Designing With The Freespace; 4400 System; Introduction; Basic Design Steps - Bose FREESPACE 4400 Owner's Manual

2.0 Designing with the FreeSpace

2.1 Introduction

This section describes the basic steps for designing a FreeSpace
4400 system and includes an example. It is assumed that a com-
plete loudspeaker design and layout has already been created.

2.2 Basic design steps

There are five basic steps in designing a FreeSpace 4400 system.
2.2.1 Step 1 – Determine source routing
Decide which sources will be played in each area. Create a
"source map" such as the following one that shows which
sources will be played in each major area of the facility.
Source 1 Source 2
Area 1
Area 2
Area 3
Area 4
Area 5
2.2.2 Step 2 – Determine Auto Volume

requirements

Identify which areas will use Auto Volume. Each Auto Volume
zone must use one AVM (Auto Volume) user interface and one
Bose ® sensing microphone to control the volume.
When using Auto Volume, remember that you will be adjusting
the volume of an overall area. Imagine that you have a dining area
and a bar adjacent to one another. If the sensing microphone is
placed above the bar, the music may become too loud in the din-
ing area. Likewise, if you place the sensing microphone above
the dining area, the music may never be heard in the bar.
Source 3 Source 4
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4400 System

®
Guidelines for establishing Auto Volume zones
Loudspeaker Background noise
height is... is uniform
>25 ft (7.6 m)
12-25 ft One Auto Volume
(3.7-7.6 m) zone for every
2
3600 ft (324 m
<12 ft (3.7 m) One Auto Volume
zone for every
1800 ft 2 (162 m
Loudspeaker mounting height and the overall quality of the back-
ground noise is used to determine the Auto Volume zoning
requirements. Uniform background noise is found in an area
where no part of the area is louder or quieter than any other. A
room with non-uniform background noise would seem louder in
some areas (people talking, machinery running, etc.) and quieter
in others.
Mounting guidelines for sensing microphones
• The sensing microphone must be mounted at the same height
as the loudspeakers or higher. A sensing microphone must
never be mounted lower than the loudspeaker height.
• In all cases, there must be 6 ft (1.8 m), minimum, between the
loudspeaker and the sensing microphone. This is so that the
microphone does not receive signals only from a loudspeaker.
• There must be 35 ft (10.7 m), minimum, between the sensing
microphones of two adjacent Auto Volume zones.
• Avoid placing the microphone near unique noise sources like
HVAC equipment, dishwashers, motors, etc.
Separating the microphones as much as possible for two zones
is the best practice. Consider the previous example of the dining
area and a bar adjacent to one another. If each of these areas
uses Auto Volume, it is possible to create a situation in the dining
area where the music is too loud simply because the microphone
is too close to the bar.
Background noise
is non-uniform
Not recommended
One Auto Volume
zone for every
2 2 2
) 1800 ft (162 m )
One Auto Volume
zone for every
2 ) 900 ft 2 (81 m 2 )