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DRPA and amps configured, now what?

robbernsrobberns Posts: 15
edited August 2013 in PA Configuration Wizard
Have my first gig with my new PA this weekend and am at a loss as to what the next step in getting the rig tuned in should be.
Basic specs are:
JBL PRX415M (x2) for HF/Mains
JBL PRX 418M (x2) for LF/Subs (in mono)
Powering the HF/Mains with QSC GX7 (stereo)
Powering the subs with 2 x QSC PLX3402 in Bridged Mono
Went through the gain setting exercise and have the amps dialed in, and set the Limiters on the DRPA.
Gains on the Crossovers in the DRPA are at 0.
When I play some well-recorded music from a CD (Steely Dan, Toto), the high end is a bit much and there is not enough oommff.
So at this point, would you:
• Attenuate (turn down the gains) on the HF crossover?
• Turn up the gain on the LF crossover to get more low-end?
I have not EQ'ed anything at this point.
Any direction would be appreciated!


  • DraDra Posts: 3,777
    Remember that you have set the amps and DRPA limiters to prevent clip at your "max" output from the mixer. If you increase the gain of the low's in the DRPA, you will increase the level to the amp... causing limiting and/or clipping. You should decrease the gain of the DRPA high x-over, or turn the amp down to balance the sound.
    You are providing 725w to each top cab.
    You are providing 2200w to each sub.
    The subs are 3db less efficient, so that is like cutting you power in half (1100w) to get to the same output. A lot of people like to have a boost of about +6db from their subs.
    Math and science can be fun, so lets play.
    Subs: 95db @ 1w1m..... 128db @ 2048w1m. The other wattage does make any real difference. (You need another 2048w to get another 3db.)
    Tops: 98db @ 1w1m..... 124db @725w1m. That is a 4db raw output difference, but that is not outputting the same content. You probably need to dial the GX7 back about 3 or so db. An output of 350 would about do it. That is 53v. You can output a sine wave and measure the AC voltage across binding posts.
    The PLX would be 133v, by the way.
    The voltages would be measured with mixer output set to your established max. Make sure you turn off the limiters in the DRPA and the amps for this and unplug the speakers. Be advised, the GX7 has 4db more gain. Which, if I understand it right, mean that the GX7 gets to max output faster than the PLX. It might not play a factor since you will have a lot more headroom because you are dialing it's potential (from input) back quite a bit.

  • robbernsrobberns Posts: 15
    Wow, that's some heavy math for so early in the morning.
    You must have some good coffee where you are.
    The more I thought about it last night, the more I realized that turning the sub gain up would throw off my gain setting exercise.
    So turning the High gain down in the DRPA is one option, the other is turning the attenuators on the GX7 down.
    Am I getting that correctly?
    I guess it would easier for me to just tweak the DRPA High Gains when i run the CD through the board at the club. Get a balance that sounds good to my ear.
    Now what about the Auto EQ deal? From the posts I've read, I can't determine if it is a good idea, bad idea, or both.
    Back in the old days we'd have a dual 31-band graphic on the mains to sweeten the whole mix based on the room we were in.
  • DraDra Posts: 3,777
    The DRPA+ is much better, but the DRPA AutoEQ is best suited for establishing a baseline flatness by going outdoors, away from are reflective surfaces (buildings, cars, etc). Then transferring the data to the PEQs. This get's you in the best possible starting point in a room. The general perception is that only 160-700 should be totally trusted when indoors because of comb filtering, cancelations and standing waves. The rest is suspect, at best. Some of the best reading on the subject can be found on the "former forum" tab above.

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