Altec Lansing INCREMENTAL POWER SYSTEM 2220 User manual

ALTEC
LANSING · INCREMENTAL
POWER SYSTEM
OPERATING
INSTRUCTIONS
Reference Documents for Incremental
Power System:
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ALTEC
L.ANSING
IICW4h'WPOri~fflm.l2200
42-02-045:?91
42-02-045284
42-02-045285
42-02-045286
42-02-045287
42-02-045288
42-02-045362
42-02-045289
Modular Block Di?gram Kit
Model 2220/2221 Input Modules
Model 2250/2250SA Driver Modules
Model 2251/2251SA Driver Modules
Model 2252/2252SA Driver Modules
Model 2275 Power Amplifier
Module
Model 2276 Power.Amplifier
Module
Main Frame
CAUTIO~"""'"'"cmo,,"""""°"""""''°"'""""-""'-"'"_'°_,,.,.,,,-
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INTRODUCTION Tci THE INCREMENTAL
POWER SYSTEM
The ALTEC Incremental Power System con-
sists of a main frame with plug-in modules .
The rackmount main frame accepts modular
input, crossover, driver, and up to eight
75-watt power amplifier cards.
The ALTEC Incremental Power System can:
ALTEC
LANSING'
SOUND P R O D UC TS DIVISI ON
• Control high, mid, and low frequency
loudspeakers v.:ith _s~parate power
amplifiers .,
• Connect far, middle, and near-throw
horns to separate power amplifiers while
providing s~parate level contro .ls.
• Power up to four separate balanced 70-
volt systems from a single main frame.
• Power extremely complex sound systems
by combining the'abilities of two or more
. Incre mental Power Systems. .· . ·
Power amplifier ·modules may be combined
in increments of 75 watts to meet most con-
ceivable audio applications. Parallel modes
may drive high power, low impedance loads.
Bridged modes may drive balanced 70-volt
lines . A parallel-bridge mode may drive high
power balanced 70-volt lines or other loads.
Sp eci fi cation s and compon ent s subject to chang e without
notice . Overall ~performance will be maintained or imp roved.
1515S. Manchester Ave., Anaheim, Calif. 92803
42-02-045121-04
LITHO IN U.S.A. 1278-1M

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 UNBAL 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 special 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 120Vac. 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.
CHANNEL1
CHANNEL4
MODEL2220 MODEL2221
Figure 2. Model 2221 and 2220 Input
Card Modules
2
One input module card may be inserted in
the main frame to process four primary in-
puts. These four input s may be balanced or
unbalanced by using the Model 2221 (trans-
former isolated) Input 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 frame are unbalanced,
it is not always necessary to use an input
card module, because the Model 2250 and
2252 Driver Modules have attenuators to ad-
just signal levels. However, the Model 2251
Crossover Driver Module 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 feed 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 modules are equipped
with two or more drive r-amplifier circuits ,
with the input of each circuit independently
adjustable . Driver modules 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 types 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 Crossover Driver Card
Module is specially designed to provide
two-way or three-way electronic crossover .
The module includes three driver-amplifier
circuits and an 8-channe l output switching
matrix. 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 drive the power amp-
lifier modules directly, or feed into another
driver module to create different signal
levels from one crosso ver driver output.
One or two crossover driver modules may
be inserted in the main frame for a monaural
or stereo biamplified or triamplified 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 driver module slot).

2251
Figure 3. Driver Card Modules for the Incremental Power System
POWERAMPLIFIER MODULES
Up to eight Model 2275 Power Amplifier
Modules may be inserted in the main frame
for the desired power rating and power con-
figuration. The power amplifier modules are
rated at 75 watts each and may be combined
in 75-watt increments for up to 600 watts
output power from each main frame system .
Power output level and power distribution
configurations may be selected to meet
most audio applications. Figure 4 illustrates
the Model 2275 Power Amplifier Card
Module.
Typical operating configurations of the
Model 2275 Power Amplifier Module
include:
• Independent mode for separate loud-
speaker loads.
• Parallel mode to increase output power in
increments of 75 watts for higher power,
low impedance loads.
· • I;!ridged mode to drive balanced 70-volt
lines. Two power amplifier modules,
driven out-of-phase to each other, have
the loudspeaker load connected to the
'hot' terminals of the two modules. Power
available is 150watts.
• Parallel-bridged mode to drive higher
power balanced 70-volt lines, or other
high power loads. Two sets of parallel
power amplifier modules may be bridged
Model 2275
Model 2276
Figure 4. Model Power Amplifier
Card Modules
3
to obtain maximum output power ratings
of 300 watts (2 sets of 2 modul_es), 450
watts (2 sets of 3 modules) , or 600 watts
(2sets of 4 modules).
Up to 4 Model 2276 Model 2276 Power Amp-
lifier Modules may be inserted in the main
frame for the desired power rating and
power configuration. Each module is rated
at 150watts. The modules may be combined
in 150-watt increments for up to 600 watts
output power from each main system . Oper-
ating configurations are similar to the
model 2275 Power Amplifier Module , except
for the power rating of 150 watts per mod-
ule. Figure 4 illustrates the Model 2276
Power Amplifier Card Module.
Typical operating configurations of the
Model 2276 Power Amplifier Module
include:
• Independent mode for separate loud-
speaker loads.
• Parallel mode to increase output power in
increments of 150watts for higher power,
low impedance loads. Power available is
300, 450, or 600 watts .
• Bridged mode to drive balanced 70-volt
lines . Two power amplifier modules,
driven out of phase to each other, have
the loudspeaker load connected to the
'hot' terminals of the two modules . Power
available is 300 watts.
• Parallel-bridged mode to drive higher
power, balanced 70-volt lines, or other
high power loads . Two sets of parallel
power amplifier modules may be bridged
to obtain an output power of 600 watts .
If fewer than four Model 2276 modules are
used in a main frame system, Model 2275
Power Amplifier Modules may be installed
in remaining power module positions. The
Models 2275 and 2276 modules may be used
in independent modes, or intermixed in
various combinations of parallel, bridged, or
parallel-bridged modes .
As shipped from the factory , the main frame
and each power amplifier module operate
into a load impedance of 16 ohms. By
selecting other taps on the ac power trans-
former of the main frame and removing two
jumper leads of each power amplifier
module, the main frame system can operate
into a load impedance of 8 ohms. For
parallel and bridged configurations , speci-
fic loudspeaker load requirements are dis-
cussed within the installation portion of the
instructions.
INSTALLATION
VENTILATION
The Incremental Power System must be ad-
equately ventilated to prevent excessive·
temperature rise. Maximum rated ambient
operating temperature is 55°C (131°F).
------ CAUTION------,
Do not block the side ventilation
apertures on either side of the main
frame. Allow at least 2" on each side
of the main frame to assure adequate
ventilation. Do not operate within a
completely closed, unventilated
housing.

