Niles CM8SW Installation & Operation Manual page 9

Using Speaker Selectors With
Using Impedance Magnifying
Standard Volume Controls
Volume Controls
In multi-room systems with standard vol-
ume controls w Niles speaker selector
will maintain a four ohm load if you leave
one set of room outputs unused for every
speaker system with an impedance of less
than four ohms (such as a CMBSW con-
nected to a pair of four ohm satellite
speakers). The protection switch must be
constantly engaged. Niles HDL series
speaker selectors have a rear panel con-
stant protection feature.
(See Figure 8).
The simplest way to increase the imped-
ance of a satellite/subwoofer system is to
install a Niles VCS-2D-IM or VCS-2S-IM
impedance magnifying volume control
instead of a standard volume control. This
control has a behind the wall jumper
which is set at the time of installation to
"magnify" the speaker system impedance.
(See Figure 9).
The benefit of a speaker selector is that
even with the protection circuit constant-
ly engaged, more power will be delivered
to any single pair of speakers playing by
itself (all other speakers off).
MAGNIFIC4TION
MAGNIFICATION
FACTOR
FACTOR
16x
8x
JPI (LEFQ
(RIGHT) JP2
In a multi-room system there is one indis-
pensible control for true convenience-a
local volume control. It allows you to
adjust the volume of the speakers and the
subwoofer without leaving the room.
Niles makes a wide range of high perfor-
mance indoor and outdoor volume controls
in Standard or Decora@ style face plates
(just like your light switches and dimmers).
All of these volume controls enable full
power to be delivered to each speaker sys-
tern when turned all the way up.
For example: In the two times position, an
IM volume control will enable an eight
ohm stable amplifier to play a 4 ohm
speaker system without overheating. The
available power will decrease, which you
will perceive as a 3dB drop in maximum
undistorted volume.
The combination of a speaker selector and
a standard volume control will deliver
high volume when only one pair of speak-
ers is playing.
If the jumper is set to the 4x position, a
6dB drop in volume will be perceived.
If the jumper is set to the 8x position, a
9dB drop in volume will be perceived.
A 1OdB drop is perceived as half as loud,
so there are limits to the amount of magn-
fication you can use unless the amplifier is
very powerful (3dB increase every time
you double the power) or you never listen
at high volumes. Consult the Decibels and
Power chart on page 4.