Loudspeaker coverage
Speaker Coverage Angle Chart
Quick answer
A 90 degree horizontal loudspeaker covers 80 feet of seating width at a 40 foot throw and 120 feet at 60 feet, because coverage width equals twice the distance times the tangent of half the angle. A 60 degree box covers only 46 feet at that same 40 foot throw.
Coverage is the half of loudspeaker specification that gets ignored, and it is the half that decides whether the outside seats hear the same service as the middle ones. A loudspeaker is not a light bulb. It radiates into a defined wedge, quoted as horizontal degrees by vertical degrees, and outside that wedge the level falls away by 6 dB and the high frequencies disappear faster still.
The arithmetic is one line: width = 2 x distance x tan(angle / 2). Everything below is that formula applied to the patterns loudspeakers are actually sold in. Work your own room with the speaker coverage calculator or the sanctuary coverage calculator.
On this page
Which coverage pattern suits which room?
These are the five patterns that cover almost every point-source loudspeaker sold for installed church work. The horizontal figure is quoted first and is the one that decides how many boxes a room needs.
The default 90 by 50 degree box covers 80 feet of width at a 40 foot throw, while a 60 by 40 degree box covers 46 feet and a 120 by 60 degree box covers 139 feet at the same distance.
| Pattern | Where it belongs | Width at 40 ft | Width at 60 ft | Width at 80 ft |
|---|---|---|---|---|
| 90 by 50 degrees | The default point-source box, wide rooms of normal depth | 80.0 ft | 120.0 ft | 160.0 ft |
| 60 by 40 degrees | Narrow, deep rooms and long throws; keeps energy off side walls | 46.2 ft | 69.3 ft | 92.4 ft |
| 100 by 100 degrees | Fills, front fills and very wide fan-shaped rooms | 95.3 ft | 143.0 ft | 190.7 ft |
| 120 by 60 degrees | Short-throw wide coverage, small rooms and balconies | 138.6 ft | 207.8 ft | 277.1 ft |
| 70 by 70 degrees | Under-balcony delays and square-ish side rooms | 56.0 ft | 84.0 ft | 112.0 ft |
Widths are the nominal coverage at the stated throw, measured at the points where output has fallen 6 dB from the on-axis level. Real cabinets narrow with frequency: a box quoted as 90 degrees at 2 kHz is often 60 degrees or less at 8 kHz and close to omnidirectional below 250 Hz.
Coverage width at every throw distance
The full grid. Find your throw distance down the left, read across to your pattern, and compare the result to the width of your seating at that distance. If the number is smaller than your seating, the outside seats are outside the coverage and no amount of level will fix it.
At a 60 foot throw a 90 degree box covers 120 feet of width, a 60 degree box covers 69 feet and a 120 degree box covers 208 feet.
| Throw distance | 60 degrees | 70 degrees | 90 degrees | 100 degrees | 120 degrees |
|---|---|---|---|---|---|
| 20 ft | 23.1 ft | 28.0 ft | 40.0 ft | 47.7 ft | 69.3 ft |
| 30 ft | 34.6 ft | 42.0 ft | 60.0 ft | 71.5 ft | 103.9 ft |
| 40 ft | 46.2 ft | 56.0 ft | 80.0 ft | 95.3 ft | 138.6 ft |
| 50 ft | 57.7 ft | 70.0 ft | 100.0 ft | 119.2 ft | 173.2 ft |
| 60 ft | 69.3 ft | 84.0 ft | 120.0 ft | 143.0 ft | 207.8 ft |
| 70 ft | 80.8 ft | 98.0 ft | 140.0 ft | 166.8 ft | 242.5 ft |
| 80 ft | 92.4 ft | 112.0 ft | 160.0 ft | 190.7 ft | 277.1 ft |
| 100 ft | 115.5 ft | 140.0 ft | 200.0 ft | 238.4 ft | 346.4 ft |
Width is measured at the listening plane at the stated distance from the loudspeaker, not from the front of the platform. Measure the throw to the furthest seat the box is responsible for.
What pattern does your seating width need?
Working the formula backwards is more useful, because you know your room and you are choosing a box. Measure the widest part of the seating the loudspeaker has to cover and the distance from the loudspeaker to that point.
Covering 50 feet of seating width from a loudspeaker 60 feet away needs a 45 degree horizontal pattern, so a single 90 degree box would be wasting more than half its energy on the walls.
| Seating width to cover | Throw distance | Pattern required | Nearest standard box |
|---|---|---|---|
| 30 ft | 50 ft | 33.4 degrees | Narrow 40 degree or a line array element |
| 40 ft | 60 ft | 36.9 degrees | Narrow 40 degree box |
| 40 ft | 30 ft | 67.4 degrees | 70 by 70 degree box |
| 50 ft | 60 ft | 45.2 degrees | 60 by 40 degree box |
| 60 ft | 80 ft | 41.1 degrees | 60 by 40 degree box |
| 80 ft | 100 ft | 43.6 degrees | 60 by 40 degree box |
These figures are for one loudspeaker covering the full width alone. A left and right pair each cover roughly half the width, which is why a pair of 60 degree boxes often solves a room that one 90 degree box cannot. Energy outside the seating is energy spent exciting the room rather than reaching a listener.