RACKMOUNTING
The main frame of the Incremental Power
System is designed for installation in a
standard 19-inch equipment rack. Vertical
space required for mounting is 7" for each
main frame.
1. Remove four screws that secure the
front panel. Open and lower front panel
asshown in Figure 5.
2. Install main frame in equipment rack,
using appropriate four screws supplied.
,------CAUTION------
While positioning the main frame in
the equipment rack, do not use the
large filter capacitors as handles. Lift
or handle only by the chassis and
power transformer .
3. After installing all modules, close front
panel and secure with four screws pre-
viously removed.
SHELF MOUNTING
In handling the main frame for shelf mount-
ing, be sure to observe the CAUTION of
Step 2, in RACK MOUNTING. Four rubber
feet with attaching screws are supplied with
each main frame. Position the main frame
on one side and attach the feet to the under-
side of the chassis.
MODULEINSTALLATION
The input, driver, and power modules are in-
stalled in the main frame according to the
functional locations of Figure 5. The ac
primary power module is installed in each
main frame shipped from the factory. Re-
maining modules must be unpacked and in-
stalled in the main frame as follows:
1. Remove four screws that secure the
front panel. Open and lower front panel
asshown in Figure 5.
DRIVER MODULE NO. 1
DRIVER MODULE NO. 2
•1
2. Guide channels align and support each
card module, which plugs into a con-
nector at the rear of the main frame.
Insert each module so that the card
edges fit into the flanged portion of the
top and bottom guides. Gently push the
card module into the guides until it en-
gages the rear connector. Press firmly
until fully seated.
,------- CAUTION------
Do not insert or remove any driver
card module from the main frame
when primary ac power isapplied.
3. After all modules are installed (and all
driver module switch matrices are set up
correctly), close the front panel and
secure with four screws previously
removed.
------- NOTE-------,
When fewer than 8 Model 2275 Power
Amplifier Modules are installed in the
main frame, install modules in slots
nearest the fan for optimum cooling.
ELECTRICAL
120 Volt, 50/60 Hz Power Connections
Equipment is supplied for domestic use with
the power transformer primary strapped for
120volts. The power input rating appears at
the rear of the main frame chassis, adjacent
to the power cord (see Figure 8). Verify that
line voltage is in accordance with the volt-
age rating before connecting the Incre-
mental Power System to line power.
Alternate 50/60 Hz Primary Power
Connections
The Incremental Power System may operate
from an ac primary power source having
100V, 120V,200V, 220V, or 240Vat 50160Hz.
As shipped from the factory, the power
Figure 5. Installation of Card Modules in Main Frame
4
transformer primary is strapped for 120
volts. The voltage rating is at the rear of the
main frame chassis, adjacent to the power
cord.
Qualified service personnel may change the
transformer primary straps for the desired
operating voltage. The primary power straps
are located at terminal board TB301, within
the ac primary power module . To change
the straps:
1. Unplug ac cable from ac power source.
Remove ac primary power module from
main frame. Locate terminal board T8301
on the card module (Figure 6).
2. Remove three 120-volt straps from ter-
minals 2to 3,6to 7,and 8 to 9.
3. See Figure 6 to connect necessary
straps to proper term inals for the desired
operating voltage.
4. From accessory kit supplied with main
frame, select corresponding voltage rat-
ing sticker . Peel sticker from backing
and affix new voltage rating over 120V
designation at rearof main frame.
5. Install ac primary power module in main
frame.
Conversion for 8-Ohm Load Impedance
All Incremental Power Systems are shipped
from the factory with internal wiring con-
nected for 16 ohms load impedance. The
systems may be altered by qualified per-
sonnel for 8 ohms load impedance. Appro-
priate alterations must be made at the
main frame and every Model 2275 Power
Amplifier Module used in the modified
main frame . To accomplish the 8-ohm
conversion,
TB301
100V_
120V_
200V_
220V_
240V_
STRAPS INSTALLE D FOR
120-VOLT OPERATI ON
®®@CV®@@@@G)
L_,I L_,I L_,I
- - L_,I _L_,1 _ - - - _L_,1_ - -
L_,I L_,I
___ L_,1 _______ L_J_
L_,I L_,I
IACSWITCH
Figure 6. AC Primary Power Module and
Alternate 50160Hz Power Connections

1. Unplug ac cable from ac power source .
2. Remove screws that secure top cover to
main frame. Lift front edge of cover and
pull cover forward to clear rear lip from
chassis. Lift cover off.
3. Locate terminal board TB101 (Figure 7).
Disconnect top lead from terminal 1 and
reconnect to terminal 2. Disconnect top
lead from terminal 4 and reconnect to
terminal 3. This wiring change modifies
the main frame to operate at 8 ohms
load impedance.
4. For each power amplifier module used
with a modified main frame, locate jump-
ers J8A and J8B on component side of
module (Figure 7). Remove these two
jumpers to modify each power amplifier
module to operate at Bohms rated load
impedance.
....------ CAUTION-----~
The 8-ohm modified power amplifier
module may not be used in a main
frame not modified as in Step 3. To
avoid possible mixup, clearly tag or
mark the 8-ohm modified modules
"for 8-ohm operation only". Similarly ,
the modified main frame should be
tagged for "8-ohm operation only".
5. Install top cover of main frame and
secure with screws previously removed
(Step 2). Note that all card modules may
require removal and re-installat ion after
top cover is secured, to assure proper
alignment in card guide channels .
6. Install modified power amplifier modules
inmain frame.
SETUPAND OPERATION
MODULARBLOCK DIAGRAM
The Modular Block Diagram Kit consists of
a simplified Main Frame Wiring Diagram
(42-02-045233)with designations for con-
necting power amplifier modules . To com-
plete the Main Frame Wiring Diagram, sel-
ected module diagrams are taken from the
Module Diagram Sheets (42-02-045232) and
affixed to appropriate spaces within the
Main Frame Wiring Diagram. The Main
Frame Wiring Diagram then becomes the
Modular Block Diagram. Switch and cable
connections are then drawn on the Modular
Block Diagram to complete a orawing of the
system configuration . The finished Incre-
mental Power System block diagram may be
copied on any standard blue-line machine or
other large-format copier .
To use the Modular Block Diagram Kit in an
orderly way,
1. Choose input ,driver,and power amplifier
modules as needed from the Module Dia-
gram Sheets. Remove the module dia-
grams from the sheets and carefully affi x
each module diagram to the appropriate
space on the Main Frame Wiring Dia-
gram. Pressure-sensitive adhesive on the
back of the module diagrams will hold
them securely . Do not allow the adhesive
to touch the Main Frame Wiring Diagram
until the module diagram is oriented
accurately .
2. Indicate switch closures on the driver
matrices by drawing a line between
switch contacts, or by circling the entire
switch , or both . As necessary, refer to
setup procedures for the appropriate
driver module.
3. Draw simplif ied loudspeaker connection
diagrams to the right-hand side of the
power amplifier modules . As necessary ,
refer to OUTPUTCONNECTIONS in this
manual.
4. Make as many copies of the fin ished
Modular Block Diagram as required .
Finished examples of the Modular Block
Diagram are illustrated in Figures 19
through 23. Additional Modular Block Dia-
gram Kits may be ordered from the ALTEC
Literature Department. For each kit desired ,
ask for one copy of the Main Frame Wiring
Diagram, AL-1212 (42-02-045233) and one
copy of the Module Diagram Sheets,
AL-1213 (42-02-045232)
INPUTCONNECTIONS
All input connections to preampli fiers or
other signal processing equipment are
made at the rear panel of the main frame
(Figure 8). Connections should be made
with two-conductor , twisted-pair shielded
cable such as Belden 8450or 8451.
For balanced input at the CH-1 through
CH-4 receptacles , the Model 2221 (trans-
former isolated) Input Card Module must be
installed in the input module slot of the
main frame. For unbalanced input at the UN-
BAL jacks , either the Model 2220 (trans-
formerless) Input Card Module or the Model
2221Input Card Module may be installed .
If electronic crossover is to be incorpor-
ated, the Model 2251 Crossover Driver Card
Module must be installed in the appropriate
locations. Inputs for electronic crossover
are dedicated at CH-1 and CH-3 BAL or UN-
BAL INPUT. The CH-1 connector requires a
crossover driver module to be installed in
the main frame at the #1 (left) driver module
posit ion; the CH-3 connector requires a
crossover driver module to be installed in #2
(right) driver module slot.
Always be sure to use the correct plug in
the main frame connectors (Figure 8). The
J213 thru J216 receptacles require use of
stereo phone jacks .
~----- CAUTION-----~
Standard phone plugs (tip and sleeve)
will short-circuit internal wiring when
inserted in jacks J213, J214, J215, or
J216.
Unbalanced Inputs
For unbalanced input signals connected to
the UNBAL INPUT jacks of Channels .CH-1
thru CH-4, install the Model 2220 Unbal-
anced Input Card Module in the input module
slot of the main frame. Each of the four
channels has two UNBAL jacks wired in par-
allel; this makes available a convenient
signal to feed a second Incremental Power
System, a Model 9440 Power Amplifier, or
other alternate unit.
J8A
J8B
MODEL
2275
POWER
AMPLIFIER
MODULE
MAIN
FRAME
Figure 7. Modification of Main Frame and Power Amplifier Modules for 8-Ohm Operation
5

