Speakers always out of phase

[Roy]

I`m doing church sound,meaning plenty of mics for the praise band.I however have 3 sets of tops(4x eminece delta 15s,4xdelta pro 12s,4xomegapro 12s) and 6eminence kilomax 18 subs.).The mid bass frequencies are always out of phase when I combine them together for more power and I could hear some being cancelled out and some being accentuated when I reverse polarity with my Dbx 260. Can something be done to make them work as one?

[yeahforbes]

I would say there are 3 issues that could likely be the problem here.

1. Some cables are wired wrong. Open up the connectors and check that the same color wire goes from tip to tip (1/4") or 1+ to 1+ (Speakon) and so forth.

2. Some speaker cabinets are just in reverse polarity for some reason. Take off the input panel and reverse the wires soldered to the positive and negative terminals of the input jack(s).

3. All the woofers in some cabinets were replaced and they were hooked up backwards. Take the woofers out and reverse the wires clipped to the positive and negative terminals of the woofers.

Unless #1 solves the problem, you'll have to first determine which speakers are out of phase. I use the 9 volt battery method. It's easy to do with 1/4" plugs, banana plugs, and bare wire, but if you use Speakon you'll have to take them off. Touch the tip of the 1/4" to the 9v's + (smaller) side and the ring to the - (larger) side, or similar procedure for the other types. Have it connected only as long as necessary to see the result. If it causes the woofers to jump out, it's wired correctly. If they suck in, they're backwards. Unfortunately this doesn't tell you whether it's the whole cabinet or just the woofers that are backwards. Perhaps the only way to determine that would be to play a sine wave into the speaker exactly at the crossover frequency and see if it's louder with the woofers reversed or left alone (while listening from at least several feet away, speaker pointed right at you). When it's loudest is when the woofers are in phase with the tweeter. There is also software like SMAART that can do all of this for you, but that's way beyond the scope of this discussion.

Honestly, out of phase tweeters probably aren't really that noticeable. Solving the problem with only #1 and #2 (and not checking the crossover) would get you where you need to be.

[dboomer]

Running multiple speakers always have phase cancellation issues. You can't just throw together a bunch of speakers and expect them to work together in harmony.

You would probably benefit from getting a better single speaker than trying to combine a bunch of them. There are some that are carefully engineered to work together but even then there are always phasing issues when any two speakers play the same frequencies.

[scottmo]

I agree with the above respondent. in sound it may not seem so but less is better. with multiple speakers especially in large and/or non acoustically treated environments you often need a Digital Signal Processor (or DSP) if you are running a digital board, these are often built in but on older ones you have to run it as an outboard processor which i often do even with digital boards anyways for personal preference. What you want for something like this is probably an EAW ux8800, Electro-voice DC-One, or a Symetrix 322 DSP. What these do are allow you to alter the current flow (polarity), add delay and tune the system's equalization settings. The EQ can help make sure that the post-speaker mix doesn't cause natural phasing.

[Roswell_King]

Hey man this is not a burn,
But read the manuel on your 260.I do not like 260 the are crunchy in a bad way.
But if you use the 260 as an optimazation and alignment tool you are good to go.
The othe rthing is the cable runs probably have a low capacitance and are acting as a low pass and high pass filter.
This combined with inaccrate postioning and alignment will do exactly what you are talking about .
Check your cabling.
And use meyer mapp ,meyer mapp is for meyers only ,so you'll have to find speakers of comparable throw and power.
Roz

[Landon]

Interesting.... this goes beyond my basic sound and music physics courses. I have only encountered one type of phase cancellation and it was remedied by a simple speaker relocation