Pre-amp INPUT tube in Mesa Mark V

Discussion in 'Gear & Equipment' started by Prude, Oct 12, 2018 at 7:49 AM.

  1. Prude

    Prude SS.org Regular

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    Hi!
    Have anyone tried to switch the ordinary 12AX7 input tube in a mesa mark V, or maybe all of the pre-amp tubes, to a premium SPAX7-A tube? Did you in that case notice any difference?
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  2. TedEH

    TedEH Cromulent

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    I could be wrong, but I vaguely remember those -A tubes being meant to improve reliability moreso than tone. I have a couple of them and they sounded no different than any other tube, to my ears.
     
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  3. DudeManBrother

    DudeManBrother Hey...how did everybody get in my room?

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    You can use them anywhere, but they’re typically most effective in V1. They are low noise/low microphonic selections with the heat shrink on top to help keep them that way.
     
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  4. mnemonic

    mnemonic Custom User Title

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    Yeah I remember reading up on them a while back and they were supposed to just be selected specifically for low noise or something. I guess the shrink wrap may help with that also. Also obscures the internals so you can’t see where it’s made.

    I think their normal 12ax7’s are all JJ’s and have been for some time. If you google SPAX7 some of the pics have shorter pieces of shrink tubing on them and you can see they’re chinese tubes. But I don’t know how old those pics are and if the SPAX7 is still chinese or not.

    I doubt they’re really any better than selected low noise tubes from groovetubes, ruby, etc. They all do the same thing, buy tubes from either JJ (Slovakia), New Sensor (Russia) or Shuguang (China) and test/relabel.
     
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  5. Prude

    Prude SS.org Regular

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    If they relly keep noise away, then maybe I should try one in V1. My amp picks up noise from lamps and other electrical stuff nearby.
     
  6. DudeManBrother

    DudeManBrother Hey...how did everybody get in my room?

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    Yeah they work great for that. It is the V1 signa that gets amplified through the preamp, so having that one as clean as possible is best. I’ve always had good luck with those SPAX-7’s, I think I have maybe 5 of them. I just audition them in V1 along with Ruby HG7’s, 7025’s and the like.
     
  7. pearl_07

    pearl_07 SS.org Regular

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    Best preamp tube that I've found for V1 is the good 'ol Tung Sol 12AX7. I tried a variety of tubes in my Mark V and the Tung Sol is there to stay. If you're looking to "improve"/alter your Mark V's tone, I'd do some research on the Saturation Mod which is just changing the V4 and/or V6 preamp tubes to a 12AT7 (lower gain). This only changes channel 3, but I really liked the changes it made.
     
  8. TedEH

    TedEH Cromulent

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    +1 for Tung Sol. I've got one in the V1 of my IV and V:25.
     
  9. TheWarAgainstTime

    TheWarAgainstTime "TWAT" for short

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    Tung Sol is a good V1 tube, though I prefer an EHX since it has a bit more midrange and won't overdrive the clean channel as easily. The Tung Sol is pretty high gain and aggressive overall :2c:

    I still need to try a 12AT7 in the V4 spot of my Mark V one of these days :lol:
     
  10. LiveOVErdrive

    LiveOVErdrive CNC hack

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    I like 5751 in v1 and v4
     
  11. Voron

    Voron SS.org Regular

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    I used TAD for v1, was very cool, but now it's original mesa and there is not much of a difference :)
     

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