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Power Base Series Power Amplifiers
Page 14
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-3
only): 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.
Output Connector: Two sets of color-coded 5-way bbinding
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.