Genz Benz GBE1200 Tube swap

Discussion in 'Amps and Cabs [BG]' started by LowEndWooly, Jan 27, 2014.

  1. So, I went from a streamliner 600 paired with two aggie gs 112's to the GBE1200 paired with an Aggie GS 412. Love the headroom and sound dispersion.. but I think the tubes in it could be swapped for something a little better.*

    I play anything from Motown to RHCP style bass. I (hesitantly admit) like the mid scoop sound. I don't scoop much, because I still enjoy being heard in a band setting, but it is slightly scooped, especially if I get to a slap riff.

    Any suggestions, or should I leave the tubes alone?

    *I know very little to nothing about tubes, other than they can change the character of the sound
  2. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa, Product Support-Genz Benz
    The difference between the Streamliner and the GBE is pretty large because they have a vastly different architecture. Changing the tube will result in a very small difference by comparison.
  3. The 1200 isn't so largely affected by it's single pre amp tube
  4. So.. waste of time, pretty much? I'm not necessarily trying to get the streamliner sound.. I was just stating that I played that previously. I'm more interested in getting a "better" sound (I know, subjective).
  5. Selta


    Feb 6, 2002
    Pacific Northwet
    Total fanboi of: Fractal Audio, AudiKinesis Cabs, Dingwall basses
    IMO, tube rolling in pres isn't generally worth it. Unless you change to a drastically different tube, but even then mostly you're just messing with gain changes more than adding in or removing inherent EQ (granted, you'll change the overall feel of an amp with this, but it's tonal characteristic will still be there, IMO). Give it a whirl if you want to see if you hear anything, as som people seem to. To me, not worth it though.
  6. Thanks, guys. This was good info..

    I think I'm gonna try to trade this up for an Aguilar DB 751.
  7. TheRealKong


    Mar 17, 2011
    Yes, some people do hear a difference when swaping tubes.

    As preamp-tubes are not that expensive I would give it a try. Maybe you find a tube that fives you a more warm sound on the tube-preamp of the GBE 1200.

    There was no need to open up my GBE until now, not a bad sign at all btw, so please help me out: That kind of tube is there?

    I like the sound of my GBE 1200 as it is, I will not swap tubes unless the original will show some issues. I don't think it will, because preamp tubes are known to last long.

    Just for your information, here is a link to a so called tube-map of the German tube-specialist TubeTown. It describes the behaviour of different tube brands and types.
  8. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa, Product Support-Genz Benz
    Tube behaviors depend greatly on the specific circuits they are used in. Many comments on tube's sound make assumptions that are not always accurate.
  9. that tube chart is crazy awesome. Thanks.
  10. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa, Product Support-Genz Benz
    ...and only as accurate as the specific circuit that the OPINION was developed from.
    TheRealKong likes this.
  11. Sure. But from the standpoint of knowing diddly, it WAS awesome.

    I bought this tube to swap. Read some reviews, thought it would be cool to try out. I'll let you guys know as it comes in.
  12. wcriley


    Apr 5, 2010
    Western PA
    From my experience:

    I swapped various new and old 12AX7s in a very simple circuit similar to a vintage Fender Champ and I heard huge differences in "sound".
    Swapped the same tubes in a modern "high gain" guitar amp and the differences (if they existed at all) were so small they definitely wouldn't have been noticeable in a full band setting.
  13. So, I've documented the tube swap, because I thought it would be cool.

    Attached Files:

  14. The guts inside the GBE 1200

    Attached Files:

  15. The preamp tube and comparison. Looks like the original preamp tube is a Ruby Select 12AX7, which is marketed as being a lower gain tube

    Attached Files:

  16. here is a description of the JJ tube from one of the amazon reviewers:

    "This is my favorite preamp tube. Imagine if a NOS RCA 12ax7 and a Telefunken Smooth plate made love. This would be that love child. Totally smooth and rich sweet tone. Gain is full and robust but not overpowering. Highs are sweet and super dynamic, mids are strong, lows are deep and bassy. Like I said - Mother Of All 12ax7s!"
  17. LowEZ


    Mar 29, 2011
    Central NJ
    I tried a bunch of different 12ax7's in my GBE 750. I settled on an old Amperex. The new production Tung Sol was really good for a $12 tube too. I'm not much a fan of JJ's preamp tubes - I had poor results in guitar amps so I never consider them. Keep in mind that you'll notice a very, very subtle difference in the GBE. There's a lot in there shaping the tone besides that lone 12ax7.
  18. Thanks, LowEZ. The JJ tube sure looks pretty, anyway. I haven't had a chance to turn it on, yet.. but I will.

    I actually like the looking into the guts, and I'll probably leave the top off for practice so I can see that pretty tube light up.
  19. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa, Product Support-Genz Benz
    All those descriptions of tube character are IMO absurd. But, they appear to sell tubes now, don't they?
  20. svtb15

    svtb15 Commercial User

    Mar 22, 2004
    Austin,TX - McKinney,TX - NY,NY, - Nashville,TN
    I play it all. Whatever works for the gig
    I dont wish to be argumentative... But Honestly .. I have tried and tried to hear a noticeable difference in tube swaps that i have done.. I really wanted to hear a difference too... I honestly have to say that i cant tell the difference in most situations.. And my ears are good according to my audiologist.. Ive used protection for 30+ years... I can hear an ant pass gas.. I can hear gain changes form a 12ax7 to a 5571 or 12au.. microphonics , yes...but not tonalities.. Im thinking some of the time it what people wish to hear... sp they hear it.... just sayin
    But what ever makes peoples boats float ...