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Pre-amp tube recommendations for 18 Watter?

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by Pedro58, Jun 27, 2005.

  1. Jun 27, 2005 #1
    Pedro58

    Pedro58 Supporting Member

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    I have a TMB 18 Watter built from a GDS Kit. I run it in a combo with a Celestion Blue 12" and a Weber Silver Pup 10". It is a killer amp. The Marshall-voiced side has one tone knob and a volume. It runs from a 12AX7. I tried a GT/Mullard copy and it was too smooth. No high end. I have a JJ ECC83-S in it and it sounds good, but the high end isn't there until you turn the volume WAY up and get crunch. I would like a 12AX7 that has some sparkle before it gets really driven. A good clean tone... Any suggestions? I would like to have it on the edge of breakup and have some sparkle.
     
    Pedro58, Jun 27, 2005
    Pedro58, Jun 27, 2005
    #1
  2. Jun 27, 2005 #2
    TAVD

    TAVD Guitar Player Gold Supporting Member

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    Interesting. Both of my 18 watters lose high end when the volume is turned up. I'm using a Westinghouse branded tube in one and a RCA in the other.

    One of mine really opened up after I changed the tone pot from 250k to 1m.
     
    TAVD, Jun 27, 2005
    TAVD, Jun 27, 2005
    #2
  3. Jun 27, 2005 #3
    Swarty

    Swarty Member

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    Short plate Mullards and Amperex are typically quite bright. I've got a bunch collecting dust, send me email if you're interested.
     
    Swarty, Jun 27, 2005
    Swarty, Jun 27, 2005
    #3
  4. Jun 27, 2005 #4
    goneracin

    goneracin Member

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    A telefunken 12ax7 will add sparkle and high end. They are hard to find without getting a microphonic one, but a non microphonic one sounds like what you are looking for.
     
    goneracin, Jun 27, 2005
    goneracin, Jun 27, 2005
    #4
  5. Jun 27, 2005 #5
    Pedro58

    Pedro58 Supporting Member

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    e-mail sent...

    Anything that isn't NOS?
     
    Pedro58, Jun 27, 2005
    Pedro58, Jun 27, 2005
    #5
  6. Jun 27, 2005 #6
    goneracin

    goneracin Member

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    an EH 12ax7 is usually brighter than the jj's. Also, the new jj ecc803 is a decent tube IF you can get a non microphonic one.
     
    goneracin, Jun 27, 2005
    goneracin, Jun 27, 2005
    #6
  7. Jun 27, 2005 #7
    TAVD

    TAVD Guitar Player Gold Supporting Member

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    Sovtek are bright although I find them harsh in most amps. Funny, I don't usually think of EH as being bright. They do seem to have more gain though.
     
    TAVD, Jun 27, 2005
    TAVD, Jun 27, 2005
    #7
  8. Jun 27, 2005 #8
    Pedro58

    Pedro58 Supporting Member

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    Denyle-Guitars-- I think I'll look into the tone pot. I'm not sure what mine is...
     
    Pedro58, Jun 27, 2005
    Pedro58, Jun 27, 2005
    #8
  9. Jun 28, 2005 #9
    Blue Strat

    Blue Strat Member

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    Microphonic Telefunkens? Nothing is immune from problems, but you've had abnormally bad luck (or you don't have real Telefunkens).

    In new tubes, the EHs and Ruby STR 7025s are candidates.
     
    Blue Strat, Jun 28, 2005
    Blue Strat, Jun 28, 2005
    #9
  10. Jul 10, 2005 #10
    Pedro58

    Pedro58 Supporting Member

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    Okay, I tried the Ruby 7025... still not enough top end. I think I'll try hte larger value pot. When I go to a 1 Meg, do I need to stick with audio taper or do I go with linear? It seems that most suppliers have a 1 Meg linear only... Is there a reason for that?
     
    Pedro58, Jul 10, 2005
    Pedro58, Jul 10, 2005
    #10
  11. Jul 11, 2005 #11
    phsyconoodler

    phsyconoodler Member

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    I find that the speaker is a BIG change in high end response.What speaker are you using?I have tried everything from a celestion vintage 30 to a randall jaguar(my fav) to a Cannabis rex(very nice too)in my 18 watter. All except the randall has high end sparkle.Maybe you have a bypass cap thet is too high a rating,letting only lows by in the frequency range.What are you using for a cathode bypass cap?

    Note: Heyboer transformers are notoriously dark.
     
    phsyconoodler, Jul 11, 2005
    phsyconoodler, Jul 11, 2005
    #11
  12. Jul 11, 2005 #12
    Pedro58

    Pedro58 Supporting Member

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    I'm using a Celestion Blue and a Weber Silver Pup... It's a GDS kit, so the trannies are Heyboer, I think. But the TMB side has plenty of top end... I still think a simple pot change might do the trick. The amp isn't dark. I just need the treble frequencies to open up a little. I'll probably purchase both kinds, linear & audio taper, and see what gets what I want.
     
    Pedro58, Jul 11, 2005
    Pedro58, Jul 11, 2005
    #12
  13. Jul 11, 2005 #13
    jrigg

    jrigg Gold Supporting Member

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    Another vote here for NOS tubes. I have tried multiple Mullards, Amperex, Valvo, Telefunken, RCA, Sylvania, Tung-Sol, Raytheon etc in all positions and the great thing about the 18 watt format is you can really hear the difference good tubes make. Right now I am using an Amperex in V1 and a Telefunken as the PI with a RCA blackplate for the trem channel. Power tubes are late 50's Sylvania blackplates.
     
    jrigg, Jul 11, 2005
    jrigg, Jul 11, 2005
    #13

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