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Replacing CAD Tube with GT or NOS

Discussion in 'Pro Audio Equipment' started by MigrantRecords, Jul 1, 2005.

  1. Again I can't find the referring topic, but I read on here that a user replaced the tube in his CAD mic with a nice Groove Tubes tube, and that he was saving up for a Telefunken NOS.

    Is this wise? Is it worth it? I have a CAD VSM-1, and I like it a lot, but if replacing the stock tube means that I have a vastly improved mic, I'll spend $50-75 to do it.

    For that matter, is that a good practice all around? If I have mid-level tube preamps, would it be good to replace their tubes with better ones? Mostly, I need to know about the CAD mic, however. I'd like any and all relevant opinions, please.

    Thanks in advance,

    Fred auf der Rockwells
    Migrant Records
  2. sdelsolray

    sdelsolray Active Member

    I have a CAD VX2, which shares a similar head amp design with the VSM. In addition, the capsule used in the VSM is identical to one of the two capsules that comes with a VX2. What is clearly different is the output area of the two mics, the VSM having solid state, and the VX2 have another tube stage using a pair of nickel wound output transformers.

    I changed the two tubes in my VX2. The head amp uses a 12AX7 (so does the VSM). I chose a Valvo NOS tube made by Siemens. I also swapped out the 12AU7 output/line driver tube for a Telefunken smooth plate.

    There's a noticable difference in the sound of the VX2 now, for the better. It's a bit smoother (it's very smooth to begin with) and a bit tighter in the lower mids. All in all, the differences are subtle at best, but I like it better with the NOS tubes.

    Hope that helps.
  3. CoyoteTrax

    CoyoteTrax Well-Known Member

    I don't think you can lose with the JAN-Sylvania fi you're willing to pop a little coin.

    It's cheap enough to go to a JAN-Philips or one of my faves, the Tesla/JJ ECC83S.

    http://tubestore.com/ (good info. and good vendor here )
  4. TornadoTed

    TornadoTed Guest

    I don't know much about valves. I know that my AKG Solidtube has a ECC 83 (12AX7) tube from their website. Can you replace this with any model with 12AX7 or ECC83 in the model number? ie a Electro-Harmonix 12AX7-EH, a JAN-Philips 12AT7WC or a Tesla (JJ) ECC83-S / 12AX7 or is not that simple.
  5. TornadoTed

    TornadoTed Guest

    Shows what I know :roll: the JAN-Philips I mentioned below is a 12AT7 and not a 12AX7, what's the difference?
  6. CoyoteTrax

    CoyoteTrax Well-Known Member

    The differences are subtle but they are all what you call a 12AX7 "type" tube.

    These guys explain it a lot better than I can.

  7. jonyoung

    jonyoung Well-Known Member

    Great descriptions of the various models and variations found at http://www.vacuumtubes.com also. Go to the 12AX7 page. Anything labeled for "microphonics" is suitable. BTW, for the mid level pre upgrades, see if you can find a 12DF7. Gain factor of 70 (harder to clip on transients) and warm as your momma's lap :D
  8. moonbaby

    moonbaby Mmmmmm Well-Known Member

    A 12AT7 is a similar tube to the 12AX7, but with less gain. While the operating voltages of some mics let you play with tube choices, I don't know that the SolidTube does. A tube with less gain can, in some mics, sound better for the reasons that Jonyoung stated.
    BTW, I have heard rumours that the tube in a SolidTube was actually soldered into place! Is that true?
  9. Guys,

    This info kicks ass. Thanks so much for steering me in the right direction.

    Take care,

    Fred auf der Rockwells
    Migrant Records
  10. TornadoTed

    TornadoTed Guest

    I've never taken the mic apart Moonbaby but I will have a look to see if it is soldered and get back to you.

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