The outputs of the power amplifiers in a biamplifica-
tion system may be connected to any high-power,
two-way speaker system with separate driver connec-
tions such as the Shure SR108. The only important
restriction placed on speaker systems is that the
crossover frequency of the speaker system must match
the crossover frequency selected on the back of the
SR106. Damage to the high-frequency drivers may
result if the crossover frequency of the SR106 is set
below that recommended for the speaker system.
For three-way speaker systems, a second SR106
may be used to split the high-frequency output of the
first SR106 into mid-range and high-frequency outputs.
The two SRlO6's thus separate the line level signal
into three components for routing to three power am-
plifiers and into the three-way speaker system (see
Figure G). This is called triamplification, and may be
used with any three-way speaker system with cross-
over frequencies matching those of the SR106. NOTE:
Certain three-way speaker systems are designed for
biamplified operation only, and use their internal cross-
over networks to separate the mid- and high-frequency
signals. When using a speaker system of this type,
follow the instructions under Biamplification and the
speaker system manufacturer's instructions.
Crossover Frequencies
The three crossover frequencies available (500, 800
and 2600 Hz) on the SR106 rear-panel selector switch
(7)
are designed for use with the Shure SR108 Ex-
tended Range Speaker System (2600 Hz) and other
popular speaker systems. In connecting the SR106,
it is imperative that the crossover frequency of the
speaker system be known and the SR106 CROSS-
OVER FREQUENCY Switch be set before operating the
system.
CAUTION
High-frequency drivers may be damaged or
destroyed if the electronic crossover is not
set to match the speaker system crossover
frequency.
If a crossover frequency other than the three pro-
vided (500, 800, and 2600 Hz) is desired a qualified
service technician can change the crossover frequency
to a new desired frequency. Refer to the section on
Alternate Crossover Frequencies.
Phasing
The SR106 high- and low-frequency output signals
are intentionally wired out of phase (opposite polarity).
The low-frequency output is in phase with the input,
and the phase of the high-frequency output is re-
versed. This phase relationship is consistent with the
requirements of the passive 12 dB/octave crossover
networks used in most popular speaker systems. The
Shure SR108 Extended Range Speaker System is in-
ternally wired out of phase and provides the correct
acoustic output when operated in the biamplification
mode.
Proper wiring is necessary to maintain the correct
phase relationship of the high- and low-frequency
speakers in the crossover region. Failure to maintain
proper phasing may cause incorrect overall response
characteristics in the critical mid-range frequencies.
The speaker system instruction manual should be con-
sulted for information on proper phasing when con-
necting the speakers to the power amplifiers.
The following considerations should be given to
phasing: When using the SR106 and identical power
amplifiers (Shure SR105 or equivalent) to power a
Shure Model SR108 Speaker System, the phasing is
correct. Different speaker systems or dissimilar high-
and low-frequency power amplifiers may be used
as
long as all low-frequency sections are in phase with
one another and all high-frequency sections are in
phase with one another, as well as maintaining proper
high- to low-frequency phasing.
To check for a possible out-of-phase condition in
a single speaker system (high- to low-frequency phas-
ing), the following listening test should be performed.
Connect the SR106, program input equipment, and
power amplifiers to a single speaker system. Feed the
system with program material (vocal or instrumental)
and adjust for a moderate level. Listen carefully to
the speaker system output and reverse the phase of
either the high- or low-frequency section of the speaker
system while listening to the same program material.
Choose the connection that produces the most uni-
form sound quality.
CAUTION
Do not interchange high- and low-frequency
speaker cables. Damage to high-frequency
drivers from high level, low-frequency sig-
nals may result.
FIGURE G.
TRlAMPLIFIED OPERATION
SPEAKER SYSTEM
r-------
7
HE
L
-------
J
-
POWER
AMPLIFIER
POWER
AMPLIFIER
POWER
AMPLIFIER
SRlO6
ELECTRONIC
CROSSOVER
(2600 HZ)
I
,
I
HIGH
-
MID
-
(LOW)
LOW
AUDIO CONSOLE
OR MIXER-PREAMP-
OR MIXER
-
HIGH-FREQUENCY
I
SR106
CROSSOVER
(500
HZ)
I
I
I
I
I
I
I
I
I
-
-
I
SPEAKERS
I
I
I
I
I
I
I
MID-FREQUENCY
SPEAKERS
LOW-FREQUENCY
SPEAKERS
