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In sound system design, step one is to define speaker coverage. Lucky for you, Daniel Lundberg and I have created a great new speaker coverage calculator that makes this initial step quick and easy. The calculator will give you a consistent coverage result for any scenario, but unfortunately it’s not very smart. It doesn’t know about walls and other speakers, so it works best for single-speaker applications like balconies, side fills, and smaller venues.
Consistent coverage means that SPL will not vary more than 6dB. So if the highest measured level in the audience is 100dB SPL, then no part of the audience may be lower than 94dB SPL. This calculator is designed to give you the least amount of level variation across the listening area, but there are many more variables at play here. With that in mind, let’s proceed.
Step 1 And Done
Put your measurements into the Speaker Coverage Calculator above. That’s it! Listen to my conversation with Lundberg for a more details on how it works.
Example 1 – Balcony
Let’s take the room from How To Tune A Sound System In 15 Minutes, add a balcony, and raise the ceiling. I used visual aids to show a four-foot seated audience height covered by four speakers: Main, Balcony, Sidefill, and Under Balcony. Download my MAPP Online Pro project to follow along.

Put your measurements into the speaker coverage calculator above. It recommends a nominal vertical coverage of 51° and a UPQ-1P aimed 25.3° above the front. You can manually work out the angle in MAPP, or use the speaker coverage calculator. Input the angle of your architectural guide (the one showing distance to front) and the calculator will tell you exactly what to put into the Rotation About CDRM box in MAPP. I put in a 139° front angle and got -15.7° for the speaker aiming angle.

Here’s a prediction at 8kHz. Did we meet our criteria for consistent coverage? Just looking at the graph I would say there’s no more than a 3dB difference from on-axis to off-axis, and consulting the virtual SIM I see there is no difference in average SPL and only about a 4dB difference in the high end. Great success!

Example 2 – Side Fill
The speaker coverage calculator recommends a UPA-1P aimed 21.2° above the front. Virtual SIM tells me that there is about a 8dB difference from on-axis to off-axis. This doesn’t meet our requirements, but I found that if I aim it lower I can can get more even coverage and meet the crossover point with the main speaker.

Example 3 – Under Balcony
With limited height, it’s going to be hard to cover this listening area with one speaker. The speaker coverage calculator recommends subdivision, but it also keeps recommending a giant JM-1P (see prediction below). Now I know how Dr. Frankenstein feels: I asked for consistent coverage and I got it, but I also got a mob of angry townspeople. I tried a UPM-2P here aimed at the last row and that worked a lot better.

Example 4 – Small Venue
Let’s take a look at Ashkenaz, one of the first music venues I worked at when I moved to Berkeley. When I first put the triangle lengths into my speaker coverage calculator (9.5′, 28.5′, 25′), it gives me some crazy results and recommends that I subdivide the array. Let’s assume that I use a down fill to cover the first ten feet of the audience. With new results, I try a UPQ-1P and see that it provides even coverage. I also observe that aiming it further down will get me less consistent coverage, but will let me send more of those expensive decibels into the audience, providing more bang for the buck.

To Subdivide or Not To Subdivide
How do we determine when we need to subdivide our coverage into more than one segment? Here’s a nice rule of thumb that I learned from Bob McCarthy’s seminar: measuring from the speaker, take the ratio of the distance from the first row to the last and subtract one. So in our example the first row is 9.4ft from the speaker array and the last row is 28.5ft from the same array. That’s a ratio of 1:3. 3 – 1 = 2. So a two-segment array would probably work better for this coverage area. How many speakers in each segment? That’s up to you and your budget. For a much better explanation of this topic, read McCarthy’s article, Array Or Not To Array.
Finding Speaker Coverage When Front And Back Are Equal
The horizontal coverage plane of a sound system often looks like an isosceles triangle (two equal sides and angles) and the loudspeaker nominal coverage can be found with basic trigonometry. Remember soh cah toa from trigonometry? No?! Me neither. Lets watch this video! To find speaker coverage angles in the field, find the lengths of the triangle for the area you are trying to cover and solve for the inside angles. There are also plenty of free triangle solvers online and iPhone apps.
Please test this out the speaker coverage calculator and send me your results! If you have suggestions for a better calculator, let me know in the comments below. After I get some more comments and suggestions I’ll publish a second version and Daniel and I will do another podcast with a better explanation and more case studies.
How do I use the calculator. I can click on it, but no way I can fill in anything. Can you provide the XLS file?
Hi Jan,
It’s working fine for me. Try clicking where it says Name and type something in.
Could you email me a screen shot of what it looks like for you?
Hi, Nathan! Sorry, this is about triangle calculate:
after set 19.9 – 35.9 – 20.6 in MY calculator i have front angle not 139,
but 124.84…..
Where are my mistake?
Thanks!
Hi Ruslan. Thanks for trying out the calculator. The front angle is not calculated. It comes from MAPP Online Pro. See example 1 – “Input the angle of your architectural guide (the one showing distance to front).”
Make sense?
Nathan, Its CLEAR, THANKS, it is my problem and my inattention…
I am Sorry to bother You, i hope to be attentive.)
Hello, I am confused about the angle above the front, can you please explain specifically what it is? In the balcony example picture, it doesn’t seem like the front angle is 25.3 degree. Thank you.
Hi Hien,
Thanks for writing in. 25.3 is the calculator result when you put in the numbers from the example. Does that make sense?
In case it helps anyone else: I found that I needed to wait some minutes for the actual calculator to appear in Chrome. In Edge, it appeared as the page loaded.
Thanks Sven!
Sorry to disturb but I can’t seem to download or open MaPP online Pro project and the video link doesn’t work.
Thanks Blue. I fixed the video link, but I test the MAPP project file download and I didn’t have a problem. Could you try it again?
You have inadvertently exposed a fundamental flaw in common speaker design.
Which is: The vertical coverage is symmetrical.
This is a flaw because the target area is NEVER vertically symmetrical.
No one is EVER sitting on the ceiling!
You have an opportunity here to show a soloution for this exhausting problem.
The WRIGHT “Directed Coverage” horn is vertically skewed to project the most energy to the back of the room, with even coverage all the way down to the front row.
http://wrightsound.com/1311.dcpage.html
(It works the same outdoors, no one is sitting in the trees either.)
I realize you were trying to predict coverage of conventional speakers, but the fact is, no combination of conventional speakers will ever properly cover ANY real listening environment.
Thanks Perry!
You might also find PAcalculate useful. It’s a free multi-platform multi-lingual mobile app which I developed which includes over 25 calculators:
iOS : https://itunes.apple.com/us/app/pacalculate/id793460437
Android : https://play.google.com/store/apps/details?id=com.PAcalculator
Thanks Joe! I have it. Very cool.
Greetings Nathan! I can’t get a way to open the calculator, the page shows an error
Hey Bernardo, thanks for catching that. I’ll get it fixed this week. Until then you can download the excel version from here: https://u.pcloud.link/publink/show?code=XZLuIxXZgRa67bw5Hq5Yk0Bnekz9hJ2GtmzX
reviewed, thank you very much !!! successes