Amplifier Modules

The Aux. and Main line level inputs are de-balanced and pass via level controllers and an analogue switch into a summing amplifier where they are mixed. If the contact input is asserted (470 ohms to ground) a logic circuit disconnects the aux. input.

The protect circuit disconnects the output transformer when the voltage rails fall below 22 volts, exceed 36 volts, or when a d.c. offset is present on the output rails. The signal then passes through to the output stage, which is a feed-forward current-mode bridge circuit and the output level meter monitors the level at this stage.

The output current is passed through the primary of the output transformer and through a low value output-sensing resistor. The output of the transformer is tapped at 50 and 100 volts. If the 50 volt taps are connected in series the unit provides a single 400 watt output at 100 V line.

Power Supply

A large capacitor reservoir provides a very smooth output, even under large current surges. Two separate 10 amp fused outputs connect to the two amplifier modules.

A separate feed passes, via the Aux. on LED (this shows that the Aux. power is available on the rear connector) through a 3 amp fuse to the Aux. power connector. With mains voltage operation this unregulated output is at approximately 32 Vd.c. When mains has failed, this output is connected to the battery and therefore operates at battery voltage level.

A 27.2 volt regulator is also taken off this line and used to charge external batteries via a 20 amp fuse. All fuses are accessible by removing a plate on the rear panel.

PSU and amplifier faults are returned into the monitoring circuit from both amplifiers, slugged to prevent false faults being reported externally, and passed to the (normally high) fault outputs on the CAT5 SIP pfourth open collector output is normally set as OK (normally closed) and opens when any fault occurs.

Amplifier Performance Specification

Sensitivity: 0dB for both Main and Aux. Inputs
Impedance: 10K balanced (Main and Aux.)
CMRR: Better than 60dB
Switch input: 470Ω to GND = on; 6k8Ω to GND = off
Output power: 200W Continuous average power
Frequency Response: 30Hz to 20kHz -3dB +0dB
THD: Better than 0.1% , 1kHz
SINAD: Better than -80dB
Regulation: Better than 2dB
Output voltage: 100V line
Operational mode: Current mode, feed forward system
Protection: Over voltage, under voltage, d.c. offset, short circuit, thermal and safe operating area
Standby current: 75mA (150mA with fault lights lit and full load monitoring)
Full load current: 11A

Physical

Material: 18swg Zintec sheet steel
Colour: Black (RAL 9500 semi-gloss)
Width: 430mm
Height: 88mm
Depth: 315mm (behind front panel)
Weight: 17kg

Power supply & charger

AC input: 230 VAC +/- 20%
DC input: 22 to 34 V DC
Charging voltage: 27.2 V DC
Charging current: 3A Max
Monitoring: Short circuit and battery high impedance. Battery under-voltage cut-off.
Aux. Supply: 1A with self-resettable fuse.
CAT5 SIP Port: User assignable faults for the SigNET network

Monitoring

Detection frequency: 22.05kHz
Detection type: Window comparator system
Window: 5% to 20% user adjustable
Sensitivity: -40dB to -10dB, user adjustable
End of Line units, one required per channel: 0.047μF in series with 100Ώ RS365-7227

Fuses
Mains Inlet: 5A 250V 20mm HBC
Internal Automotive Blade Amp feeds: 10A x 2
Internal Automotive Blade Battery: 20A x 1
Internal Automotive Blade Aux: 3A x 1

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