How to read a coverage specification honestly
The quoted angle is a nominal figure at one frequency. Manufacturers usually quote the pattern averaged across a band, commonly 1 to 4 kHz. Below about 250 Hz almost every point-source cabinet becomes close to omnidirectional regardless of what the data sheet says, which is why the low end spills everywhere and why a room’s low frequency problems are rarely solved by aiming.
The coverage edge is the 6 dB down point, not a wall. Sound does not stop at the edge of the wedge. A listener just outside it hears the system at about half the pressure and with noticeably duller high frequencies. That is why the outside seats in a poorly covered room complain that the words are unclear rather than that the system is quiet.
Vertical pattern is what controls the room. The horizontal figure decides how many boxes you need. The vertical figure, usually 40 to 60 degrees on a point-source box, decides how much energy hits the back wall and the ceiling. A box aimed so that its vertical pattern lands on seats rather than on a rear wall is the single biggest improvement available for free.
Aim, then measure. A box tilted down towards the back row with its upper edge just clearing the rear wall reaches further and excites the room less than one hung flat. Loudspeakers aimed flat into a room are the most common installation fault in churches. See how to aim and place church speakers.
Where this chart does not apply
It does not describe line arrays. A line array does not follow the inverse square law or a simple wedge in the vertical plane within its near field, which is the whole point of using one. Its horizontal pattern behaves roughly as tabulated, but its vertical coverage is a function of the array length and the splay between boxes. For rooms deeper than about 80 feet see line array against point source.
It ignores the room entirely. These figures are free field geometry. In a reverberant sanctuary the reflected energy fills in behind the coverage edge, which sounds like coverage but carries no clarity. Good coverage is about direct sound reaching the listener, not about level reaching the listener.
It assumes the loudspeaker is aimed at the area being measured. A cabinet mounted flat on a wall is often aimed at the back wall rather than at the congregation, in which case the tabulated width is being delivered somewhere nobody is sitting.
It does not cover ceiling systems. Distributed ceiling loudspeakers are a conical coverage problem measured from the ear plane rather than a seating-width problem, and they are covered in the ceiling speaker coverage chart.
Two boxes covering overlapping areas interfere. Where the coverage of a left and right box overlaps in the middle seats, the two arrivals comb filter, which is audible as a hollow, phasey quality directly on the centre line. A centre box or a mono cluster avoids it; a stereo pair in a wide room cannot.
Sources
- Loudspeaker manufacturer published horizontal and vertical coverage figures for installed point-source cabinets
- Coverage width geometry as implemented in this site’s speaker coverage calculator
Frequently asked questions
What coverage angle do I need for my church?
Measure the width of seating the loudspeaker must cover and the distance from the loudspeaker to the furthest part of it, then apply the formula width equals twice the distance times the tangent of half the angle. As a guide, covering 50 feet of width from 60 feet away needs about 45 degrees, so a 60 by 40 degree box is the right choice and a 90 degree box would waste most of its energy on walls.
What does 90 by 50 degrees mean on a speaker spec sheet?
Ninety degrees of horizontal coverage and fifty degrees of vertical coverage, measured to the points where output falls 6 dB below the on-axis level. The horizontal figure decides how many boxes cover your seating width. The vertical figure decides how much energy lands on the back wall and ceiling rather than on people, which is what controls reverberation.
Is a wider coverage angle always better in a church?
No, and this is the most common mistake. A wide box in a narrow room sprays energy onto the side walls, and that reflected energy arrives late at the listener and destroys intelligibility. In a deep narrow sanctuary a 60 degree box will sound clearer and reach further than a 120 degree box, even though the wider box covers more seats on paper.
Why do the outside seats sound dull rather than quiet?
Because loudspeaker coverage narrows as frequency rises. A box quoted at 90 degrees may be only 60 degrees at 8 kHz, so a listener at the edge of the nominal pattern is well outside the high frequency pattern. They receive most of the midrange and little of the top, which reads as muffled rather than as quiet.
Do I need a centre speaker as well as a left and right pair?
In a wide room, usually yes. Where the coverage of the left and right boxes overlaps down the centre line, the two arrivals comb filter and the middle seats get a hollow, phasey sound. A single centre cluster, or a mono centre box with the pair used for width, removes the problem. Rooms wider than about 50 feet almost always benefit.
Does coverage angle affect how much amplifier power I need?
Indirectly but significantly. A narrower box concentrates the same acoustic power into a smaller area, so it has higher on-axis sensitivity and reaches a given level with less amplifier power. That is why a long throw box is both narrow and efficient, and it is one reason a narrow pattern often saves money twice over in a deep room.
Researched, not professional advice. This page is compiled from published manufacturer specifications, operator manuals, FCC rules, published standards and owner-review consensus, not hands-on testing. Sound system design, rigging loudspeakers overhead, and any electrical work are jobs for a qualified professional: have flown loudspeakers and their attachment points signed off by a structural engineer or a certified rigger, and have all wiring done by a licensed electrician to your local code. Wireless microphone rules change, so confirm the current FCC position before buying. As an Amazon Associate we earn from qualifying purchases.