50 Watt RMS into 4 or 8 Ohm.
Better than 0.01% distortion.
Over-current and over-temperature protection.
Differential (Balanced) or Single Ended Input.
The PM221 power amplifier uses a National Semiconductor LM3886
Integrated Circuit to implement a 50 Watt
power amplifier on a single circuit board.
The powe supply is also on the circuit board.
The PM21 has differential inputs that can be
used as balanced inputs or as single ended
inputs. The input is AC or DC (cutoff frequency -3dB at 6 Hz). The
the amplifier is 20X (26 dB). Other gain
factors can be realized by a change of
resistors. The power Integrated Circuit is mounted
on a solid aluminum bar of 1"width and 3" length. This bar should
be mounted on a heatsink supplied by the
user. Several PM221 modules can be
mounted on the same heatsink. The
heatsink should have a total surface area of 50 square inches or
for each PM221
The circuit is electrically isolated from the heatsink bracket in order to make mounting easy.
The 80VA, 25VAC+25VAC transformer is included with the PM221; no DC power supply is required. Other transformers are available for connecting multiple modules to a single transformer.
The amplifier module is protected with an output safe operating area current limiter and a temperature sensor, all on the power IC's. The output current of the amplifier will be limited to a safe value, so that it can not be damaged by short circuits at the output. In the event of overheating the amplifiers will turn off until they cool down again. The PM221 amplifier module is available as a bare board, as a complete kit and completely assembled and tested.
The PM221 is available with the 80VA toroidal transformer or without.
Specifications:For free manuals download go here.
Frequency response: 10Hz - 50KHz +/- 1dB
THD at 1KHz: better than 0.01%;
Voltage gain: 26 dB (20x), non inverting or inverting;
Input impedance: 100 KOhm.
Output load: 4 or 8 Ohm, DC coupled.
Max power output: 50 Watt RMS , continuous, into 4 or 8 Ohm
Dimensions: 3.9" X 3.0" X 1.25"
PM221-A Power amplifier
PM221-ANT Power amplifier without transformer