Dolby Professional Support：《How to Design a Dolby Atmos Mix Room》（2026-02）、《Best Practices for Dolby Atmos Music Studios》（2024-09）、《5.1.4 Speaker Placement for Dolby Atmos Mix Rooms》（2026-07）、《Is 85 dBC the recommended monitoring level》、《DARDT HE+Music FAQs》、《What is time alignment》、《What is Bass Management》、《Case Study: Designing a Dolby Atmos Studio》。
Dolby Professional Support：《How to Design a Dolby Atmos Mix Room》（2026-02）、《Best Practices for Dolby Atmos Music Studios》（2024-09）、《5.1.4 Speaker Placement for Dolby Atmos Mix Rooms》（2026-07）、《Is 85 dBC the recommended monitoring level》、《DARDT HE+Music FAQs》、《What is time alignment》、《What is Bass Management》、《Case Study: Designing a Dolby Atmos Studio》。
Version 2026-09-11. This manual covers every panel and column of the tool. Start with “Quick start” if you want to get going; jump to “Sources” if you want to know where the numbers come from.
What it is
A Dolby Atmos mix-room planner that runs in your browser. Give it the room’s depth, width and height plus your mix position, and it returns:
where every speaker goes on the walls or ceiling (from the left wall, from the front wall, above the floor)
each speaker’s distance to the mix position, the delay to add, the level trim, and how far to aim it
whether the layout sits inside the tolerances of Dolby’s “How to Design a Dolby Atmos Mix Room” (2026) or ITU-R BS.2051-2
whether the room itself passes Dolby’s hard limits (minimum speaker distances, mix-position ratio, overhead height)
whether your chosen speaker models are loud enough at that position (DARDT-style headroom) and whether they need bass management
It runs entirely in the browser and uploads nothing; the design lives in the URL and in localStorage.
Not a Dolby tool and not Dolby’s DARDT database. Spec numbers come from Dolby Professional Support articles and the ITU recommendation; speaker specs from the manufacturers’ websites. For a formal design use the Dolby Atmos Room Design Tool and a Dolby Certified Service Partner.
Quick start
Measure the room: depth (front wall to rear wall), width (left to right), height (floor to ceiling); enter them under “Room”.
Set the mix position: how far your ears are from the front wall and the left wall when seated, and ear height (Dolby: 1.2–1.3 m).
Choose the setup: layout (7.1.4 and up), spec (Dolby or ITU), monitoring level (85 / 82 / 79 dBC).
Read the result: the summary bar at the top of the right column says how many speakers are in range and how many room checks pass; the plan and 3D show positions; the table gives coordinates and delays.
Match the real room: type measured coordinates into the table and the angles are recomputed; then “Export CSV” for the installer or “Copy link” to share.
Plan view of the default room (5.5 × 4.2 × 2.8 m, 7.1.4, Dolby spec): front wall at the top, red = ear level, blue = overheads, grey square = LFE, dashed square = the four overheads.
Screen overview
Top bar
Control
What it does
Language 繁中 / 简中 / EN / 日本語
Interface language, remembered in the browser. Japanese is machine-written and not proofread by a native speaker.
Units m / ft
Display and input only; internally everything is metres.
Theme System / Light / Dark
Follows the system by default.
Export CSV
Speaker list with coordinates, delays, models, headroom — 26 columns.
Export / Import JSON
Save and restore the whole design.
Copy link
Encodes the whole state into the URL; whoever opens it sees the same design.
Print
Hides the controls and prints plan, elevations, room checks and the table.
How to use (collapsible), summary bar, plan and 3D, elevations (side and front), speaker list.
Room and mix position
Coordinate conventions
The origin is the corner where the front wall, left wall and floor meet. x from the left wall, y from the front wall, z above the floor, in metres.
Azimuth 0° is straight ahead (facing the front wall); positive = left, negative = right (the ITU-R BS.2051 sign convention; Dolby’s figures say “30° left and right”, which is the same thing).
Elevation is polar (true) elevation. Overheads also have Dolby’s “side-view / rear-view angles”, explained in the next chapter.
