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Sounding sterile...

Discussion in 'Glowing Bottle Tube Amp Forum' started by Danjabellza, Jul 8, 2018.

  1. Danjabellza

    Danjabellza Tele-Afflicted

    Sep 22, 2014
    Pahrump, nv
    So, I have an egnater tweaker 15, I recently had an issue with a blown resistor and shorting tubes. I replaced the resistor and put in new tubes. The only 6v6 tubes I could get on short notice were groove tubes from guitar center. The tubes that were there before were tung sols. Since putting in the new tubes and resistor the amp has been quieter than before(noise wise), but, it sounds very sterile and lifeless compared to prior.

    Could it be that I just need to break in the tubes? Are groove tubes that bad?

    I was considering getting a set of 6L6s and maybe some new preamp tubes too, would that be of any benefit?
     
  2. viccortes285

    viccortes285 Tele-Holic

    Age:
    69
    980
    Jan 14, 2017
    Phoenix
    Did you bias your amp, after you replaced tubes?
    Tubes are rated for different output and tones.
     
  3. heltershelton

    heltershelton Tele-Afflicted

    Sep 14, 2016
    not houston
    were the tubes 6v6s or 6v6r?
    and the tweaker 15 is self biasing. there is no adjustment.
     
  4. JD0x0

    JD0x0 Poster Extraordinaire

    Age:
    28
    Feb 22, 2009
    New York
    New tubes probably just run and sound a bit different. They may pull less current and be biased cooler. Cooler bias may sound more 'sterile' and lose some 'power' and 'punch'
     
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  5. corliss1

    corliss1 Friend of Leo's Platinum Supporter

    Sep 13, 2008
    Lansing, MI
    There's always adjustment. It may be by replacing a resistor or two though instead of tweaking an available pot.
     
  6. Danjabellza

    Danjabellza Tele-Afflicted

    Sep 22, 2014
    Pahrump, nv
  7. heltershelton

    heltershelton Tele-Afflicted

    Sep 14, 2016
    not houston
    emisilly likes this.
  8. JD0x0

    JD0x0 Poster Extraordinaire

    Age:
    28
    Feb 22, 2009
    New York
    If the GT 6V6S is in fact the JJ (which I don't doubt) that's a 14W tube, while the typical 6V6's tend to be ~12W.

    Tung Sol 6V6GT appears to be 12 watts max dissipation according to this datasheet. This means the JJ is biased cooler with respect to its max dissipation @ 14W

    http://tungsol.com/specs/6v6gt-tung-sol.pdf



    Just plugging some stuff into Rob's tube bias calculator, if you biased a 12W 6V6 @ 90% a JJ would be @ 77.1% dissipation with all the same numbers, just plugging in a 14W rated tube. That's quite a bit cooler, and could definitely explain the OP's observations, IMO.
     
    Last edited: Jul 8, 2018
  9. heltershelton

    heltershelton Tele-Afflicted

    Sep 14, 2016
    not houston
    i think you just explained what is going on with his amp perfectly.
    here is a groove tube chart that shows what you are actually getting when you buy groove tubes.
    https://www.thetubestore.com/tube-brands/groove-tubes
     
  10. Danjabellza

    Danjabellza Tele-Afflicted

    Sep 22, 2014
    Pahrump, nv
    So what’s the fix then? New tubes?
     
  11. heltershelton

    heltershelton Tele-Afflicted

    Sep 14, 2016
    not houston
    yeah.....just get the tung sol power tubes and your amp should sound like it did.
     
    Danjabellza likes this.
  12. JD0x0

    JD0x0 Poster Extraordinaire

    Age:
    28
    Feb 22, 2009
    New York
    Easiest fix is new tubes, with the same 12W dissipation rating. If you want to continuously use 14W tubes, you could rebias the amp by changing the cathode resistor(s) but then if you ever go back to a 12W tube, for whatever reason, those will be running (too) hot. Though, I supposed you could always just add a bias switch to toggle between values for either tube, if you wanted to do that.
     
  13. SngleCoil

    SngleCoil Tele-Holic

    560
    Apr 13, 2010
    Charlotte, NC
    The Tweaker is cathode biased so not strictly necessary to re-bias. The 6V6S has a different sound than the 6V6GT. Firmer more defined lows and a little more strident highs...guess you might describe it as sterile. I didn't notice that big a difference in mine, though.
     
  14. Danjabellza

    Danjabellza Tele-Afflicted

    Sep 22, 2014
    Pahrump, nv
    And actually, I’m pretty sure that they’re 6V6R, I’m not sure where I got 6V6S from... the Tung Sols were 6V6GT
     
  15. Danjabellza

    Danjabellza Tele-Afflicted

    Sep 22, 2014
    Pahrump, nv
    A922F4BE-4A9E-4A10-90E4-87899AE0A2B7.jpeg
    Confirmed 6V6R. Not sure why I thought 6V6S.
     
  16. heltershelton

    heltershelton Tele-Afflicted

    Sep 14, 2016
    not houston
    in that case, what you have are electro harmonix tubes. it is also a 14 watt max tube just like the jj.
     
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  17. schmee

    schmee Friend of Leo's

    Jun 2, 2003
    northwest
    I would double check the resistor you replaced. Did you get the value wrong? You shouldn't have a huge difference in sound from the tubes.
     
  18. Danjabellza

    Danjabellza Tele-Afflicted

    Sep 22, 2014
    Pahrump, nv
    The resistor is the same value. I made sure to verify that prior to the install in the other thread.
     
  19. telemnemonics

    telemnemonics Doctor of Teleocity

    Age:
    59
    Mar 2, 2010
    Maine
    In addition to the useful info above about putting a 14w tube where a 12 tube used to be in a cathode biased amp, even among 12w 6v6 tubes there may be a difference in sound from one make to another.
    I have a cathode biased 6v6 amp and there are some 6v6 pairs that sound brighter and stiffer than other brands.
    Tubes are cheap, buy some Tung Sols if you like the sound.
    According to marketing info, those Tung Sold were designed to sound more like vintage Tung Sol 6v6, which have a nice fat tone.
    I've run both the reissue and original Tung Sol 6v6 back to back and they do both sound fat and "vintage".
    This may be as much the current draw of a given design, irregardless of the 12w vs 14w rating.
    You could certainly experiment with the cathode resistor and a meter to try to get the same bias from the tubes you don't like the sound of, but there isn't a huge motivation to mod your amp to sound better with EH tubes, since they are nothing special.
    It's also possible you still won't like the EH as much as the Tung Sols after tweaking the bias.
     
    Last edited: Jul 10, 2018
    Danjabellza likes this.
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