Sound Design Live

Build Your Career As A Sound Engineer

  • Podcast
  • Training
    • My Courses
  • Archive

Can you estimate line array splay in the field without software while the riggers are waiting?

By Nathan Lively

I have developed, what seems to be, a lesser known method to find target coverage angle and quickly estimate average splay for a line array in the field in relatively few steps. I discovered it by necessity while creating Pro Audio Workshop: Seeing Sound 3 years ago. Recently a student challenged me on a couple of points and it motivated me to take a closer look to see if I could make it more efficient.

Here’s how I have seen other people do it.

Bottom speaker down angle – Top speaker down angle = Target coverage angle

bottom angle
Bottom speaker angle
top angle
Top speaker angle

17º – 6.78º = 10.22º target coverage angle

Target coverage angle
array splay
Result using auto-splay in MAPP

This works fine when you are using modeling software, but I was looking for a solution for the field with a laser disto and a calculator while I have a team of people waiting on me. After playing around with some right triangles for a bit, I discovered a pretty simple method

In short, if you know the array’s rigging height and where the audience starts and ends, you can find the target coverage angle without software.

Find target coverage angle without software

Here are the steps:

  1. Solve triangle Y. You need the length of two sides or one side and one angle. I would go with two sides since that seems to be more reliable.
  2. Solve triangle Z. You can find the length of the opposite side (6.07′) by subtracting the array height from the from the rigging height. You can estimate the array height by multiplying the number of boxes by a single box height.
triangle1

Then plug those numbers into a triangle solver.

triangle2

16.88º – 7.03º = 9.85º

What about inclined audiences?

But that only works for flat audience planes. What if the audience is at an angle?

inclined audience

The process is a similar. To solve triangle Y, we’ll subtract the the height of the end of the audience plane from the rigging height above the audience.

rectangle2

14.8 – 6 = 8.8ft

Solve for the missing angle. 4.19º

We already have the solution for triangle Z (16.88º).

16.8 – 4.19 = 12.61º target coverage angle

inclined
array splay inclined
Result in MAPP using auto-splay

Now what?

With one more step we can calculate average splay.

tar cov ang / available splay angles = average splay

12.61º / 11 = 1.2º

total splay

My speakers don’t offer a 1.2º splay, so I’ll round down to 1º and make up for the loss with a few of the last speakers. Now I have plan to hand the riggers.

angles 1

What is the result using average splay?

avg splay prediction

It’s not great, but in a pinch I’d rather go with this result rather than leave everything at 0º or just guessing.

0deg splay

The easiest way to improve this result is to use the the automatic solvers built into your modeling software. The best way to refine the result manually for even more control is covered in detail in Pro Audio Workshop: Seeing Sound.

Warning: Software should always be used to double check rigging points and weight distribution. (Thanks Samantha Potter!)

Have you tried calculating line array splay in the field without software? How did you do it? What were your results?

Loved this post? Try these:
  1. How To Find Speaker Coverage In One Step
  2. What do I need to know about my speakers?
  3. How to Estimate Delay and Level Offset Between Speakers in Your 3D Models

Get My Top 5 Posts

about mixing and sound system tuning

I respect your privacy. I will never share your email address with anyone, period.


Smaart® and the Smaart logo are registered trademarks of Rational Acoustics LLC and are not affiliated with Nathan Lively or Sound Design Live.

Comments

  1. Peter says

    April 10, 2020 at 17:11

    Why don’t you use the tan-1 formula for a rectanglar triangle to calculate the angle, it’s much easier.
    Like triangle Z, the angle is tan-1(6.07/20) = 16.88°.
    And for Y tan-1(14.80/120) = 7.03°

    Reply
    • Nathan Lively says

      April 11, 2020 at 15:01

      Thanks Peter! I’m not a geometry expert, so my solution is just based on some trial and error. Yours looks much simpler!

      Reply

Leave a Reply Cancel reply

Your email address will not be published. Required fields are marked *

can-you-estimate-line-array-splay-in-the-field-without-software-while-the-riggers-are-waiting

By Nathan Lively

Get My Top 5 Posts

about mixing and sound system tuning

I respect your privacy. I will never share your email address with anyone, period.


Smaart® and the Smaart logo are registered trademarks of Rational Acoustics LLC and are not affiliated with Nathan Lively or Sound Design Live.

Leave a Reply Cancel reply

Your email address will not be published. Required fields are marked *

Copyright © 2023 Nathan Lively

 

Loading Comments...