Distances are to the baffle
Dolby measures every distance to the speaker baffle (front panel / acoustic centre), not the back of the cabinet. The “setback” fields are baffle-to-wall distances; allow for cabinet depth and brackets when you measure (an overhead cabinet plus bracket of 0.3 m needs a 2.7 m ceiling to reach Dolby’s 2.4 m baffle height).
Mix position
“From front wall” is your ears’ distance to the front wall. Dolby wants it at 30–70 % of the distance from the centre-speaker baffle to the rear-surround line; converted stereo rooms are often too far forward, and moving back 20–30 cm usually fixes it.
“From left wall” defaults to the centre line; “centre” puts it back.
Ear height: seated ear height, Dolby 1.2–1.3 m; ear-level acoustic centres go at this height.
Setup
Layout
Layout
Ear level
Overheads
Dolby’s position
5.1
L R C Ls Rs
—
no height, reference only
7.1
L R C Lss Rss Lrs Rrs
—
same
5.1.4
L R C Ls Rs
Ltf Rtf Ltr Rtr
usable minimum, not eligible for the Studio Directory
7.1.4
L R C Lss Rss Lrs Rrs
Ltf Rtf Ltr Rtr
preferred minimum
9.1.4
7.1 + Lw Rw
four
standard reference design
9.1.6
7.1 + Lw Rw
six (+ Ltm Rtm)
standard reference design
The “Out” column is the default Dolby Atmos Renderer output order (L R C LFE Lss Rss Lrs Rrs Ltf Rtf Ltr Rtr; in 9.1.x the wides follow Rrs and precede the overheads — check against your Renderer version).
Spec sets
Dolby (How to Design a Dolby Atmos Mix Room, 2026)
Position
Nominal
Tolerance
C
0°
—
L / R
30°
20°–45°
Lw / Rw
L/R +20°
+15°–+25°
Lss / Rss
100°
90°–110°
Lrs / Rrs
135°
120°–160°
Ls / Rs (5.1.4)
110°
90°–120°
side ↔ rear surround
—
≥ 30°
ear-level elevation
0°
front and side ≤ 20°, rear ≤ 25°
overhead side-view angle
45°
30°–55°
overhead rear-view angle
45°
45°–55°
Dolby does not define overheads by polar elevation. It says: seen from the side, the vertical angle from the mix position to the front / rear overheads is 45°; seen from the rear, the angle to the left / right overheads is 45°. The four overheads therefore form a square centred on the mix position with sides of 2 × (vertical distance from ear height to the overhead baffle). A corner of that square is at 35.3° true elevation, not 45°. In 9.1.6 the middle pair sits between front and rear at the same height, 45° in rear view.
ITU-R BS.2051-2 (Systems B / D / I / J)
Position
Azimuth
Elevation
L / R
30°–45° (Systems B / D: 30° fixed)
0
Ls / Rs (5.1)
100°–120°
0–15°
Lss / Rss
85°–110°
0
Lrs / Rrs
120°–150°
0
Ltf / Rtf
30°–45°
30°–55°
Ltr / Rtr
100°–150°
30°–55°
same-side surround spacing
30°–60°
ITU has no wides or top middles; the tool borrows Dolby’s values and marks them “borrowed”.
Monitoring level
Only affects the speaker-model headroom estimate. Dolby: commercial music studios 85 dBC; small / single-operator rooms 79–82; HE / post 79 (79–85 acceptable).
Placement mode
On walls / ceiling (default)
C / L / R / wides follow their nominal azimuth until they hit the front or a side wall (minus the ear-level setback).
Side surrounds land on the side walls.
Rear surrounds sit on the rear-wall line; when the nominal angle does not reach the side wall they are pushed into the corners, and the actual angle is checked against the tolerance. This is what the Dolby Room Design Tool does for its “ideal” positions and what Dolby’s case study shows.
Overheads use Dolby’s square: overhead baffle height (blank = ceiling − setback) minus ear height = dz; front/back distance dz / tan(side-view angle), left/right distance dz / tan(rear-view angle). If the square does not fit, the speaker is clamped to the wall and the projected angle is flagged.
Equidistant sphere
Every speaker at the same radius (overheads along their projected-angle direction), so all delays are zero.
