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Low microphonics 12ax7 for V1 use?

Discussion in 'Glowing Bottle Tube Amp Forum' started by beyer160, Aug 8, 2017.

  1. beyer160

    beyer160 Tele-Holic

    911
    Aug 11, 2010
    On Location
    I've been fooling around with my VHT "Standard 12" 5e3 clone, and it REALLY exacerbates any microphonics in the V1 tube. The best one I have is the Chinese 12ax7 it shipped with, which isn't bad but it rings a little when you have it running flat-out (and it's a 5e3, so I do that a lot). I don't want to drop big bucks on NOS, is there a reasonably priced new production 12ax7 that is known to be resistant to microphonics?
     

  2. Axis29

    Axis29 Poster Extraordinaire Ad Free Member

    Jan 2, 2007
    Virginia, USA
    I have had good luck with GTs, EHs, JJs and Tung Sols. They may not always sound the best, but for the most part they've been sturdy.
     

  3. Dacious

    Dacious Friend of Leo's

    Mar 16, 2003
    Godzone
    Sovtek 12AX7LPS - 'long plate spiral' filament, meant to be quiet. The 12AX7B is meant to be selected for low noise, too. Mesa SPX also 'special selected' although I think they're JJ which most people don't seem to highly regard in V1
     

  4. slider313

    slider313 Tele-Holic

    Age:
    60
    916
    Jan 6, 2011
    NC
    If you're comfortable working on a live amp; try moving the wires connected to V1. Sometimes the placement, or lifting off the chassis, of certain wires will lessen or rid the amp of microphonics. Use a plastic or wooded probe to do this. ;-)
     

  5. Televised

    Televised Friend of Leo's

    Apr 26, 2009
    Portland, OR
    All of the above is correct and also did good with a Mullard RI.
     
    Axis29 likes this.

  6. corliss1

    corliss1 Tele-Afflicted Gold Supporter

    Sep 13, 2008
    Lansing, MI
    TubeDepot (no affiliation, etc) has a "low noise/microphonics" option on their preamp tubes that I've found very useful.
     

  7. JD0x0

    JD0x0 Friend of Leo's

    Age:
    27
    Feb 22, 2009
    New York
    LPS= LONG PLATE spiral

    Longer plate = More gain and potential for microphonics.

    From the tube store on the Sovtek LPS
    The tube store on JJ ECC803s (long plate)

    OP- Look at the lead dress on the tubes in the amp. The lead dress can affect microphonics greatly. Also, sometimes the tube shield causes microphonics. I ran into that issue on my Hiwatt.
     

  8. Dacious

    Dacious Friend of Leo's

    Mar 16, 2003
    Godzone

    Oops you're right. I was thinking noise not microohonics for some reason.... Not enough coffee today.
     

  9. theprofessor

    theprofessor Tele-Afflicted

    Aug 8, 2016
    Chattanooga, TN
    TAD (Tube Amp Doctor) sells rebranded Chinese (Shuguang) tubes that have been tested and labeled for low microphonics and so forth. They're not too dear. For example, the 7025 is the classic "hi fi" low noise tube. I think their 7025 WA would be their best. Check out their website.

    There's also PM tubes, which are another line of rebranded Chinese tubes. They're even less expensive than TAD's. In the US, they can be acquired through Tube Boutique: https://www.tubeboutique.com/preamp/
     

  10. beyer160

    beyer160 Tele-Holic

    911
    Aug 11, 2010
    On Location
    Thanks for the responses! I can't believe I didn't think of adjusting the lead dress, I'll give that a shot first.
     
    asnarski, jtcnj and slider313 like this.

  11. waparker4

    waparker4 Doctor of Teleocity Ad Free Member

    Nov 9, 2011
    Philadelphia, PA
    +1 on the TAD 7025wa

    After looking for issues with the lead dress.
     
    MilwMark likes this.

  12. Are you dead set on a 12ax7 at V1? 5E3 "normally" uses a 12ay7 at V1, not that the lower gain tube can't be microphonic.
     
    jtcnj likes this.

  13. Guitarteach

    Guitarteach Poster Extraordinaire

    Aug 6, 2014
    UK
    Avoid the long plate Mullard and Mullard style designs. I've had microphonic issues with those.

    Tung Sols seem quietest of the bunch of new cheap tubes but the glass on those can be chunky and not fit the can if the amp has one on V1.

    As mentioned above Mesa do a selected SPax7 low microphonic tube esp. for V1 in high gain amps. I quite like Mesa tubes even if they are JJ/Chinese these days. Even the standard ones don't get microphonic in my high gain Boogie.

    IMG_3848.JPG

    I think the rubber jacket is largely cosmetic but it might do something
     

  14. jtcnj

    jtcnj Tele-Meister

    Age:
    53
    353
    Feb 2, 2015
    Brick, N.J. USA
    I prefer the 12ay7 at v1 as well.
     
    Viejo likes this.

  15. DaveKS

    DaveKS Friend of Leo's

    Oct 21, 2013
    KS
    ++ on TAD 7025wa, their short plates and also slightly lower gain than most 12ax7 types which means less noise and subsequently less prone to microphonics.

    Hunt around though and you might find a ANOS GE 5751for $10-15 more, that's what they were designed and built for, low noise and microphonics in military communications use. Many ruggedized with extra support rods and extra thick mica to withstand vibration, one of main causes of tubes going microphonic in combo amps. Go for the short plates.
     
    MilwMark and Archtop Bill like this.

  16. Kevin Wolfe

    Kevin Wolfe TDPRI Member

    Age:
    59
    6
    Jun 13, 2017
    Lakeland FL
    Been using a 5751 "low noise" option from t-depot in V1 and love it!
     

  17. MilwMark

    MilwMark Poster Extraordinaire Ad Free Member

    Apr 29, 2013
    near Arnold's
    Another happy TAD 7025wa guy here. They go in all my amps.
     

  18. Silverface

    Silverface Poster Extraordinaire Ad Free Member

    Age:
    65
    Mar 2, 2003
    Lawndale CA
    ^^ This.

    I don't care for 12AX7's in 5E3's - or most tweeds - in the V1 position. Much harder to control and a thinner type of sound to my ears. The interactivity of the controls also becomes far less useful - you can't fatten up the sound the same way.
     
    Commodore 64 and ocduff like this.

  19. jclute

    jclute TDPRI Member

    27
    Jan 5, 2017
    Atlanta, Georgia
    I also have the VHT 5e3 clone. I changed out all the tubes except rectifier for tung sol. When I first got it I noticed a lot of noise. I think the tube change helped but I've made so many mods it could of been something else.

    I haven't tried a 12ay7 in V1 but would like to. The VHT has a pretty high negative feedback resistor on the bright channel of v1 so this helps tame the gain some.
     

  20. beyer160

    beyer160 Tele-Holic

    911
    Aug 11, 2010
    On Location
    I tried a 12AY7 and it just didn't give me enough dirt... I'm a Neil Young fan, after all. My amp's got a Celestion G12H, so it's definitely not thin with the 12AX7. The "sweet spot" on the volume controls is a bit narrow, but I have no trouble getting there.

    I've been traveling a lot, but I hope to get into the back of the amp with a chopstick to play around with the leads soon.
     

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