Stewart Audio PA50B Data Sheet

PA Half Rack Series

Power Amplifier

The PA Series was specifically designed to meet the rigorous

requirements of Sonic Accuracy, High Efficiency, Low Power

consumption and extended duty cycles all in a very compact

Half Rack Package. Low cost, lightweight and convection cooling

make this Amp perfect for high quality commercial, industrial and

Pro Audio sound installations. Our flexible design allows bridging

to mono for increased power and will also accept balanced or

unbalanced signals by way of 1/4” TRS input connectors.

With thousands in operation across a broad range of applications,

this hardworking Class AB amplifier has passed the test of time

again and again.

PA50B

50W x 2 @ 4 Ohms
25W x 2 @ 8 Ohms
100W x 1 @ 8 Ohms bridged

Features:

• Compact Half Rack Package

• Two Channel Amplifier, Optimized To

drive 4 Ohm And 8 Ohm loads

• Convection Cooled (No Fans)

• Clean Full–Range Dynamic Power

• World Class Reliability

• Bridgeable

• Ultra Efficient Switch Mode Power Supply

• Made In The USA

Applications:

• Audio Video Production

• Pre/Post Productions

• Project Studios

• Broadcast Applications

• Instrument Rigs

• Sound Reinforcement

• Fixed installations with amplifiers

located in listening environment

14397 Cuesta Court Ste D1 • Sonora Ca 95370 • TEL: [phone] • www.stewartaudio.com

PA50B

50W x 2 @ 4 Ohms
25W x 2 @ 8 Ohms
100W x 1 @ 8 Ohms

Specifications

8 Ohm Stereo Power
4 Ohm Stereo Power
8 Ohm Bridged Power
Frequency Response (+0, –0.5 dB, 1W)
Power Bandwidth (+3, –3 dB)
THD+N
Damping Factor
Slew Rate
Input Sensitivity
Standard Voltage Gain
Input impedance (Balanced / Unbalanced)
Idle Current Draw SW On & 1/8 power draw
Class
Input Connectors
Output Connectors
Power Supply
Cooling
Controls
LED Indicators
Construction
Dimensions (height, width, depth)
Weight
Warranty

25 W
50 W
100 W
20 Hz—20 kHz
5 Hz—100 kHz
>98dB
>200
30V/microsecond
1V (0 dBV)
40X (32dB)
20k Ohms/10k Ohms

0.13/0.56 Amps
A B
TRS
Terminal Strip
High Speed Switching
Convection–Cooling (No Fans)
Power on/off, Channel Gain
Power & Clip
Steel & Aluminum Chassis

1.75”H x 8.2” W x 6.2” D

3.5 lbs
3 years

Architects & Engineering Specifications

The power amplifier shall consist of 2 channels. Model PA50B
shall deliver a minimum of 25W at 8 Ohms , both channels driven,
20 Hz—20 kHz, < .1% THD. The amplifier shall be convection
cooled with no fan required. Amplifiers using fan cooling will not
be accepted. The amplifier shall have circuitry to protect itself and
the speaker loads from output short circuits, DC voltage on the
outputs, and thermal overload. The amplifier shall have a voltage
gain of 40X (32dB) and an input Sensitivity of 1V for rated power
at 4 Ohm output. The hum and noise level shall be greater than 98
dB below rated output “A” weighted. The amplifier shall have a
high–speed Switch Mode Power Supply. Non Switch Mode Power

Supplies will not be accepted. The frequency response shall be
greater than 20Hz to 20 kHz +0, – 0.5dB at rated power. The
amplifier shall operate on 120VAC. The front panel shall contain,
for each channel, a thru-panel adjust, level control, LED indicators
for Clip, and Power. The power switch shall be a power supply
enable switch. The Rear panel shall have a captive AC line cord,
1/4” TRS input terminals and terminal strip output terminals. The
PA50B shall weigh 3.5lbs (1.6kg) and shall be 8.2” (20.8 cm) wide,

1.75” (4.6 cm) high, and 6.2” (15.7cm) deep. The amplifier shall be
designated the Stewart Audio Model PA50B.

14397 Cuesta Court Ste D1

Sonora Ca 95370

TEL: [phone]

www.stewartaudio.com