JTM45 and the useless bass control!

Discussion in 'Amps and Cabs' started by protoangel, Jan 8, 2006.


  1. protoangel

    protoangel Member

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    EVery single new JTM45 I've tried since '95 has the same problem... Turn the bass control anywhere above "off" and it becomes a useless flubby beast at any useable volume,,, What a load of uninspiring crap!

    I tried one yesterday at Chandlers in Kew near London to test a THD Hotplat, and the combination of the amp and new Marshall 4x12 "vintage" cab had me singularly UNIMPRESSED!

    The only exception is this original JTM45 PA my friend had in the 90s with the original PA stack and original KT66 tubes... That was NICE... Pretty gnarly and retro, but nice, specially with the 20 watt speakers!

    On another note, the guy was telling me that AC/CD have a demo studio in nearby Twickenham where they have the original 20 Watt "1974" (?) 1x12 combos. Marshall came by to compare their new re-issues with these oldies, and found the new ones to be singularly lacking in all areas! So they took a few measurements from the AC/CD ones and went scurrying back to the woodshed
     
  2. Roe

    Roe Member

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    try el34s or 4x10" ceramic speakers
     
  3. riffmeister

    riffmeister Gold Supporting Member

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    hmmmm....the Germino Classic 45 is not flubby in the bass......
     
  4. Roe

    Roe Member

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    some of the problem may come from the RI g12m speakers in a open cab
     
  5. Roe

    Roe Member

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    try a strat w/ a maple board
     
  6. Pentode

    Pentode Supporting Member

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    That, combined with the thick bass coming from a JTM 45, would make for some really farty sounding lows.
     
  7. trisonic

    trisonic Member

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    That's weird.
    Most JTM45's I've played have a generous bass response that sounds good through Greenbacks. Listen to Mick Taylor on the Bluesbreakers' "Crusade".

    I have never played a reissue, though........

    Best, Pete.
     
  8. michael.e

    michael.e Supporting Member

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    Hmm, no flub from my Reinhardt 45 either.

    I too have played re-issue Marshall 45's that utterly sounded flat and lifeless.

    I do not think that real 45's from Marshall have the unimpressive tone and flubby bass, at least not the ones that I have heard.

    Now who around here was saying that the RI's KILLED any of the boteek offerings?? I forgot.

    Anyhoo, attention to detail is what makes the difference between playing a RI and a well made boteek offering. M.E.
     
  9. johnspeck

    johnspeck Member

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    My '45 has a pretty 'tubby' bass to it, as did the original couple I played when we (tech and myself) wired mine together.

    By tubby, I mean that, depending on tubes used and bias, as well as volume, cab/speakers, the bass knob is kept much lower than the other controls.

    With new tubes, my amp's bass is tightest, as well as a good rectifier tube (NOS Mullard, in my case).

    Also, it helps to think of this amp along the lines of a Fender, as it was based upon the Bassman. My tech showed me a cool trick for Fenders with a midrange control: crank the mid all the way, bass and treb to taste, with the volume cranked. I usually have the treb around 4, bass no higher than 2.5-3. Gives you that good Nugent crunch, especially from a Pro Reverb. On your Marshall, try the same thing. Crank the mids, volume and presence, then a little treble and bass to taste. Gives you great crunch that cleans up well via the guitar's volume.
     
  10. michael.e

    michael.e Supporting Member

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    That is pretty much how I run mine. I keep the mid's high at around 3/4, bass around 3/8 or so and treble at 1/4 to 3/8, depending on where I am. I adjust the presence depending on the volume that I am playing at. When it cleans up, it sounds so beautiful! M.E.
     
  11. big mike

    big mike Fixed Bias Moderator Staff Member

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    No problem with my Rockytop. Though it runs EL34's.
     
  12. johnspeck

    johnspeck Member

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    Yeah, with KT-66's, it's a different character to the power tube compression. Especially comparing new '66's to old.
     
  13. riverastoasters

    riverastoasters Member

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    I don't find this with my Louis Electric JTM45 clone. It gets a bit more watts though. Try EVM-12Ls.
     
  14. doctord02

    doctord02 Member

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    The original JTM 45 schematic calls for a 300uF cathode cap on V1. Most folks find this to be too flabby/woofy sounding. Try substituting a 2uf cap instead.

    Many of the boutique builders reduce this value in their builds and that may be why folks dont have issues with the woofy bass. I changed mine and it immediately fixed the problem.
     
  15. drbob1

    drbob1 Silver Supporting Member

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    I have a 65, and I keep the bass almost off. I really don't like the buzz/rattle that my old cabs seem to develop with the bass cranked up at all. Same with my 59 Bassman. Both amps love Tubescreamers for just this reason-more rip with less buzz...
     
  16. Tag

    Tag Gold Supporting Member

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    :confused: :confused: :confused: :confused: :confused: .

    No Flub from the two Bluesbreaker RI Combos I tried with both PRS and Strat guitars. No Flub from the 3 HW RIs I have played, and no flub from the 2 standard RI heads I have played wide open. No Flub from the Blockhead 45 clone either. All were nice amps, the standard Bluesbreaker combos my favorite.
     
  17. Tag

    Tag Gold Supporting Member

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    I did.

    The Bluesbreaker RI combos sounded far better than any clones OR the HW RIs I have played in A/B situations. Great amp!! I do not care how much more the Boutiques cost, or what trannies they use, they sound worse.
     
  18. jkr

    jkr Supporting Member

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    My Germino Classic 45 is crunches tight like a drum when I keep the bass low. I don't know what cab you are going into, but try a Classic 45 and you won't have that problem. I get the killer AC/DC rhythm crunch when I crank mine up.. no flub in sight unless I were to dime the bass knob (but who would do that with JTM 45 type amp?).
     
  19. big mike

    big mike Fixed Bias Moderator Staff Member

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    C'mon tag. You can't make a blanket statement like that. It has to be case by case. You like the sound of the bluesbreaker RIs.Cool. As a matter of fact, so do I. But you cant say they're better than all the Boutiques until you've put it up next to every single brand for comparison.
     
  20. drbob1

    drbob1 Silver Supporting Member

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    Whaddya mean he can't say it, he just did! ;)
     

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