Crown 1, 3, 2 manual Indicators, Input/Output, Output Signal, Protection, Construction

Power Base Series Power Amplifiers

Required AC Mains: Current, frequency and voltage requirements are provided on each unit’s back panel. All models draw 90 watts or less at idle.

Power Base-1: Draws up to 6 amps of current.

Power Base-2 : Draws up to 10 amps of current.

Power Base-3 : Draws up to 15 amps of current.

Low-Voltage Power Supply: A ±24 VDC fanformer supply (fan motor winding) regulated to ±15 VDC.

AC Connector: An appropriate AC line cord and plug are provided. 120 VAC, 60 Hz units have a standard 3-wire, 15-amp grounded connector (NEMA 5-15P).

Controls

Power: A front panel rocker switch used to turn the amplifier on and off.

Level: A back panel rotary potentiometer for each chan- nel used to control the output level.

Stereo/Mono: A three-position back panel switch used to select Stereo, Bridge-Mono or Parallel-Mono mode.

Sensitivity: A three-position switch inside the back cover plate used to select the input sensitivity for both channels: 0.775 volts or 1.4 volts for standard 1 kHz power, or 26 dB voltage gain (see Section 2.3).

Input Ground Lift: A two-position back panel switch used to isolate the phone jack and chassis grounds.

Reset (Power Base-3only): A back panel push but- ton used to reset the circuit breaker that protects the power supplies.

Indicators

Power: This amber indicator shows the on/off status of the low voltage power supply.

Input/Output

Input Connector: Balanced ¼ inch phone jacks. See Section 5 for XLR and barrier block accessories.

Input Impedance: Nominally 20 K ohms, balanced; 10 K ohms, unbalanced.

OutputConnector:Twosetsofcolor-coded5-waybbinding posts (for banana plugs, spade lugs or bare wire).

Output Impedance: Less than 10 milliohms in series with less than 2 microhenries.

DC Output Offset: Less than 10 millivolts.

Output Signal

Stereo: Unbalanced, two-channel.

Bridge-Mono:Balanced, single-channel. Channel 1 controls are active; Channel 2 controls should be turned down and not used.

Parallel-Mono:Unbalanced, single-channel. Channel 1 controls are active; Channel 2 controls should be turned down and not used.

Protection

Power Base amplifiers are protected against shorted, open or mismatched loads; overloaded power supplies; excessive temperature, chain destruction phenomena, input overload and high-frequency blowups. They also protect loudspeakers from input and output DC, as well as providing protection from turn-on/turn-off transients.

If operating conditions are unreasonable, the patented ODEP circuitry proportionally limits the drive level to pro- tect the output transistors, particularly in the case of el- evated temperature. A thermal switch imbedded in the transformer protects the power supplies from overload. In the rare event that a transformer overheats, the ther- mal switch removes power, waits until the unit has cooled to a safe temperature and then resets itself.

Turn On: Four second delay with no dangerous tran- sients. Contact us if you need to change the delay.

Construction

Durable black finish on steel chassis with special “flow- through” ventilation from front to side panels.

Cooling: Internal heat sinks with forced-air cooling for rapid, uniform heat dissipation.

Dimensions: Standard 19-inch (48.3 cm) rack mount width (EIA RS-310-B), 3.5-inch (8.9 cm) height and 16-inch (40.6 cm) depth behind the mounting surface.

Approximate Weight: Center of gravity is 6 inches (15.2 cm) behind front mounting surface.

120 VAC, 60 Hz Units:

Power Base-1: 30 pounds (13.6 kg) net; 34 pounds (15.4 kg) shipping weight.

Power Base-2: 34 pounds (15.4 kg) net; 38 pounds (17.2 kg) shipping weight.

Power Base-3: 36 pounds (16.3 kg) net; 40 pounds (18.2 kg) shipping weight.

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