PUSH-ON TERMINAL CONNE CTORS
SHIELD
r-+-+--- ± SIGNAL
"----tf--....._ __ ± SIGNAL
........_ ___ --\--j,__ __ coMMON
J213,J214, J215,J216
SHIELD
191---1+--(-)-
__..,,__,__ __ (+)--
®
SHIELD
:- S~G;AL
COMMON
----
J205THAU J212
UNBAL INPUT
CH-1 thru CH-4 Connect balanced input signals to channels 1 through 4,
BAL Receptacles respectively . Channels 1 and 3 are dedicated to the
electronic crossover option. XLR-type receptacles .
2 UNBAL Phone
Jacks
3 J213, J214, J215
and J216 Special
Input/Output
Jacks
4 OUTPUT
Terminals
Connect unbalanced signals to channels 1 through 4. One
pair of jacks are wired in parallel for each channel.
Standard ¼" tip and sleeve phone jacks.
Connect eight unbalanced input signals directly to the
driver modules . Tip and ring carry separate input signals .
Sleeve is common. Do not use standard phone plugs (tip and
sleeve), as this will short-circu it internal wiring. Standard
¼ " stereo (ring, tip and sleeve) phone jacks .
Connect outputs of power modul es to the loudspeaker
system. Eight sets of HIGH and COM ¼" push-on type
terminal connectors correspond to eight power amplifier
module positio ns in the main frame.
Figure 8. Input and Output Connectio ns at Main Frame
Up to eight unbalanced inputs may be con-
nected to special input/output jacks J213,
J214,J215, and J216, using stereo (tip, ring,
and sleeve) phone plugs. Two inputs con-
nect to each jack, with tip and ring carryi ng
separate signals with respect to the com-
mon sleeve. These input signals are applied
directly to the driver modules and may be
controlled by the attenual ors on the Model
2250 or 2252 Driver Modules. Since these
special inputs bypass the input module, it is
not necessary to install an input module if
no other inputs are connected to the·main
frame.
6
.-- - -----NO TE-------
Although a total of 8 unbalanced
inputs may be applied to special
input/output jacks J213, J214, J215,
and J216, this does not imply that
these 8 inputs plus a number of addi-
tional inputs may be applied through
the input card modules. Each Incre-
mental Power Syste m may process a
maximum of 8 channels through
separate paths having independent
level controls .
Balanced Inputs
For balanced input signals, install the
Model 2221 Balanced Input Card Module in
the input module slot of the main frame.
Connect up to four balanced input signal
cables to the BAL INPUT connectors of
channels CH-1, CH-2, CH-3, and CH-4. Wir-
ing of the XLR-3 type balanced connector is
shown in Figure 8.
The four pairs of UNBAL INPUT phone
jacks, adjacen t to the BAL INPUT con-
nectors, receive signals from the secondary
of the module input transformers. These
phone jacks may be used to feed a second
Incremental Power System, a Model 9440
Power Amplifier, or other device.
Balanced inputs may not be connected to
special input/output jack s J213, J214, J215,
or J216. These special jacks are intended
for use only with unbalanced connections.
However, balanced signa ls from the Model
2221 Input Module may be routed through a
driver input matrix to appear as an un-
balanced signal at thes e special jacks . A
study of the modular block diagram will in-
dicate avariety of possibl econfigurations.
OUTPUT CONNECTIONS
(MODEL2275 ONLY)
~----CAUTIO N -----~
This section applies only where the
Model 2275 Power Amplifier Modules
are used. Refer to tec hnical publica-
tion 42-02-045362, Model 2276 Power
Amplifier Module, for appropriate out-
put connections regard ing the Model
2276.
Output connections from the power amp-
lifier modules are made at the OUTPUT
HIGH and COM terminals on the rear panel
of the main frame . Figure 9 illustrates var-
ious output configurations for independent,
parallel, bridged, and parallel-bridged
modes of operation. Note that the voltage
specifications given in Figure 9 enable cal-
culation of power delivered to a loud-
speaker system where loudspeaker load im-
pedance is higher than the rated load im-
pedance listed, where:
Power (VxA) =(Voltage)2 + Impedance
Voltage specifications given in Figure 9 are
based on 16 ohms load impedance for the
Incremental Power Syste m. If a system is
modified for a load impedance of 8 ohms,
impedance values of Figure 9 must be
halved. At the same time, the 70-volt specifi-
cations must be changed to 49 volts, and
the 35-volt specifications changed to 24.5
volts.
Use the Modular Block Diagram to deter-
mine all necessary input/ output connec-
tions, and to determine set-up of all driver
switching matrices for the desired output
conf iguration.

IndependentOperation BridgedOperation +
Rated Rated RatedRMS Rated Rated RatedRMS
Power Load Sine-wave Power Load Sine-wave
Output Impedance VoltageOutput Output Impedance VoltageOutput
75watts 16ohms 35volts 150watts 32ohms 70volts
Parallel Operation Numberof ParallelModel2275PowerAmplifiers
1 2 3 4 5 6 7 8
RatedPowerOutput 75watts 150watts 225watts 300watts 375watts 450watts 525watts 600watts
RatedLoadImpedance 16ohms Bohms 5.3ohms 4ohms 3.2ohms 2.7ohms 2.3ohms 2ohms
RatedRMSSine-Wave
VoltageOutput 35volts 35volts 35volts 35volts 35volts 35volts 35volts 35volts
2275's
Parallel/Bridged Operation
2275's +
LOAD
+
2275's LOAD
LOAD
2SETSOF(2)2275's(4TOTAL) 2SETSOF(3)2275's(6TOTAL) 2 SETSOF(4)2275's(8TOTAL)
Rated Rated RatedRMS Rated Rated RatedRMS Rated Rated RatedRMS
Power Load Sine-Wave Power Load Sine-Wave Power Load Sine-Wave
Output Impedance VoltageOutput Output Impedance VoltageOutput Output Impedance VoltageOutput
300watts 16ohms 70volts 450watts 102/:iohms 70volts 600 watts 8ohms 70volts
Figure 9. Power Output, Impedance, and Voltage Output for Various Combinations of Model 2275 Power Amplifier Modules. Voltage specifica-
tions are based on 16ohms load impedance. For systems modified for 8 ohms load impedance, change listed impedance values to one-half
value;change 70-volt listings to 49volts, and 35-volt listings to 24.5volts. For Model 2276PowerAmplifier Modules, refer to separate technical
publication (42-02-045362).
70-VoltLoudspeakerDistributionSystem
For 70-volt loudspeaker distribution sys-
tems, connect the HIGH OUTPUTterminals
as described in 'Bridged Operation', and In
'Parallel/Bridged Operation'. These configu-
rations are based on 16 ohms load Im-
pedance for the main frame and for the
Model 2275PowerAmpllfier Modules.
25-VoltLoudspeakerDistributionSystems
For 25-volt loudspeaker distribution sys-
tems, modify the main frame, and each
Model 2275 Power Amplifier Module to be
used therein, for 8-ohm load Impedance;
refer to 'Conversion for 8-0hm Load
Impedance. Connect HIGH and COM OUT-
PUTTerminals as described In 'Independent
Operation'and in 'Para/le/Operation'.
It Is possible to use 16-ohmpower ampllfier
modules Ina main frame modified for 8-ohm
operation. However,at 25volts output, max-
imum power available for each power amp-
lifier module is 37.5 watts per module (into
16ohms).
IndependentOperation
To operate one or more power amplifier
modules independently, each module must
7
receive a separate input signal and drive a
separate loudspeaker load (Figure 10).Input
signals must be routed through a driver
module. No input signals may be routed
from an input module directly to a power
amplifier module, or from special input/out-
put JacksJ213, J214, J215, and J216directly
to apower amplifier module.
Connect the loudspeaker load to the appro-
priate terminals of the HIGH (TB201)and
COM (TB202) OUTPUT terminal boards.
Rated load impedance for a single power
amplifier module in the independent mode
is 16 ohms (or 8 ohms in modified version).
Rated power output is 75watts.

