Tell me about KT77 in place of EL34

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by dazco, Feb 18, 2012.

  1. dazco

    dazco Member

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    I keep reading how these are better than EL34, but of course mostly from biased sources and i can't help but wonder why most 34 users aren't using these instead if they really are superior. And of course to complicate things, it is subjective. Or do they simply sound better in ways most anyone would agree with. Educate me. How do they differ sonically?
     
  2. Ronsonic

    Ronsonic Member

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    KT77 is, was, sorta British for kickass 6CA7. A beam tetrode tube that would operate in place of the EL34 Pentode.

    They were like the legendary 6CA7s of the past an awesome tube.

    I have no idea what is being sold under that label nowadays.

    I have installed them and biased them up and seen them sound good. Can't say that they're all that and a bag of chips.
     
  3. big mike

    big mike Moderator - EL34 Emeritas Staff Member

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    Depends on the amp.
    In my experience JJ vs JJE34L it adds more low and high end and cleans up the mids some.

    More full range and balanced.
     
  4. Scott Whigham

    Scott Whigham Member

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    I haven't tried KT77s but I do use KT66s in my Xits X50 instead of the EL34s. My friend has the exact amp and he has EL34s in his. We put them in the same room and just plugged each head into the same cab. There were about 5 other guitar gear nuts around and only Chris and I claimed to have heard any difference. I could hear more bass and fullness in the KT66s but he didn't hear that. He thought he heard more growl and roundness in the EL34s. But I didn't hear that haha.

    In the end, I like the KT66s and I'll stick with them but, if there was a KT66 shortage, I wouldn't feel like I was losing anything by going back to EL34s.
     
  5. big mike

    big mike Moderator - EL34 Emeritas Staff Member

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    There's a huge difference in tone between KT66 and Kt77
     
  6. EFK

    EFK Supporting Member

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    My two cents, for what it's worth: the old KT77, and good luck finding any now, were like a super EL34 with a hint of the big 6L6 bottom thrown in. I've had them, but no longer have any and I wish I did. I don't find the newer JJ KT77 to sound like them. To my ear, they are very aggressive (much more so than most EL34 or 6L6) and while I did *think* I am hearing more bass as opposed to most new EL34, I find it to be fairly ragged and sloppy. Kind of like a tube that has been pushed just way too far.
     
  7. Jose Luis Garci

    Jose Luis Garci Member

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    I have recently put Genalex Gold Lion KT77 in two of my amps, and i have to say i didn't like them at all.
    First of all, the tone lost a lot of lows, really unpleasant.
    And second, i'm having a hard time trying to identify some character or personality in them.

    I went back to =C=.
     
  8. Scott Whigham

    Scott Whigham Member

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    Can you elaborate? I haven't tried any of the KT77s. I know the difference between the EL34s and, to my ears, it's a pretty minor difference. I tried to think of an analogy but I can't!!!
     
  9. Joegalaxy

    Joegalaxy Member

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    I've been running two JJ 77s in my Roccaforte C30 for a while now and prefer them over my other options which are four JJ 6v6s and a hot pair of winged C's. Less in your face mids than the other options. Just enough is carved out. Either that or increased low and high end; however you choose to look at it. With this amp, the cleans are more usable with them.
     
  10. INX

    INX Member

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    Note the higher impedance spec of the tube...it's Ra is 23K, whereas EL-34 is 15K, which means it likes a 6L6 spec OT. I mismatch my Rivera M60 so a pair gets 7K, rather than 3K5 stock.

    Also, like the E34L and 6L6GC it IS a 30+ watt tube and will need to be biased similarly.
     
  11. Jose Luis Garci

    Jose Luis Garci Member

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    Due to both tubes diameters, the amount of lows and mid-lows a KT66 is huge. KT77 sound good but the response is centered in highs.

    To me, Genalex Gold Lion KT66 is the best current production power tube, it sounds elegant and fat, it is a pleasure.
    And about the Gold Lion KT77, which is the only kt77 i know, i would never replace a =C= El34 with it, for instance.
     
  12. guitarcapo

    guitarcapo Senior Member

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    I've always had problems with the heater current in those KT power tubes.

    It seems to really push most power transformers beyong their capacity.
     
  13. Jose Luis Garci

    Jose Luis Garci Member

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    You are refering to both or only to KT77?
    Thanks.
     
  14. midnightlaundry

    midnightlaundry Member

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    I tried them in my Trainwreck. They did add a lot of bass, but were to floppy sounding. However, that amp is all power distortion. Maybe they would work better in an amp that has more preamp gain.

    EL34's were way tighter in that amp.
     
  15. guiltless

    guiltless Member

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    Here is a little size comparison. From left to right: 5V4G, KT66, KT77, 6L6, 12AY7

    [​IMG]
     
  16. solitaire

    solitaire Senior Member

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    Yes, kind of the same type of dynamics and degree of sheen, but as JLG stated the 77 is far brighter, like a KT66 wanting to be an EL34 but can't really hide its true identity.
     
  17. GT100

    GT100 Member

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    Huh?
    The JJE34L is a pentode. A real KT77 is like a 6CA7 in that it is a beam formed tetrode.
    This is why JJ now makes a KT77 as well as an EL34 and a E34L...

    Lloyd
     
  18. big mike

    big mike Moderator - EL34 Emeritas Staff Member

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    It's my perception of the tone difference in the same amp between a JJ KT77 and a JJ E34L
     
  19. donnyjaguar

    donnyjaguar Member

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    That KT77 look like an EL34. Ehumm... [​IMG]
     
  20. hosenlander

    hosenlander Member

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    If you want to hear the difference between the JJ EL34, EL34L and KT77: check http://www.youtube.com/watch?v=xjgKtpTjK0o
    I recorded this just to make a systematic comparison between the 3 types.
    I hope it helps!
     

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