A radius that reaches past the nearest wall flags that speaker and shows in the room checks. “Suggest” uses the distance to the nearest wall.
Setbacks and overhead height
Ear-level setback: baffle to wall, default 0.3 m.
Overhead setback: baffle to ceiling or wall, default 0.2 m.
Overhead baffle height: blank = ceiling − setback; type a value when brackets limit the height.
Reading the result
Summary bar
“11 speakers · 11 in range · room checks 7/7 passed · max delay 4.87 ms”. With models assigned it adds how many are short of headroom and how many need BM. All green: go straight to the table. Anything red: scroll down for the reason.
Plan view
Front wall at the top. Hover a speaker or a table row: ear-level speakers show their azimuth tolerance wedge and nominal line; overheads show the allowed floor-position rectangle (derived from the side/rear-view ranges). Clicking a speaker scrolls to its row.
3D preview
Drag to orbit, wheel or + / − to zoom, double-click to reset. Four views: iso, front, top, mix position (looking out from the chair; dragging then turns your head). Hovering a speaker highlights it in the table too.
3D preview of the same room (iso): 0.5 m floor grid, dashed overhead square, dotted drop lines to the floor.
Elevations
Side view (front wall on the left) and front view (facing the front wall). Mirror pairs coincide in projection and their labels merge (“Ltf/Rtf”). Hovering an overhead shows the side-view tolerance wedge in the side view and the rear-view wedge in the front view.
Side view: ear level at 1.2 m, overheads at 2.6 m, 1.4 m in front of and behind the mix position — a 45° projected angle.Front view: left and right overheads 1.4 m either side of the centre line, 45° rear-view angle.
Room checks
Check
Limit
Why
Source
Side-surround baffle to baffle
≥ 3.0 m
too close collapses lateral imaging; Dolby uses it instead of a minimum width
Dolby 2026
Centre baffle → rear-surround line
≥ 3.5 m
too short collapses depth; 5.1.4 uses a notional 135° rear
Dolby 2026
Mix position
30–70 % of centre → rear line
too far forward and the balance will not translate
Dolby 2026
Floor → lowest overhead baffle
≥ 2.4 m
overheads too low blur into the ear-level layer
Dolby 2026
Ear-level height
≤ 70 % of overhead height
raised too high, not enough separation from the overheads
Dolby 2026
Side ↔ rear surround
≥ 30°
too close in angle acts like one pair
Dolby 2026
Ear height
1.2–1.3 m (note)
seated ear height
Dolby Best Practices
Headroom
every speaker ≥ 0 dB
see “Speaker models and headroom”
DARDT FAQ
Needs bass management
info
speakers that do not reach 40 Hz
Dolby Best Practices
Overhead square, distance spread
info
square sides; farthest minus nearest = delay to compensate
computed
“Why” in the panel header expands the reason for every line.
Speaker list
“Simple columns” by default; “Advanced columns” shows everything. Every header has a tooltip.
Column
Meaning
Editable
Speaker
label, name, where it landed (front wall / left wall / ceiling / pushed to corner / manual)
Out
default Renderer output number
Nom. az / el (advanced)
the spec’s target angle
yes = new nominal, still placed by the placement mode; wides follow L/R
Side / Rear (advanced, Dolby)
overhead projected angles
yes
Actual az / el
derived from the real position
x from left / y from front / z height
baffle coordinates
yes = manual placement; angles and status recomputed
Distance
to the mix position
Delay ms
(farthest − this) ÷ 343 m/s; farthest speaker 0
Trim dB (advanced)
−20·log10(farthest ÷ this), free-field estimate
Aim (advanced)
toe-in / toe-forward and tilt in degrees
Model (advanced)
speaker model
select
Peak SPL@1m (advanced)
the model’s DARDT-equivalent peak; typable when no model is chosen
type
Headroom (advanced)
dB above monitoring level at the mix position
Status
OK / marginal (< 5° outside) / out (≥ 5°); with the amount
↺
restore this speaker
Adjusting and overriding
Nominal angles: set L/R to 35° and watch the wides move to 55° and the status stay in or out of tolerance.
Manual coordinates: type the measured baffle coordinates into x / y / z; angles and status update immediately — this is the “is my room right?” workflow.
