In-ceiling Loudspeakers

Design Guide

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Contents PRO.BOSE.COM

Overview 3
Introduction.................................................................................................................................................................................................. 3
System Design Resources............................................................................................................................................................... 3
Overview........................................................................................................................................................................................................ 3
Design Guidelines............................................................................................................................................................................... 3

Design Worksheet 4
Choosing a Model .....................................................................................................................................................................................4
Step 1: Loudness .................................................................................................................................................................................4
Step 2: Ceiling Height ......................................................................................................................................................................4
Step 3: Response................................................................................................................................................................................ 5
Step 4: Coverage ............................................................................................................................................................................... 5
Step 5: Calculate Required Amplifier Size................................................................................................................................ 8

Tap Charts 9
DM2C-LP........................................................................................................................................................................................................ 9
FS2C................................................................................................................................................................................................................. 9
DM3C............................................................................................................................................................................................................... 9
FS4CE........................................................................................................................................................................................................... 10
DM5C............................................................................................................................................................................................................. 10
DM6C............................................................................................................................................................................................................. 10
DM8C...............................................................................................................................................................................................................11

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PRO.BOSE.COM Overview

Overview
Introduction
Using this design guide, you will be able to create designs for applications that utilize in-ceiling loudspeakers.
We offer additional design guides for surface-mount and pendant-mount loudspeakers, as well as dedicated
design guides for EdgeMax and FreeSpace 3 sub-satellite systems. To learn more about our loudspeakers and
technology capabilities, as well as access additional trainings and tutorials, visit proedu.Bose.com/learn.

System Design Resources

In addition to this guide, we offer the following tools at PRO.BOSE.COM on the software and individual
loudspeaker product pages:
• Bose Modeler: advanced acoustical design simulation tool, with direct and reflected energy, and Speech
Transmission Index (STI). Free at pro.Bose.com/modeler
• Bose Business Music System Designer: Web-based auto-loudspeaker layout tool. Free at
pro.Bose.com/BMSD
• EASE .gll files: for use in the AFMG EASE application, and the EASE GLL Viewer application. EASE allows
the simulation of reverberation times, speech intelligibility, and other acoustical parameters. EASE is a
paid download. EASE GLL Viewer is free.
• EASE Address files: for use in the AFMG EASE Address (2D tool, direct field coverage) or EASE Evac.
EASE Address is free.
• BIM files: includes the Revit format. Revit is a paid download.

Overview
All system designs begin with a set of requirements. The system requirements can be as simple as, “it has to
sound great” or as detailed as, “it must play background-level music at 5 dB above the ambient noise level of
the restaurant's main dining room, which is 65 dB.” The challenge is to gather the right set of requirements,
and then turn them into a set of criteria that you can use to create your design. It is important to remember
that you are the designer and should use your own intuition and decision skills when planning a project in
addition to calculations. Applications with mounting heights between 2.4 meters and 10 meters (8 feet and 32
feet) are supported through the in-ceiling loudspeaker models listed in this guide.
There are four key requirements that need to be identified to deliver the right system:
Loudness: What sound pressure level (SPL) is required for this application?
Ceiling Height: What loudspeakers will work best for my room’s ceiling height?
Response: What bandwidth is required for the type of program material that will be used?
Coverage: How consistent must the sound be across the entire coverage area?
Each of these requirements can be easily converted into a specification that we can use to create our system
design. If we understand the customer’s needs in these four areas, we can deliver a design that will—at a
minimum—meet their needs and—at best—exceed their expectations.
For the purposes of this design guide, we will assume that you are familiar with the system requirements for a
commercial audio system and are ready to focus on loudspeaker selection, creation of a loudspeaker layout,
and defining the necessary amplifier power needed to power the design.

Design Guidelines
When creating a design, you should consider the following:
• Ceiling Height
• Maximum SPL for the application (for example 70 dB-SPL, Z-weighted)

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Design Worksheet PRO.BOSE.COM

Design Worksheet
Use the following worksheet to create a design using Bose Professional loudspeakers.

