Lowell PA250 - Manual (Page 3)

Instruction Sheet
IS-PA250
Issued: 5-1-14
Lowell Manufacturing Company 100 Integram Drive Pacific, Missouri 63069 U.S.A.
Call: 800-325-9660 Fax: 636-257-6606 Click: www.lowellmfg.com
3
PA250 Power Amplifier Block Diagram
Technical Specifications
Dimensions: 19" wide x 3.5" high x 12"deep (482mm wide x 88mm high x 305mm deep) Color: Black
Frequency Response: 20Hz-20KHz + 1dB (8
W direct output), 20Hz-16KHz + 1dB (25V/70V transformer output)
Mixing
And
Control
Section
TEL-PAGE
and 600 W
Inputs Mute
the Aux Input.
The mute
function may
be defeated by
changing an
internal circuit
board jumper.
Speaker Level Outputs: Screw terminal strips, 8
W Bridged, 25V, 70V, 250W RMS.
Convenience AC Outlet: 120VAC @ 2A maximum unswitched outlet
Total Harmonic Distortion: < 0.3% at 1kHz at rated power (8
W direct output)
Hum and Noise: > 90dB below rated output (unweighted)
Weight: 26LBS. (11.8KGS) Shipping Weight: 30LBS. (13.6KGS)
Power
Amplifier
250W RMS
TEL-PAGE Input
& 600 W Input
Gain
Control
SPEAKER LEVEL OUTPUTS
TEL-PAGE Input: Screw terminals. 50mV @ 600
W balanced (required for full rated output power)
AUX Input: Parallel RCA Connectors, 500mV @ 10k
W unbalanced (required for full rated output power)
Amplifier Muting-Priority Scheme
The amplifier includes unique voice-activated (VOX) ducking/muting
circuitry. When a page is made into the TEL-PAGE input or 600
W line
level input, music that is feeding the Aux input will duck in volume (not
be completely muted). If the incoming page is strong enough in level,
the music volume will be completely muted. When the page has been
completed, the volume of the music will return to its normal level. The
muting circuit can be defeated by a qualified technician, by removing
the chassis cover and repositioning the X2 MUTE jumper that is
located behind the recessed gain control on the input circuit board.
Parallel
RCA Jacks
(Pin +, Sleeve )
TEL-PAGE
GND
600 W
Note: Both the TEL-PAGE input and the 600 W input
are 600 W balanced line level inputs, but the 600W
input has lower input sensitivity than the TEL-PAGE
input. In other words, the TEL- PAGE input is a “hotter”
input so it takes less input signal to drive the amplifier
to full power when using the TEL-PAGE input.
Red Peak LED Note: If the red peak LED flashes, it indicates the peaks are approaching
full power. A steady bright red glow could indicate that the amplifier is being
over-driven, has oscillation in the system, or has a shorted speaker line.
Peak LED (Red): If the red peak LED flashes, it indicates the peaks are approaching full power. A steady bright
red glow could indicate that the amplifier is being over-driven, there is sub-sonic or ultra-sonic
oscillation in the system, or the amplifier is loaded with a shorted speaker line.
“Power On” LED (Green): Lights when the power amplifier is switched on.
600
W Input: Screw terminals. 500mV @ 600W balanced (required for full rated output power)
Note: This output is bridged. Do not ground either of these terminals.
AC Supply Voltage: 120VAC 60Hz + 10%, 6A Circuit Breaker, Power Consumption: 720W @ Rated Power
Jumper X2 in Mute-Active
Position as set at the Factory
Jumper X2 shown in
Mute-Defeated Position
+ +
_ _
8 W
BRIDGED
DO NOT GND
25V(+)
2.5 W
70V(+)
20 W
C( )
+
_
_
AUX
Input
_
Paging Horn Protection Low-Cut Filter
The PA250 includes a low-cut filter ( also called a “trumpet protect” filter) that is not activated
when the amplifier is shipped from the factory. When the amplifier is to be used to power
paging horns that can be damaged by the low frequency energy that is often present in
paging/music signals, we recommend that a qualified technician activate the low-cut filter by
removing the chassis cover and cutting the blue jumper that is located directly behind the
recessed gain control on the input circuit board. The blue jumper is labeled as shown in the
picture to the right. The low-cut filter has a 3dB down point at 400 Hz.
A low-cut filter may be activated by cutting a
circuit board jumper. Activating the low-cut
filter is recommended when using the PA250 to
power paging horns (for trumpet protection).