The amplifier shall contain all solid-state circuitry, using complementary silicon output devices. The amplifier shall operate from 50–60 Hz AC power. The amplifier shall draw 684 VA or less when driven with random program material at 1/8 rated power into four-ohm loads. The amplifier shall equipped with a 320-C19 16A IEC mains connector and a removable power cord. Units configured for 120V use shall operate safely from a 15A 120V AC outlet, and their power cords shall have a standard NEMA AC plug. Units configured for 230V use shall have a power cord with a standard Schuko AC plug. The amplifier shall comply with FCC part 15 Class B requirements.
The amplifier shall employ forced-air cooling with a temperature-controlled fan, variable in speed from zero to full for minimum acoustic noise. Air flow shall be from rear to front to avoid temperature rise inside the rack. Rack mounting shall be possible without clearance between amplifiers for ventilation. The amplifier shall be capable of continuous operation at 1/3 power at 70 volts output, in ambient temperatures up to 104F (40C).
The amplifier shall contain two independent amplifier channels powered by a low-impedance switching power supply. All amplifier protection systems shall be synchronized and self-resetting upon removal of fault. Each channel shall have circuitry to protect against short circuits or mismatched loads. Each channel shall independently monitor heat sink temperature and shall trigger fan speed boost, and if necessary, signal muting to prevent excessive temperature rise. Both channels shall have synchronized on-off muting, acting for three seconds after turn-on, and within _ second after turn-off or loss of AC power. Each channel shall have DC fault protection for the load, consisting of a shutdown of the power supply. Each channel shall have an independent and defeatable clip limiter and 12 dB per octave high-pass filter. The corner frequency of the filter shall be selectable between 50 and 75 Hz.
The front panel shall contain these features: an AC power switch; LED status indicators for power (green), bridged mono (yellow), and parallel inputs (yellow); independent LED output metering indicators for each channel for signal present or –30 dB (green), -20 dB (green), -10 dB (green), and clip (red); and a recessed, detented gain control for each channel with 21 attenuation settings. From 0 to 14 dB, the attenuation steps shall be 1-dB increments. The labeled attenuation settings shall be 0, 2, 4, 6, 8, 10, 12, 14, 18, 24, and • dB. The 0 dB attenuation settings shall also be labeled with the amplifier's equivalent voltage gain in dB. A removable security panel shall be provided for covering and preventing unauthorized access to the gain controls, when needed.
The output connector for both channels shall be a barrier strip located on the rear panel, with screw terminals and a safety shroud. The terminals shall be arranged to facilitate bridged mono connection.
The inputs shall be located on the rear panel, consisting of a 3-pin detachable terminal block and a 3-pin XLR connector for each channel. The XLR input shall be wired with pin 2 high. Inputs shall be electronically balanced, with a minimum impedance of 12 kilohms balanced and 6 kilohms unbalanced, and a common mode rejection of at least 50 dB from 20 Hz to 20 kHz.
A High Density 15-pin DataPort connector shall be provided for carrying both audio and amplifier operational status signals to and from a QSControl network. The DataPort shall also accommodate plug-in crossover filters and other such accessories.
A set of DIP switches on the rear panel shall be provided for: setting bridged mono and parallel-input operation; selecting clip limiters; and selecting high-pass filters and setting their frequencies.
Each channel shall be capable of meeting the following performance criteria: 70-volt sine-wave output power of 200 watts, 20 Hz to 20 kHz at <0.05% THD, with both channels driven; and 300 watts, 1 kHz at <0.1% THD, with one channel driven. Each channel shall be capable of driving directly a 70-volt line at rated power, without requiring an output transformer. Frequency response (with filters not engaged) at 3 dB below rated power shall be 20 Hz to 20 kHz 0.2 dB. The voltage gain shall be 56.6, equivalent to 35 dB, and the input sensitivity shall be 1.26 Vrms (+4.2 dBu). The unweighted signal to noise ratio over the range of 20 Hz to 20 kHz shall exceed 106 dB, referenced to full output. IHF damping factor shall exceed 500.
The amplifier chassis shall occupy two rack spaces and have provisions for securing the rear corners. Depth from mounting surface to tips of rear supports shall be 14" (35.6 cm).
The amplifier's weight shall not exceed 21 lb. (9.5 kg). The amplifier shall be the QSC Audio Products CX 302V.