HIGH
16Q +
.------OUTPUT----,
FROM
DRIVEROR
CROSSOVER
CARDS COM
i-t-+---}16Q
J:i;~~t-1----}16Q
1TO 8 MODEL 2275 POWER
AMPLIFIERS RECEIVE
SEPARATEINPUTS AND
DRIVE SEPARATELOADS.
}--I-+--- }16Q
} 16Q
16Q ~~iil!}-•-1-f-_l-~------}1sQ
FROM
DRIVER OR
CROSSOVER
CARDS
FROM
DRIVEROR
CROSSOVER
CARDS
TYPICAL CONNECTIONS FOR
5 INDEPENDENT SPEAKERS
Figure 10.Typical Independent Mode of Operation
1TO 8 MODEL 2275 POWER
AMPLIFIERS RECEIVE
THE SAME INPUT AND
DRIVE THE SAME LOAD.
TYPICAL CONNECTIONS FOR 4 PARALLEL
AMPLIFIERS TO 4QSPEAKER SYSTEM
Figure 11.Typical Parallel Mode of Operation
,-----OUTPUT----,
HIGH NO CON-
NECTION TO
COM
TERMINALS
FROM
INPUT
OR
CROSS-
OVER
CARD
Ja--31E-+-if---} 32Q
NOT
CON-
NECTED - - - _J
DRIVER AMPLFIERS ON
MODEL 2250 OR 2252 CARD
I
NOT
CONNECTED
2 MODEL 2275 POWER AMPLIFIERS RECEIVE OUT-OF-PHASE INPUTS
AND DRIVE THE SAME LOAD.
TYPICAL BRIDGED
CONNECTIONS TO
THREE32Q
SPEAKER SYSTEMS
Figure 12.Typical Bridged Mode of Operation
8
} 32Q
ParallelOperation
Upto eight power amplifier modules maybe
paralleled. Parallel power amplifier modules
must receive one (common) input signal and
drive one (common) loudspeaker load (Fig-
ure11).
Route a single input signal to the power
amplifier modules by closing the correct
switches of the driver module switching
matrix. Parallel outputs of the desired num-
ber of power amplifier modules by con-
necting jumper bars (supplied with the ac-
cessory kit) to the HIGH and the COM
terminals.
.-------CAUTION------.
If the outputs of two or more power
amplifier modules are paralleled, the
inputs to the same modules also
must be paralleled by closing the
proper switches of the driver output
switching matrix. Mismatched (non-
parallel) or unassigned input paths to
power amplifier modules having par-
alleled outputs may cause fuses to
blow within the modules.
Connect the loudspeaker load to the par-
alleled HIGH terminals and paralleled COM
terminals.
Rated power output in the parallel mode is
75 watts x (number of parallel power amp-
lifier modules). Rated load impedance is 16
ohms (or 8 ohms in modified version),
divided by the number of parallel power
amplifier modules.
BridgedOperation
Bridged operation requires that 'out-of.
phase' signals must be applied to the inputs
of the two power amplifier modules to be
used in this mode. The input to the first
module must be inverted and applied to the
second module. See Figure 12. This in-
version may be accomplished with either
the Model 2250 or 2252 Driver Module. The
Model 2251 Crossover Driver Module may
not beusedto accomplish this Inversion.
Route the input signal to the first driver
amplifier circuit by closing the appropriate
switch of the driver input switching matrix.
Close bridging switch S202;this applies the
input signal to the 'inverting input' of the
second driver amplifier circuit. Do not
assign any input signal to the normal (non-
inverting) input of the second driver amp-
lifier ciruit with the driver input switching
matrix; in addition, turn the input attenuator
of the second driver amplifier circuit fully
counterclockwise to minimum level; for SA
type driver modules, set all rocker switches
to the right for maximum attenuation of 63
dB. Route the output of the first driver amp-
lifier circuit to the Input of one power amp-
lifier module by closing the appropriate
switch of the driver output switching
matrix. Route the output of the second
driver amplifier circuit to. the input of an-
other power amplifier module by closing the
appropriate matrix switch. Connect the
loudspeaker load to the HIGH OUTPUTter-
minals of the two power amplifier modules.
Do not connect the loudspeaker load to the
COMterminals.

,-
FROM I
INPUT
OR I
CROSS-
OVER I
CARD I
NOT
CON- L
NECTED - - -
COM
l
DRIVER AMPLIFIERS ON
MODEL 2250 OR 2252 CARD NOT
CONNECTED
TYPICAL PARALLEUBRIDGED CONNE CTION S
TO TWO 16Q SPEAKER SYSTEMS
2 SETS OF UP TO 4 MODEL 2275 POWER AMPLIFIE RS PER SET RECEIVE
"OUT OF PHASE" INPUTS AND DRIVE THE SAME LOAD.
Figure 13. Typical Parallel/Bridged Mode of Operation
Ratedoutput power from two bridged power
amplifier modules is 150 watts. Rated load
impedance is 32 ohms (or 16ohms in modi-
fied version). The bridged output is a 70-volt
(or 49-volt in modified version) balanced
(non-floating) output which may drive
70-volt or 49-volt commercial sound loud-
speaker lines.
Parallel/Bridged Operation
The parallel/bridged mode produces a
70-volt (or 49-volt in modified version)
balanced output at a higher power level
than the simple bridged mode.
First parallel two identical sets of power
amplifier modules as described in Parallel
Ooeration. Each set must contain the same
number of paralleled power amplifier mod-
ules (two, three, or four modules per set).
INPUT MATRIX SWITCHES
Then, bridge the two sets of paralleled
power amplifier modules as described in
Bridged Operation, as if each set were a
single module (Figure 13).
Always bridge two sets of paralleled power
amplifier modules; do not parallel two sets
of bridged power amplifier modules .
Rated power output for the parallel/bridged
mode is equal to 75watts times the number
of power amplifier modules connected into
the configuration . Rated load impedance is
64 ohms (or 32 ohms in modified version)
divided by the number of power amplifier
modules in the configuration. The parallel/
bridged output is a 70-volt (or 49-volt in modi-
fied version) balanced (non-floating) output
which can drive high power 70-volt or 49-volt
commercial sound loudspeaker lines or
other high power loads.
IS103 I
IS203 I MODEL
2250 MODEL
2252
(/)
w
J:
(.)
I-
~
(/)
~
a:
I-
~
~
I-
::>
Q.
I-
::>
0 BRIDGING
SWITCH S202
SETUP OF DRIVERCARD MODULES
Input Switching Matrix
An input switching matrix is provided for
the Model 2250 and 2252 Driver Card Mod-
ules. The Model 2251 Crossover Driver con-
tains no input switching matrix. Incoming
signals to the input switching matrix arrive
from an input card module, a Model 2251
Crossover Driver Module, or special input/
output jacks J213, J214,J215,or J216.
Input matrix switches of the Model 2250
Driver are designated S103and S203;for the
Model 2252 Driver, designations are S103,
S203, S303, and S403. Use the input matrix
switches to assign an input to one of the
driver amplifier circuits on the driver card
module. For example, to assign an input
from line 6 to the #1 driver amplifier circuit,
close the #6 switch of S103 in the driver in-
put switching matrix . To assign an -input
from line 3 to the #2 driver amplifier circuit,
close the #3 switch of S203. Input switching
matrices are identical for SA type modules .
Always leave all unused (unassigned) input
matrix switches OFF (open) to avoid possi- .
ble misrouting of input signals.
Output Switching Matrix
An output switching matrix is provided on
all driver card modules to assign driver amp-
lifier circuit outputs to the appropriate
power amplifier modules . For example, to
assign the output of the #4 driver amplifier
circuit (Model 2252 Driver Module) to the
input of power amplifier module #2, close
the #2 switch of S401 in the driver output
switching matrix . To assign the output of
driver amplifier circuit #3 to the inputs of
power amplifier modules #5 and #6, close
the #5 and #6 switches of S301. Output
switching matrices are identical for SA type
modules.
Always leave all unused (unassigned) out-
put matrix switches OFF (open) to avoid
INPUT
MATRIX
SWITCHES
IS103 I
IS203 I
IS303 I
IS403 I
OUTPUT
~il-??':r: =--MA TRIX
SWITCHES
IS201 I IS101 I
IS401 I IS301 I
BRIDGING
SWITCH S402
Figure 14. Bridging and Matrix Switch ing for Model 2250 and 2252 Driver Modules
9

