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GE preamp tubes??

Discussion in 'Amps and Cabs [BG]' started by BassGreaser, Jan 30, 2003.

  1. BassGreaser


    Aug 22, 2002
    Austin, TX
    I have GE 12AX7 preamp tubes in my all tube Trace. Are these good preamp tubes? I'm going to re-tube my head soon. ANy info would help ALOT
  2. DigMe


    Aug 10, 2002
    Waco, TX
    I have a GE 5 star 5751 tube in my SM-500 and it's been a great tube. It just very slightly rounded out the tone vs. the GT tube that was in there. I'm guessing the ones in your trace are actually 5751 tubes (early "heavy duty" versions of the 12AX7). They're the same size as 12AX7's.

    brad cook
  3. I've used the GE preamp tubes.
    Darn good.
  4. lneal


    Apr 12, 2002
    Lee County, Alabama
  5. Great NOS tube for the money.
  6. I guess I get to be the lone naysayer. I don't like GE preamp tubes for bass. To my ears, they're brassy with too heavy a midrange and tend to be lacking in the extreme highs and lows. I prefer Sylvania/Philips (same tubes) for bass much better. They're more clean and "hifi" sounding to me.

    Why are you retubing your amp? I can see swapping preamp tubes to taste, but unless you have some sort of power amp problem, there's no point in pulling good tubes. If this is related to your hum problem you mentioned awhile back, take the amp to a tech first. Contrary to what most tube sales people tell you, 90% of all tube amp problems are NOT the tubes. Your hum might be fixed by a simple bias adjustment!
  7. BassGreaser


    Aug 22, 2002
    Austin, TX
    well I have four Sylvania 6550s, and two Mesa Boogie 6550s. I want to get all the same power tubes, plus I want to try some KT88s.
  8. What do the Mesa 6550's look like? If they're the "coke bottle" shaped ones, yes by all means, replace them ASAP, but if they're the straight sided 6550A's they ARE Sylvania's, just rebranded.
  9. BassGreaser


    Aug 22, 2002
    Austin, TX
    they're coke bottles. were can I get 6 matched kt88s? Also, Oh the back of the amp there is a ohms switch. but the ohms are rubbed off. I'm guessing it's 4ohms switched to the left and 8 ohms to the right. this is my head....
  10. I get my KT88's from Ned Carlson here:


    However, he doesn't always have matched sextets of them. Lord Valve carries them, so you could try him, too. I would avoid Svetlana KT88's, which is what everyone will tell you to buy instead of the Sovtek KT88. Svet's have BAD microphony problems after a few hours use.

    The Sovtek KT88 will look very similar to the Mesa tubes you have in there now. They're coke bottle shaped, but they will fit. Also be sure to have a tech install them. The Trace has bias adjustment pots, so it's not hard to do.

    I looked on my Trace V6 for the impedance switch; 4 ohms is on the right, 8ohms on the left, BUT yours MAY be different. With the amp turned off and unplugged, use a DMM to measure the changes in impedance at the output jack. It won't read 4 or 8 ohms, but the higher impedance reading of the two will be the 8 ohm setting.
  11. BassGreaser


    Aug 22, 2002
    Austin, TX
    thanks!!! that helps so much