Choosing a Model
Step 1: Loudness
Maximum SPL Capability
Confirm that your chosen loudspeaker model will meet your loudness requirement. Find your ceiling height
and follow the column down until you reach your desired maximum continuous output level. Models with a
higher sensitivity and higher tap settings will be able to play at higher levels. Individual model tap charts are
available at the end of this document.
Example: For a ceiling height of 5 meters (16 feet) in a project that requires 90 dB, you would choose FS4CE.

In-ceiling Models: Maximum Continuous Output Level

Ceiling Height m 2.4 2.7 3 3.7 4 4.3 5 5.5 6 6.7 8 9.8
ft 8 9 10 12 13 14 16 18 20 22 26 32
9W tap 94 92 90 87 86 85 83 82 80 79 77 75
DM2C-LP
16W / 16Ώ 97 94 92 89 88 87 85 84 83 82 80 78
DM3C 25W 98 95 93 90 89 88 86 85 84 83 81 79
FS2C 16W 99 96 94 91 90 89 87 86 85 84 82 84
FS4CE 40W 105 102 100 97 96 95 93 92 91 90 88 86
dB-SPL
DM5C 50W 105 102 100 97 96 95 93 92 91 90 88 86
80W 108 105 103 100 99 98 96 95 94 93 91 89
DM6C
100W / 8Ώ 109 106 104 101 100 99 97 96 95 94 92 90
80W 111 108 106 103 102 101 99 98 97 96 94 92
DM8C
125W / 8Ώ 113 110 108 105 104 103 101 100 99 98 96 94
Note: The above table assumes standing ear height at 1.5 meters (5 feet), in minimum overlap configuration.
Room reverberation could add as much as 4 dB system gain, which is not factored into the measurements
above. Use of the transformer on 70/100V systems will introduce an insertion loss of 1 to 2 dB.

Step 2: Ceiling Height

Average Conical Coverage and Woofer Sizes
Smaller woofer models have wider average conical coverage and provide better results in low ceilings. Larger
woofer models with narrower average coverage angles are better suited for higher ceilings. Choose the
models that will work with your ceiling heights and rule out the other models.
Mounting Height
Mounting Height

m 2.5 5 9.7
ft 8 16 32
SPL Range (at listener height)

<75
C
C, FS2
85 D M3
C- LP,
M2 CE
D FS4
8C
95
6C , DM
C , DM
DM5
>105

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PRO.BOSE.COM Design Worksheet

Highest Tap / Recommended Ceiling

Woofer Size Model Sensitivity (dB)
Power Handling Heights
DM2C-LP (70/100V) 9W
84
DM2C-LP (16Ώ) 16W
2"–4" DM3C 83 25W 2.5 m–6.1 m (8'–20')
FS2C 86 16W
FS4CE 88 40W
DM5C 87 50W
DM6C (70/100V) 80W
88
5"–8" DM6C (8Ώ) 100W 3 m–10 m (10'–32')
DM8C (70/100V) 80W
91
DM8C (8Ώ) 125W

Step 3: Response
Confirm that the chosen loudspeaker will meet your low frequency response requirement.

Vocal-range Low Frequency Full-range Low Frequency Extended- Low Frequency

(–10 dB) (–10 dB) range (–10 dB)
DM2C-LP 85 Hz FS4CE 70 Hz FreeSpace 3 40 Hz
system
FS2C 83 Hz DM5C 65 Hz EdgeMax 45 Hz
EM90/EM180
DM3C 75 Hz DM6C 59 Hz
DM8C 52 Hz Any vocal- 38 Hz
range or
full-range
loudspeaker
combined with
DM8C-SUB
subwoofer

Step 4: Coverage
Determining Loudspeaker Quantity and Spacing
The goal is to fill a rectangle-shaped room with coverage circles at your desired density. Using the graph
paper on the last page, create a sketch layout of the room. Using your sketch of the room, follow the steps
below to create a layout with the loudspeaker spacing that meets your coverage requirement. Calculators or
software can simplify this process. Medium-sized or larger distributed installed systems for background music
or voice typically have four or more ceiling loudspeakers in a room. Use Loudspeaker Spacing Distance (LSD)
for small rooms that only need one.
A. Calculate the Loudspeaker Spacing Distance (LSD)

