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Power Base Series Power Amplifiers
Page 7
1 Welcome
Congratulations on choosing a
Power Base
amplifier.
Power Base
amplifiers are compact, professional ste-
reo power amplifiers engineered to meet the most de-
manding sound reinforcement needs. They compare
very favorably to more expensive amplifiers, providing
uncolored sound and signal-to-noise ratios commonly
associated with recording studios.
This manual will help you successfully install and use
your amplifier—we strongly recommend you read all
instructions, warnings and cautions. If you plan to oper-
ate in one of the two mono modes, be sure to read Sec-
tion 2.2. Also for your protection, please save your bill
of sale as it is your official proof of purchase.
1.2 Features
❏ Rugged, professional power amplifier built for the road.
Mounts in a standard 19 inch (48.3 cm) rack.
❏ Crown’s patented
grounded bridge
circuitry gener-
ates large voltage swings while avoiding electrical
stress on the output stages. This results in low distortion
and high reliability.
❏ Front panel power switch with turn-on delay for loud-
speaker protection.
❏ Patented Output Device Emulation Protection (
ODEP
®
)
keeps the amplifier working when others would fail.
❏ High damping factor provides superior control over low
frequency drivers for a clean, accurate low end.
❏ Safe with any load. Bridge-Mono and Parallel-Mono
modes offer optimal load-matching performance.
❏ Complete protection against shorted outputs, mis-
matched loads, overheating, DC input/output and high-
frequency overload; full internal fault protection.
❏ Balanced phone jack inputs with internal three-position
sensitivity switch. Optional XLR or barrier block input
connectors are available with the
MT-XLR
or
MT-BB
ac-
cessories.
❏ Ground lift switch is provided to isolate the chassis
ground from the phone jack input ground.
❏ Efficient heat sinks and self-contained forced air cool-
ing system dissipate heat quickly and evenly for extra
amplifier protection and greater power output.
❏ Three year “No-Fault” full warranty and guaranteed
specifications protect your investment.
Fig. 1.1 Power Base Front and Back Panels
CAUTION:
THIS COVER IS NECESSARY FOR
EFFICIENT COOLING OF THE AMPLIFIER.
REMOVE ONLY TO ACCESS GAIN SWITCH.
REG. U.S. PAT. OFF.
4,330,809
4,611,180
CAUTION:
TURN OFF AMPLIFIER
BEFORE CHANGING THIS SWITCH!
STEREO
BRIDGE
MONO
PARALLEL
MONO
BRIDGE-MONO WIRING
TURN AMPLIFIER OFF.
SET STEREO/MONO
SWITCH TO
BRIDGE-MONO.
OUTPUT ACROSS
RED TERMINALS
ONLY. (CH-1
IS POSITIVE.)
PARALLEL-MONO WIRING
TURN AMPLIFIER OFF.
SET STEREO/MONO SWITCH
TO PARALLEL-MONO.
ADD JUMPER (14
GAGE OR LARGER)
ACROSS RED TERMINALS.
OUTPUT ACROSS CH-1
TERMINALS ONLY.
1
2
3
4
1
2
3
CH-2 CH-1
+
–
–
+
THIS AMPLIFIER IS EQUIPPED WITH SELECTABLE INPUT SENSITIVITY. REMOVE COVER PLATE (ABOVE) TO ACCESS SENSITIVITY SWITCH.
CH-2
INPUT GROUND LIFT
(AFFECTS PHONE INPUTS ONLY.)
(MONO)
MODEL: POWER-BASE™ 3 12.5 AMPS
AC VOLTS: 120 60 Hz
MAXIMUM OUTPUT: 700 WATTS
PER CHANNEL INTO 4 OHMS AT 1 KHz
WITH NO MORE THAN 0.1% THD.
INPUT
GAIN
CH-1
INPUT
GAIN
CLASS 2
OUTPUT
WIRING
REQUIRED.
OUTPUTS
CAUTION:
TO PREVENT ELECTRIC
SHOCK DO NOT REMOVE TOP OR BOTTOM
COVERS. NO USER SERVICEABLE PARTS
INSIDE. REFER SERVICING TO QUALIFIED
SERVICE PERSONNEL. DISCONNECT POWER
CORD BEFORE REMOVING REAR COVER
PLATE TO ACCESS SENSITIVITY SWITCH.
ATTENTION:
DÉBRANCHER AVANT
D'OUVRIR.
WARNING:
TO
REDUCE THE RISK OF
FIRE OR ELECTRIC
SHOCK, DO NOT EXPOSE
THIS EQUIPMENT TO
RAIN OR MOISTURE.
LIFT
PUSH TO RESET
BALANCED
INPUT WIRING
+
–
TIP
RING
SLEEVE
GND
UNBALANCED
INPUT WIRING
+
TIP
SLEEVE
GND
0
1
2
3
4
5
6
7
8
9
10
11
12
0
1
2
3
4
5
6
7
8
9
10
11
12
®
INTERNATIONAL, INC.
ELECTRONIC EQUIPMENT
ELKHART, IN 46517
MADE IN U.S.A.
SERIAL NUMBER
0000
000000
P
R
E
S
S
R
E
S
E
T
OFF
POWER
Removable grille
and dust filter
Power
Indicator
Power
Switch
Stereo/Mono
Switch
Ch.1
¼ Inch
Phone
In
p
ut
Ch.2
¼ Inch
Phone
In
p
ut
Ground
Lift
Switch
Ch.1
Level
Control
Ch.2
Level
Control
5-Way Binding Post
Output Connectors
Access
Cover
Reset
Switch
(Power Base–3 Only)
Power
Cord
1.1 Unpacking
Please unpack and inspect your new amplifier for any
damage that may have occurred during transit. If dam-
age is found, notify the transportation company imme-
diately. Only you, the consignee, may initiate a claim
with the carrier for damage resulting during shipment.
Even if the unit arrived in perfect condition, as most do,
save all packing materials so you will have them if you
ever need to transport the unit. NEVER SHIP THE
UNIT WITHOUT THE FACTORY PACK.