↺ restores one speaker; “Clear all overrides” resets everything; the override count shows at the bottom of Setup.
My rooms: saves the current state (name, date) in the browser; “Example” loads Dolby’s case-study room.
The whole state lives in the URL hash; “Copy link” and paste it anywhere.
Speaker models and headroom
Database
70 models from 15 brands (Genelec, Neumann, Kali Audio, Focal, ADAM Audio, JBL, Dynaudio, ATC, HEDD, Barefoot Sound, Meyer Sound, Ex Machina, PMC, EVE Audio, KRK), each with the manufacturer’s published maximum SPL (and its measurement basis), low-frequency extension and the source URL.
Using it
Pick a model per speaker in the advanced columns, or use “Assign models quickly” above the table for all ear-level / overheads / LFE at once. With a model selected:
“Peak SPL@1m” becomes the model’s DARDT-equivalent peak (hover for the basis: a DARDT value published by the manufacturer, or converted from the manufacturer’s spec).
Headroom = equivalent peak − 6 (peak → continuous) + 2 (room loading) − 20·log10(distance) − (monitoring level + 20 for L/C/R, + 17 for surrounds and overheads, + 30 for LFE). This is the formula from Dolby’s DARDT FAQ.
Models whose −3 dB point is above 40 Hz get a BM flag: Dolby wants every speaker to cover 40 Hz–18 kHz ±3 dB, otherwise route the low end to a sub. “BM?” means the manufacturer gives no −3 / −6 dB figure.
Normalising the bases
Manufacturers define “maximum SPL” differently: Genelec quotes peak per pair with music, Neumann publishes Dolby DARDT values directly, ADAM gives sine-burst and IEC-noise peaks, PMC gives half-space continuous, EVE’s tables say per pair, Kali and KRK do not say. The tool converts each to a “DARDT-equivalent peak @1 m”:
Manufacturer basis
Conversion
published DARDT value
as is
peak per speaker @1 m
+0
peak per pair
−6
3 % THD average, full space (Neumann)
+2
continuous @1 m
+6
continuous, half space (PMC)
+3
“Max SPL”, basis unstated
+0 (taken as peak)
sub peak (half space)
+0
sub short-term sine
+6
The full table and every judgement call are in docs/SPEAKERS.md in the repository. Because the bases differ, headroom is an estimate — treat it conservatively and calibrate with pink noise.
Reading it
Negative headroom: this speaker is not loud enough at this distance and level. Four ways out: lower the level (85 → 82 → 79), move closer (shrink the radius in equidistant mode), go one size up, or add a second sub for the LFE.
Example: the default room (5.5 × 4.2 × 2.8 m) with Genelec 8341A at ear level, 8330A overheads and one KH 750 DSP for LFE gives, at 85 dBC, L/R −3.8 dB, rears −4.9, overheads −9.7, LFE −12.8; at 79 dBC it becomes L/R +2.2, rears +1.1, overheads −3.7, LFE −6.8. “8341A is not enough at 85 dBC” is what DARDT users report, and the tool agrees.
A subwoofer chosen for a main channel, or a monitor for the LFE, shows up in the room checks.
Custom models
Left column “Speaker database → Custom models”: brand, model, type, SPL, basis, −3 dB low end. Stored in this browser; deleting one clears it from any speaker using it.
The first line is a comment (room, mix position, mode, level, timestamp). Coordinates are always metres; x_dardt_from_centreline_m is the Dolby Room Design Tool’s coordinate system (origin on the front-wall centre line).
JSON, link, print
JSON: the whole state (room, setup, overrides, models); “Import JSON” restores it.
Link: the state is base64-encoded into #s=; language and units are not included (each browser remembers its own).
Print: plan, elevations, room checks, table and a one-line summary; 3D and controls are not printed.
Tutorial: walking through Dolby’s case-study room
Dolby’s case study is a home stereo room converted to 7.1.4: 13.5 × 12 × 8.8 ft ≈ 4.1 × 3.7 × 2.7 m, mix position originally 3.5 ft (1.1 m) from the front wall. Follow along:
In “My rooms” press Example: room 4.1 × 3.7 × 2.7, mix position 1.5 m, ear 1.2, overhead baffle 2.375 m, monitoring 79 dBC.