Loudspeaker

H = Ceiling/Mount Height
CA
CA = Coverage Angle
Small Woofer 120°
Large Woofer 105°
Note: Small woofer and large woofer
coverage angle take into account
L=L
 istener Height linear dispersion at ear level and
–6 dB
Seated: 3.5 ft | 1 m room reverberation considerations.
Standing: 5 ft | 1.5 m

Floor

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Design Worksheet PRO.BOSE.COM

Loudspeaker Loudspeaker
Spacing

LSD = Spacing Distance LSD is also the coverage

M = Multiplier Loudspeaker area for one loudspeaker
Spacing
LSD = (H – L) × M
For small rooms such
as bathrooms, you may
only need one or two
loudspeakers to cover the
room; look at LSD

2"–4" Small 5"–8" Large

M (multiplier) Models M (multiplier) Models
Woofer Coverage Woofer Coverage
Edge-to-edge 3.46 FS2C Edge-to-edge 2.61
DM5C
DM2C-LP
Minimum Overlap 2.45 Minimum Overlap 1.84 DM6C
DM3C
DM8C
Center-to-center 1.73 FS4CE Center-to-center 1.30

Multipliers are created from Coverage Angles (CA). These are multipliers we have found to work for most
applications. For more precise results, and to adjust for obstructions, use Bose Modeler, EASE, EASE
Address, EASE Evac, or another calculator.
Edge-to-edge coverage can provide fidelity in fixed-location seating/standing and can generally work well
for installations on a budget. It also works well for ambient-level and low-level background music. Center-
to-center installations will have higher density and can accommodate people listening in many different
positions and moving floor plans due to uniform coverage. They will also have fewer dead zones. Minimum
overlap (or center-to-center) may also be needed if critical communication is happening over the system.
Bose Modeler or EASE Evac can help with speech intelligibility evaluation.
B. Place the first loudspeaker at ½ LSD from any corner of the room.

1/2
Loudspeaker
Spacing

1/2
Loudspeaker
Spacing

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PRO.BOSE.COM Design Worksheet
C. The remaining loudspeakers are arranged on a square grid pattern using the LSD. If a loudspeaker would
be placed on or beyond the perimeter of the room, delete that row/column of loudspeakers.

Loudspeaker
Spacing

Loudspeaker
Spacing

D. After the last loudspeaker is placed, center the loudspeakers in that row to create new offset distances
out from each wall, which may be unique from ½ LSD.

E. (Optional) To quickly calculate the total Loudspeaker Quantity (LQ) needed to fill the rectangular room
without using graph paper, follow this method. In square layouts, the final total is sometimes slightly
reduced as you lay out rows. You can also determine final quantity by following Step B on graph paper
until the room is filled.

Loudspeaker Area = Square footage of room

(Length × Width)

CA = Coverage Angle Area

LQ =
M 2
[(H – L)—]
–6 dB point (coverage edge) 2

Edge-to-edge = Minimum overlap = Center-to-center =

LQ/4 LQ/4 LQ/4
–6 dB touching –3 dB touching –1.5 dB touching

Subwoofers: Quantity and Placement of Subwoofers

The number of subwoofers to use, where to position them, and how loud to set them can vary depending on
the individual situation. Details such as placement, boundary loading, room size, coupling quantity of multiple
loudspeakers to subwoofers, type of music, type of activity, budget, and the expectations of the listeners
should all be considered. The following guidelines are general rules to follow.
• Add one subwoofer for every group of four vocal- or full-range loudspeakers.
• Subwoofer spacing should be as far apart as is practical. 12.2 meters (40 feet) or greater subwoofer-to-
subwoofer spacing distance within the same zone is desirable.
• When the suggested subwoofer count is two within a single zone, it may be preferable to use either
one in a corner to avoid audible interference; or increase the count to three, which creates more
audible interference locations but limits them to smaller sizes where the reverberant field (added room
reflections) tends to mask them.
• Placing a ceiling subwoofer within 0.9 meters (3 feet) of a wall increases its output by 3 dB. Placing it
within 0.9 meters (3 feet) of a corner increases its output by another 3 dB (6 dB total) and also reduces
reflections that can create audible interference (bass cancellations) in the listening area.
• Listening positions located below the subwoofer should be supported by a nearby vocal- or full-range
loudspeaker to provide better tonal balance in the low-frequency pressure zone.