..-------CAU TION------.
INPUT MATR IX SWITCHES Do not actuate any switches on the crossover driver module while pri-
mary ac power is turned on. Failure to
observe this precaution will introduce
a large transient which may cause
damage to loudsp eakers connected
to the system .
OUTPUT MATRIX
SWITCHES
IS201 I IS101 I
IS401 I IS301 I
ATTENUATION
SWITCHES
ISS03 I
IS502 I
IS501 I
IssooI
BRIDGING
SWITCH S402
Matrix switches S101, S201, and S301 con-
nect the high-freque ncy, mid-frequency ,
and low-frequency driver amplifier circuits
to the inputs of the power amplifier mod-
ules. For example, to route high frequency
signals to power ampli fier module #1, close
the #1 output matrix switch of S301. To
route low frequency signals to power amp-
lifier modules #4 and #5, close output
matrix switches #4 and #5 of S101.
Figure 15. Typical SA Type Driver Module (Model 2252 SA Shown)
A study of the Modular Block Diagram will
indicate a variety of configurations to dis-
tribute signals for biamplification and tri-
amplification . Note that the biamplification
mode of operation enables the mid-
frequency driver amplifi er circuit to be used
as a full range driver amplifier, with level
control , by connecting this signal source at
special input/output jack J214; see appli -
cations example given in Figure 20 for an
illustration of this case.
possible misrouting of driver output
signals.
BridgingSwitches
Bridging switches are provided on the
Models 2250 and 2252 Driver Modules to
bridge outputs of two (or two equivalent
sets) of power amplifier modules for a bal-
anced 70-volt (or 49-volt in modified version)
output. Refer to Figure 12 and appropriate
paragraphs under OUTPUTCONNECTIONS.
The bridging switch for the Model 2250
Driver Module is designated S202; see Fig-
ure 14. Bridging switches for the Model
2252Driver Module are designated S202 and
S402. Always leave the bridging switches
OFF (open) unless the application specifi-
cally requires closure for a bridged con-
figuration. Bridged switching is identical for
SAtype modules .
AttenuationControls
An attenuation control is provided for each
driver amplifier circuit of the driver module.
Attenuation is continuously adjustable
from Oto - 60 dB for Models 2250, 2251and
2252. See Figure 14. Step attenuato rs are
provided for the SA type modules, adjust-
32d B
SWITCH
16dB
SWITCH
8d B
SWITCH
4dB
SWITCH
2dB
SWITCH
1dB
SWITCH
CLOSE SWITCHES BY
DEPRESSING ROCKER
TO LEFT (ADD
ATTENUATION)
OPEN SWITCHES BY
DEPRESSING ROCKER
TO RIGHT (REMOVE
ATTENUATION)
Figure 16. Attenuation Switch ing of SA
Type Driver Modules
able in increments of 1 dB from 0 to - 63
dB. See Figure 15. A study of the modular
block diagram illustrates that the attenu-
ation controls are especially useful to es-
tablish several signal levels from a single
source signal.
Attenuation Switching of SA Type Driver
Modules
SA type driver modules are equipped with
step attenuators . Six attenuation switches
for each driver amplifier circuit provide 1, 2,
4, 8, 16 and 32 dB attenuation. By closing
the switches in various combination, any
atte nuation may be obtained in 1 dB steps ,
to a maximum of 63 dB. See Figure 16. For
example, closing switches 1, 2, and 5 pro-
vide an attenuation of 19dB.
ElectronicCrossoverSwitching
The option of elect ronic crossover is pro-
vided on the Model 2251 Crossover Driver
Module; see Figure 17. Two-way or lhree-
way crossover operation may be selected
with Bl/TRI switc h S3. Crossover frequen-
cies may be select ed with switches S1 and
S2. Switches S1 and S2 each have four posi-
tions to select crossover frequencies as
indicated in Figure 17.
TRI
t-B1/TRI
SWITCH
S3
Bl
HF DRIVER OUTPUT
MATRIX SWITCH S301
LF DRIVER OUTPUT
MATRIX SWITCH S101
Filter output lines 10, 11 and 12 respectively
feed the low, mid, and high frequencies to
the input of a Model 2250 or 2252 Driver
Module, and to the special input/output
jacks J213, J214, J215, and J216. Thus the
low, mid, and high frequ ency outputs of the
crossover driver modul e are accessible to
feed another Increment al Power System, a
Model 9440 Power Amplifier, or other
device.
Rated load impedance of low, mid, or high
frequency direct filter outputs of the cross-
over driver is 3000ohms minimum.
MODULE EXTENDERCARDS
Module extender cards permit any of the
system modules to remain operational ·
when physically removed from the main
frame. This facilitates final adjustments of
the input and driver modules, and simplifies
troubleshooting . Use the Model 2299 Ex-
tender Card with any input module or driver
module; use the three adjustment nuts to
MID- HIGH
FREQUENCY
SWITCH S2
N N N N
::c:::c:::c:::c:
0000
0001/)
ooo.--
00 1/) q- (')
ATTENUATION
CONTROLS
LOW-M ID
FREQUENCY
SWITCH S1
NNNN
::c:::c:::c:::c:
0001/)
0Ll)ON
CON COCO
,- ,-
Figure 17. Electronic Crossover Switching for Model 2251 Driver Module
10

•
•
~ /--
TYPICAL CARD MODULE
PLUGGED INTO EXTENDER CARD
MODEL 2279 ______ ....,._;;;,-....
EXTENDER CARD POWER AMPLIFIER MODULE
PLUGGED INTO EXTENDER CARD
Figure 18. Extender Cards for Use with System Modules
properly orient the card and frame with re-
spect to the module plugged in. Use the
Model 2279 Extender Card with any power
amplifier module. Figure 18 illustrates the
two types of extender cards.
Always turn off primary ac power to the
Incremental Power System before changing
the settings of any switches on the driver
(or crossover driver) module. Adjustment of
attenuators on the input and driver modules
may beaccomplished while the system is in
operation.
SUMMARY OF PRECAUTIONS AND GOOD
PRACTICES
1. Do not operate or store an Incremental
Power System with paralleled power
amplifier modules unless driver amp-
lifier outputs are properly assigned to
the inputs of the paralleled power
amplifier modules.
2. When paralleling power amplifier mod-
ules, make all parallel connections only
at terminal blocks TB201 (HIGH) and
TB202 (COM), using jumper bars sup-
plied with the accessory kit. Do not
parallel power amplifier modules at the
loudspeakers, or the modules may
overheat due to improper sharing of
load.
3. When outputs of two or more power
amplifier modules are paralleled, their
inputs must also be paralleled . Mis-
matched (non-parallel or unassigned) in-
puts to paralleled power amplifier
modules will cause fuses to blow within
the amplifier modules.
4. Do not operate an Incremental Power
System without installing at least one
driver card module.
11
5. Never remove any driver card module
from the main frame while primary ac
power is turned on.
6. Do not operate any switches of driver
(or crossover driver) modules while pri-
mary ac power is turned on, with the
exception of step attenuation switches
of SAtype driver modules .
7. Use only stereo (tip, ring, and sleeve)
phone plugs in special input/output
jacks J213, J214, J21~ and J216. Stand-
ard phone plugs (tip and sleeve) will
short-circuit internal wiring .
8. If the power amplifier modules are mod-
ified for 8 ohms load impedance, make
certain that the power supply voltage
secondary taps (main frame) are con-
nected for the low voltage position; see
Figure 7. Do not mix 8-ohm and 16-ohm
power amplifier modules within a given
main frame. Power amplifier modules
modified for 8 ohms. Power amplifier
modules with a load impedance of 16
ohms may be used either in a 8-ohm or
16-ohm main frame.
9. Leave all unused (unassigned) driver
matrix switches OFF (open) to avoid
possible misrouting of input signals .
10. It is good practice to assign the highest .
power demands to the power amplifier
module nearest the cooling fan.
APPLICATIONS EXAMPLES FOR THE
INCREMENTAL POWER SYSTEM
A few typical configurations of the In-
cremental Power System are given in Fig-
ures 19 through 23. These illustrations are
photo-reductions of finished Modular Block
Diagrams. A study of these systems will
reveal the versatility and flexibility of the
Incremental Power System.

