perature status LEDs shall appear on the front panel, one to indicate normal operation (COLD) and one to indicate thermal protection (HOT).
7.PROTECTION FEATURES. The amplifiers shall provide delayed activation of the outputs at turn-on. Each channel shall have a short- circuit protection circuit for detecting excessive current flow at the output that, when activated, mutes the output for four seconds. The short- circuit protection shall con- tinuously cycle on and off until the shorted condition is remedied. The amplifier shall have a thermal protec- tion circuit to protect the power devices from over- temperature operation. The circuit shall activate when the internal temperature crosses the safe-operating threshold and, when activated, mute the outputs until the internal temperature cools to a safe-operating tempera- ture, at which time the ampli- fier shall resume normal operation. The amplifier shall have a fan to cool the heat-producing internal components. The fan shall operate at two speeds, the speed being determined by the internal temperature and the signal level present at the output. The amplifier shall have an SCR crowbar circuit to protect the speak- ers against a catastrophic amplifier failure. The circuit shall activate in the pres- ence of continuous DC at the speaker outputs, and shall shut the amplifier down by turning off the high-voltage rails.
8.OUTPUT CONNECTIONS. M•1200: Each channel shall have heavy-duty5-way bind- ing post speaker output connectors appearing on the rear panel, with 3/4" spacing for accommodating standard double banana plugs as well as spade lugs or bare wires. Each channel shall have a 1/4" TS phone speaker output jack appearing on the rear panel in parallel with the binding post output.
M•1400: Each channel shall have heavy-duty 5-way binding post speaker output connectors appearing on the rear panel, with 3/4" spacing for accommodating standard double banana plugs (120V versions only) as well as spade lugs or bare wires. Each channel shall have a Neutrik brand Speakon® speaker output jack appearing on the rear panel in parallel with the binding post output.
9.AMP MODES. The ampli- fier shall have a three-way switch appearing on the rear panel for selecting the mode of operation, which shall include stereo (two channels in, two channels out), mono (one channel in, two channels out), and bridge (one channel in, one channel out bridged between both speaker outputs).
10.OUTPUT APPLICATION. The amplifier shall have a three-way switch appearing on the rear panel for selecting between limiter on, limiter off, and subwoofer mode. The defeatable electronic limiter circuit shall sense the onset of clipping and shall limit the input signal and thereby prevent the output from clipping. The amplifiers shall have a two- way switch appearing on the rear panel for selecting be- tween a 63Hz and 125Hz low-pass cutoff frequency when subwoofer mode is selected.
11.LOW-CUT FILTER. Each channel shall have a low-cut filter with a variable frequency control appearing on the rear panel covering a range of 10Hz (OFF) to 170Hz.
12.CONSTANT DIRECTIVITY HORN EQ. Each channel shall have a two-way switch appearing on the rear panel for selecting a constant directivity horn equalization circuit. When selected, this circuit shall provide a 6dB per octave high frequency boost. The EQ shall have a variable frequency control appearing on the rear panel covering a range of 2kHz to 6kHz. The 6kHz position shall be called AIR.
13.PHYSICAL CONFIGU- RATION. The amplifier shall be rack-mountable with rear support rails for extra support, and shall have a steel chassis frame painted grey-black. The amplifier shall be 19" wide, 3.5" tall (2U) and 15.25" deep, and shall weigh 36 pounds.
