eh eh 20 15 power amplifier section. The amplifier begins with a PNP differential pair with a PNP transistor current source in their emitters. The input goes through a 33 k ohm resistor to ground. The input also goes to the base of the left hand transistor in the differential pair. The emitter of the left hand transistor goes to the emitter of the right hand transistor. The two emitters go to the collector of the current source. The base of the current source goes to the anode of a 3.6 volt zener diode. The cathode of the zener goes to plus 39 volts. The emitter of the current source goes through a 2.2 k ohm resistor to plus 39 volts. The anode of the zener goes through a 15 k ohm resistor to minus 39 volts. The collector of the right hand of the pair goes to minus 39 volts. We will come back to the base later. The collector of the left hand of the pair goes through an 820 ohm resistor to minus 39 volts. The collector goes through a 33 pf cap to its base, which is also the input terminal. The base also goes through a 180 pf cap to ground. The left hand collector connects to the base of the predriver an NPN transistor. The emitter goes through a 2.7 ohm resistor to minus 39 volts. There is a 47 pf cap from the base to the collector of the predriver. The collector of the predriver goes through the parallel combination of a 0.05 microfarad cap and a 68 ohm resistor. The other end of this combination goes to the cathode of the first of three seriesed diodes. The anode of the third diode goes to the collector of the predriver current source. The emitter goes through a 100 ohm resistor to plus 39 volts. The base goes through an 820 ohm resistor to plus 39 volts. The base also goes through a 2.2 k ohm resistor to the anode of the 3.6 volt zener mentioned earlier. The junction of the 0.05 microfarad cap, the 68 ohm resistor, and the cathode of the first of the three diodes goes to the base of the lower driver a PNP transistor. There is a 200 pf cap connected between the base and collector of the lower driver. The junction of the predriver current source and the anode of the upper diode connects to the base of the upper driver, an NPN. There is a 200 pf cap connected between the base and collector of the upper predriver. The collector goes to plus 39 volts. The emitter of the upper predriver goes to the base of the upper output an NPN. The base of the upper output goes through a 75 ohm resistor to the amplifier mid point. The collector of the lower driver goes through a 75 ohm resistor to minus 39 volts. The collector also goes to the base of the lower output, an NPN. The emitter goes to the cathode of a diode. The anode goes to the collector of the lower output. There is a 39 ohm resistor in parallel with the diode. The collector of the upper output goes to plus 39 volts. The emitter of the upper output goes through a 0.33 ohm 5 watt resistor to the amplifier mid point. The amplifier mid point goes through another 0.33 ohm 5 watt resistor to the collector of the lower output. The emitter of the lower output goes to minus 39 volts. The amplifier mid point goes through a 22 k ohm resistor to the base of the right hand transistor in the PNP differential pair. This base also goes through a 470 ohm resistor then a 250 microfarad capacitor in series to ground. Plus 39 volts connects to the cathode of a diode. The anode connects to the amplifier mid point. The amplifier mid point goes to the cathode of a diode. The anode goes to minus 39 volts. The amplifier mid point goes through a 3 microhenry coil to the hot speaker output. There is a 10 ohm resistor in parallel with the coil. The hot speaker output goes through a 0.1 microfarad capacitor then a 20 ohm 2 watt resistor to ground. The cold speaker output is grounded. End verbal description.
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