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Tube Confusion

Discussion in 'Amps and Cabs [BG]' started by rickbass, Aug 8, 2002.

  1. rickbass

    rickbass Supporting Member

    I have two amp heads with 12AX7's (probably Chinese or whichever is cheapest). The have worked reliably for countless hours at high volume, night after night. Ryder truck after Ryder truck, for over a year. But I want to replace them before I'm onstage and go through a melt down.

    My central question is;

    If you were going to replace these tubes, what would you use??? (I like a fat, Aguilar-type tone if that helps)

    I've heard/read - get rid of your 12AX7's and get 5751's - they are direct 12AX7 replacements that blow 12AX7's out of the box.

    I've also heard that the "tube in the preamp" deal is just bull from the 90's.

    I don't even know if a replacement tube would make a perceptible tonal difference. Then there's the whole "Russia"/"China"/"Czech"/"Pago Pago" factory thing.

    I'd very much appreciate hearing from any of you tone surgeons about what you might consider in the same situation!

    Thanks for any input!
  2. As reflected in my SWR the 5751 that I use
    has made a significant improvement.

    SWR SM400-S through Henry 8x8 & Goliath Jr. III.

    Real world test.

    For the past 3 years.


    Your amp, your speakers, your brain may vary.
  3. dougray


    Apr 16, 2002
    western maryland
    i was going to post a similar topic. i have a hartke3500 which has the sovtek12ax7 pre amp tube(which sounds good) i was wondering if i would hear any improvement if i was to replace it with a 12ax7"groovetube"? all my marshall buddies use groovetubes... plus i read that 5751's are a good tube(lower gain/more low end?) any info,thnx..:cool:
  4. rickbass

    rickbass Supporting Member

    Thanks very much Psycho and very much Donne!

    Donne - That reference you cited is one of the main reasons I've been so friggin' confused! That site has been my main reference and all the blather there caused me to put up this thread.
    Actually, I value your personal experience you described much more because you are a bassist.

    Psycho - Thanks very much for your input. I always consider you one of the "high priests" of tube tech at Talkbass. I may not always understand everything you explain but you always seem to be able to convey some aspects in plain English for tech dunces such as I.
  5. Hey, what does it hurt to try a Military Sylvania or a five star GE 5751?

    E-Bay sells 'em for $10 a pop.

    They are definitely built better.
  6. rickbass

    rickbass Supporting Member

    Thanks, Donne. Cost isn't a consideration because we're not talking megabucks. Shoot, if a $100 tube makes a difference, I'm there!
  7. Rick, different manufacturers utilize the single 12ax7 preamp tube in different ways. Many SWR owners (including myself) have found that changing out the tube will make a difference. Folks with amps from other makers have had little result. It's really a case of try it and see.

    Be advised that replacing a single preamp tube will NOT give you that "Aguilar" sound. Aguilar uses FOUR tubes in the preamp section of their hybrid amp.

    As far as the great "5751 vs 12AX7" debate goes, I take it with a grain of salt. Note that Joe of the tube lore page hates the sound of ALL 12ax7s and Kurt K in his original newsgroup post hated the sound of his 12AX7 equipped SWR.

    For myself, I love the sound of my SWR rig (9 years old at this point), but found myself attenuating the highs for my current style of playing. After way too much research, I took the advice of a local tube guy to try the current model EH 12AX7. It smoothed the highs and thickened the mids just a bit. Works for me, as always, your milage my vary. A search for 12ax7 in this forum will provide plenty of good reading.

    Good luck!
  8. rickbass

    rickbass Supporting Member

    Thanks for more enlightenment, Joe!

    It gets very confusing. One guy who writes up new NAMM products every year refers to the "tube in a preamp" thing as some sort of myth perpetrated in the `90's. Others, such as yourself, swear it's true.

    It would be cool to try out many to find that "right" one but, man, it could get expensive real quick especially with NOS!!!
  9. Yeah, you can spend hours reading up on it, then more hours and bucks searching for the magic tube. OTOH, you can pick up a 70's era military 5751 for $10-15 if you just want to get your feet wet.

    After just a bit of trying things, I ended up with a half dozen tubes and close to $90 bucks invested. I've tried to snipe up some of the 50's era milspec Sylvania 5751s, but last time I checked they were going for $60+.

    I finally talked to a local tube guru who asked me "Do you want a good tube or do you want a hobby?"
    He then seconded the recommendation of Lord Valve, current production EH or JJTesla 12AX7. I tried the EH and I've stopped looking. As I've said elsewhere, it works for me, your milage may vary.

    Hmmm, here's a thought. Most anybody who's gone through this ends up with tubes they are not going to use. Maybe we could put together a TB supporting member tube lending library so folks could try before they buy?
  10. jokerjkny


    Jan 19, 2002
    NY / NJ / PHL
    well, rick,

    tubes can only do so much. but they are fun to try, cause once you start hearing differences, it does become addictive and a hobby.

    5751's are, i think, tougher military versions of 12AX7's that were supposedly used for recon and spy missions ala british SAS. cool semi-backhistory, but the real deal is that bout 70% lower gain, built to take abuse in WWII wartime, and they've got lots of chimey detail ontop. So, its great for slap tones and for a dark sounding preamp. most NOS from Sylvania, JAN GE, JAN Philips, etc. sound great. NOS RCA Command series are supposedly the best.

