Single sub sounds great, connect 2 and both are crap

[spitfire0x00]

Hello all, long time watcher so I'm new around these parts and finally had to post something of my own because the search feature didn't turn up anything for me.

to start my setup is:: [in progression of connection]
Behringer Mixer BEHUB1204fxp (source is aux in from PC)
|(left/right XLR)|
Behringer CX2310 2 channel mode
|High out|_____|Low Out|
(L/R XLR)_____(L/R XLR)
Marathon 4000_____Marathon 5000
|(L/R Spkon)|_____|(L/R Spkon)|
SeismicAudio_____SeismicAudio
SA-15t_____SA-15ss
350rms_____400rms

The problem I am having is when I use both SA-15ss together. With a single unit in the system it sounds wonderful, just not as much volume as I would like.
When both are applied they sound awful and have next to no volume. I have tried running them from the low outs from the xover and the mono subW out
from the xover, also tried with a splitter from the subW-out and mono to the M5k in bridged mode then chained them. No matter which way I apply these subs
they are terrible when used together, but awesome alone.

Please spit ball anything, my partner and I have just ordered a Behringer Ultralink Pro in hopes that the channel isolation would fix the problem.

[Al Poulin]

Sounds like you might have a reversed polarity issue which makes the speakers out of phase. Check to make sure your polarities + and - are correct. With budget equipment from the mentionned brands, problems like this are certainly more likely...


Al

[ampnation]

+1 on what Al said... almost without a doubt this is your issue. I think the easiest way to fix it would be at the Speakon cables where you can usually just unscrew and swap the wires. If that works though, you really should figure out where the problem lies. It's doubtful the Speakon cable is where the problem is now and by doing just this fix, you now have two pieces wired wrong which cancel each other out. That's fine till you use any of this equipment with other equipment.

I would also add an audio interface between your PC and mixer. You should be able to tell the difference in sound quality immediately.

[Bill Fitzmaurice]

Sounds like you might have a reversed polarity issue which makes the speakers out of phase.

+1. And do not place the subs left/right, they should be placed together, preferably facing a wall from about a foot to two feet away.

[spitfire0x00]

Thanks so much for the immediate replies all!

Sounds like you might have a reversed polarity issue which makes the speakers out of phase.

I Have had my suspicions about one the the subs. One of them "doesnt play well with others" per say, but the other one does. Ill check the wiring on that one.

I would also add an audio interface between your PC and mixer. You should be able to tell the difference in sound quality immediately.

We use a Numark external processor, it was very noticeable.

+1. And do not place the subs left/right, they should be placed together, preferably facing a wall from about a foot to two feet away.

Roger that!

[unsafe8989]

Yea those Marathon Amps are only Capable of 4 ohms a side. Lower than the suggested ohm load on these amps make them sound horribpe at very low volumes. I know form experience I have two a 4000 and a 6000.