Potentially Stupid Tube Question

Discussion in 'Amps and Cabs' started by stevel, May 29, 2008.

  1. stevel

    stevel Member

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    I've found some charts online that describe the output differences between preamp tubes

    12AX7 100 percent, AT, AU, AY varying degrees less, etc.

    But, do these tubes also have an affect on the tone as well? Make it brighter, warmer, fatter, rounder, etc?

    If so, anyone care to list characteristics (or point to a good source). I realize that there's going to be variation among manufacturers and even production runs, but any generalities are good.

    TIA,
    Steve
     
  2. SatelliteAmps

    SatelliteAmps Member

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    It's not a percentage, but a gain factor.

    How the different tubes change in a specific amplifier really depends on the amp, and the actual tube. Some amps really respond to different types, and others don't. It's a very difficult thing to make specific generalizations about these things.
     
  3. Blue Strat

    Blue Strat Member

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    What Adam said.

    One brand of 12AY7 may sound slightly different than another brand, just as with 12AX7s.

    No generalizations can be made...in general. This is something that everyone has to experience for themselves in their particular application.
     
  4. stevel

    stevel Member

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    Darn it all.

    Ok, more money falling out of pockets...

    Steve
     
  5. rockon1

    rockon1 Member

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    Tell me about it!....argh! lol! Bob

    [​IMG]
     
  6. Guinness Lad

    Guinness Lad Silver Supporting Member

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    I think of tubes like guitar string brands, they all sound like strings but are slightly different tonally. If the gain factor is the same this is what you will notice the most but some tubes work better with effects then others. I was using some 12ax7s with a overdrive pedal and one type would compress a lot when gain was added while the other seemed to not do it as much and got a little louder still (more headroom?)

    Lower gained tubes are good for when you want the preamp to stay clean, this is good for amps that tend to run a hot preamp signal. By using a lower gained preamp tube many times you can get the amp to be clean for a longer time, typical applications are tweed deluxes and bassmans.

    The opposite can also be done with blackface amps, since they use a 12at7 in the phase inverter I have found I can get a little more sparkle/hair on the tone if I put a 12ax7 there, I lose the crystal clear clean, but I don't like that anyway.
     

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