Mullard CV4024, nice!!

Discussion in 'Amps and Cabs' started by Bajan, Mar 4, 2006.

  1. Bajan

    Bajan Member

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    I just popped in a pair of Mullard CV4024s into the PI and reverb driver slots of my new (to me) Fargen Blackbird 40 combo and the improvement in tone over the JJs that were in there is quite noticeable. The amp sounded pretty damn good before but the Mullards seemed to open things up in the mids and gave better detail in the highs, the low end is nice and taught too. Going back to the JJ ECC 81s made the amp sound congested and a bit boomy by comparison. I have seen others say how much they liked these tubes and I just wanted to say that I do too. And thanks to KCA for getting them to me so quickly (2 days!). Oh, and the Fargen Blackbird 40 is a fantastic amp.

    Shane.
     
  2. stratovarius

    stratovarius Supporting Member

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  3. Chrissy

    Chrissy Member

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    Those Mullard 4024 seem to get on well with Fargens! Seegs and I both have 'em in our Fargen Dual Classics - I thoroughly agree, especially how sweet the whole tone got with 'em.

    Chris
     
  4. reaiken

    reaiken Member

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    In case anyone is interested, they are not good at all in the first preamp position of a Tomcat - they were so microphonic they were unusable with the gain boost switch on. In addition, they hummed and buzzed with a tube shield on (strangely enough, they didn't hum or buzz with the shield off - go figure).

    Now, granted, not too many amps use 12AT7s as the first preamp tube (although they sound fabulous in the right circuit), but the JJ ECC81's will stomp all over the Mullards in this application.

    The CV4024's are good for PIs as Shane and others noted.

    Randall Aiken
     
  5. GenoBluzGtr

    GenoBluzGtr Supporting Member

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    I have two in my Super Reverb Reissue... does wonders for the tone and the volume. I can get it up a notch or two higher and more into the best "tone zone" without pissing off the rest of the band. Tightened up the bass a great deal, which is a big improvement on Blackfaces, especially the reissues.
     
  6. Blue Strat

    Blue Strat Member

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    Like most 12aT7s (or other preamp tubes) some are more microphonic than others. The CV4024s seem to be no worse than other 12AT7s that I've tested (100s of).
     
  7. Blue Strat

    Blue Strat Member

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    Happy to help Shane. These are definitely the favorite 12AT7 for just about every application including high end audio.
     
  8. aleclee

    aleclee TGP Tech Wrangler Staff Member

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    That tube is the shiznit as the reverb driver in my Two Rock. :AOK
     
  9. bbarnard

    bbarnard Member

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    Or pretty much any reverb driver slot in most any amp. Equally great in my Super Champ reverb slot.
     
  10. reaiken

    reaiken Member

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    Pehaps so (although these were bought as specially tested for lowest microphonics), but the strange buzzy noises weren't exhibited by any other brand of tube. I suspect these have some internal construction that makes them more suspectible to filament-induced hum and noise, which, of course, won't show up in high-level stages like PI and reverb tube drivers. I still don't know why it showed up mainly with the shield on, though. That's truly bizarre.

    In addition, compared to the JJ ECC81s, the CV4024's sounded like they had a blanket over the speakers - very dull by comparison, without the top end "chime" of the JJs. It's funny, because I stopped using JJ ECC83s because they sounded dull and flat compared to the Chinese 12AX7s, but they are doing something right in the ECC81 that suits the Tomcat to a "T". :)

    Randall Aiken
     
  11. Blue Strat

    Blue Strat Member

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    That is bizarre about the hum/shield situation.

    BTW, kudos for being the first (that I know of) to use a 12AT7 in the first stage. I was wondering if we'd see more of that with the supply of NOS 12AX7s dwindling and since there seem to be plenty of NOS AT7s around. I guess it's less and less of an issue with better new production AX7s hitting the market.
     
  12. Bajan

    Bajan Member

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    Well this goes to show that there is no 'best' tube, it's what works well in which position in which amp etc: I have heard similar comments about the microphonic tendencies of the Mullard but it sure does seem to make a great PI in my Fargen. I also tried the new Tung Sol 12ax7 in the amp in place of the Electro Harmonix tubes in there now. Based on everyones comments I expected this tube to be brighter and sound real nice but to be honest I liked the EH better. I am using a humbucker guitar (Hamer Artist Korina) and it is almost like the Tung Sol has more gain but pushes the lows up a bit too much with the buckers and things get congested with them. Wierd, the opposite of what I expected out of these tubes but once agian it is the combination and interaction of all the parts that gives us our tone.

    Shane
     
  13. reaiken

    reaiken Member

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    Normally, I wouldn't make sweeping generalizations about microphonics and noise without testing a bunch of them, but these were pre-tested to be the lowest microphonics of the batch by a tube vendor I trust, so I feel certain they were the "pick of the litter". While I'm sure microphonics will vary greatly from tube to tube, the bizarre noise and "blanketed" tone was the same on each of the tubes I tried, so I feel sure it is inherent in the tube itself. I'll be the first to admit that I could be wrong about this, but based on the tone alone, I don't think this tube is suitable for a first-preamp tube in the Tomcat.

    Randall Aiken
     
  14. reaiken

    reaiken Member

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    I originally decided to use the 12AT7 because I wanted a very low impedance output on each of the tube stages to keep hum and noise pickup to a minimum, and I didn't need a whole lot of gain, but wanted a huge headroom to be able to really whomp the phase inverter.

    After finding out how difficult it was to get good low-microphonics 12AT7s, I tried redesigning for a 12AX7, but none of them had the "openness" of the ECC81/12AT7, so I had to just cherry-pick them. There's something very special lurking inside that tube when used as a first preamp tube with the proper plate and cathode resistors. It kind of reminds me of an EF86 sort of tone, which is strange, because the EF86 has an extremely high output impedance, so it should be completely different. It would be a perfect first tube for a clean or "vintage" gain level amp where the microphonics wouldn't bother you as much.

    Randall Aiken
     
  15. Roodboy

    Roodboy Supporting Member

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    The cv4024 also helps get more definintion in V1 of a high gain amp. I love it in the PI also.
     
  16. Timbre Wolf

    Timbre Wolf GoldMember Supporter Gold Supporting Member

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    I agree. I use a Mullard CV4024 in my Triaxis V2 (main input for cleans and Lead 2 channels). It provides amazing clarity, from solid lows, to open/airy highs, and helps increase the dynamic range in this notoriously compressed preamp. It makes a superb PI for my Mesa 20/20 power amp, too.

    Nothing but praise for this tube here! But I wouldn't use it indiscriminately...

    - T
     
  17. brad347

    brad347 Member

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    anyone notice a bright flash at the base near the pins of these when first applying power to the amp? I bought one for the PI in my Deluxe from Mike (KCA) a month or so ago and notice this. The tube seems to perform fine, but the improvement wasn't really all that dramatic over the old RCA 12AT7 that was in there. Is this bright flash on startup normal or a sign of a fault in the tube?
     
  18. hipfan

    hipfan Member

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    Flash = normal. Both of the ones I have (bought years ago from KCA) do this as well.
     
  19. brad347

    brad347 Member

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  20. Blue Strat

    Blue Strat Member

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    Flash is normal in European preamp tubes.
     

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