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Design Worksheet PRO.BOSE.COM

Step 5: Calculate Required Amplifier Size

All FreeSpace FS, DesignMax, and EdgeMax loudspeakers are compatible with 70-volt, 100-volt, and low-
impedance amplifiers.
Use the Tap Charts to determine which loudspeaker tap is required for this design
A. Locate the loudspeaker tap chart and find the column for mounting height for this design.
B. Follow the column to the desired maximum SPL.
C. Follow the row across the chart to determine the required loudspeaker tap.
D. Calculate the required amplifier power:

× =
Number of Loudspeakers Required Required Loudspeaker Tap Power Required

E. Calculate the required amplifier size:

× 1.10 =
Power Required Headroom Amplifier Size

Amplifiers: Example Amplifier Configurations

Modern amplifiers come in a variety of channel counts and configuration options to allow for different output
configurations, zoning options, and varying loudspeaker quantities. A properly optimized system may only
need a low 1- or 2-watt tap setting to achieve 70 dB in a typical room. The below example lists how many
FS2C loudspeakers can be handled at the loudspeaker’s highest 70/100V tap setting.

FreeSpace FS2C Loudspeaker Maximum Loudspeakers at Higher Tap Settings EQ Preset Average SPL*
Amplifier Example
FreeSpace IZA 190-HZ 5 at 16W, 10 at 8W tap FS2C/SE/P
FreeSpace IZA 2120-HZ 5 at 16W, 13 at 8W FS2C/SE/P
87 dB at 16W, 84 dB at 8W
PowerShare PS404D 22 at 16W, 45 at 8W FS2C
PowerSpace P4150+ 8 at 16W, 17 at 8W FS2C
* 3 meter (10 foot) ceiling height room with edge-to-edge density, standing listener, 12 dB crest factor of pink
noise/compressed music, direct-field, no room gain.
SmartBass: Application of SmartBass processing
If your design is using a PowerSpace+ amplifier; or your design utilizes a dedicated Bose DSP, such as the
Commercial Sound Processor CSP models; or any of the ControlSpace ESP or EX models; you have the option
of applying SmartBass to your loudspeaker output channel. This uses Bose EQ presets, dynamic EQ, and
excursion limiting tuned to each model and room calibration. This will prevent lower background-level music
from sounding thin, but also ensures the sound is consistent at various SPL levels. At louder levels, SmartBass
also allows for more musical limiting than traditional voltage limiters.

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PRO.BOSE.COM Tap Charts

Tap Charts
Individual Loudspeaker Continuous Output Level
Note: The following tap charts assume standing ear height at 1.5 meters (5 feet) in minimum overlap spacing.
Room reverberation could add as much as 4 dB system gain, which is not factored into the measurements.
Designing without room gain will ensure you don’t under-plan your design, and amp attenuation is possible at
the job site if you exceed the average room SPL target during measurement. Values below 70 dB are omitted,
select a higher tap.

DM2C-LP
DM2C-LP
(standing listener height)
Ceiling Height m 2.4 2.7 3 3.7 4 4.3 5 5.5 6 6.7 8 9.8
ft 8 9 10 12 13 14 16 18 20 22 26 32
1.2W 85 83 81 78 77 76 74 73 72 70 — —
2.3W 88 86 84 81 80 79 77 76 74 73 71 —
TAP 4.5W 91 89 87 84 83 82 80 79 77 76 74 72 dB-SPL
9W 94 92 90 87 86 85 83 82 80 79 77 75
16Ώ 97 94 92 89 88 87 85 84 83 82 80 78

