what do el-34's sound like in jtm45's?

Discussion in 'Amps and Cabs' started by sabbath90, Mar 8, 2006.

  1. sabbath90

    sabbath90 Member

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    how would you compare a jtm45 with el-34s to one with kt-66s. i'm not terribly concerned with it sounding vintage just with it sounding good. i'm guessing el-34s would push it in a more traditional marshall direction, correct?
     
  2. Roe

    Roe Member

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    yes, and a bit less bass
     
  3. trisonic

    trisonic Member

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    El34's in a JTM45 are brasher and more trebly. In your face.
    The KT66's are smoother have more mids.

    Both have their place depending on your taste.
     
  4. KLB

    KLB Member

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    I used to have one of those and had a lot of fun experimenting with various tubes and circuit changes.

    Aside from properly biasing the EL-34, set the impedence selector one notch higher than the speaker load. That is, if using an 8 ohm cab, put it on the 16 ohm setting. This is because the OT is designed for a 6.6K primary load, not the 3.4K normally used with EL-34. Setting the impedence selector this way reflects a more correct impedence back to the EL-34, giving the most output, dynamics and harmonics.

    Change the Negative Feedback resistor from 27K to 56K, which will greatly open up the amp and increase midrange bloom, even with KT-66. Better yet, replace one of the speaker jacks with a 100K linear pot wired in series with the 27K NFB resistor so you can vary the NFB to taste.

    If you find you prefer the tone with EL-34, consider replacing the OT with an interleaved Drake EL-34 replica from Heyboer, Mercury Magnetics, Marstran, OEI, etc. Not only will it sound better than the stock JTM-45 OT, it will allow you to use the 16 ohm setting into your 16-ohm series-wired 2x12 or series/parallel 4x12.

    Another cool option with the JTM-45 reissue is to use 6V6 tubes. No need to do any impedence matching because the 6V6 like to see around 7K or more. Try a 12AT7 phase inverter with them to cut down on the grid signal hitting the 6V6. A 5U4 or 5R4 will lower plate voltages closer to 400v if you are using more fragile old or new stock 6V6. The JJ 6V6 can take 450v or higher.

    Get rid of the Brite cap on the Brite channel volume control!
     
  5. Nativ H

    Nativ H Member

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    When I got my white '65 block logo JTM45, the previous owner had Mullard EL34's in it. Sounded much more aggressive than my other JTM45 with GEC's. I assumed that this is what a JTM50 would sound like.

    It was fun for awhile but I went back to the GEC's because that is what my ears expect from a JTM45.
     
  6. big mike

    big mike Moderator - EL34 Emeritas Staff Member

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    My JTM Clone has them, it's a bit brighter and crisper, slightly closer to plexi, but more like a normal model with more teeth and less mid.

    Good stuff!
     
  7. sabbath90

    sabbath90 Member

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    cool. i might try a set. i'm pretty happy with kt-66's but i might as well try the 34's and see for myself, right? thanks.
     
  8. myles111

    myles111 Member

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    I personally do not like this at all.

    If you want an EL-34 Marshall get a model 1987.
     
  9. big mike

    big mike Moderator - EL34 Emeritas Staff Member

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    I like it, but then again, I'm not trying to get the tone of a 1987.

    <shrug>
     
  10. myles111

    myles111 Member

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    You mention the Greer CAM 18 ....

    That is one more for the list as is his Underdog 15. Two amazing amps.

    www.nickgreerexpdesigns.8m.com
     
  11. ericb

    ericb Silver Supporting Member

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    Yea , when I got my jtm45 RI in the early 90's I found I liked EL34's in there more than kt66's or 6l6's or 5881's, and used it FOR YEARS that way ! I very much wouldn't agree with Myles or Trisonic's descriptions. Then I got it modded back to the vintage specs and have used kt66's since and it kicks butt. I guess there's all kinds of likes huh! ERIC
     
  12. big mike

    big mike Moderator - EL34 Emeritas Staff Member

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    Yeah, Nick is making KILLER amps! Can't wait for the cam to get here.
     
  13. myles111

    myles111 Member

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    I have been going through his Marauder 35 and Underdog 15 that belong to Patrick Selfridge and it has been a real eye opener.

    Miranda Lambert ( http://www.cmt.com/artists/az/lambert_miranda/artist.jhtml ) whose guitarist Alex Weeden uses a Thunderbolt 30 has a great tone and she is currently at #1 in the Top 20 countdown on CMT.
     

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