[. . . ] Variable low-cut filters on each channel, with a range from off to 170Hz, enable tighter bass response and a Constant Directivity Horn EQ improves high-frequency reproduction. The CD Horn EQ is 6 dB/octave and its "knee" position is sweepable from 2kHz to 6kHz. The built-in limiter is channel independent and helps eliminate clipping. Inputs are balanced/unbalanced 1/4" and XLR, and XLR thru connectors allow the full-range signal to be routed to another M·1400/M·1400i. [. . . ] In single-channel operation it shall deliver 850 watts RMS into 8 ohms and 1260 watts into 4 ohms, with no more than 0. 05% total harmonic distortion. The amplifier 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 shortcircuit protection shall continuously cycle on and off until the shorted condition is remedied. The amplifier shall have a thermal protection circuit to protect the power devices from over-temperature operation. The circuit shall activate when the internal temperature crosses the safeoperating threshold and, when activated, mute the outputs until the internal temperature cools to a safe-operating temperature, at which time amplifier shall resume normal operation. The amplifier shall have a fan to cool the heat-producing internal components, drawing cool air in from the front, and exhausting warm air out through both sides. 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 speakers against a catastrophic amplifier failure. The circuit shall activate in the presence of continuous DC at the speaker outputs, and shall shut the amplifier down by turning off the high-voltage rails. M·1400i: Each channel shall have a heavy-duty 5-way binding post speaker output connector 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. M·1400: Each channel shall have a heavy-duty 5-way binding post speaker output connector 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. The amplifier 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). The amplifier shall have a three-way switch appearing on the rear panel for (continued on page 7) 6 OF 8 PAGES High-Current Power Amplifier (continued from page 6) selecting 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 amplifier shall have a two-way switch appearing on the rear panel for selecting between a 63Hz and 125Hz low-pass cutoff frequency when subwoofer mode is selected. [. . . ] When activated, the signals appearing at the left and right inputs are summed, directed to a low-pass filter, and routed to both output stages. The inputs are summed regardless of stereo, mono, or bridge amp mode selection. A switch selects the cutoff frequency of the filter at either 63Hz or 125Hz. Electronic files for this product available at: www. mackie. com This Specification Sheet Owner/Operator's Manual M1400_SS. PDF M1400_OM. PDF www. mackie. com LOUD Technologies continually engages in research related to product improvement. New material, production methods, and design refinements are introduced into existing products without notice as a routine expression of that philosophy. [. . . ]