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    That's interesting!
    Will the 30W JTM45 amp break up before my 50W BB or is there no difference?
    I have no idea why my BB RI is 50W but it says so on the back...:banana
     
  5. Zuper

    Zuper Supporting Member

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    Try one or more of these:
    -H-magnet speakers or G-1265s for better bass response
    -Jumper channels
    -Swap out the V1 tube
    -Disconnect the trem

    Not sure about the transformers on the marshall, but every JTM45 clone I've had, I've run into a 8 ohm cab. This does provide an impedance mismatch, but is safe with most amps. The mismatch will lower the volume slightly, and, IMO, changes the tone for the better.
     
  6. Babaji

    Babaji Member

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    ...JTM 45's don't break up until wide open(the original plexi ones), that's just the way the work. A glorious sound...but LOUD!
    Bill
     
  7. sixstring531

    sixstring531 Supporting Member

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    I converted my BB (92) as close as I could get to original specs. Through in NOS tubes, KT66s (you can put Goldlions in the thinner cab) -- updated big blue caps to original specs and DISCONNECTED THE TREMOLO CIRCUIT (HUGE DIFFERENCE, REALLY OPENED IT UP).

    To do the trem circuit, simply open her up, look for the largest grey wire (running from trem circuit along side of chassis, connects to single solder underneath PCB) and desolder it. I left it in there with electrical tape on the end for someone else if they wanted it back. I also put in weber blue and silver bell speakers (alnicos) to get her back to the old times. Great rock amp! Just straight up no frills rock'n roll.
     
  8. ToneMasting

    ToneMasting Member

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    Hi there sixstring531
    I'm doing the trem circuit trick - Exactly where did jo desolder the grey wire?
    Underneath the PCB or by the 'Intensity' potentiometer?
    I'm finding it quit difficult to dismount the PCB...

    And thanks for all your feedback everyone!
     
  9. saltydogg

    saltydogg Rock & Roll Enthusiast Gold Supporting Member

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    You might try a MetroJTM45 (Metropolous). PTP wiring, sounds crystal clear and has a PPIMV on the back so you run at lower volume levels and get it to break up. I love mine and they're reasonably priced compared to the Marshall Re-issues.

    [​IMG]

    [​IMG]

    [​IMG]
     
  10. big mike

    big mike Fixed Bias Moderator Staff Member

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    You don't have a 50 watt Blues Breaker BTW, it's 35 watts like a JTM.
    They're loud. Nothing you can do about that without some attenuation or a master volume of some sort.

    Now, i also think the Marshall RI's are really not as close as they should be. Tons of other options for a JTM that sounds more correct, and will give up the goods like you require.

    Also, push that mid control. That's where the love is...
     
  11. big mike

    big mike Fixed Bias Moderator Staff Member

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    What's the sozo coming of the PPIMV for?
     
  12. saltydogg

    saltydogg Rock & Roll Enthusiast Gold Supporting Member

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    "What's the sozo coming of the PPIMV for?"

    I have no idea. Since I'm not technically savvy I had Metro do the build. Good question, though.

    To the OP- there are several very good "small market" JTM makers, BTW. I happen to have the Metro and am thrilled with the tone and dynamics of the amp considering what I paid for it (with the upgrades in electronics and the white tolex it was still less than a Marshall RI). That being said, I have not played Marshall Re-issue, but I'd bet the farm that the tone, response and quietness of the Metro far surpasses that of a Marshall RI. Build time and customer service were excellent as well.
     
  13. myfoot

    myfoot Member

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  14. ToneMasting

    ToneMasting Member

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    Hey guys,
    Here's a picture of the backside of my amp - it says 50W. That's what led my to think it's a 50 Watter. It's not exactly as neat as yours but what the heck... By the way - for some reason thet tubes are KT-77's. Someone must have been mingeling with it before I bought it.

    [​IMG]

    The trem-trick: Do I desolder the grey wire by the potentiometer or on the PCB? I'm finding it difficult to pull the PCB out of the amp. Maybe it doesn't matter where I do it?

    [​IMG]
     
  15. Roe

    Roe Member

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    I thought the BB RIs were all 30w amps. none of these are lound. and a healty one should not sound thin
     
  16. Roe

    Roe Member

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    that's the 100nf phase inverter coupling caps
     
  17. mrscott99

    mrscott99 Member

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    If you have the money, change the caps to some that are higher quality, change the output Transformer to a mercury radio spears, do the raw sewage mods. I have one I converted mine to a head and changed the guts and it sounds awesome. The best cleans, very punchy and dynamic. Takes pedals better that any amp I have heard.
     
  18. Roe

    Roe Member

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    a marstran is much better than a mercury - and more inexpensive as well.
     
  19. mrscott99

    mrscott99 Member

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    your basis is you have you heard them side by side? and I have a discount level with Mercury that brings it down to this price range. What about the Power tranny, are they better as well or are you going by price. Not saying that Marstran are not good, just haven't had much experience with them.
     
  20. muzacman

    muzacman Supporting Member

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    Maybe consider the hand wired Marshall 1974X 18 watt bluesbreaker. It breaks up beautifully at 5 at a very usable volume level. I typically mic mine up if I need more volume.
     

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