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Matching pre-head QSC PLX2402 and fx-1

Discussion in 'Amps and Cabs [BG]' started by pedroims, Apr 6, 2009.


  1. pedroims

    pedroims

    Dec 19, 2007
    Michigan
    I read Bongomania thread about matching pre and power head, but still have a question, currently I have a QSC PLX4202 with an input sensivity of 1.5 Vrms @8ohms and 1.3 Vrms @ 4ohms, and I want to add a pre amp, will an Alembic FX-1 drive this head? I could not find the specs for the FX-1.

    Really appreciate your comments, this is my first time buying a preamp.

    My other options are DB689 or a Demeter.
     
  2. pedroims

    pedroims

    Dec 19, 2007
    Michigan
    Anyone?
     
  3. They all should do well, I run an Aguilar DB680 into a QSC PLX 3102 and sometimes, an Ampeg SVT IIP, with no problems.
    The preamps you mention all have enough output to match the input sensitivity of the QSC.
    Just one question....a PLX 4202? Are you trying to start a black hole?:bassist:
     
  4. pedroims

    pedroims

    Dec 19, 2007
    Michigan
    Thanks !!

    actually is a 2402 but I bet there are some crazy guys around that will be happy with a 4202 giving 20,000 @ 4ohms :D
     
  5. bongomania

    bongomania Gold Supporting Member Commercial User

    Oct 17, 2005
    PDX, OR
    owner, OVNIFX and OVNILabs
    Just for clarity, and no offense intended to wonkey, but he does not say he actually knows what the output voltage rating of the Alembic is. ;) Then again, neither do I.
     
  6. Mo'Phat

    Mo'Phat Supporting Member

    Oct 1, 2003
    San Diego, CA, USA
    I would assume that most rack mount pre's have plenty of voltage to drive a power amp sufficiently. It's those little tabletop ones that are normally used in-studio that I'd think you should be concerned with.
     
  7. bongomania

    bongomania Gold Supporting Member Commercial User

    Oct 17, 2005
    PDX, OR
    owner, OVNIFX and OVNILabs
    That would be an incorrect assumption.
     
  8. Mo'Phat

    Mo'Phat Supporting Member

    Oct 1, 2003
    San Diego, CA, USA
    So MOST don't have plenty of voltage to drive a power amp sufficiently?

    Not trying to start a pissing contest, but I didn't say 'all'. Where is my assumption wrong?
     
  9. bongomania

    bongomania Gold Supporting Member Commercial User

    Oct 17, 2005
    PDX, OR
    owner, OVNIFX and OVNILabs
    Your assumption is wrong because there is not just one sensitivity rating for "a power amp". They can typically be anywhere from .7V to 1.5V. Rackmount preamps may be capable of anything from .5V to 12V or higher. A pre that puts out an average of .7V (very common, especially with older pre's like Alembic) cannot properly drive a power amp with a higher-than .7V sensitivity rating. Yes, you'll get sound; and if the power amp has a lot of wattage, you can even get "loud". But you'd get significantly better results driving the power amp with a signal higher, on average, than its sensitivity rating.

    Also, there is nothing inherent to "rackmount" versus "little tabletop ones" that indicates the output voltage.
     
  10. Mo'Phat

    Mo'Phat Supporting Member

    Oct 1, 2003
    San Diego, CA, USA
    So you agree that I didn't say 'all'?

    :p
     
  11. bongomania

    bongomania Gold Supporting Member Commercial User

    Oct 17, 2005
    PDX, OR
    owner, OVNIFX and OVNILabs
    Au contraire! ;)
     
  12. Mo'Phat

    Mo'Phat Supporting Member

    Oct 1, 2003
    San Diego, CA, USA
    That's against the forum rules! Objection, your honor.

    Thou shalt not edit a quoted post to suit your needs...like this:


     
  13. synaesthesia

    synaesthesia

    Apr 13, 2004
    UK
    First off, it is Alembic F-1X. eff - one axe.

    I use one and I use with the QSC 2402 variously. You won't have a problem in normal performing circumstances. I haven't measured the output of the F-1X but I have used it with various models of Carver, Soundtech, Bryston, Yamaha, Stewart, QSC, Amcron, & Samson power amps.
     
  14. pickles

    pickles Gold Supporting Member

    Mar 23, 2000
    Ventura, CA
    I used the F1-X with a 1602 for a while, though my 1602 was modded for higher gain by lord valve. Sounded great!
     

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