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View Full Version : QSC GX5 powering 2 mains and 2 subs??



DJ Sunshine
03-30-2012, 07:39 PM
Hey guys,

So I have a QSC GX5 power amplifier that currently powers two 500W RMS speakers. I am using a Gemini powered subwoofer at the moment, but I'd like to eventually move to two passive subs. My question is this:

The GX5 has a built-in crossover that allows you to run a subwoofer on Channel 1, and a main on Channel 2. The amp is able to handle a 4-ohm load. I was thinking of running my mains in parallel on Ch. 2 and getting 2 8-ohm subs and running them in parallel on Ch. 1. This doesn't sound like a problem, but here's the catch: It's a stereo power amp, so does this mean I'd only be getting one half of the stereo signal coming out of the mains? I really would rather not buy another GX5, as they ain't cheap and my rack is already pretty much full (not to mention an amp rack is a bitch to haul around).

Anyone run this kind of setup before?

Incognito
03-30-2012, 07:52 PM
Page 9 of your owners manual http://media.qscaudio.com/pdfs/manuals/GX_Series_User_Manual_revD.pdf

http://img528.imageshack.us/img528/1790/captureeh.png

& yes your speakers would then me playing in mono instead of stereo.

ampnation
03-30-2012, 09:46 PM
You need to sum to mono pre-amplifier in this case and feed just one input as shown above.

There are a variety of ways of doing summing to mono from stereo. Do NOT use a Y-cable to sum, only to split. You need some soft of active device like a mixer. I have used a similar setup in the past and one way of going mono from stereo is by using a small format mixer like the PV6. Run L & R to two channels of input, pan both channels all the way left or right and then use that main output to the amp.

I have also had good luck with the Behringer MX882 mixer/splitter.

There are also a number of mini mixers and line mixers that do similar functions out there. Stay away from Nady. And even though I've had good luck with my MX882's I am leary of Behringer quality overall. I have a UB802 mixer from them that has channel bleed.

Good luck.

DJ Sunshine
03-31-2012, 02:25 AM
Page 9 of your owners manual http://media.qscaudio.com/pdfs/manuals/GX_Series_User_Manual_revD.pdf

http://img528.imageshack.us/img528/1790/captureeh.png

& yes your speakers would then me playing in mono instead of stereo.

Thanks, just didn't know if the same would apply with 2 mains/2 subs as it would with 1 main/1 sub. Thank you, + rep.

Incognito
03-31-2012, 04:15 AM
Look to the far right of the picture I posted & in small writing above where it says "top" & sub", you'll see it tells you this configuration will work in both 8 or 4 ohms. This means it will work with both a single 8 ohm speaker as well as two 8 ohm speakers per channel respectively so no worries, you'll be fine.

Incognito
03-31-2012, 05:50 AM
You need to sum to mono pre-amplifier in this case and feed just one input as shown above.

There are a variety of ways of doing summing to mono from stereo. Do NOT use a Y-cable to sum, only to split. You need some soft of active device like a mixer. I have used a similar setup in the past and one way of going mono from stereo is by using a small format mixer like the PV6. Run L & R to two channels of input, pan both channels all the way left or right and then use that main output to the amp.

I have also had good luck with the Behringer MX882 mixer/splitter.

There are also a number of mini mixers and line mixers that do similar functions out there. Stay away from Nady. And even though I've had good luck with my MX882's I am leary of Behringer quality overall. I have a UB802 mixer from them that has channel bleed.

Good luck.
Most decent mixers offer a summed mono out by the flick of a switch so no problem really.