Change “Mix position from front wall” back to 1.1. The summary bar shows “room checks 5/7”: mix position 23.6 % (< 30 %) fails and overheads 2.375 m (< 2.4) fail — exactly the two messages DARDT gave the case-study owner.
Mix position 1.1 m: the front three are too close, and the overhead square is squeezed against the front wall (2.35 × 2.08 m).
Set it back to 1.5: mix position becomes 34.7 %, pass; only the overhead height remains, 2.5 cm short — in the case study the Dolby Certified Service Partner accepted that, and so can you.
Mix position 1.5 m: rear surrounds pushed into the rear corners (145.8°, still inside 120–160°), overhead square 2.35 × 2.35 m.
Read the table: C 1.25 m from the mix position, L/R 1.44 m, side surrounds 1.62 m, rear surrounds 2.84 m (farthest, delay 0), overheads 2.04 m. Delays: C 4.64 ms, L/R 4.08, sides 3.55, overheads 2.36. Max delay 4.64 ms.
Switch to “Advanced columns” and assign: ear level Kali LP-6 v2, overheads LP-6 v2, LFE WS-6.2 (the gear from the case study). At 79 dBC the headroom is C +10.1, L/R +8.8, sides +10.8, rears +5.9, overheads +8.8, LFE +2.9 — all ≥ 0, the “Headroom” check turns green, matching the case study’s “LP-6 has 20 dB of headroom at 79 dB”.
All eleven ear-level and overhead speakers carry a BM flag: the LP-6 v2’s −3 dB point is 47 Hz and Dolby wants 40 Hz, so bass management is required — in the case study the WS-6.2 does both LFE and bass management.
Try 85 dBC and watch the headroom drop; switch to 9.1.6 to see where the wides and top middles land; press “Export CSV”.
FAQ
Why is the true elevation of the overheads 35°, not 45°? Dolby’s 45° is a projected angle in the side and rear views. A corner of the square sits at (h, h, h), whose true elevation is atan(1/√2) = 35.3°. ITU’s 30–55° is true elevation, and 35.3° is inside it.
Why are the rear surrounds not at 135°? Wall mode puts them on the rear-wall line; when the room is not wide enough for 135° to reach the side wall, they are pushed into the corners and end up at 140–160°. Dolby allows 120–160°, and the status tells you if you are outside. For exactly 135°, use equidistant mode or type the rear-surround coordinates on the side walls.
Equidistant or on walls? Dolby accepts both. Equidistant needs no delays but in large rooms puts speakers far from the walls; wall placement saves space and relies on delays. Small rooms usually go on the walls.
Negative headroom? See “Speaker models and headroom → Reading it”.
My speaker is not in the database. Add a custom model with the maximum SPL and basis from the manufacturer’s spec sheet, or type a “Peak SPL@1m” directly in the advanced columns.
How is this different from Dolby’s DARDT? Same design guide, same headroom formula, but DARDT’s speaker data are entered by manufacturers to Dolby’s definition, while these come from public spec pages. DARDT also has amplifier data and a commissioning sheet; this tool does not.
Does it work offline? Yes. Save the single HTML file and double-click it; it makes no external requests.
Sources and disclaimer
Dolby Professional Support: “How to Design a Dolby Atmos Mix Room” (2026-02), “Best Practices for Dolby Atmos Music Studios” (2024-09), “5.1.4 Speaker Placement for Dolby Atmos Mix Rooms” (2026-07), “Is 85 dBC the recommended monitoring level”, “DARDT HE+Music FAQs”, “What is time alignment”, “What is Bass Management”, “Case Study: Designing a Dolby Atmos Studio”.
Rec. ITU-R BS.2051-2 (2018-07).
Speaker specs: manufacturer product pages (URL with every entry).
Dolby, Dolby Atmos and DARDT are trademarks of Dolby Laboratories; speaker brand and model names belong to their manufacturers. This tool is not affiliated with any of them.
Glossary
Azimuth az: horizontal angle of the speaker from straight ahead, seen from the mix position; positive left, negative right.
