Line Array Spacing Calculator

Enter your top and bottom throw distances, audience rows, and box count to calculate optimal splay angles and per-box coverage zones for your line array system.

Created by Luis GonzalezLast updated: May 9, 2026

How to Use This Calculator

1
Enter Top Box Throw (m)
Input the distance from the line array to the farthest edge of the audience, in meters.
2
Enter Bottom Box Throw (m)
Input the distance from the line array to the nearest edge of the audience, in meters.
3
Enter Audience Rows
Input the total number of audience rows from the front to the back of the seating area.
4
Enter Number of Boxes
Input the total number of individual loudspeaker boxes comprising your line array.
5
Review Your Results
The calculator will display the total spread, splay per box, SPL variation, and detailed coverage zones.

Example Calculation

A sound engineer is setting up a line array for a poolside event, with the farthest audience row 30m away and the nearest 10m away, using 12 boxes to cover 20 rows.

Top Box Throw (m)

Bottom Box Throw (m)

Audience Rows

Number of Boxes

Results

45 °

Tips

Consider Audience Geometry

Accurate throw distances are crucial. Use laser rangefinders to measure the distance to the front and back of the audience area, as well as the height of the array, for precise splay angle calculations.

Balance SPL Uniformity

Aim for minimal SPL variation (ideally less than 6 dB) across the entire audience area. Adjusting splay angles is key to achieving consistent sound levels from the front to the back rows.

Account for Box Vertical Coverage

Each loudspeaker box in a line array has a specific vertical coverage angle. Ensure your 'splay per box' settings do not exceed this angle, or you risk creating gaps in coverage or unwanted comb filtering.

Precision Sound Design: Optimizing Your Line Array Spacing

The Line Array Spacing Calculator is an indispensable tool for sound engineers and event planners, enabling precise configuration of PA systems for optimal audience coverage. By calculating splay angles, predicting SPL variation, and defining per-box coverage zones, this tool ensures uniform sound distribution across any venue. Achieving consistent sound pressure levels from the front to the back rows is paramount for high-quality audio experiences at concerts, festivals, and large-scale events.

Optimizing Audio for Poolside Entertainment Systems

While this Line Array Spacing Calculator is primarily designed for large venue professional audio, its underlying principles of sound distribution are directly applicable to optimizing outdoor sound systems, such as those installed around pools. Proper speaker placement and aiming, analogous to a line array's splay angles, are crucial to minimize sound spill into neighboring areas while ensuring uniform sound coverage for poolside guests. The goal is often to achieve a balanced sound pressure level (SPL) of 85-90 dB in listening zones, without excessive volume that could disturb others, creating an enjoyable and immersive audio experience that complements the poolside ambiance.

The Geometry of Line Array Sound Coverage

The Line Array Spacing Calculator determines optimal splay angles and coverage zones by applying geometric principles to the audience area. It considers the Top Box Throw (farthest audience distance) and Bottom Box Throw (nearest audience distance), along with the Number of Boxes in the array and the Audience Rows.

The core calculations involve:

Total Vertical Coverage Angle: This is derived from the inverse tangent of the audience depth relative to the array's height.
Splay Angle Per Box: The total vertical coverage angle is divided by the number of boxes to get an initial splay angle.
Individual Box Angles and Zones: Each box is then assigned a specific splay angle, often with tighter angles at the top (for distant throw) and wider angles at the bottom (for near-field coverage), to create a smooth, continuous sound field.

This method ensures that sound energy is efficiently directed to the entire audience.

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Worked Example: Configuring a Poolside Line Array

A sound engineer is preparing for a large poolside event. The Top Box Throw is 30 meters, the Bottom Box Throw is 10 meters, there are 20 Audience Rows, and the system uses 12 Number of Boxes.

Input Top Box Throw (m): Enter 30.
Input Bottom Box Throw (m): Enter 10.
Input Audience Rows: Enter 20.
Input Number of Boxes: Enter 12.

The calculator first determines the overall vertical coverage needed to span the distance from 10m to 30m. It then divides this total spread among the 12 boxes, adjusting for the varying distances. For instance, the top boxes might be splayed at 1-2 degrees for long throws, while the bottom boxes might have a wider splay of 5-8 degrees to cover the front rows.

The Total Spread for this setup is estimated to be around 45 degrees, ensuring comprehensive vertical coverage across the entire audience area, from the closest to the farthest listeners.

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Standard Splay Angles and SPL Targets in Live Sound

In professional live sound reinforcement, standard splay angles and Sound Pressure Level (SPL) targets are meticulously planned to achieve optimal coverage and sonic impact. For the main line array, splay angles typically range from 0.5 to 5 degrees between adjacent boxes, with tighter angles (e.g., 0.5-2 degrees) used for the top boxes to achieve long throws (over 50 meters) and higher SPL (105-110 dB at front-of-house). Wider angles (e.g., 3-5 degrees) are common for the bottom boxes to cover closer audience areas with a broader dispersion, maintaining an SPL of 95-100 dB. Front-fill speakers, used for the very first rows, might have even wider splay angles (10-15 degrees per box) to ensure consistent coverage, aiming for a smooth SPL transition and minimal variation (ideally less than 6 dB) across the entire audience plane.

Frequently Asked Questions

What is a line array PA system?

A line array PA (Public Address) system is a loudspeaker system composed of multiple identical loudspeaker elements mounted in a vertical column, designed to create a coherent wavefront. Unlike traditional point-source speakers, line arrays use constructive interference to project sound over long distances with a narrow vertical dispersion pattern, providing more uniform sound pressure levels across large audience areas, from the front rows to the very back of a venue or outdoor space.

Why is splay angle important in line arrays?

Splay angle, the angle between adjacent loudspeaker boxes in a line array, is critically important because it controls the vertical coverage and sound distribution across the audience. Properly setting splay angles ensures that sound energy is directed precisely to where the audience is located, minimizing wasted energy and maximizing sound pressure level (SPL) uniformity. Incorrect splay can lead to uneven coverage, hot spots, or dead zones, compromising the listening experience.

What is SPL variation in line arrays?

SPL (Sound Pressure Level) variation refers to the difference in sound loudness measured at various points within the audience area covered by a line array. The goal in professional audio is to achieve minimal SPL variation, ideally within a 3-6 dB range from the front to the back of the audience. High SPL variation means some audience members experience much louder or quieter sound than others, leading to a poor and inconsistent listening experience across the venue.

How does the number of boxes affect line array performance?

The number of boxes in a line array significantly affects its performance, particularly its vertical directivity and throw distance. More boxes allow for finer splay angle increments, enabling more precise tailoring of the vertical coverage pattern to the audience geometry. A longer array (more boxes) also typically provides better control over low-frequency directivity and can achieve greater throw distances with less sound decay over distance, which is crucial for large outdoor events or very deep venues.