75 Watt RMS into 8 Ohm.
Complementary Darlington output stage.
Integrated Circuit driver circuit.
Over-current and over-temperature protection.
Class A or class B operation.
These conservatively rated power amplifier modules
will deliver a clean, low distortion 50 Watt of power to
any 8 Ohm loudspeaker.The amplifiers are rated to
drive reactive loads with a phase angle of up to 45
degree at full output voltage.The amplifiers make use
of an integrated circuit driver chip and two
complimentary darlington power transistors that are
mounted directly on the heavy-duty heat sink for the
The PM2 and the PM22 have a very similar circuit and performance; the main difference is the heat-sink arrangement of the output transistors. On the PM2 the output transistors are mounted on a integral heavy duty heat sink. The PM22 has the power transistors mounted on an aluminum bracket. This bracket should be mounted on a heatsink supplied by the user. Several PM22 modules can be mounted on the same heatsink. The circuit is electrically isolated from the heatsink(PM2) or bracket(PM22) in order to make mounting easy.
The available output power depends on the voltage and current rating of the power supply and the impedance of the load (8 Ohm or 4 Ohm). The power for the modules can be from a dual regulated power supply of up to +/- 45 VDC or from an unregulated source. A simple unregulated supply can be assembled from a 48 Volt @ 1.5 Amp center-tap transformer, a bridge rectifier and two 10.000uF filter capacitors; This supply is good for 50WRMS into an 8 Ohm load. The assembly manual has complete diagrams of the amplifier and of suggested power supplies. The Marchand PS11 power supply is able to drive 3 amplifier modules at full power. It has a toroidal power transformer for application in high performance systems. The PS11 output voltage is +/- 40Volt at full load.
The amplifier modules are protected with an output safe operating area current limiter and a temperature sensor. The output current of the amplifiers will be limited to a safe value, so that they 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. These " bullet proof " amplifier modules are almost inpossible to damage with the output loading. Low impedance, shorts and open circuits will not damage the circuit. The PM2 and PM22 amplifier modules normally operate in class AB mode, but can also be adjusted to operate in class A mode. In class A mode the available output power is limited to 10 Watt RMS. The PM2 has a single ended input, and operates in non-inverting mode. The PM22 has a differential input and can also be operated in both inverting and non inverting modes. The PM2 and PM22 power amplifier modules are available as a bare board, as a complete kit and completely assembled and adjusted.
Frequency response: 5Hz-50KHz +/- 1dB
THD at 1KHz: better than 0.01%;
Voltage gain: 20 dB (10x), non inverting;
Input impedance: PM2: 100 KOhm, AC coupled.
PM22: 25 KOhm, AC or DC coupled.
Output load: 4 or 8 Ohm, DC coupled.
Max power output with 75 Watt RMS, continuous, into 8 Ohm,(Class AB)
+/- 40 Volt power supply
Max power output with: 10 Watt RMS, continuous, into 8 Ohm,(Class A)
+/- 18 Volt power supply
Power supply voltage range:+/- 15 Volt to +/- 45 Volt
Dimensions: PM2: 5" X 3" X 2.5"
PM22: 5" X 3" X 1 "
PM2-B Bare board with manual
PM2-K Kit with manual and all parts
PM2-A Fully assembled and tested
PM2-M Manual only
PM22-B Bare board with manual
PM22-K Kit with manual and all parts
PM22-A Fully assembled and tested
PM22-M Manual only
see other amplifier modules