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Dedicated Power amps

Discussion in 'Amps, Mics & Pickups [DB]' started by Joe Smithberger, Jul 31, 2002.


  1. Joe Smithberger

    Joe Smithberger Supporting Member

    Mar 8, 2002
    Canton, Ohio, USA
    I have been having good luck with my Tech 21 Acoustic DI and Bass Max pickup going direct to the PA (mixing board EQ flat). So now I'm wondering if there is any problem going straight from the Tech 21 into a QSC (or similar) power amp without another preamp in the chain.

    Does anyone know if this is OK? Is there any electrical problems with this thinking?

    Since the DI will do tone shaping before the XLR out, I think I can take the line out to a power amp and 1x12 cab and still run the XLR to the board. A good clean power source can be had pretty innexpensively and without a huge weight penalty if I don't need another preamp.
     
  2. Bob Gollihur

    Bob Gollihur GollihurMusic.com

    Mar 22, 2000
    New Joisey Shore
    Big Cheese Emeritus: Gollihur Music
    You can feed the output of your SansAmp to a power amp. FYI, the output of the SansAmp is not high enough to drive a QSC-- (I own one, tried it, and did the research-- A mod can be done by a factory authorized dealer that will increase its input sensitivity.
     
  3. Joe Smithberger

    Joe Smithberger Supporting Member

    Mar 8, 2002
    Canton, Ohio, USA
    Thanks Bob.

    Do you know if there are other brands that are more suited for this? What kind of input sensitivity should I be looking for or is this just not a good approach?
     
  4. I've used (for higher volume gigs with no sound reinforcement) a Ramsa power amp driven only by my SansAmp bassdriver. Works great, plenty of output from the SansAmp.
     
  5. Bob Gollihur

    Bob Gollihur GollihurMusic.com

    Mar 22, 2000
    New Joisey Shore
    Big Cheese Emeritus: Gollihur Music
    This was the info from Lord Valve, the guy I bought my QSC from.

    The QSC site gives input sensitivity for the PLX series at 1.0 Vrms 1.2 Vrms 1.5 Vrms 1.7 Vrms 1.9 Vrms for the 1202-3402 series, so I imagine twice the sensitivity would be desirable.
     
  6. Joe Smithberger

    Joe Smithberger Supporting Member

    Mar 8, 2002
    Canton, Ohio, USA
    Thanks again. Great info.

    IOW I am looking for an input sensitivity about 2.5 or at least I need to be aware that the entire power of the amp may not be available without a real preamp?
     
  7. Joe Smithberger

    Joe Smithberger Supporting Member

    Mar 8, 2002
    Canton, Ohio, USA
    Just an update in case anyone else is following this thread. I found a good deal on a Stewart World 250 power amp (7lb, single rack space, 210 Watts into 8 ohm when bridged mono). It turns out that the Tech 21 Acoustic DI is a bit hotter than the Bass Driver DI. There is also a switch to pad down the XLR so that the direct line out doesn't have to run as low as the balanced out for the PA. According to Lloyd at Tech 21, the Acoustic DI is designed so that it can drive an amp like the Stewart. It won't go to +4 db (as required by a QSC) but it will go -10 to 0db. It sounds good at home but the first trial is this weekend.