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Valve (tube) compatibility

Discussion in 'Amps and Cabs [BG]' started by Jeff Moote, Dec 24, 2001.


  1. Jeff Moote

    Jeff Moote Supporting Member

    Oct 11, 2001
    Beamsville, ON, Canada
    I tried searching for my answer, with no avail so...

    My question is if a preamp has a number or 12AX7 valves, and I want to replace them with an alternative for a different sound, can I have say some 12AX7s and some 5751s? I think that this is possible, but you couldn't "mix and match" like this with power amp valves.

    thanks, MP :)
     
  2. I believe you can mix & match all the twin triodes. 12AX7, 12AU7, 12AT7, 5751, 7025, ECC83.

    There are more, but if they have the same purpose, the mini tubes can.

    As a rule, power tubes (valves) NO. There are exceptions.
     
  3. Jeff Moote

    Jeff Moote Supporting Member

    Oct 11, 2001
    Beamsville, ON, Canada
    Thanks, that's what I was looking for.
     
  4. Bass18

    Bass18 Guest

    Jul 21, 2001
    Australia
    arrrgghhh!!! VALVES!! Thats guitar talk! Quarantine this man immediately!
     
  5. Tapp

    Tapp

    Aug 29, 2001
    USA, Mississippi
    Actually Bass18, you'll notice that Monty is from Canada; they usually use the British nomenclature for tubes which is the "valve". Actually USA uses "tubes" for an asthetic description whereas the british use "valve" as a functional description. Valves/tubes are current "chokers" among other things which is where the term valve comes from.

    Monty, I would not stray very far from the 12AX7 type tube since the designers of the amp/pre probably had this in mind. I would try the 5751 if you just want to try something different since some TB'ers have had good/different results with this type.

    Tapp
     
  6. Jeff Moote

    Jeff Moote Supporting Member

    Oct 11, 2001
    Beamsville, ON, Canada
    Thanks, I was considdering in an Ampeg SVP-pro (5 tubes) I would do this:

    1st and 2nd gain stage tubes: 5751s
    3rd: 12AX7
    4th and 5th: 12AU7s

    Thus hopefully achieving a neat variety of clean and overdriven sounds.

    Sounds good? Thanks for the help, MP
     
  7. Tapp

    Tapp

    Aug 29, 2001
    USA, Mississippi
    Monty, that sounds fine but for the 4th & 5th positions I would try a 12AT7 first. The AU7 will give much lower mu(amplification factor/gain) and will draw more current. I'm not real familiar with the Ampeg pre's but I don't think it would hurt to try either one.

    Tapp
     
  8. Jeff Moote

    Jeff Moote Supporting Member

    Oct 11, 2001
    Beamsville, ON, Canada
    Cool, thanks.
     
  9. Bass18

    Bass18 Guest

    Jul 21, 2001
    Australia
    Well you learn something everyday...
     
  10. I think that is a bit wrong... I am from Canada and believe me tube is far more common than valve to describe such items..


    later


    Drake