Speaker Placement on 24' Horizontal Truss

[Randy L]

Thought I'd ping y'all for this question.
If you had 4 full range 2-way speakers (QSC K12's I believe) and wanted to mount them on a 24 foot long truss (above the stage), how would you arrange the speaker for the best overall coverage. This will be for a large school dance. The subwoofers will be on the floor, center stage.

Some say evenly spread out, which would be 8' center to center per speaker. But wouldn't this pose some comb filtering problems?

Others suggest, 2 per side, splayed and pointed downward.

Still another suggestion is 1 on each end and 2 at the center, splayed.

[Sydney]

Re: Speaker Placement on 24' Horizontal Truss

The 3 dimensional specifics of the "large school dance" are missing and are part of the details necessary for setup. As well as the dispersion of the QSC cabs

Some say evenly spread out, which would be 8' center to center per speaker. But wouldn't this pose some comb filtering problems?

That also depends on what each channel is reproducing and the degree of pattern overlap. Bob McCarthy ( for one ) explains this in much better detail.

The subwoofers will be on the floor, center stage.

The distance of separation wasn't mentioned, but are you implementing delay to compensate?

[Randy L]

Re: Speaker Placement on 24' Horizontal Truss

Setup will be in a typical school gymnasium. Truss will be erected at front edge of the stage and the subwoofers will be placed at the front of the stage. The intended focus of the sound will be onto the large dancefloor area imemdiately in front of the stage, and maybe a good 50' back.

If I recall, the K12 speakers have a 75 degree conical dispersion pattern for the horn.

[Sydney]

Re: Speaker Placement on 24' Horizontal Truss

I've seen gyms with inset stages and the boxed in stage area created a lot of boom and low end mud.
Is this for a band or recorded music?

[billfitzmaurice]

Re: Speaker Placement on 24' Horizontal Truss

2 per side, vertically arrayed, the upper cab upside down, placing the HF horns adjacent. But unless you have certified flying hardware and a certified person to install them and the requisite insurance don't even think about flying anything.

[Sydney]

Re: Speaker Placement on 24' Horizontal Truss

The aforementioned MTTM array is one that I have used provided the layout warranted it.
Not sure what a typical gym is - seen a lot of variation.

[Mipsconsult]

Re: Speaker Placement on 24' Horizontal Truss

2 per side, vertically arrayed, the upper cab upside down, placing the HF horns adjacent. But unless you have certified flying hardware and a certified person to install them and the requisite insurance don't even think about flying anything.

I'll just add to take what Bill said very seriously, for legal liability issues.

If a cab falls & hurts someone, unless all hardware & operator cert's can be verified, you'll be working to have your wages go to someone else for the rest of your life.

Business insurance is a prudent buy. Knowing how to perform high risk tasks and being certified to perform high risk tasks are two completely different things.

[Randy L]

Re: Speaker Placement on 24' Horizontal Truss

^^Agreed. The good thing is that the QSC K speakers do have fly points on them, and you can purchase the required brackets and accessories to fly them.

On the topic of insurance, I wonder if they would deny the claim if the performer who flew the speakers using the mfg's recommended procedures, but wasn't certified to fly them.

[billfitzmaurice]

Re: Speaker Placement on 24' Horizontal Truss

On the topic of insurance, I wonder if they would deny the claim if the performer who flew the speakers using the mfg's recommended procedures, but wasn't certified to fly them.

If it's not stated in the policy find out from the underwriter.

[Taterworks]

Re: Speaker Placement on 24' Horizontal Truss

Are there four tripod stands available for the speakers? The preferred solution might actually have one speaker on a stand in all four corners of the room, with subwoofers (either 2 or 4) placed midway along the walls equidistant from the speaker locations. If you have enough cable, this is what I'd personally do in your situation. This will avoid having a 'loud end' of the room, and it will help mitigate the smearing effects of the reverberant room because everyone will be able to hear clear first-arrival audio from the nearest speaker.

[Speaker] . . . . . . [DJ Booth]. . . . . . . [Speaker]

[Sub]. . . . . . . . . .[dancers] . . . . . . . . . [Sub]
[Sub]. . . . . . . . . .[dancers] . . . . . . . . . [Sub]

[Speaker] . . . . . [wallflowers]. . . . . . [Speaker]

This will also put the maximum output right in the middle of the room, mostly time-aligned, and will put the subwoofer power alley in the middle of the room as well. In this setup, the speakers are all on tripod stands, subs are on the floor, and the truss can be used for lighting or for hanging a promotional banner. Hanging speakers from truss may seem like something the 'big boys' do, but K12s are not 'big boy' gear so they'd probably look silly flying from truss, and the 'big boys' use tripod stands too, FWIW. Your goal is to look professional and clean, not like redneck engineering.