Instruction Sheet
IS-PA250A
Issued: 1-18-19
Lowell Manufacturing Company
100 Integram Drive
Pacific, Missouri 63069 U.S.A.
Call: 800-325-9660
Fax: 636-257-6606
Click: www.lowellmfg.com
5
MOUNTING THE AMPLIFIER:
The PA250A may be placed on a wooden or metal wall-mount shelf. Do not
remove the rubber feet from the bottom of the amplifier chassis . When the amplifier is placed on a countertop or is
shelf-mounted, the rubber feet maintain the proper spacing under the amplifier for passive convection cooling . Do
not place anything on top of the amplifier where the vents on the top of the chassis would be blocked . Rack mount
ears are built into the front panel of the PA 250A. If the amplifier will be rack mounted, we recommend that you
provide a minimum of 1.75
” of open space above and below the unit to assure proper ventilation. Provide
ventilation fans in the equipment cabinet if that is required to maintain an amplifier operating temperature of no
higher than 92
o
F. To mount the amplifier in a Lowell equipment cabinet, use standard 10-32 Phillips-head machine
screws (like the Lowell model RS or RSP rack screws) with integral plastic washers to protect the finish of the front
panel of the amplifier. The PA250A is very heavy, so we recommend that you provide rear support for the amplifier
when rack mounting it to remove some of the load from the built-in rack mount ears.
LINE LEVEL AUX INPUT:
The amplifier includes a mono high -impedance unbalanced auxiliary input which may be
used for connecting signal sources such as an AMFM tuner , CD player, Cassette deck, or an unbalanced feed from
an equalizer or mixer/preamplifier. Two (2) parallel RCA-phono connectors are provided for the aux input so stereo
input cables can be connected to this mono input. Mono inputs need only use one or the other of the RCA-phono
connectors. Note: Connecting 2 pieces of equipment that have grounded AC plugs with a standard unbalanced
RCA cord can cause a ground loop that will cause a
“hum” or “buzz” in the speakers. If this occurs, feed the
amplifier using the
“Tel” or “600
W
” inputs because the built-in isolation transformer will eliminate the ground loop.
POWER WIRING:
The AC power cord is equipped with a North American style NEMA 5-15P plug and the
“VOLTAGE SELECT” switch is set to operate on a 115 VAC 50/60 Hz. power source. If this unit is to be used
where the
“VOLTAGE SELECT” must be switched to 230 VAC, remove the plug from the end of the cord and
replace it with one appropriate for the local power grid receptacle standards. The internal wire color code for the
cord supplied with this unit is: Green: Earth
“E” or Safety Ground, White: Neutral “N”, and Black: Line “L” or Hot.
Note: If a British Standard BS1363 plug is installed, it must be provided with a 5 Amp fuse. Since electrical color
codes vary around the world, make sure that the correct connections are made to the cord even if the local color
code is different. If in doubt, obtain the services of a locally qualified electrical professional.
NOTE: THIS UNIT
MUST BE EARTH GROUNDED.
600
W
CHANNEL INPUT WIRING
From an
External
Device
Balanced
Line-level
600
W
Output
600
W
Stranded Twisted-Pair Wiring
Shielded wiring from an external device feeding the 600
W
balanced line level would typically be required as shown below.
BUTT SHIELD
(No connection)
DRAIN
SHIELD
The amplifier includes a 600
W
line level input channel. This input accepts a low impedance balanced 600
W
line
level signal that would typically be fed from an equalizer, from another system, or from some other outboard device.
Note: The
“TEL” (telephone page) input and the 600
W
Line Level Input are both 600
W
balanced line level inputs,
but the
“TEL” input is a “Hotter” input requiring less input signal to drive the amplifier to full power. If distortion
results from feeding the
“TEL” input with a high level signal, use the 600
W
Line Level input instead.
600
W
INPUT CHANNEL
+TEL-
GND
+600
W
-
TEL-PAGE INPUT CHANNEL:
The amplifier includes a
“TEL” telephone page input. This input accepts a low
impedance balanced 600
W
line level signal that would typically be available as a page port output from a telephone
system. Note: The
“TEL” Input and the 600
W
Line Level Input are both 600
W
balanced transformer isolated line
level inputs, but the
“TEL” Input is a “Hotter” input requiring less input signal to drive the amplifier to full power. If
distortion results from feeding the
“TEL” input with a high level signal, use the 600
W
Line Level Input instead.
“TEL” TELEPHONE PAGE CHANNEL INPUT WIRING
From the
Telephone
System
Page-Port
Output
600
W
Twisted-Pair Wiring
Shielded wiring from the telephone system is typically not required, but if
shielded wiring is used, drain the shield at the telephone input and butt
the shield (no connection) at the telephone system page port output.
BUTT SHIELD
(No connection)
DRAIN
SHIELD
+TEL-
GND
+600
W
-