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NO.
1
DRIVER MODULE SLOT
NO.
2
DRIVER MODULE SLOT
AC PRIMARY
POWER
MODULE
4
2
1
Figure
1.
Main Frame and Position Assignments of Card Modules
MAINFRAME
The main frame accepts one primary
power
(ac) module, one input module, up to two
driver or crossover driver modules, and up
to eight power amplifier
modules.
Each
plug-in module is inserted into the
appro-
priate
connector
within
the
main frame, ac-
cording
fo
functional position as shown in
Figure
1.
A hinged panel covers the module
positions after installation and adjustment.
All input/output
connections are located on
the rear panel of
the
main frame
.
Four
XLR-3
type
female receptacles connect balanced
signals to the selected input module.
Eight
1/4"
phone jacks connect up to four
sep-
arate
unbalanced
input
signals.
Four
special
input/output
stereo
1/4"
phone
jacks (J213,
J214,
J215,
and J216) connect
up to eight unbalanced signals direct
ly
to
the
driver modules. Separate output con-
nections are
provided
for each power
amp-
lifier
module position.
When balanced input signals are fed
to
the
appropriate XLR-3
type
connectors, output
signals may be derived at the UN BAL
phone
jack connectors
.
The eight (UNBAL)
phone
jacks adjacent to the XLR-3 connectors may
CHANNEL2
CHANNEL3
CHANNEL4
become
unbalanced
outputs,
deriving
signals
from transformer
secondaries of the
Model
2221 Input
Card Module. The
four
special
input/output
jacks may become
special
outputs,
deriving signals from the
high
,
mid
,
and
low
frequency
outputs of the
Model
2251 Crossover
Driver Card Module.
This capabili
ty
of spec ial signal routing
is
readily
indicated
from study of the Modular
Block Diagram
.
As shipped
from
the
factory,
each main
frame
is equipped
with an ac primary power
module,
installed as
in Figure
1.
The module
is
equipped
with
an ON-OFF ac power
switch
(circuit
breaker type) with built-in
pilot
lamp. A terminal
strip permits strap-
ping the power
transformer
primary for 100V,
120V,
200V,
220V,
or 240V at 50/60 Hz; as
shipped
from the
factory, straps are
in-
stalled
for 120 Vac.
A
fan is
incorporated in
the
module
for forced-air
cooling of power
amplifier modules.
INPUT
MODULES
The main
frame
of the Incremental Power
System
has four
primary input connectors
(XLR-3 type) which
accept balanced inputs.
CHANNEL 1
CHANNEL4
MODEL 2220
MODEL 2221
Figure
2.
Model
2221 and 2220
Input
Card
Modules
2
One input module
card
may be inserted in
the main frame to pro cess four primary
in-
puts. These four
input
s
may be balanced or
unbalanced by using
t
he Model 2221 (trans-
former
isolated)
Inpu
t
Card Module
.
The
four inputs may be unbalanced by using
the
Model 2220 (transfor merless) Input Card
Module. Each input
card
module has four
adjustable
attenuato
rs
to
set
levels
separately
for each input.
Figure
2 il-
lustrates each type of input card module
.
If
inputs
to the main
fr
ame are unbalanced,
it
is
not always neces sary to use an
input
card module, because
t
he
Model 2250 and
2252 Driver Modules have attenuators
to
ad-
just signal levels. How
ever,
the Model 2251
Crossover Driver Mod
ule
requires use of
either Model 2220 or Model 2221 Input Card
Module
,
because this
driver input
cannot
access
special
input/ output
jacks
J213,
J214,J21~orJ216.
DRIVER
MODULES
The driver modules fee
d
the inputs
·
to the
power amplifier
modul
es
for the desired
..
combinations
of output
for
low, mid, high,
or full
frequency
ranges
.
One or
two
driver
modules, of any
type
and in any combina-
tion,
may be inserted in
the
main
frame
to
process the inputs. A
switching
matrix
is
built into each driver
module for
the power
amplifier modules to be
operated in
parallel,
bridged,
parallel-bridge
d,
or
independent
modes
.
The
driver mod ules are equipped
with two or more drive
r-amplifier
circuits
,
with the
input
of each circuit independently
adjustable
.
Driver mod
ules
with the (SA)
suffix are adjustable wit
h
step attenuators
in
increments
of - 1 dB
,
to
a maximum of
-
63 dB.
Modules
withou
t
the
(SA)
suffix are
continuously
adjustable
to
a maximum at-
tenuation
of at least
-
60 dB. Figure 3 il-
lustrates
the
various
ty
pes of driver card
modules
.
The Model 2250 Driver Card Module in-
cludes
two
driver-amp
lifier
circuits,
an
a-channel
input
switching
matrix
,
and an
a-channel output switchi ng matrix.
The Model 2252 Driver Card Module in-
cludes
four
driver-amp
lifier
circuits,
an
a-channel input switchi ng matrix, and an
8-channel output switchi ng matrix.
The Model 2251 Cross over Driver Card
Module
is
specially
designed
to provide
two-way
or three-way electronic crossover
.
The module
includes
thr ee driver-amplifier
circuits and
an
8-channe
l
output switching
matr
ix.
Selectable frequ
encies
are 625 Hz,
800 Hz, 1250 Hz, and
1600
Hz for low
to
mid
frequency; 3150 Hz, 4000 Hz, 5000 Hz, and
8000 Hz, for mid to high
frequency
.
Slope
rate is fixed at 12 dB per octave. The cross-
over driver module can dr
ive
the power amp-
lifier modules directly, or
feed into
another
driver module to creat
e
different
signal
levels
from
one crosso
ver
driver output.
One or two crossover dr
iver
modules may
be
inserted in the
main frame for a monaural
or stereo biamplified or tr
iamplified
system.
Input to the
Model 2251 Driver must come
from
Model 2220 or 2221 Input Card Module
via
channel 1 (left-hand driver module slot)
or channel 3 (right-hand dr
iver
module slot).
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