Mackie M800 Owner's Manual - Page 13

If you're using low impedance loads at high power levels, we recommend that you use the binding post speaker outputs rather than the 1/4" TS jacks. Although 1/4" jacks and plugs are convenient and easy to use, they are not designed to handle high-level currents. Make sure that the amplifier is off before making connections or reconfiguring the signal routing. INPUT RING SLEEVE SLEEVE RING TIP TIP Balanced 1⁄4" TRS Plug Unbalanced RING (COLD) TIP (HOT) SLEEVE (SHIELD) Unbalanced TS (Tip-Sleeve) lines can be accommodated via the TRS jack. Make sure the cord terminates with a TS plug (like a guitar plug), or if it's a TRS plug (like a headphone plug), make sure the ring is tied to the shield, preferably at the source end. The M•800 gives you a choice of inputs - it has XLR as well as 1/4" TRS (Tip-Ring-Sleeve) input jacks. Sonically (and electrically) they're identical, so choose either one. Since these two inputs are in parallel, don't use both at the same time. The amplifier expects to see a nominal signal level anywhere between the -10 dBV "semipro" and +4 dBu "pro" standards, meaning almost any line-level mixer or other device can be plugged into the amp's INPUTs. Use the GAIN controls to adjust the gain of the amplifier to match the signal level you're using. Each type of input can be used with either balanced or unbalanced signals. Balanced Use the balanced connections if your source has balanced outputs. This will greatly reduce any noise picked up in your system. When connecting a balanced signal using the XLR or 1/4" jacks, they're wired thusly, per AES (Audio Engineering Society) standards: SLEEVE TIP Unbalanced 1/4" TS Plug SLEEVE TIP RING (COLD) TIP (HOT) SLEEVE (SHIELD) THRU The THRU jacks allow you to feed the input signal to the inputs of other amplifiers. In this way, multiple amplifiers can receive an input signal from your single mixer or preamp. This is accomplished as follows: • Make sure all your equipment is turned off before making any connections. • Plug the signal source outputs into the first amp's INPUTs. • Patch from that amp's THRU jacks to the next amp's INPUT, and so on, daisy-chaining to other amps in your system (assuming your mixer has low impedance outputs). Hot (+) Cold (-) Shield (Ground) XLR Pin 2 Pin 3 Pin 1 TRS Tip Ring Sleeve SHIELD 2 HOT COLD 3 1 SHIELD 1 COLD 3 2 HOT 1 3 2 SHIELD COLD HOT Balanced XLR Plug (prior to Lunar orbit insertion) To prevent excessive loading of your source, a general rule of thumb is to maintain a load impedance 10 times or more than the source impedance . If your console has an output impedance of 100 ohms, then you can daisy-chain up to twenty M•800 amplifiers, which presents a load of 1000 ohms to the console (input impedance of 20 kohms divided by 20 amplifiers = 1000 ohms). The THRU jacks can also be used to relay the input signals on to other devices such as a DAT or cassette recorder. They are wired in parallel with the XLR and TRS INPUTs, so the signals coming out of the THRU jacks are exactly the same as the signals going into the amp, unaffected by any of the amp's switches and controls. 13