Mackie SR244 / SR324 Owner's Manual - Page 15

OO OO OO OO OO OO OO OO down, there's still sound until just before you reach the infinity (off) marking. About 2/3 of the way up the slot you will see a "U" on the panel which stands for unity gain. The fader markings are calibrated in dB (deci- bels) from 10dB above unity gain to 60dB below unity gain, and finally to infinity (or off). VERY IMPORTANT: Unity gain is the point at which no level is added to or subtracted from the nominal signal. Many level controls on a Mackie mixer have a unity gain "U" mark and a detent, a little "bump" in the otherwise silky-smooth travel of the con- trol. The unity gain point can be very helpful in setting levels throughout the SR24•4 for best headroom and noise figures. See Impor- tant Sensitivity Adjustment Procedure! in the Introduction and Setting Levels With Solo later in this section. The channel fader OL is your main mixing tool, like the brush in an artist's hand. L R PAN Everything which -20 passes through the channel strip (with 2 MUTE the exception of pre-aux sends) is controlled by the channel fader. MUTE / SOLO THE MUTE SWITCH dB Next up is the 10 SOLO MUTE switch [2], which lives up to its 5 name by muting its channel strip. When U 1-2 the MUTE switch is depressed, the signal 5 in that channel strip 3-4 is removed from the 10 main left/right mix buses and the submix 20 L-R buses, the solo buses 30 (both PFL and AFL) and from any aux 40 buses selected. 50 60 Even though the channel is muted, there can still be audio within the channel strip. The -20 LED might light and signal will still be available at the output of the INSERT jack. The red MUTE/SOLO LED just below the MUTE switch will glow steadily when the MUTE switch is depressed. OL AND -20 LEDs The red LED [3] above the MUTE switch is marked OL, and that stands for OverLoad. The channel strip overload circuit constantly checks at a critical point in the channel strip, just after the EQ circuit. If the channel strip amplifiers are being driven too loud into overload, the OL light will flash bright red. This is to be avoided. Overloading a mixer circuit forces the audio signal to clip and seriously distort the sound. When the OL light flashes, it means something is too loud. It could be the level from the microphone or tape track plugged into the SR24•4 input connection or a device you plugged into the INSERT jack; maybe you have the TRIM control turned too high or an extreme amount of EQ (which lifts the gain in certain frequency ranges). You need to find out which source is too high and make things right. Start by turning down the TRIM control until the OL LED no longer lights. That will lower the level of all the circuitry that follows. Also, if you have a processor plugged into that channel's INSERT jack, temporarily unplug it. The level should remain about the same. If not, the processor's level needs to come down, too. The green LED is marked -20, and it will light whenever there is a signal level in the channel strip that has a level at or more than 20dB below the nominal circuit level (0dBu). In practice, this LED will flicker or light almost constantly when there is activity in that channel, and it basically serves as a convenient indicator for you, a way of figuring out who's singing now or what's plugged into where. Whether it lights rarely or is on all the time is not really important; it's just to reassure you that there is some audio in the channel. Some days that may be all the reassurance you get. MIC GA-1IN0 U TRIM 1 10 60 +10dB -40dB U AUX 1 PRE +15 U 2 PRE +15 U 3 +15 U 4 +15 U PRE 5 +15 U 6 +15 U EQ HI 12k -15 +15 U -15 +15 MID FREQ 100 8kHz U -15 +15 LOW CUT 75 Hz 18dB/OCT LOW 80Hz OL L R -20 PAN 1 MUTE MUTE / SOLO dB 10 SOLO 5 U 1-2 5 3-4 10 20 L-R 30 40 50 60 13