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Swapping the preamp tubes in my M-2000

Discussion in 'Amps and Cabs [BG]' started by Mad Subwoofer, Apr 30, 2002.

  1. My M-2000 sounds flat, boring and small. I haven't had a truly great tone from it in God knows how long. As a last resort I want to at least try swapping the 12AX7's in it (three of them.) I play lots of fat dub bass and push my tubes fairly hard with quite a bit of subsonic energy in the form of my various bass synths and filters. I have bought some GT's (12AX7R's) and was wondering what other tubes i should consider.....Mesa? I haven't tried the new tubes out yet. My GT's are Russian...what is the difference tone wise between them and a set of chinese tubes? I need a deeper tone overall; mine is just too "shallow." Folks seem to like Ruby?
  2. Try these... (NOS Mullard CV4004 (12AX7)) from KCA NOS Tubes. There site is at: http://users.erols.com/bluestat/

    This is the tubes description: British military spec'd version of the 12AX7 with box plates! Excellent guitar amp or audiophile tube (also great for bass heads). This is a sweet sounding tube which is in short supply. Some players prefer these to the Mullard ECC83/12AX7s!!! Also an excellent selection for audiophiles. These are more extended range than the Mullard ECC83/12AX7.

    This is a bass customers review: Hi Mike. Ward here. Thank you for recomending the cv4004 (12ax7) for my Sunn bass head. I changed tubes before band practice tonight and when we started playing the amp it intimidaded me in a way. That thing was kicking, but it was so cleen and had so much balls (for lack of a better word) it scared me at first.
    Thank you Mike!

    They ain't cheap... $50. ea... but they just might be worth it to you!
  3. Thanks...good tip. Geez..those folks are a' gushin' about those tubes eh? Har dto know when to take them seriously sometimes. At $50 a pop...What makes you think i should go with these instead of Ei 12AX7's (also sold as GT 7025.)
  4. TCollins


    Apr 4, 2000
    I have a M-2000 also. Let me know how you like your new tubes in your M-2000. My amp is fairly new and I won't need to change mine for a while-but it would be nice to know what tubes to try out.

    Many thanks!!
  5. Well Those Mullards sound the most promising so far. Check this link out;
  6. Steven Green

    Steven Green

    Jul 25, 2001
    Pacific NW
    The guy I bought my M-2000 from said he thought it sounded waay better in his opinion with 12AT7s rather than the 12AX7's...mellower, but better...I never tried this though...just a thought.
  7. OK, I've had a chance to try a whole whack of 12AX7's and found some very interesting results. If you folks are still out there I'll fill you in with an extensive review of the JAN 12AX7WA's, Ei 12AX7 (GT 7025) and the Sovtek 12AX7EH (Mesa) tubes that I tried in my M-2000.
  8. fast slapper

    fast slapper

    Dec 11, 2001
    Fresno, CA
    How are the EI's and Mesa tubes?
  9. Pre EB

    Pre EB

    Mar 15, 2002
    Denton, Tx
    Yeah- let us know! The M2000 was my dream head before I decided to do the Pre/power thing. I thought it very strange that ANY Boogie product would be disappointing; especially one that looks like the bridge from the Enterprise! I've still got the hots for a 400+, though:D I've got a bad case of the wants- I now want a Shifterkart too.
  10. the Sovtek 12AX7EH (Mesa) tubes actually sounded great. They added a lovely "snarl" to my M-2000 that was missing previously. They also had a rather throaty midrange that really stood out. I was all set to hat ethese bottles due to their itty-bitty plate design but they actually ended up as my favs. Crunchy.
    The Ei 12AX7's (GT 7025, silver plates) were probably my least favourite. They sounded fine but lacked the character of the EH's and the JAN's. Not as rich.
    The JAN 12AX7WA's were very nice with a smooth, round tone. They were deep with good upper-mid detail and maybe kinda "brown" or mellow. very rich tho' which was nice.
    I am now on the look out for three Sylvania 5751's to try and also three Sovtek LPS tubes so if anyone wants to swap for three brand-spankin' new Ei 12AX7's, let me know?
  11. mgmadian


    Feb 4, 2002
    Austin, TX
    NOTE: Thread resurrection in progress...

    Hey Mad SubWoofer,

    Did you ever experiment with the 5751's in your M2000? I swapped out the AX7's in my Kern preamp with 5751's, and really prefer the lower-gain 5751's: smoother, cleaner sound. Maybe a tiny bit less low-end when set flat, but the Kern still has tons of low-end with the 5751s, and is clearer overall.

    Anyway, I'm kicking around the idea of adding an M-2000 to the arsenal as it allows one to easily switch between tube and SS preamps. So I'm curious about your experiences here. Any insight appreciated.

  12. If you are into rack set-ups at all the M-2000 is one of the damn finest choices one could make (IMHO!) Why? Well, each of the switching options (channels, fx loop, both EQ's, etc..) have a dedicated 1/4" jack on the back that you could attatch to say your GCX MIDI rack switcher; too great! a teerrific design with features up the yin-yang but ultimately a headache for me I am sorry to say. All those buttons...switches...features and rarely did I ever find a sound that really worked for me. Not the amps fault I now know as it is geared towards that "aggressive" style (funk, metal) not the deeep low end booty shaker stuff I needed. My new F-1X has just about 0 features and sounds 10x better, for me at least.
    I actually ended up really digging the Mesa labelled Sovtek EH tubes for their midrange snarl and toothy growl. Maybe the preamp is designed to get the most from that tube, i dunno. 5751's I did try and they were very smooth and a tad on the darker side. I think they would be best in like an SWR or similar "harsh" sounding (too my ears) rig that needed mellowing out.

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