lNORMAL INPUTS i
-
BAL IN-1
J201
-;---
..
"-'
BAL IN-2
J202
CE
BAL IN-3
J203
B-
BAL IN-4
J204
,-...
~-
CH. 1
UNBAL
IN/OUT-1
I!!
~
0..
...
~
0 CH. 2
a:
0 UNBAL
..... ...IN/OUT-2
~
2
0
:;;
w
...
0 CH.3
"'z UNBAL
0
u IN/OUT-3
0
i5
~
...
"'
:;; CH. 4
0 UNBAL
a:
..
IN/OUT-4 9
(/11J<:
!
::;-i~
J
INPUT MODULE JACK (J506)
,---7 ID
LEVEL-1
LEVEL-2
L LEVEL-4
ALTEC-22J~ I
INPUT CA~
SPECIAL
INPUT/OUTPUT
J213n~
--C, ~ _R
J214n~
~ ~ _R
J215nv-o!-
~ ~ _R
--4 ~
""~
r/n- rts..-.:...·---r
LEFT DRIVER MODULE JACK (J505)
,-----
N/C N/C N/C
L ~12 ~" -J;o
12 11 10
RIGHT DRIVER MODULE JACK (J504)
7 1TO 8
MODEL 2275
POWER
AMPLIFIERS
~ 1.b~bl ~L~ -))1111i ((I? >r 1
;;> J,,'I j' I j1 ~ )Y-111111 t «1~» · •
N/C I
g AUEC-2252
~ 4-CHANNEL DRIVER CARD I
- - -- -- -- .:..J
75WATT/160R SOHM
OUTPUTS
4 x 604-8G/620A
~ac;;;o -;;;;;;,e each of Models 2250, 2251, or 2252 7
Four-channel system with four
unbalanced inputs. Two power
amplifier modules are parallel-
ed for each channel to provide
a rated output power of 150
watts per channel, or a total of
600 watts.
L_ _J
12 11 10
Figure 19. Four-Channel System with Rated Output of 600 Watts
J
28
27
26
25
24
22
21
System uses one Model 2220
Input Module, one Model 2252
Driver Module, and eight Model
2275 Power Modules. Each
channel consists of one driver
amplifier circuit feeding one
pair of power amplifier
modules.
J

w
,
!NORMAL INPUTS l
..
::,
IL
..
::,
0 BAL IN-1
a: J201
w
N~
::::i ••
c(
::,
Cl
IU BAL IN-2
li: J202
~~ ... .
BAL IN-3
J203
»-
BAL IN-4
J204
-'
~
UNBAL
IN/OUT-1
UNBAL
IN/OUT-2
UNBAL
IN/OUT-3
UNBAL
IN/OUT-4
11 I I 4
INPUT MODULE JACK (J506)
,---7 (D
LEVEL-I
ALTEC-2221
~PUT CA~
SPECIAL
INPUT/OUTPUT
,--
1
I
'- J214
--
J215
J216
1h
,
LEFT DRIVER MODULE JACK (J505)
i-----
~-----rl~ I
I 3(~
__ __,.(I~
I •
~~
7 lTOB
MODEL 2275
POWER
AMPLIFIERS
-~
75WATT/16OR BOHM
OUTPUTS
I
6,~ J414 .._
I I I I I --) ) 111I I I <(-16>-7)!-o
....
I
7,~
I
J415 .._
~ HF I ~ I ~ t ~ -->>1111IIT «~!>-7)!---<>, - ,
·y-jii iiii;~((-1~>-7)Lo
·~~
~
I
L MF ILF N/C ALT!:C-2251 I
10 J,,s Bl-AMP/TRI-AM~
11 DRIVER CARD
-------
12 '11 110 Ys
RIGHT DRIVER MODULE JACK (J504)
,------ 7
S203 S103 S101 S201
S202
(- t T 8 .......... y ...,..t21)1)....21____ .....
L
N/C N/C N/C N/C I
I12 J 11 I10 I9 ALTEC-22~~ I
_ -.j;_ ,J;_ -.j;_ ..J_.; 2-CHANNEL DRIVER CAR~
12 11 10 9
Figure 20. Biampllfied Configuration with Far, Middle, and Near-Throw Horns
.... -=-
One balanced input for a bi-
amplified system having far,
middle and near-throw horns.
Crossover frequency is 800 Hz.
One HF channel feeds one
power amplifier module to
drive far-throw horn (203B).
Two additional HF channels
each feed one power amplifier
module to drive middle-throw
(803B) and near-throw (1003B)
horns. LF channel feeds one
pair of parallel power amplifier
modules. Note that mid·
frequency driver amplifier cir-
cuit is available for a HF fre-
quency range application by
patching J213 and J214.

.....
.i,.
!NORMAL INPUTS i
cc
w
N
::;
..: BAL IN-1
:,
0 J201
w ~
,:
CJ
:,
0
0:
,: BAL IN-2
~ J202
"'
~
....
:,
0.
....
:,
0 BAL IN-3
w J203
....
0 Go)
"'z
0
u
::;; BAL IN-4
0
fl: J204
0
..
UNBAL
IN/OUT-1
UNBAL
IN/OUT-2
UNBAL
IN/OUT-3
UNBAL
IN/OUT-4
MON.1
mon. 2
J
I I I I 4
INPUT MODULE JACK (J506) LEFT DRIVER MODULE JACK (J505)
,---7 (D
lL ,------
S1 J BOO
! 7
21~
I~
-
~=--f-_;;:- ➔ )7)•'"1 1 ,~ I (
( I (" •(I~
SPECIAL
INPUT/OUTPUT
J213
J214
J215
J216
T
R
T
R
T
R
T
R
I s_l~
6,1~
I
7, {!--
I
a,~
I
L MF ILF
11 10
11 Y,o
~
I
N/C ALTEC-2251 I
19 81-AMP/TRI-AMf_J
DRIVER CARD
-------
Ys
RIGHT DRIVER MODULE JACK (J504)
,------ 7
S103 S101 S201
S202
l r
L N/C N/C N/C N/C I
I12 I11 I10 I9 ALTEC-225~ I
~ ~ ~ -.j,, 2-CHANNEL DRIVER CAR£._j
--- -- -- ---------
12 11 10
Figure 21. Triamplified Configuration and Two Full Range Channels
J
1TO 8
MODEL 2275
POWER
AMPLIFIERS
75WATT/160R BOHM
OUTPUTS
Two balanced inputs drive two
independent power amplifier
modules. One balanced input
is configured into atriamplified
system. LF channel (crossover
at 800 Hz) drives four parallel
power amplifier modules. MF
channel (crossover at 5000 Hz)
drives one power amplifier
module. HF channel drives one
power amplifier module.
J

....
C1I
··~
iNORMAL INPUTS l
BAL IN-1
"' J201
"
~
0 MS DELAY
>
"'
Q
>
:5 BAL IN-2
"' J202
Q Cf.)~ MS DE~ Y
.,
"'
::;
i=
... BAL IN-3
0 J203
~
~
40MS DELAY
:,
..
I-
:,
0
::; BAL IN-4
0 J204
II:
~
UNBAL
IN/OUT-1
UNBAL
IN/OUT-2
UNBAL
IN/OUT-3
UNBAL
IN/OUT-4
60 MS DELAY
INPUT MODULE JACK (J506)
,---7
SPECIAL
INPUT /OUTPUT
CD
J213 n v--e-!----+++;
R
J214 T
R
J215 T
J216
=-
,
LEFT DRIVER MODULE JACK (J505)
,----
NIC
L '1-12
12
NIC
-J,,11
11
NIC
-j;o
10
RIGHT DRIVER MODULE JACK (J504)
,------
N/C N/C NIC
7
N/C g AL"I EC-2252
~ 4-CHANNEL DRIVER CARD I
_______ :___J
7
NIC I
L -J,,'
2 -J,," -j;o -J.,,-9 ALHC-2252
_ __ _ _ _ _ _4-~NNEL DRIVER CAR~
I I I I v;, Y,1 Y,o y,
Figure 22. Bridged Configuration Incorporating Time Delay
-~
nos 11 75WATT/16OR BOHM
MODEL 2275 OUTPUTS
POWER
AMPLIFIERS
I) TB202 (COM)
':849A N/C
±849A N/C
±849A N/C
±849A N/C
±849A N/C
±849A N/C
±849A N/C
--
--
±849A I N/C
Four balanced channels each
introduce four different delay
times. Each channel drives two
bridged power amplifier
modules.
-=-

