DRPA+ 4 full range outputs + subs

seventh

PA system gear:
- Peavey 20 mixer
- Driverack PA+
-4 JBL JRX125 (passive main)
-2 JBL JRX118S (passive sub)
-3 QSC RMX 2450 amps

currently i have the following setup in the pa+ (2x4):

2 jbl prx125 for mains driven by one rmx 2450 amp
2 jbl prx118s for subs driven by one rmx 2450 amp

would like to add another pair of jbl prx125 to the system, diven by the third mrx 2450 amp.

my questions:
1. how do i setup the DRPA+ to have 4 full range outputs + subs where the mid L/R outputs are high L/R outputs (same setup as 4 full range + subs on your Training Modules website)?
2. will there be any sonic issues? if there are how do i resolve them?
3. is paralleling the 2 amps to drive the 4 prx 125 as high mains a better option (using 2x4 configuration)?

i am a new pa+ user and to this forum. any help is much appreciated.

Gadget

1. how do i setup the DRPA+ to have 4 full range outputs + subs where the mid L/R outputs are high L/R outputs

In DRPA lingo that's bi-amp stereo tops and subs (2X5 or 2X6) set it up in the wizard.

2. will there be any sonic issues? if there are how do i resolve them?

Yes, you don't want to do fullrange on the tops, cross the tops and the subs at the same (roughly) point like :

Tops:
HPF 100hz LR24

Subs:
HPF 45hz BW18
LPF 100hr LR24

There will also be sonic issues where ever the horn patterns overlap. and with those JRX tops with their 90 degree horizontal pattern, about you only hope is to go for 360 degree coverage, or invert one 125 on each side and try and get the horns to couple. If you covering some other area other than say the stage front then that would be fine.. but overlapping coverage will cause issues. This could prove dangerous so you would want to strap the speakers down since they are so tall..

3. is paralleling the 2 amps to drive the 4 prx 125 as high mains a better option (using 2x4 configuration)?

That is a viable option as well, as is bridging and paralleling the speakers for more power (if your speakers can handle the extra power. Remember to divide the power output @ 4 ohms by the number of speakers and for DJ work try and NOT exceed the speakers rating.. for livesound which is much more dynamic 2-4 times the RMS value is appropriate for short periods. For instance,JBL issues the spec of 500 watts "power capacity" with a 2000 watt peak, that's 500 watts RMS 1000 watts program, 2000 watts instantaneous peak. (meaning no more than an occasional peak for a millisecond or so)

So the RMX 2450 offers 500 watts into 8 ohms in a perfect world, fine for disco,music playback, but short for livesound, 750 watts for 4 ohms which is what you have in the 125's... but well short of what you could use safely (1000 watts) for livesound.

You cannot bridge an amp lower than 4 ohms...they will not take it, so your stuck with one speaker per channel.

Gadget

seventh

Gadget,

Thank you. Your response and advice are well received and much appreciated. This is a great forum and I plan on visiting frequently to read and learn from your posts. Again thank you for your time.

seventh

Gadget

No problem.. I had a much more complete answer written and the computer ate it... :roll: :roll: :roll: the thing I meant was to put one JRX 125 on top of the other flipped upside down... remember to strap them down so you don't end up with them falling on someone... that would be BAD :shock:

Rock on...
G