Speaker Placement Calculator

RP22 is the Immersive Audio Design Recommended Practice from CEDIA and the Consumer Technology Association: a vendor-neutral way to design and grade a home theater’s sound for every seat, not just the best one. It sets four Performance Levels across 21 parameters — from how many speakers there are and where they sit, to output, noise and frequency response.

This tool grades the spatial parameters: seat distance from the walls, speaker count, speakers in their zones, the angles between neighboring speakers, and how evenly each group plays across the seats. The others need measurements in the finished room.

The format guidelines say where speakers go for one listener: target angles and acceptable ranges from the main listening position, so the format’s renderer has the speakers it expects. RP22 does not replace them — it takes them as the starting point and adds what they leave out when there are several seats and rows: zones each speaker must stay in, limits on the angle gaps between speakers as seen from every seat, and limits on how much louder one speaker of a group is than another at each seat.

The two can pull in different directions. A surround at the format’s ideal angle from the reference may be too close to an end seat for RP22, and RP22’s more even layout may sit near the edge of a format’s range. The calculator checks both and shows which one is limiting.

RP22: CEDIA’s Immersive Audio Design page is where CEDIA publishes the recommended practice, and the current version is a free download.

Dolby Atmos home: the Home Theater Installation Guidelines, and Dolby’s speaker setup guides, one page per layout.

Dolby Atmos studio: the Home Entertainment Studio Technical Guidelines, on Dolby’s professional support site — the reference the mixing rooms are built to.

DTS and DTS:X: DTS publishes no placement specification of its own. The guidance most designers use is RP22’s summary of DTS:X, with the extra DTS:X Pro positions following ITU-R BS.2051.

Auro-3D: the Home Theater Setup Guidelines.

These documents are revised from time to time; check the publisher for the latest edition.

The home guidelines are written for living rooms and dedicated theaters and allow wider ranges. The studio guidelines are what Atmos mixing rooms are built to, with tighter targets. Designing to the studio angles puts the speakers where the mix was made; the home ranges are what Dolby considers acceptable at home. The calculator uses the home guide by default and can switch to the studio targets.

1. Describe the room first: its dimensions, the screen, and every row of seating with its riser, ear height and recline. Positions are only as good as these numbers.

2. Decide on the speaker layout — 5.1.2, 7.1.4, 9.1.6 and so on. It is usually set by what your receiver or processor can drive, what the room is already wired for, or both. Then choose the formats you want to play — Atmos, DTS:X, Auro-3D — and whether to hold the design to RP22.

3. Set the mounting for each pair: in-wall, on-wall, on a bracket, on a stand or floor-standing, with the cabinet’s size and the product’s rated coverage if you have them. Both change where a speaker can go and how it covers the seats.

4. Run Optimize for RP22, then look at what limits the level: the panel names the parameter and the seat holding it back.

5. Adjust by hand with each pair’s sliders, watching the plan, the side section and the 3D view, and the seats viewed from the back row and the ends.

6. Optimize the aim last, once positions are settled, and check the estimate with aim.

7. Save or share the layout: the link carries the whole room.

RP22 grades how evenly each group of speakers plays across the seats from distance alone, as if every speaker radiated equally in every direction. That is the standard’s own method, so the RP22 level is what the room scores by the book — and aiming a speaker never changes it.

In reality a speaker is loudest straight ahead and quieter off to the side, so where it points matters. The estimate with aim adds each speaker’s off-axis loss toward every seat, from its rated coverage, and grades the result with RP22’s thresholds. It is an estimate, not an RP22 level: it shows whether aiming makes the seats more even or less. RP22 recommends aiming every speaker at the reference position but does not score it.

A speaker on a bracket or stand has to be turned to point at the seats, and a deep cabinet turned toward the room swings its back corner into the wall. The calculator keeps each cabinet far enough off the wall, the ceiling and the neighboring wall to point the way it is aimed, and draws it at that size. Without figures it assumes a typical cabinet for the type and says so; the product’s spec sheet gives width, height and depth.

Look on the spec sheet for “coverage”, “nominal coverage”, “dispersion” or “directivity”. It is usually given as two angles, horizontal × vertical — for example 90° × 90° — and they are the angles at which the speaker’s output has fallen 6 dB below what it plays straight ahead. Speakers with a horn or a waveguide around the tweeter publish it most often; many conventional speakers do not publish it at all.

A single figure, such as 120°, means the same angle both ways, which is common for coaxial speakers: enter it as both the horizontal and the vertical. A speaker that rotates its tweeter or horn swaps the two figures when you turn it.

When the spec sheet has nothing, independent reviews often publish off-axis (polar) measurements: a set of response curves at 10°, 20°, 30° and so on from straight ahead. Find the angle where the treble — roughly 2 to 10 kHz — has dropped about 6 dB from the on-axis curve, and double it: that is the coverage. Reviews that follow the ANSI/CTA-2034 standard (often called a spinorama) show the same data in a consistent form.

With no figure at all, keep the calculator’s default of 90° × 90° — about 45° either side of the speaker’s axis, which is what Dolby describes as wide dispersion and the most common figure among the manufacturers that publish one. It is an assumption, and the calculator labels it as one.

Either way, the off-axis levels the calculator shows are estimates. Real speakers narrow as frequency rises, so a single coverage figure is an average, and the model treats every speaker as a point source — tall panel or line-source speakers, such as electrostatics, spread differently in the vertical direction than the estimate assumes.