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Mesa 400+: clean preamp tubes?

Discussion in 'Amps and Cabs [BG]' started by Chef, Jun 15, 2005.


  1. Chef

    Chef Moderator Staff Member Supporting Member

    May 23, 2004
    Columbia MO
    Staff Reviewer; Bass Gear Magazine
    I have a Mesa 400+ that I liked a lot for electric bass. It has new Ruby power tubes in it, dunno what preamp tubes are in it. I can check and report back...I'm now playing primarily upright, and wish the Mesa were cleaner. Is it possible to swap in cleaner preamp tubes and clean up my mesa? Alternatively, I've been using an eden navigator with a qsc/plx power amp that I like a lot. The Eden has a single preamp tube, and while solid state, it is definitely not "sterile and hifi."
    Can you guys help me find cleaner preamp tubes for my Mesa?
     
  2. tombowlus

    tombowlus If it sounds good, it is good Gold Supporting Member

    Apr 3, 2003
    North central Ohio
    Editor-in-Chief, Bass Gear Magazine
    I have the Mesa Strategy 400, which is a stereo amp using six 6L6's (or four 6L6's and two EL34's) per channel. Each channel has two preamp "driver" tubes. After much debate, I tubed mine with JJ's all around (pre and power) on one channel for my "cleaner" sounding channel, and EH pre and power tubes on the other channel, for a slightly more "agressive" sound.

    Of the new preamp tubes available, I tend to think of JJ's as being fairly "clean" sounding. What do you have in there now? In the NOS field, you have tons of great options, but I'd try Telefunken (smooth or ribbed plate), if you go the NOS route.

    Tom.

    P.S.
    I am hoping to do a fairly massive preamp tube "shootout" here fairly soon, so keep an eye on my blog (and here on TB, too).
     
  3. mgmadian

    mgmadian

    Feb 4, 2002
    Austin, TX
    You could also try putting in some 5751s, which have a little lower gain. I actually haven't tried them in my 400+ yet, but really liked the sound of (Sovtek) 5751s in my Kern.
     
  4. lo-freq

    lo-freq aka UFO

    Jan 19, 2003
    The Republic of Texas
    I get a very good clean sound from my Dem 201S with Jan Philips 12AX7WA & Sylvania 7025 (essentially the same tube design & sonicly indestinguishable).
     
  5. Chef

    Chef Moderator Staff Member Supporting Member

    May 23, 2004
    Columbia MO
    Staff Reviewer; Bass Gear Magazine
    From Bob at Eurotubes:
    Ruby tubes are mainly chinese and some russian tubes so I can't say that you will ever get a great clean tone from them. You can replace the four 12AX7's with ECC81's ( 12AT7's ) which will clean up the front end.
    Your Mesa 400+ uses a matched set of twelve 6L6's and for the cleanest and warmest tone I would match up a set of 12 of the JJ 6L6GC's in a grade #35 which would give maximum headroom.
     
  6. Chef

    Chef Moderator Staff Member Supporting Member

    May 23, 2004
    Columbia MO
    Staff Reviewer; Bass Gear Magazine
    bump for more info...PsychoBassGuy, you out there?
     
  7. thejohnkim

    thejohnkim

    Sep 30, 2003
    NYC
    i also think it might behoove you to check out some 5751's if you want a more focused/tighter tone than 12ax7's, they drop right in. 12ax7's generally have a slower attack and can get more "loose" and break up easier to my ears.
     
  8. tombowlus

    tombowlus If it sounds good, it is good Gold Supporting Member

    Apr 3, 2003
    North central Ohio
    Editor-in-Chief, Bass Gear Magazine
    This sounds like good advice to me, although I would also try the 5751's first. I think that the 12AT7's are reduced gain from a 12AX7, while the 5751's should be right about the same. But the JJ 6L6GC's really are a nice, clean tube with full, yet fairly tight, lows - at least that's how they have sounded in my amps.
     
  9. Hi Chef
    I've done some tube changing when I had both my 400+ amps. I found the pre tubes to be a bit touchy in these amps. NOTE: Looking from the front and top off the far left pre tube is the "master" tube an the others are for tone etc. I had some real bad luck with the LPS Sovteks but I think it was a bad run, they just kept crapping out. I finally put the Mesa brand (what ever they are) back in and consentrated on the power section. I ended up with 3 quads of Svetlana 6L6GC tubes all matched at around 27mv. They were very nice and clean with Electric bass. Just a note the 5751 are good but at around 30% less gain which is not a bad thing to work with. I really have no experience with DB applications. I do like JJ 12ax7 in my Demeter201s and also NOS Telefunken smooth Black Plates in that preamp.
     
  10. Chef

    Chef Moderator Staff Member Supporting Member

    May 23, 2004
    Columbia MO
    Staff Reviewer; Bass Gear Magazine
    Now we're getting somewhere;)

    While I don't need I-amp800 sterility, I do need to at least be able to match my Eden Navigator pre for the Mesa to continue to be usable for me as a doubling amp...

    I think the pre's are the answer, and I may try changing them first. This was the answer in making my 1965 bassman amp wiork, which by the way makes a ptretty fine db amp with 12au7's in the pre-stage. NOS Sylvania 6L6's in the power section...Clean, full, round...nice;)