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preamp tube tone characters

Discussion in 'Amps and Cabs [BG]' started by tom once dead, Oct 2, 2008.


  1. I have a question, Do different pre amp tubes have different tonal characteristics?

    my head has an ecc83 at the moment, But I think its a bit mid scooped. Is there a different tube that is less scooped?
     
  2. jeff62

    jeff62 Supporting Member

    Oct 24, 2005
    Orlando, FL
    Time to use the search function. Lots of info available on 12AX7's and what people think about them. This link is helpful too: http://thetubestore.com/12ax7review.html

    The ECC83 is equivalent to the 12AX7
     
  3. bongomania

    bongomania Gold Supporting Member Commercial User

    Oct 17, 2005
    PDX, OR
    owner, OVNIFX and OVNILabs
    Not really, not in a predictable, reliable way; and I'll even say not a very significant way, although others will disagree.

    Different tubes can sound different, but (a) in some tube preamps there is no audible difference, and (b) in the ones where there is an audible difference my experience is that it's kind of a crapshoot what sort of tone you'll get; and it's usually a pretty subtle difference in any case.

    While I can't state this as a "fact", I suspect that it's not the tube in your preamp that's mid-scooped, but rather the design of the preamp- in which case changing tubes won't help.
     
  4. so replacing a tube, wont chance your tone dramatically, if at all?
     
  5. IMO not dramatically. Perhaps a little- need to experiment-Luckily here, pre amp tubes are pretty cheap. I put some Good old Philips 12AX7's in my Ampeg V4BH & while the actual tone didn't change much at all, the tone of the OVERDRIVE it gave when pushed was pretty different! Far smoother than the stock SOVTEK 12AX7
     
  6. It depends on the pre-amp. My Traynor yba-200-2 has a hot aggressive pre-amp. You can replace the 12ax7's with 12au7's and tame it down. But, switching brands of 12ax7's probably won't make much difference. I'm swapping out the 12ax7 in my Shuttle 6.0 with a jj ecc83 in hopes it will tame down the mids a bit but, it may make no difference at all. So, the answer is maybe :)
     
  7. Bassmec

    Bassmec

    May 9, 2008
    Ipswich UK
    Proprietor Springvale Studios
    The JJ and the original tube where probably both made at the same factory then.
    Now a Mullard ECC83 a Brimar or even into the relms of rare Mil spec valves like the STC CV 4004.
    Then you will hear a marked difference assuming we are discussing proper HT vale pre amp circuits and not the usual starved plate rubbish
    we seem to have today.
    What's the plate voltage?:ninja:
     
  8. As I said earlier, I want the mids to be more prominant.

    but looking at the manaul about the mid voicing, all of the voices are something, with a mid scoop, even the "attack" type of mid voice still says somthing like "an overall mid boost for more attack, with a deeper mid scoop. So the pre is supposed to be scooped, I guess a change in brands could have a bit of a difference.
     
  9. bongomania

    bongomania Gold Supporting Member Commercial User

    Oct 17, 2005
    PDX, OR
    owner, OVNIFX and OVNILabs
    Yeah, that's as I suspected. A lot of preamps that are marketed to slappers and other "modern" players have a mid-scoop built in, even when the EQ knobs are set "flat". And even among ones that aren't necessarily scooped, many use the "Fender tone stack" for EQ controls, and it's not obvious to first-time users that the "noon" setting is not flat on those knobs, so they inadvertently scoop their mids by leaving the mids knob at noon.
     
  10. Thank god for my sansamp...
     

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