Which preamp tubes to buy?

Discussion in 'Amps and Cabs' started by wrxplayer, Feb 5, 2012.

  1. wrxplayer

    wrxplayer Supporting Member

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    I'm having some issues w/ a new amp. Gonna try to swap out some preamp tubes before bringing it in to a tech.

    Looking for decent performing and inexpensive pair of 12AT7s and 12AX7s.

    What do you recommend in each case?

    Tnx.

    (If it matters, amp is a Blankenship Fatboy w/ Sour Cream).
     
  2. chervokas

    chervokas Member

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    What are the amp issues?

    I have no experience with modern production 12at7s; but among modern production 12ax7s I've liked the Sovtek LPS and the New Sensor modern day "Tung Sol"
     
  3. EADGBE

    EADGBE Member

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    Yeah they're my favorite.
     
  4. wrxplayer

    wrxplayer Supporting Member

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    I just swapped for a Blankenship Fatboy w/ Sour Cream. It's tweed amp w/ 2x6L6 power. In addition, it has two 12Ax7s, two 12AT7s, and one 5AR4 (GZ34) rectifier.

    Turn on, plug in, and the amp sounds great. After a few minutes, though, there's a distinct change on tone. All of the warmth is gone, a fair amount of volume is gone, and what's left is "tinny, ice picky, and bright" sound that also sounds like its coming through cupped hands or a megaphone.

    A couple of minutes later, the warm, full-bodied tone returns.

    Would appreciate if someone who's had an amp w/ these symptoms could chime in w/ an "educated diagnosis."

    http://www.thegearpage.net/board/showthread.php?p=12413039#post12413039
     
  5. mbargav

    mbargav Member

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  6. andyk

    andyk Supporting Member

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    Could be a preamp tube socket issue. When you plug the tubes in, are they loose or moving around easily? If yes, a re-tension or replacement may be needed.
     

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