!NORMAL INPUTS i
-
BAL IN-1
J201
B--
BAL IN-2
J202
»-
BAL IN-3
J203
B--
BAL IN-4
J204
@-
a: LEFT
w -
N
~ UNBAL
::, IN/OUT-1
0
w
:i:
0
::,
0
a:
_. % UNBAL
CJ) I- IN/OUT-2
"'
I-
::,
..
I-
::, RIGHT nJ209
0
a:
~ ~NSAL
:ii IN/OUT-3 nJ210
0
u
"'
Q nJ211
:ii
i UNBAL
'" IN/OUT-4 n J212
~
J
INPUT MODULE JACK (J5061
,---7 ID
/ 20) : ➔ 1L
LEVEL-1
I ID I
2,( 115)'-'L
I LEVEL-2 I
ID I
3,', ~110, ~
~- LEVEL-3 I
I ID I
~ ( ' 5) '-4L
• .} LEVEL-4 I
L AL TEC-222~
INPUT CARD
---
SPECIAL
INPUT/OUTPUT
J213
J214
J215
J216
T
R
T
R
LEFT DRIVER MODULE JACK (J505I
,------
S1 { aoo
I '(I~
I
I 3(~
I 4(1~
~I~
I
·-~
I
'·~
I
s~~
I
L MF ILF
11 10
11 Y,o
RIGHT DRIVER MODULE JACK (J5041
,------
S1 { ROO
I 1 X57
I ,
'1111'(~ I 3
I 1111( 1 ~
I 1111(~ I~
.1~
,I~
-,,,,. al~
I
L MF
11
LF
10
10
(I)
7
~
I
N/C I
ALTEC-2251
J,• Bl-AMP/TRI-AM~
DRIVER CARD
y.- - -- -- -
N/C
J,·_
ILF) (MF) (HF)
S101 S201 S301 7
Figure 23. Stereo Triamplified System
J
11111111
1TOB
MODEL 2275
POWER
AMPLIFIERS
75WATT/16OR BOHM
OUTPUTS
Two unbalanced inputs each
are configured into separate
triamplified systems. Each LF
channel is assigned to drive a
pair of parallel power amplifier
modules. Each MF and HF
channel is assigned to drive
one power amplifier module.
J
-=-

SYSTEM SPECIFICATIONS FOR INCREMENTAL POWER AMPLIFIERS
Voltage Ampliflcation (Maximum)
From input of Model 2220 Input Card through Model 2250 or
2252Driver Card to output of Power Amplifier Module.
From input of Model 2220 Input Card through Model 2251
Crossover Card to output of Model 2275 Power Amplifier.
Voltage Amplification (Maximum)
From input of Model 2220 Input Card through Model 2251
Crossover Card to Special Input/Output Jacks J213, J214, or
J215.
Minimum Load Impedance
For Special Input/Output Jacks 213, 214, and 215.
Voltage Amplification (Maximum)
From special Input/Output Jacks J213, J214, J215, or J216
through 2250 or 2252 Driver Card to output of Model 2275
Power Amplifier.
Input Sensitivity
Input voltage needed at 2220 Input Card inputs for rated output
from Model 2275 Power Amplifier with 2250 or 2252 Driver
Card.
Input Sensitivity
Input voltage needed at 2220 Input Card inputs for rated output
from Model 2275 Power Amplifier with Model 2251 Crossover
Card.
Input Impedance
35.0 dB in independent or parallel mode, 41.0 dB in bridge or parallel/
bridge mode (all attenuators at full CW rotation).
35odB to output of Power Amplifier Modules assigned to the "Low"
ou.tput of the 2251Crossover Card: 36.7dB to output of Power Amplifier
Modules assigned to the "Mid" output of the 2251 Crossover Card; 47.0
dB in Biamplifier, 50.6 dB in Tri-Amplifier to output of 2275 Power
Amplifier Modules assigned to the "High" output of the 2251Crossover
Card; 35.0dB to output of power amplifier in biamplifier mode using full
range channel (MF channel of 2251 driver). (Values apply to Power
Amplifier Modules in independent or parallel mode; add 6 dB to values
for Power Amplifier Modules used in bridge or parallel/bridge modes; all
values assume full CW rotation of appropriate attenuators.)
+15.0 dB to J213 ("High" output); +11.5 dB to J214 ("Mid" output);
- 0.5 dB to J215 ("Low" output). (All attenuators at full CW rotation.)
300 ohms.
35.0 dB in independent or parallel mode; 41.0 dB in bridge or parallel/
bridge mode.
(All attenuators at full CW rotation.)
- 2.0 dB* (0.61V) for 16Q operation, - 4.9 dB (0.44V) for 8Q operation
with appropriate attenuators at maximum CW rotation; Input Sensitivity
is the same for all operational modes of Power Amplifier Modules.
- 2.0 dB (0.61V) for 16Q operation, - 4.9 dB (0.44V) for 8Q operation
with appropriate attenuators at maximum CW rotation; Input Sensitivity
is the same for all operational modes of Power Amplifier Modules.
At Special Input/Output Jacks J213, J214, J215, J216 with 29K ohms.
Model 2250or 2252 Driver Card.
Input Sensitivity
Input Voltage needed at Special Input/Output Jacks J213,J214,
J215 or J216 for maximum output from Model 2275 Power
Amplifier with 2250 or 2252 Driver Card.
AC Power Requirements
(2200 Main Frame with 8-Model 2275 Power Amplifiers, Model
2221 Input Card, Model 2252 Driver Card.)
Export Conversion Voltages
Connectors (Main Frame)
Controls and Indicators
(Model 2220 Main Frame)
- 2.0dB (0.61V)for 16Qoperation, - 4.9 dB (0.44V)for 8Qoperation with
appropriate attenuators at maximum CW rotation; Input Sensitivity is
the same for all operational modes of Power Amplifier Modules.
120VAC, 50 or 60 Hz; 1100WAC line power at full power (600W) output.
1kHz input: 660W AC line power at 1/3power (200W)output, 1kHz input:
360WAC line power at 1/10power output (60Wor - 10dB from full out-
put power), pink noise input.
100, 120,200, 220, 240V AC, 50 or 60 Hz
(4) D3F Channel 1-4 Input Connectors. (XLR-type three-pin female.) (8)
1/4" TS Phone Jack Input Connectors (in pairs with each pair corresp-
onding to an input channel). (4) 1/4" TRS (stereo) Phone Jack Special
Input/Output connectors. (2) Eight-position terminal blocks, (one
"HIGH", one, "COM") corresponding to the outputs of the eight
possible Model 2275 Power Amplifiers. (1) Three-pin (grounded) AC
power cable connector. (8) 10-position card-edge connectors for up to
eight Model 2275Power Amplifiers or four Model 2276Power Amplifiers.
(3)28-position card-edge connectors for the Input, Driver and Crossover
Cards.
(1)Combination AC-power-switch/circuit-breaker/pilot-lamp.
• In these specifications, when dB represents a specific voltage, OdB Is referenced to 0.775 volts rms. 'dB' is a voltage level, whereas
'~bm' is a power level. 0 dB_mis rl:'ferenced to 1 mW (0.775volts driving a 600-ohm termination). For example, when 6.16volts drives a
high Impedance, the level Is designated + 18 dB. When 6.16 volts drives a 600-ohm termination, the level is designated + 18 dBm.
17

