M453 — Cue Amplifier Designed And MANUFAcTURED

Gain: 45 dB (front panel level control provided) Frequency Response: within 1 dB 50Hz to 10kHz _ Noise: 75 dB below watts. Total Harmonic Distortion: Less than 0 . 5% at lkHz at 3watts Output level. Source Impedance: 600 ohms or less balanced or unbalanced. Input Impedanace: 20 K ohms . Input Level: -10 dBm for watts out +8dBm max.

Load Impedance: ohms Output Impedance: Less than 0.5 ohms Output Level: watts max. Power Requirements: 25 to 36v dc unregulated 20 MA idling current 300 mA at full power output . Ambient Temperature: to 60Pc Dimensions 1.58W X 6.25L X 6D Weight: -75 lbs _

The M453 3 watt cue amplifier provides three 20K ohm bridging inputs each of which is isolated from one another In addition , sum input is provided which is intended to receive the cue feeds from the M441 input modules 21 and 22 form an actively balanced input which provides the necessary longitudional balance characteristics . The input amplifier is capable of handling an input level up to +l8dBn without over load.

The amplifier level control is located after the preamplifier This control may be extended via pins and 8 to permit the adjustment of the amplifier output level up to distance of 10 feet This external control operates in series with the control located on the module. For this external control type of operation, the module level control should remain in the full clockwise position_ 23 forms the driver amplifier for the output power transistor 03 through Q6 .

The output signal is coupled through to pin S . CR3 to CR6 form the overdrive protection circuit to prevent excessive power dissipation if the amplifier is inadvertently shorted while signal is present . Q1 and Q2 form regulator circuit which provides the bias voltage (approximately 1OV to pin 3 of z1 , 22 and 23) The amplifier will operate from nominal 24 to 36 V dc unregulated supply which has the negative side on the conmon terminal The unregulated dc voltage i5 applied to pin X and fed through fuse Fl and polarity reversing protection diode CRl

1 Slowly apply power and note idling current with no signal applied. This should nominally be 20 to 25 mA 2 . check dc voltage at pin should be 12 volts. of 21 to 23 _ This voltage 3 _ Apply signal and check for maximum gain (45dB)" 4 _ Confirn that the amplifier meets specifications: Gain Frequency Response Noise Distortion 5 The signal to noise ratio should decrease to approximately 85 dB with level control full counter clockwise_ 6 At watts output the supply current is 300 mA Shorting the amplifier output with signal present , the supply current Will rise to approximately 860 IA