If you've got a big arena to cover, the instinct is to spread the speakers out. Put a stack at each end, or one on each side, and let them meet in the middle. More boxes in more places, more coverage. It's a reasonable instinct and I've watched plenty of good companies build shows that way.

It's usually the wrong call, and it isn't close. Here's the math that says so.

Sound travels about 1.13 feet every millisecond. That's the whole problem in one sentence.

Two stacks sitting apart on the ground are also sitting apart in time. Anybody who can hear both of them hears the same word twice. Close together, that's a smear you can live with. Far apart, it's a slap back echo, and your announcer turns to mush in the seats that paid the most.

A Real Arena, Real Numbers

I've been working out coverage for the arena at Sandy Downs in Idaho Falls. Covered grandstand down one long side, a line of bleachers facing it across the arena, chutes in between. Seating on both sides, which is the part that makes it interesting.

The floor measures 282 by 147 feet rail to rail. Add the stands and the far corner of the seating sits right around 300 feet from anywhere you can reasonably put a lift. That's a long throw for a compact box, and there are four honest ways to cover it.

ONE HANG 10 boxes + 1 sub one power drop COVERED GRANDSTAND BLEACHER LINE 100° wedge covers both banks far corner ≈ 300 ft soft soft ARENA FLOOR   282 × 147 ft
Plan view. One hang at the center of an end, aimed straight down the long axis, drops both seating banks inside a single 100° pattern. The only seats outside it are the two small wedges beside the tower, and those are the closest seats in the house.
Four ways to cover it
Where the boxes go Time offset Verdict
One hang, center of an end None Best output, least labor, no echo
Two hangs splayed at one position Under 20 ms Fine. Costs 5 dB to fix a few seats
Two hangs either side of the chutes 130 ms Flat coverage, audible slap up close
One at each end, firing at each other 0 to 245 ms Avoid. Cannot be fixed in DSP

The One That Fools Everybody

A stack at each end pointed at each other looks tidy on paper. Both ends covered, nobody left out, and it feels generous.

Run the numbers and those two patterns overlap across 153 feet of seating. That's 55 percent of the house hearing both systems at once.

Here's the part you can't fix. The path difference changes at every single seat. Somebody at midfield hears the two arrivals 1 millisecond apart, which is nothing. A hundred feet down the bank it's 60 milliseconds. At the pattern edge it's 116. Down at the ends it's 245 milliseconds, a quarter of a second, loud and clear.

There's no delay setting that fixes that, because there isn't one offset to correct. There are hundreds. It's the reason real delay towers are always delayed and always aimed away from the main system, never pointed back into it.

More Boxes Will Not Widen Your Coverage

This one costs people money, so it's worth saying plainly.

The horizontal pattern is set by the horn, not by how many boxes you hang.

My HDL 26-A covers 100 degrees wide. It covers 100 degrees whether I fly 6 of them or 14. Stacking more boxes buys output, throw, and vertical control. It does not spread the sound sideways by one single degree.

So if your problem is horizontal coverage, adding boxes to the hang will not solve it. And splitting one hang into two piles to chase the corners costs you 5 to 6 dB everywhere else. At Sandy Downs that trade came out to 5 dB across 80 percent of the seats in order to rescue about 19 percent of one bank. That's a bad deal and I'm not going to sell it to somebody.

Your Lift Probably Matters More Than Your Box Count

Here's one that catches people, and it caught me until I ran it.

My tower tops out at 19.5 feet. Fourteen boxes is 10.9 feet of array. Hang all fourteen and the bottom box ends up around 7.8 feet off the ground, sitting in the dust and behind anybody standing at the rail.

Ten boxes puts that bottom box at about 11 feet and costs me 2 dB. Across the whole range, 8 boxes to 14 boxes is only 4 dB of output, but it's nearly 5 feet of difference in where the bottom of the array lands. That's a cheap trade and I'll take it every time.

Arena Floor
282 × 147 ft
Throw, Far Corner
300 ft
Box Pattern
100°
Stack Positions
1

Pick your box count by where you want the bottom of the array, not by what the lift is rated to pick up.

Got an arena, a fairground, or a grandstand to cover? I'll size it before I quote it.

See Corporate & Event Production

What This Means if You're the One Hiring

Ask why the gear is going where it's going.

A company that wants stacks in four places might be giving you better coverage. Or they might be handing you an echo and billing you for the extra labor to build it. Both look the same on a quote. The honest answer usually turns out to be fewer boxes in fewer places, aimed properly, and it usually costs less than the complicated version.

At Sandy Downs the answer came out to one hang, one position, one power drop. Ten boxes and a sub, up a single tower, aimed straight down the middle of the arena. That's it. Straight answer, better coverage, and it saves a day of labor I'd otherwise have to charge somebody for.

If you've got an arena, a fairground, or a grandstand and you want to know what it actually takes to cover it, give me a call. There's a decent chance you need less than you've been told.