7
3.1 Asymmetrical loads
Some applications may require the FreeSpace
®
6 amplifier to
drive varying numbers of loudspeakers from each channel.
Often this is a dual–zone application in which one zone requires
few loudspeakers and another zone requires many loudspeak-
ers to achieve ample coverage.
Note:
When using the expansion module in a dual-zone appli-
cation, there may be a difference in maximum output between
the two chan
nels. The greater the number of loudspeakers con-
nected to a single channel, the less power
each loudspeaker
receives.
An example of this type of application is the dual–zone
restau-
rant installation shown in Figure 9 (page 14). Both zones require
music; only the lounge requires paging.
The dining area is a larger room than the lounge and requires 8
loudspeakers. A low SPL is required to drive the loudspeakers
comfortably over the ambient noise floor (in this case, a maxi-
mum of 2 Watts per loudspeaker).
Although the lounge is smaller in total volume, its ambient
noise floor is higher. In order for customers to hear paging
announcements, each loudspeaker requires more than 2 Watts.
Four loudspeakers provide adequate coverage in the lounge.
For technical assistance, call the Bose
®
Application and Design
Support hotline at 1-800-992-2673 or contact your authorized
Bose Professional Products dealer.
3.2 Wiring considerations
Use stranded, heavy gauge wire for loudspeaker connections.
As a rule, the greater the distance between the amplifier and
the loudspeakers, the larger the wire diameter needs to be for
minimal power loss. For best performance from the FreeSpace
6 system, use the following table as a guide:
Negligible
SPL loss
Wire Diameter
(AWG/mm2)
18/0.75
OK OK
Not
recommended
Not
recommended
16/1.5
OK
14/2.5
12/4.0
OK
OK OK
SPL Loss per Loudspeaker Cable Length
Negligible
SPL loss Not
recommended Not
recommended
Negligible
SPL loss Not
recommended
Negligible
SPL loss
Not
recommended
3.3 Wire in a plenum space
Both UL and CSA permit the use of Class 2 wire (CL2, CL2P,
or CL2R) for loudspeaker wire. If the wire passes through a
plenum, only CL2P is acceptable. In risers such as vertical air-
handling ducts or any through passage from floor-to-floor,
CL2R is classified for this use.
See Table 725-53 of the National Electric Code (NEC) for a list
of acceptable wire substitutes.
50 ft/15 m 100 ft/30 m 200 ft/60 m25 ft/8 m
3.0 Miscellaneous