The amplifi er shall contain protection from shorted, open and mismatched
loads, general overheating, DC, high-frequency overloads, under/over voltage,
and internal faults.
The amplifi er shall contain FIT (Fault Isolation Topology), which isolates
channel-specifi c faults and prevents them from affecting remaining channels.
If an amplifi er channel starts to overheat, the Thermal Level Control
(TLC) circuit shall engage that channel’s input compressor in an amount
proportional to the amount of overheating, in order to generate less heat.
If the channel becomes too hot for safe operation, the channel shall shut
off, and the Thermal Indicator for that channel shall fl ash brightly to alert
the user that a state of thermal stress or overload has caused the channel
to shut down.
The front-panel control shall be a power switch.
Rear-mounted controls shall include Channel Level Controls and a Mode
Switch. The Mode Switch (used on each consecutive pair of channels)
is a four-position switch which selects among Dual 8/4 ohms, Dual 70V,
Bridge-Mono 16/8 ohms, and Bridge-Mono 100V.
The recommended load impedance in Dual mode shall be 4/8 and 25 ohms
(70V). The load impedance in Bridge-Mono mode shall be 8/16 ohms and
50 ohms (100V). The amplifi er shall be safe when driving any kind of load,
including highly reactive ones.
Rear-mounted output connectors shall be one four-pole terminal strip for
every two channels with a touch-proof cover. Rear-mounted input connectors
shall be removable Phoenix-style barrier connectors for balanced
Front panel indicators shall include a yellow Bridge-Mode Indicator (one
per channel pair) that illuminates when the channel pair’s Mode Switch is
set to the “Bridge” position (and fl ashes if the Mode Switch is changed
while the amplifi er is powered up, indicating that the amplifi er must be
powered off and on to reset the Mode), a green Ready Indicator (one
per channel) that illuminates when the channel is initialized and ready
to produce audio output, a green Signal Indicator (one per channel) that
illuminates to indicate the presence of input signals above -40 dBu, a red
Clip Indicator that illuminates when the THD of the channel’s output signal
rises to a level typically considered as the onset of audible clipping (and
illuminates during Thermal Level Control or input overload), a red Thermal
Indicator (one per channel) that fl ashes when a state of thermal stress or
overload has caused the channel to shut down (and fl ashes in all channels
if the power supply goes into thermal overload), a red Fault Indicator
(one per channel) that fl ashes when a fault condition has occurred in the
channel, a yellow Data Indicator that indicates IQ Loop data activity (if the
amplifi er is equipped with an IQ-MC module and is connected to an IQ
Loop), and a blue Power Indicator that illuminates when the amplifi er has
been turned on and AC power is available (and illuminates when the ampli-
fi er shuts off due to an under-/over-voltage condition on the AC mains).
The power amplifi er shall meet or exceed the following performance criteria.
Input sensitivity for rated output: 1.4 V. Rated output with eight channels
driven in Dual mode with 0.1% THD (20 Hz to 20 kHz): 175 watts per
channel into 4 ohms; 155 watts per channel into 8 ohms, and 185 watts
per channel (70V). Rated output in Bridge-Mono mode with four channel
pairs driven at 0.1% THD (20 Hz to 20 kHz): 350 watts per channel pair
into 8 ohms; 310 watts per channel pair into 16 ohms, and 185 watts per
channel pair (100V). Signal to Noise Ratio below rated power (20 Hz to 20
kHz): 100 dB unweighted. Phase Response: ±35 degrees from 10 Hz to 20
kHz at 1 watt. Frequency Response: 20 Hz to 20 kHz, ±0.5 dB at 1 watt into
8 ohms per channel in Dual mode. Damping Factor: greater than 180 from
10 to 400 Hz. Crosstalk (below rated power, 20 Hz to 1 kHz): greater than
80 dB. Intermodulation Distortion (60 Hz and 7 kHz at 4:1, from 163 milliwatts
to full bandwidth power): less than 0.05% typical. Total Harmonic
Distortion at 1 watt from 20 Hz to 20 kHz: less than 0.05%. Common Mode
Rejection (20 Hz to 1 kHz): greater than 50 dB. DC Output Offset (shorted
input): less than 5 mV. Maximum Input Level (before input compression):
+ 22 dBu rms. Power Draw at Idle (120 VAC mains, all channels in 4/8 ohm
mode): 58 watts. Power Draw at Idle (120 VAC mains, all channels in 70V
mode): 77 watts.
The amplifi er chassis shall be constructed of steel with a durable black
fi nish and shall be designed for continuously variable-speed forced-air
ventilation from the front panel to the back panel.
The dimensions of the amplifi er shall allow for 19 inch (48.3 cm) EIA
standard (RS-310-B) rack mounting. The amplifi er shall be 5.25 inches
(13.3 cm) tall, and 16.25 inches (41.3 cm) deep behind the rack-mounting
The amplifi er shall weigh 36 pounds, 6 ounces (16.5 kg).