SPA4-60 Architect and Engineer's Specifications

The amplifier shall contain all solid-state circuitry with a high-efficiency Class D output section. The amplifier shall have a universal power supply that utilizes active power factor correction and operates on 100 to 240 volts, 50 to 60 Hz, AC mains power. The power supply shall switch to a very low-power standby state after 25 minutes of inactivity and shall switch on immediately when an input signal appears, with the audio automatically ramping up quickly to prevent audible pops or other noises. The amplifier shall consume no more than 11 watts at idle and less than 1 watt at standby, and shall be ENERGY STAR certified. The amplifier shall have a chassis-mounted IEC mains connector and shall be equipped with a removable power cord.

The amplifier shall have four audio channels, each with its own input and output. Switches on the rear panel shall allow the channels to be configured for 8Ω or 4Ω loads, or to pair the channels in bridged mono for 70V or 100V distributed lines. The amplifier shall be rated at 60 watts continuous per channel into 8Ω and 4Ω. In bridged mono it shall drive a 70V or 100V line loaded at up to 250 watts, with an 80 Hz high-pass filter to reduce risk of loudspeaker transformer saturation.

The amplifier shall be cooled by passive convection and able to operate normally in ambient temperatures up to 40°C. It shall be UL 2043 plenum rated when properly fitted with its associated plenum kit accessory.

The amplifier shall be UL listed, CE and RoHS/WEEE compliant, and FCC Class B certified.

The amplifier inputs shall be balanced but also capable of operating unbalanced, with an input impedance of 10 kΩ or higher and able to handle signals of 12.3 V rms (+24 dBu) before clipping. The inputs shall use two green 5-position Euro-style connectors with 3.5 mm pitch. The output shall use a green 4-position Euro-Style connector with a 5 mm pitch and two retention screws. Two black 5-position Euro-style connectors with a 3.5 mm pitch shall allow for optional remote control of standby and each channel’s gain. The amplifier’s input sensitivity voltage shall be +4 dBu (1.2 V rms) at full gain.

Notwithstanding the 80 Hz bridged mono high-pass filter, the amplifier’s frequency response shall be flat within 0.1 dB over 20 Hz to 20 kHz. The unweighted signal to noise ratio shall be greater than 100 dB over 20 Hz to 20 kHz.

The amplifier shall reside in a black 1 rack space high, half-rack-wide chassis with dimensions (height × width × depth) 1.7 × 8.7 × 9.5 in (43 × 220 × 241 mm). A mounting kit provided with the amplifier shall allow rack mounting either solo or two side-by-side. The mounting kit shall also allow for mounting to a surface, such as a wall or the underside of a table.

The amplifier’s front panel shall have only LED indicators, and no switches, knobs, nor other controls. The front panel LEDs shall be one power indicator, along with a signal indicator and a limiter/protect indicator for each channel.

The amplifier’s rear panel shall contain all the input, output, remote, and mains connections. It shall also contain a rotary gain control and a bicolor LED indicator for each channel. Each channel’s gain control shall be labeled in dB of attenuation, with “0” at maximum gain, or fully clockwise, and a infinity symbol at minimum, or full counterclockwise. Each channel’s LED shall light green to indicate presence of an output signal or red to indicate limiting or protect mode. The rear panel shall contain four subminiature toggle switches for configuring the amplifier channels. The four possible configurations for each channel pair shall be 4 ohm stereo, 8 ohm stereo, 70V bridged, and 100V bridged. The maximum gain in these configurations shall be: 22.6 dB (4 ohm stereo); 25 dB (8 ohm stereo); 35 dB (70V bridged); and 37.4 dB (100V bridged).

The amplifier’s net weight shall be 4 lb (1.8 kg) and its shipping weight, 6.5 lb (3 kg).

The amplifier shall be the QSC SPA4-60.