Mackie M800 Owner's Manual - Page 14

You can use the THRU jack as an input, if necessary, since it's wired in parallel with the other input connectors. You can also use the 1/4" TRS INPUT jacks as THRU jacks. Simply connect the 1/4" TRS INPUT jacks on the first amplifier to the TRS 1/4" INPUT jacks on the second amplifier using 3-conductor shielded cables with TRS plugs on both ends. Warning: If you are using a balanced input to the first amp, do not use TS unbalanced connections to feed other amplifiers. This will unbalance the input connections of your first amp by grounding pin 3. LOW CUT FILTER Every woofer has frequency response specifications. It's usually expressed in Hertz (or cycles per second), like "40Hz-300Hz." The "40Hz" refers to the low-frequency point (usually, but not always) where the speaker's output drops by 3 dB, and will "roll off" completely as the frequency goes down. There is no point in sending a woofer any frequencies it can't reproduce - you can't hear it, and worse yet, it's a waste of amplifier power that can be better used reproducing frequencies you can hear. 5dB 0dB Level, dB -5dB -10dB -15dB 1Hz 10Hz 100Hz 1kHz Frequency, Hz Low CuLt FCilterFFil requency Response 10kHz 20kHz In order to match the output bandwidth with your particular speaker system, the M•800 amplifier has a tunable LOW CUT FILTER. The frequencies are clearly marked along the knob's travel: • Fully counterclockwise, the frequency is below 10Hz, effectively bypassing the filter. • Center detent is 35Hz, labeled TYPICAL, since few woofers actually go below that. • 3/4 of the way up is labeled STAGE MONITOR, 100Hz, perfect for, well, stage monitors (they seldom reproduce below 100Hz; besides, it prevents low frequency "leakage" into the house). • Fully clockwise is labeled 170Hz. LOW CUT FILTER TYPICAL 35 Hz STAGE MONITOR 100 Hz OFF 170 Hz So, grab your woofer's spec sheet and find the low roll-off spec. Then set the M•800's LOW CUT FILTER at the same frequency. If you do this correctly (and make sure the meters are happy), you'll never again see your woofer moving sporadically without audible signal. Your system will play louder and cleaner, and you may never blow another woofer again! CH 1 + - (MONO BRIDGE) 800 WATTS 4 OHM LOAD MIN. 400 WATTS CH 2 OHMS LOAD MIN. MONO BRIDGE CH 2 + - SPEAKER OUTPUTS 1 CHANNEL INPUT BAL/UNBAL 120 VAC 60 Hz 1500 WATTS THRU LOW CUT FILTER TYPICAL 35 Hz STAGE MONITOR 100 Hz CONSTANT DIRECTIVITY HORN EQ /AIR EQ 4.5k Hz OFF ON OFF 170 Hz 2k Hz 6k Hz AIR EQ TYPICAL AMP MODE STEREO MONO BRIDGE CAUTION RISK OF ELECTRIC SHOCK DO NOT OPEN WARNING: TO REDUCE THE RISK OF FIRE OR ELECTRIC SHOCK, DO NOT EXPOSE THIS EQUIPMENT TO RAIN OR MOISTURE. DO NOT REMOVE COVER. NO USER SERVICEABLE PARTS INSIDE. REFER SERVICING TO QUALIFIED PERSONNEL. AVIS: RISQUE DE CHOC ELECTRIQUE - NE PAS OUVRIR CONCEIVED, DESIGNED, AND MANUFACTURED BY MACKIE DESIGNS INC • WOODINVILLE WA • 98072 • USA • MADE IN USA • PATENTS PENDING • COPYRIGHT ©1999 SERIAL NUMBER MANUFACTURING DATE THE FOLLOWING ARE TRADEMARKS/REGISTERED TRADEMARKS OF MACKIE DESIGN INC.: "MACKIE", "FR SERIES", & THE "RUNNING MAN" FIGURE LIMITER OFF ON CONSTANT DIRECTIVITY HORN EQ /AIR EQ OFF ON 4.5k Hz LOW CUT FILTER TYPICAL 35 Hz STAGE MONITOR 100 Hz 2 CHANNEL INPUT TYPICAL TYPICAL TYPICAL 2k Hz 6k Hz AIR EQ OFF 170 Hz THRU BAL/UNBAL 14