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Turns out my subs are cancelling each other

dj_soo 2:54 AM - 16 December, 2012
Same make, model, etc.

I don't think it's placement as I have them coupled and moving hasn't fixed it - should I be opening up one to see if the wiring the correct? (Should probably have a pro look at it as I know nothing abou wiring).
Many suggestions?
DPR250R 3:15 AM - 16 December, 2012
I assume you have 2 subs?

If the lows sound better with one of the subs off then usually they are out of phase.

Yes... checking the wiring is a good place to start. Instead of opening up the box you can make your own cables. Whatever you are more comfortable with.

www.audiocheck.net
dj_soo 3:28 AM - 16 December, 2012
So just go to a custom cable place and ask for inverted phase XLR cables?
DPR250R 3:40 AM - 16 December, 2012
Quote:
So just go to a custom cable place and ask for inverted phase XLR cables?


I have never tried to invert the signal. Not sure if that will work.

Are these subs powered?

Is there a phase switch on them?

You may have to pop them open and swap the wires on one of the subs. It shouldn't be too difficult.

I still use passive stuff and if I have to mess with phase then I do it at the binding posts on the back of the amp.
DPR250R 3:56 AM - 16 December, 2012
Quote:
Is there a phase switch on them?


Messing with the phase switch should be first the step with your troubleshooting before taking anything apart or getting custom cables.

This random powered sub has one...

www.guitarcenter.com
dj_soo 4:10 AM - 16 December, 2012
Yea powered and there's no phase switch unfortunately
DJ Dac 4:14 AM - 16 December, 2012
don't feel bad, it took me a year and a half once to figure out why the speakers were canceling each other out, there was crazy hot and cold spots all over the room, pressed the phase switch and bang it worked... felt like an idiot...
dj_soo 4:47 AM - 16 December, 2012
Yea, I rarely bring my 2nd sub out unless the room is really big so when I did, I just assumed my subs weren't powerful enough...
DJJOHNNYM_vSL3 8:28 AM - 16 December, 2012
Chances are either the cable is wired incorrectly, or someone screwed up the wiring inside the sub....assuming it's been worked on before...

I'm assuing they're passive, cuz if they're not, that would suck...

First just try "inverting" one of the cables at the binding post, and see if the base becomes "solid" from both...

There's more I want to say, but I'm mad sleepy, so start there.
DJJOHNNYM_vSL3 8:28 AM - 16 December, 2012
Wow I spelled "bass" as "base"...yeah I'm sweepy....
dj_soo 12:35 PM - 16 December, 2012
Tried multiple cables so I don't think it's that...

I'm going get an inverted XLR cable and see if inverting the signal works before I open up my sub.

And yes, it's a powered sub, so I may just take it into the shop...thanks guys!
djcrap 3:55 PM - 16 December, 2012
This is what i use ibetween my rane 68 and qsc subs

www.guitarcenter.com
DJJOHNNYM_vSL3 4:04 PM - 16 December, 2012
Quote:

And yes, it's a powered sub, so I may just take it into the shop...thanks guys!


Eww @ a powered sub being inverted.....smh.
DJ DisGrace 4:27 PM - 16 December, 2012
Quote:
Quote:
And yes, it's a powered sub, so I may just take it into the shop...thanks guys!


Eww @ a powered sub being inverted.....smh.

+1
You would expect a powered sub to be phased properly. This stuff happens, unfortunately.

I know Johnny would just use the old 9V battery trick to check the phase of his speakers.
DJ DisGrace 4:28 PM - 16 December, 2012
If you have a sine wave generator, or a way run a 1Hz signal to your subs, you could actually visually identify which sub is out of phase. Just be careful not to run too much power to it with that kind of excursion.
ancientyouth 4:54 PM - 16 December, 2012
Yo contact qsc.... I wouldnt be too surprised if they just sent you a new speaker ( it costs them more to ship the other one back and work on it than to just send u a new one)
DJ GaFFle 5:32 PM - 16 December, 2012
Quote:
This is what i use ibetween my rane 68 and qsc subs

www.guitarcenter.com

I used that unit once inline with my old QSC HPR181i's. They do make things sound better and fuller but even with careful adjustments, my HPR's would thermal once in a while. I found I had more headroom w/o the Sonic Maximizer and returned it promptly. I don't recommend them unless you have very cheap PA equipment (ie: JBL JRX, Sonic stuff, etc.).
DJ Reflex 11:38 PM - 16 December, 2012
Quote:
If you have a sine wave generator, or a way run a 1Hz signal to your subs, you could actually visually identify which sub is out of phase. Just be careful not to run too much power to it with that kind of excursion.


iPhone has an app for that... check out ScorpionZZZ SGenerator Lite. It has 180 degree phase shift for left and right channels. I've not used it to check subs yet, but it does produce clear sine waves at any frequency.
You can also use NCH Tone generator. Free trial for 14 days, but worth the price to buy if you need a good frequency generator for laptop.
dj_soo 2:53 AM - 29 December, 2012
Update:

Got a phase inverted cable and it totally did the trick...

Thanks guys!
DJ DisGrace 3:14 AM - 29 December, 2012
Quote:
Update:

Got a phase inverted cable and it totally did the trick...

Thanks guys!

now.... are they in phase with your main speakers??? =P
DJ Reflex 3:57 AM - 29 December, 2012
^^ LOL Yeah, which sub did you fix? ^^
DouggyFresh 6:36 AM - 29 December, 2012
Really this could be tested easily with a sound file that's summed mono and then normal left channel, inverted right... (provided you're running stereo subs and not summed mono). If it's wrong, it will be way louder overall on one side (audibly). If it's right and you're in the right spot between the speakers, the sound will sound muffled and un-directional.
HandsomeRobDJ 4:37 PM - 29 December, 2012
Wow. Really tough solutions. It's a phas problem. I learned about by accidentally wiring one of a pair of subs backward when I was doing car audio. I could see that both subs were REALLY moving but no sound whatsoever. My boss explained it great. He said as one of the subs was "pushing" sound the other was simultaneously "pulling" sound and they were essentially canceling one another out. I get the same problem with my PA subs all the time. The EASY fix is not to sit and point them parallel. If they're out of phase and canceling I can just point mine toward the rear corners of the room, so they are pointing at roughly a 90 degree difference from one another and the problem is solved. Give that a try before you blow a ton of time and effort on unnecessary stuff. Good luck : )
HandsomeRobDJ 4:38 PM - 29 December, 2012
*phase problem- typo
PorkyG 5:28 PM - 29 December, 2012
Good source to test your speakers www.testsounds.com
DJ Reflex 6:53 PM - 29 December, 2012
Quote:
Good source to test your speakers www.testsounds.com



Nice!

I purchased the full SGenerator app for iPhone as well. Amazing portable device... phase testing, frequency generation, and more. Well worth the $1.99.

Funny, I teach science and specifically built a dual speaker box with phase reversal to show the effects of wiring speakers out-of-phase. Like HandsomeRobDJ said, the kids can see the speakers moving, but hardly any sound comes out until I flip the phase switch back to normal. It's a cool demo!