FS2C
FS2C
(standing listener height)
Ceiling Height m 2.4 2.7 3 3.7 4 4.3 5 5.5 6 6.7 8 9.8
ft 8 9 10 12 13 14 16 18 20 22 26 32
1W 87 84 82 79 78 77 75 74 73 72 — —
2W 90 87 85 82 81 80 78 77 76 75 73 75
4W 93 90 88 85 84 83 81 80 79 78 76 78
TAP dB-SPL
8W 96 93 91 88 87 86 84 83 82 81 79 81
16W 99 96 94 91 90 89 87 86 85 84 82 84
8Ώ 99 96 94 91 90 89 87 86 85 84 82 80

DM3C
DM3C
(standing listener height)
Ceiling Height m 2.4 2.7 3 3.7 4 4.3 5 5.5 6 6.7 8 9.8
ft 8 9 10 12 13 14 16 18 20 22 26 32
3W 88 86 84 81 80 79 77 76 75 73 72 —
6W 91 89 87 84 83 82 80 79 78 76 75 72
TAP 12W 94 92 90 87 86 85 83 82 81 79 78 75 dB-SPL
25W 98 95 93 90 89 88 86 85 84 83 81 79
8Ώ 98 95 93 90 89 88 86 85 84 83 81 79

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Tap Charts PRO.BOSE.COM

FS4CE
FS4CE
(standing listener height)
Ceiling Height m 2.4 2.7 3 3.7 4 4.3 5 5.5 6 6.7 8 9.8
ft 8 9 10 12 13 14 16 18 20 22 26 32
2.5W 93 90 88 85 84 83 81 80 79 78 76 74
5W 96 93 91 88 87 86 84 83 82 81 79 77
10W 99 96 94 91 90 89 87 86 85 84 82 80
TAP dB-SPL
20W 102 99 97 94 93 92 90 89 88 87 85 83
40W 105 102 100 97 96 95 93 92 91 90 88 86
8Ώ 105 102 100 97 96 95 93 92 91 90 88 86

DM5C
DM5C
(standing listener height)
Ceiling Height m 2.4 2.7 3 3.7 4 4.3 5 5.5 6 6.7 8 9.8
ft 8 9 10 12 13 14 16 18 20 22 26 32
3W 92 90 88 85 84 83 81 80 79 77 76 73
6W 95 93 91 88 87 86 84 83 82 80 79 76
12W 98 96 94 91 90 89 87 86 85 83 82 79
TAP dB-SPL
25W 102 99 97 94 93 92 90 89 88 87 85 83
50W 105 102 100 97 96 95 93 92 91 90 88 86
8Ώ 105 102 100 97 96 95 93 92 91 90 88 86

DM6C
DM6C
(standing listener height)
Ceiling Height m 2.4 2.7 3 3.7 4 4.3 5 5.5 6 6.7 8 9.8
ft 8 9 10 12 13 14 16 18 20 22 26 32
2.5W 93 90 88 85 84 83 81 80 79 78 76 74
5W 96 93 91 88 87 86 84 83 82 81 79 77
10W 99 96 94 91 90 89 87 86 85 84 82 80
TAP 20W 102 99 97 94 93 92 90 89 88 87 85 83 dB-SPL
40W 105 102 100 97 96 95 93 92 91 90 88 86
80W 108 105 103 100 99 98 96 95 94 93 91 89
8Ώ 109 106 104 101 100 99 97 96 95 94 92 90

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PRO.BOSE.COM Tap Charts

DM8C
DM8C
(standing listener height)
Ceiling Height m 2.4 2.7 3 3.7 4 4.3 5 5.5 6 6.7 8 9.8
ft 8 9 10 12 13 14 16 18 20 22 26 32
2.5W 96 95 107 104 103 102 101 99 98 97 95 93
5W 99 96 94 91 90 89 87 86 85 84 82 80
10W 102 99 97 94 93 92 90 89 88 87 85 83
TAP 20W 105 102 100 97 96 95 93 92 91 90 88 86 dB-SPL
40W 108 105 103 100 99 98 96 95 94 93 91 89
80W 111 108 106 103 102 101 99 98 97 96 94 92
8Ώ 113 110 108 105 104 103 101 100 99 98 96 94

©2021 Bose Corporation, All rights reserved. | Framingham, MA 01701-9168 USA | PRO.BOSE.COM | Rev. 00 | October 2021

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