SYSTEMSPECIFICATIONSFORINCREMENTALPOWERAMPLIFIERS(CONTINUED)
DimensionsandWeights
Full Empty
Model2200 Model2200 Model2220 Model2250
Main Frame Main Frame Input Input
Weight 70 lb 50Ib 6 oz 17oz
(31.7kg) (25.4kg) (170gm) (481gm)
Length 17-5/8" 17-5/8" 5-1/2" 5-1/2"
(447.7mm) (447.7mm) (140mm) (140mm)
Width 19" 19" 1 3/8" 1 3/8"
(483mm) (483mm) (34.9mm) (34.9mm)
Height 7" 7" 6-1/2" 6-1/2"
(178mm) (178mm) (165.1mm) (165.1mm)
Finish (Front panel of 2200 Main Frame) Altec Green
Model2220Input Module Specifications
Type
Attenuator
Specifications
MaximumInput
Level
InputImpedance
Input Card: 4 Unbalanced inputs with
attenuators on each input.
25 K ohm audio-taper potentiometer
with at least 60 db attenuation at full
CCW rotation.
+30 dB (24.5volts)
25K ohms
Model 2221Input Module Specifications
Type
Attenuator
Specifications
Transformer
Specifications
Input Card: 4 Balanced, transformer-
isolated inputs with attenuators on each
input.
25K ohm audio-taper potentiometer
with at least 60 dB attenuation at full
CCW rotation.
(Similar to Altec Model 15335A)
Turn Ratio: 1:1
Impedance: 15K ohms primary and
secondary
Frequency Response: ± 1 dB, 20 Hz
to 20 kHz
Maximum Input Level:
+21 dB (8.70volts)
Insertion Loss: 0.7 dB
Model2251 Model2275 Model 2276
Model2252 Crossover/ Power Power Power
Driver Driver Driver Amplifier Amplifier
5 oz 7 oz 7 oz 24oz 2 lbs, 12oz
(141gm) (198.4gm) (198.4gm) (680.4gm) (1.25kg)
5-1/2" 5-1/2" 5-1/2" 10-1/8" 10-1/8"
(140mm) (140mm) (140 mm) (257.2mm) (257.2mm)
13/8" 1-5/16" 1-5/16" 1-1/4" 2-5/8"
(33.3mm) (33.3mm) (33.3 mm) (31.3mm) (66.6mm)
6-1/2" 6-1/2" 6-1/2" 6-1/2" 6-1/2"
(165.1mm) (165.1mm) (165.1mm) (165.1mm) (165.1mm)
Model 2250,2250SA,2252,and 2252SA Driver Module
Specifications
Type
18
DriverAmplifiers
Switches
Performance
Specifications
Attenuators
(Models2250,
2252)
(Models2250SA,
2252SA)
Models 2250: Driver Card with 2 driver
amplifiers, input and output switch
matrix and 2 attenuators. Models 2252:
Driver Card with 4 driver amplifiers, input
and output switch matrix and 4
attenuators.
x 57.3 (35.2 ± .2 dB voltage amplifica-
tion) amplifiers designed specifically to
drive the Models 2275 and 2276 Power
Amplifiers.
Matrix Switches: DIP (dual inline pack-
age) SPST switches-8-switches per
DIP; 2 input DIPS and 2 output DIPS for
Models 2250; 4 input DIPS and 4 output
DIPSfor Models 2252.
Bridging Switches: Slide-type switch to
bridge the outputs of two Model 2275or
2275 Power Amplifliers for a 70-volt
balanced output. 1 bridging switch for
Models 2250, 2 bridging switches for
Models 2252.
Included with Model 2275 and 2276
Power Amplifier Specifications.
One 50K ohm audio taper potentio-
meter at the input of each driver
amplifier; at least 60 dB attenuation at
full CCW rotation.
One six-position DIP switch for each
attenuator with sumable steps of
1-2-4-8-16-32 dB; (maximum 63 dB
attenuation); for attenuators for the
Model 2252SA, two attenuators for the
Model 2250SA.

Models 2251and 2251SACrossover Driver Module Specifications
Type
Crossover
Frequencies
2-way or 3-way electronic crossover card
with 3 driver amplifiers and an output
switch matrix.
625 Hz, 800 Hz, 1250 Hz, 1600 Hz (Low/
Mid); 3150 Hz, 4000 Hz, 5000 Hz, 8000 Hz
(Mid/High).
MinimumLoad
Impedanceon
SpecialInput/Output
JacksJ213,J214,
J215
3000 Ohms (actual output impedance is
2700.
Switches
12dB/octave
3 DIP (dual inline package) output bus
matrix switches-8-SPST switches per
DIP; 1 "Bl/TRI" switch, 2 Crossover Fre-
quency Switches.
SlopeRate
Frequency
Response Each filter is - 3 dB at the selected
crossover frequency. The LOW output is
less than - 0.5 dB at 20 Hz; the HIGH
output is less than - 0.5dB at 20kHz.All
filters are essentially flat within their
respective passbands.
DriverAmplifiers x 57.3 (35.2± .2 dB voltage amplifica-
tion) amplifiers designed specifically to
drive the Models 2275 and 2276 Power
Amplifiers.
PhaseResponse
TotalHarmonic
Distortion
HumandNoise
All filters conform to standard "butter-
worth" phase response within ± 20°
Less than 0.1% from 20 Hz to 20 kHz
from any driver amplifier output, all
attenuators at full CCWrotation.
95 dB Signal to Noise ratio at driver amp-
lifier outputs with equal channel gains. Attenuators
Model2251
3 driver amplifiers, one each for the
HIGH, MID and LOW outputs. Driver
amplifiers drive the Models 2275 and
2276 Power Amplifiers but do not drive
the Special Input/Output Jacks J213,
J214 and J215. Mid Output may be used
as a full-range channel in bi-amplifier
mode with an input attenuator acces-
sible through J214.
LOW, HIGH and MID driver amplifiers
have 50K ohm audio taper input attenu-
ators with at least 60 dB attenuation at
maximum CCWrotation.
MaximumVoltage
Amplificationfrom
2220InputtoSpecial
Input/OutputJacks
J213,J214orJ215
+ 15.0 dB (+ 11.5 dB in bi-amplifier) to
J213 ("HIGH" output): + 11.5dB to J214
("MID" output): - 0.5 dB to J215("LOW"
output). Note: LOW, HIGH and MID att-
enuators do not affect the output level at
the Special Input/Output Jacks J213,
J214andJ215.
Model2251SA LOW, MID and HIGH driver amplifiers
each have a six-position DIP switch att-
enuator with sumable steps of
1-2-4-8-16-32dB (maximum 63 dB attenu-
ation).
Model2275PowerAmpIifier Specifications*
PowerOutput
PowerOutput at Clipping
Frequency Response
Total Harmonic Distortion
DampingFactor
ActualOutputImpedance
HumandNoise
SeparationBetweenAny
TwoModel2275's
PhaseShift
OffsetVoltage
Indicator
Fuses
IndividualModel2275DrivenbyModel2250or
2252DriverCardwithModel2220InputCard
75 watts continuous average sine wave power into
a 16-ohmload impedance.
90watts at 1kHz into a 16-ohmload impedance.
+0, - 0.5dB from 20Hzto 20kHz
Less than 0.25% from 20 Hzto 15kHz
Less than 0.03% at 1 kHz, 75 watt output into
16-ohms
57:1@ 100Hz
0.28ohm in series with 10microhenries
96dB signal to noise ratio
75dB@ 1 kHz
Less than± 15°from20Hzto20kHz
Less than ± 50mVDC
Eight Model 2275's in Parallel/Bridge Mode
Driven by Model 2250or 2252Driver Card with
Model 2220Input Card
600 watts continuous average sine wave power
into an 8-ohm load impedance.
675watts at 1kHz into an8-ohm load impedance.
+0, - 0.5dB from 20Hzto 20 kHz
Less than 0.25% from 20 Hzto 15kHz
Less than 0.05% at 1 kHz, 600 watt output into
8-ohms
57:1@ 100Hz
0.14ohm in series with 5microhenries
93dB signal to noise ratio
(Does not apply)
Less than ± 20• from 20Hzto 20kHz
Less than ± 100mV DC
One red LED"ON" indicator per2275turns off in the event of module failure.
(2)AGC-style 2.5amp "fast blow" fuses per 2275Power Amplifier
* These specifications apply only to 16-ohmoperation
19

1V1uue1u.,o t'ower Amp11nerspecitn::ations
. .
Power Output
Power Output at Clipping
Frequency Response
Total Harmonic Distortion
DampingFactor
ActualOutput Impedance
Hum andNoise
SeparationBetweenAny
TwoModel2276's
PhaseShift
OffsetVoltage
Indicator
Fuses
Individual Model 2276 Driven by Model 2250 or
2252 Driver Card with Model 2220 Input Card
150 watts continuous average sine wave power into
a8-ohm load impedance.
180watts at 1kHz into a8-ohm load impedance
+0, - 0.5 dB from 20 Hzto 20 kHz
Less than 0.25% from 20 Hz to 15kHz
Less than 0.05% at 1 kHz, 150 watt output into
8-ohms
57:1@ 100 Hz
0.14 ohm in series with 5 microhenries
96dB signal to noise ratio
75dB@ 1kHz
Less than ± 15• from 20 Hzto 20kHz
Less than ± 50 mV DC
Four Model 2276's in ParallellBridge Mode Driven
by Model 2250 or 2252 Driver Card with Model 2220
Input Card
600 watts continuous average sine wave power into
an 8-ohm load impedance.
675 watts at 1kHz into an 8-ohm load impedance
+ 0, - 0.5 dB from 20 Hz to 20 kHz
Less than 0.25% froin 20 Hzto 15kHz
Less than 0.1% at 1 kHz, 600 watt output into
8-ohms
57:1@ 100 Hz
0.14 ohm in series with 5 microhenries
93 dB signal to noise ratio
(Does not apply)
Less than ± 20• from 20 Hz to 20 kHz
Less than ± 100mV DC
One red LED "ON" indicator per 2276turns off in the event of module failure.
(2)AGC-style 5 amp "fast blow" fuses per 2276 Power Amplifier.
20