Mackie Onyx 32.4-Bus Owner's Manual - Page 10

ONYX 4•Bus Onyx 4•Bus Features Mono Channel Strips 3. 48V Phantom Power Switch The Onyx 24•4 has 20 mono channel strips and two stereo channels, and the Onyx 32•4 has 28 mono channel strips and two stereo channels. Each mono channel has a mic and line input connector and an insert jack for connecting an external signal processor. 1. PAD Switch In most cases, you will leave the PAD switch out. However, you may have a microphone that produces a higher output signal than usual, which may require you to turn the GAIN control way down. If that is the case, push in the PAD switch to insert a 20 dB pad at the input to the mic preamp, to prevent overloading the microphone preamp and provide better gain control. 2. Low-Cut Switch The Low-Cut switch, often referred to as a high-pass filter, cuts bass frequencies below 100 Hz at a rate of 18 dB per octave. We recommend that you use the Low-Cut switch on every microphone application except kick drum, bass guitar, bassy synth patches, or recordings of earthquakes. These aside, there isn't much down there that you want to hear, and filtering it out makes the low stuff you do want much more crisp and tasty. Not only that, but the Low-Cut switch can help reduce the possibility of feedback in live situations and it helps to conserve amplifier power. Another way to use the Low-Cut switch is in combination with the LOW EQ on vocals during live performances. Many times, bass shelving EQ can really benefit voices. Trouble is, adding LOW EQ also boosts stage rumble, mic handling clunks, and breath pops. Low Cut removes all those problems so you can add LOW EQ without losing a woofer. Here's what the combination of LOW EQ and Low Cut looks like in terms of frequency curves. +15 +10 +5 0 -5 -10 -15 20Hz 100Hz 1kHz 10kHz 20kHz Low Cut with Low EQ Boosted 10 ONYX 4•Bus Most professional condenser microphones require phantom power, which is a low-current DC voltage delivered to the microphone on pins 2 and 3 of the XLR microphone connector. Push in the 48V switch if your microphone needs phantom power. An LED lights just above the switch to indicate that phantom power is active on that channel. Dynamic microphones, like Shure's SM57 and SM58, do not require phantom power. However, phantom power will not harm most dynamic microphones should you accidentally plug one in while the phantom power is turned on. Be careful with older ribbon microphones. Check the manual for your microphone to find out for sure whether or not phantom power can damage it. Note: Be sure the MAIN MIX fader [72] is turned down when connecting microphones to the MIC Inputs, especially when phantom power is turned on, to prevent pops from getting through to the speakers. 1 PAD 48V 30 20 U 40 U 60 -20dB +40dB GAIN U EQ HIGH 12kHz -15 +15 2k FREQ 400 8k U HIGH MID -15 +15 400 FREQ 100 2k U -15 +15 U LOW MID LOW 80Hz -15 +15 EQ OUT IN AUX 4. GAIN Control 1 MAX O O O O O O O O O O O O If you haven't already, please read "Set the Levels" on page 5. 2 MAX The GAIN control adjusts the input sensitivity of the mic and line inputs. 3 This allows the signal from the out- MAX side world to be adjusted to optimal internal operating levels. 4 MAX If the signal is plugged into the XLR jack, there is 0 dB of gain 5 (unity gain) with the knob turned MAX all the way down, ramping up to 60 dB of gain fully up (-20 dB to +40 6 dB with the PAD switch pushed in). MAX When connected to the 1/4" jack, there is 20 dB ofPAN attenuation all the way down, and 40 dB of gain fully up, with a "U" (unity gain) mark at about 10:00. L R MUTE 1 dB 10