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RCA / Sylvanias ?

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by Mooncusser, Sep 30, 2006.

  1. Mooncusser

    Mooncusser Member

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    Hey all,

    Could anyone enlighten me as to thier own opinions on the dynamic differences between the RCA 12AX7A and the Sylvania 12AX7A?

    I appreciate the time,
    Mass
     
  2. uberpict

    uberpict Member

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    I can only compare the grey plate RCA's with square angled getter to the Sylvania long grey plate with halo getter (branded Baldwin), both late 50's early 60's. IMHO, the RCA has very good frequency response but can be a bit shrill in the highs. EQ'ing normally brings this down to a managable level. The RCA is great for cleans and for lower gain but not so great for high gain due to the potential shrillness.

    The Sylvania's are a very "hot" tube that usually read well above spec for transconductance which makes them more suitable for high gain but they aren't as clear and well defined as the RCA. I use an RCA in V1 with a Sylvania in V2 which seems to work well for both high gain and clean tones with the right EQ. Cleans are very chimey and bell like with the right guitar and high gain has lush harmonic content. Just my dos centos.
     
  3. rockon1

    rockon1 Member

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    RCA- long gray,short gray or black plate? Sylvania long gray,long black plate or short gray(less common)?OK, I imagine if your stating RCA 12AX7A then its the short grays. As far as the RCA short gray-In my JSX they seem to have less break up(less "fuzzy" distortion) than most and somewhat subdued highs(read not bright) Unlike uberpict I did not find them shrill at all. Good if your in the mood for a more clean sounding OD.As for the Sylvania long plates they do seem higher gain. They also seem less clear than most in my JSX. Ive yet to leave one in any of my amps. Thats my take on them YMMV-Bob
     
  4. Mooncusser

    Mooncusser Member

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    So I see there is a big +1 on the RCA's............
     
  5. uberpict

    uberpict Member

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    :jo Yeah, I should have stated long grey plate RCA, I have no experience with the short grey plate. The long grey plate isn't too shrill unless the treble is cranked and the guitar is Tele like, maple neck with hot pups. With the treble above 5 and driven by the bridge pup of a Tele it approaches earbleed territory, which may work for some in certain applications. I'm sure the combination would cut like a hot knife through butter in a mix heavy on snare and cymbals.

    With darker mahogany guitars the high end is quite usefull, brings out the highs and makes them very chimey and bell like, not shrill at all with these axes. As usual, YMMV, depending on your amp, guitars, speakers and the room you're in. They're not too expensive compared to Mullards and Telefunkens so you can buy a few to try out without breaking the bank. The RCA and Sylvania's are my favorite tubes but I've yet to try NOS Mullards or Telefunkens. FWIW and IMHO, the GE tubes I've tried are in between the RCA and Sylvania's, not as detailed as the RCA's but have better high gain detail than the Sylvania's.
     
  6. EXP

    EXP Supporting Member

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    the Sylvanias would be perfect for your Plexi IMO.
     
  7. Mooncusser

    Mooncusser Member

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    Right now I am running an RCA 12AX7A in my V1, A Tungsol RI 12AX7 in V2, and a EH (balanced tri's) in V3.
    Maybe I should give the Sylvania a shot in V1...never tried it yet. I keep hearing about an articulation loss with the Sylvanias, but I am willing to try anything for tone.
    I also have some Telefunkens,I am not sure how those would suit the Plexi though. I have heard mixed feelings on those. Some find them to High FI.
    I am also worried about becomming dependant on $50.00 preamps...:eek: LOL!!

    Take care and Peace,
    Mass
     
  8. rockon1

    rockon1 Member

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    It never hurts to try! Hell swap em all around,try the Sylvania and dont worry about balanced PI tubes!. The PI circuit isnt!:dude
     
  9. Mooncusser

    Mooncusser Member

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    Sounds like a plan!
    When I get a little time to mess around, I'll post what the greatest recipe seems to be.:AOK

    Take care,
    Mass
     

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