Speaker Question (How should I add subs to my setup)

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1

Speaker Question (How should I add subs to my setup)

I have 2 JBL JRX115’s (250W continuous) on a GX3 amp (300W/channel @ 8ohms).

I want to add 2 JBL JRX118S (350W continuous) on a GX5 amp (700W/channel @ 4ohms), but I cannot seem to find a way to do this without investing in a 3rd source to redistribute the frequencies.

I am considering settling by just buying another GX3 amp and using the crossover feature to separate the highs from the lows at 100hz.

  1. Would the 2 GX3’s setup provide plenty of safe power?
  2. Is there a way to do my proposed set-up? In the GX manual I saw that you can use both channels for the same signal by using an RTS jumper, but wouldn’t this still be sending the full frequency range to the subs as well as requiring a mono-output setup?
2

The GX3 puts out 425W at 4ohms, which is within the recommended 350-700W in the JRX118S manual.

3

I would recommend getting a good bass amp with more power than you need. I use a 5kw amp with two Harbinger 400w subs @8ohms or four @4ohms and I can push them to the clip line on the amp with no issues. I built a balanced Minidsp into my amp rack for processing. I use two 48db LR filters @74hz and a high pass 48db BW @38hz. You’ll get much cleaner, tighter bass crossing low.

4

Where does that put me at realistically though?

5

If I do that, then you recommend I go the mono route, or is there a better way to get stereo?

6

Also, how many people do you think I can satisfy with this setup?

Indoors and outdoors?

7

I use a mono signal out of the minidsp and parallel the input on the amp. The amp is ran in stereo. I use two 18’s indoors, and four outdoors. My tops are two powered Alto 12’s.

8

Have you noticed any downfalls in running mono?

9

You will want to run subs in mono and group them together. Subs need to be within 3ft or more than 50ft apart to avoid cancellations. If I could have done it again, I probably would have went with the peavey 7000 as it is much lighter than the Certain Vega CV5000. My 6u amp rack weighs in at around 125lbs.

10

If you only plan on running two subs, you will be fine bridging them on a less powerful amp, but I highly recommend an amp with double the combined RMS rating of the subs.

11

Okay, the amp is powerful enough to run both at twice the RMS without bridging. Would I be able to take either the R/L XLR cable from my mixer and take it straight into my subwoofer amp without any redistribution of the frequencies before that? Will the sub try and run the full range, or will it stay within the correct frequencies?

Also, neither of these amps have a bridging function on them.

12

If you are running a mono signal out of your mixer, then sure. But at $120 for a Minidsp, it’s silly not take advantage of soundprocessing.

13

Alright, thanks.