    I've tried several 12AX7's and here's my take on 'em. a good place to start is Electro Harmonix's 12AX7. good, cheap, but sizzlin', gainy tube that's great for crunchy SVT tones. midrange is a little harsh, but again, great for that overdriven Ampeg.

    a step up, but within the same price range is JAN Philips 12AX7s. smoother gain, hot, not as sizzlin', but has a wider, more open soundstage than the more compressed and squashed EH, yet its the same price. i.e. its fatter sounding. has an ever so slight dip in the mids, but only enough to add a wide feel. my overall fav. i've got them in every single freakin' amp i own. problem is, so does everyone else, cause i've heard there might be a shortage soon, so get 'em before the price increase.

    a step from that is the more expensive JAN GE 12AX7's. very fat and gorgeous tone that's even smoother, and more "audiophile". nice open top end that's to die for, with a very wide and expansive sounding soundstage. BUT, this open feeling could be due to the mids being pretty attenuated. seriously, its quite a noticible dip. after swapping it into my Demeter, i had to jack the mids knob. Would tame that same rocker raging SVT into a smooth operatin' r&b amp, but could also render an Alembic even more in the midrange pits. so, make sure you know what sound your amp has, and use appropriately.

    if you want that famed $100 Mullard 12AX7 tube tone, but dont got the bucks, try the half price Mullard CV4004's. Mike at KCA sent these to me, and i love 'em! great open top, little compression, and good complex midrange. an all around awesome tube. but it's still $50 per tube. youch!

    good places to get tubes are www.tubestore.com and of course, Mike @ KCA NOS tubes, and lets not forget our good buddy, ChuckM who's got more tubes than his pre's can handle.

    sorta surprised no one talked about tubes specifically yet...

    Chuck? where you at?
  11. jokerjkny


    Jan 19, 2002
    NY / NJ / PHL
    btw, the "Russia" tubes you speak of are usually EH, some GT, Svetlana, and Sovtek. good all around brands made today where these companies merely pick out the good consistent tubes, but i still like my NOS.

    chinese tubes like Ruby tubes are ok, and some guys love them for their guitar amps, but those same guys complain about their lack of consistency, reliability, and spotty performance.
  12. bben


    Feb 28, 2002
    Santa Fe, NM
    After years of fooling around with NOS tubes I got tired of their unpredictability and high cost, so I tend to like tubes that are in actual production.

    I like the Tesla/JJ 12AX7s, and I also like Svetlana tubes. I have had good luck with tubes from Triode Electronics, and their website has good tube info as well.

    Check out: http://store.yahoo.com/triodeel/12axec7057.html
  13. seamus


    Feb 8, 2001
    Yeah, I've mentioned the EH12AX7 in several threads around here lately. It's a reasonably priced, low noise, good sounding tube. As always, YMMV.
    I'm not one to try to reinvent the wheel though, so if something works, I just go with it.
  14. rickbass

    rickbass Supporting Member

    Me neither, seamus. But like many of us, I always wonder if I'm missing out on a "rounder wheel" that gives me an edge over the guy playing at the club down the street. :D

    Just like cavity shielding in a bass, it's the stuff most people never see that makes me look suspiciously over my shoulder.
  15. seamus


    Feb 8, 2001
    Yeah I know what you mean, I wonder about trying different valves in my preamp as well. I've read a lot on the 12AX7 vs. 5751 debate, and I always wonder if I'm missing something as well.

    The reason I decided to settle on 12AX7's was for their overdrive capacity, and the EH tubes seems to do pretty well in that category. I'm guessing those who prefer the 5751's like a cleaner sound than I am using most of the time, as I almost always have at least some amount of drive dialed in.

    Plus I'm afraid of turning tube swapping into an expensive hobby, so I settled on something cheap. :)
  16. Actually you have it backwards.

    I use a 5751 because it overdrives earlier and EASIER then a 12AX7 and does so in a smoother manner.

    I always drive the preamp tube.

    The reality is most 12AX7's is harder to overdrive and sounds harsher.
  17. KB


    Jan 13, 2000
    Chapel Hill, NC
    I've been trying and swapping a lot of tubes in my SWR SM500. So far my favorite is the Jan Philips NOS 12AX7. With the EH (current model) being a close 2nd. I tried a Jan Philips 5751 NOS and really couldn't get into it. It seemed a lot "darker" to me (I guess I like more highs and upper mids) and not as broad tonally but YMMV.

    I'd be willing to sell the Jan Philips 5751 NOS to anyone who is interested for fairly cheap. Just PM or email if interested

    The stock GT Tube that came in the SM500 is nice and smooth, but it is almost too "smooth" as I would get lost in the band mix very easily and the lows did sound a little weird and restricted.
    I plan to try more (maybe another 5751 sometime like a GE 5 star, but so far I like the 12AX7 tubes better). My next tests may be the JJ/Tesla or an Ei, but for now the Jan Philips 12AX7 is what I've been using.

    I Do think it would be a good idea to get TBers together to have some tube swaps since some of us may have a few extra tubes laying around. I'd be willing to swap my Jan phillips NOS 5751 for a JJ/Tesla 12AX7, Ei 12AX7 or even a GE 5 star 5751 (to just check it out).

  18. ....talked to a local tube guru....
    No PBG, it was a fellow named Page at Midtown Music (the vintage amp and guitar store in Atlanta). Page is a guitar player, but seems pretty level headed nevertheless. He is/was seriously into the NOS thing. He told me that after years of searching, he finally had his old Fender Twin tweaked just right and now he has spare time on his hands he might even ........... practice! :D

    BTW, if you know anybody in the Atlanta area who is good at repairing old tube amps and wants to develope a business, Midtown Music is looking to provide space and some business.
  19. rickbass

    rickbass Supporting Member

    I get "ToneQuest Report"....but some of you guys are downright scary!!!

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