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manual abstract
Each band is adjusted by a center detented fader with ± 12dB of gain available, and a master fader controls system gain for that channel. Clip and signal present LEDs, as well as a bypass switch, are also provided on each channel. Inputs and outputs for each channel are via both 1/4" and RCA jacks. The unit can also be rack mounted in only 1 rack space. FEATURES • 2 complete 30 band 1/3 octave equalizers in 1 rack space • Power up delay circuitry protects speakers by eliminating turn-on transients • ± 12dB boost or cut per band • Each channel can be bypassed individually • Clip and signal present LEDs for each channel • Inputs and outputs via both 1/4" phone and RCA jacks Applications • Feedback control in sound systems • Feedback control in stage monitor systems • Timbre contour of musical instruments • Room voicing • Special sound effects 2 SECTION 1 DESCRIPTION OF CONTROLS FRONT PANEL 1/3 OCTAVE BAND FADER Each 1/3rd octave band is controlled by a center detented fader which provides a boost or cut of 12dB. There are 30 bands per channel. MASTER CHANNEL GAIN FADER Each channel has a Master Gain Fader which controls the system's input gain by ± 12dB. CHANNEL BYPASS SWITCH Each channel's EQ can be individually bypassed by means of the Channel Bypass Switch. The Master Gain Fader affects program input level only when the channel is not bypassed. EQ IN LED The EQ In LED lights when the EQ is in use. The LED will go out when a channel is bypassed. CLIP INDICATOR The red CLIP INDICATOR LED indicates the onset of distortion (+18 dB). This LED should never light during normal use. SIGNAL PRESENT LED The green SIGNAL PRESENT LED indicates that a signal is currently being fed into the M-EQ 230. This LED lights at approximately -20dB and should be frequently lit during normal use. POWER LED The POWER button turns the unit on or off. BACK PANEL INPUT JACKS (Left & Right) Accepts instrument to line level input signals for both left and right channels. Both 1/4" and RCA phono jacks are provided. OUTPUT JACKS (Left & Right) Line level output of the M-EQ 230for both left and right channels. Both 1/4" and RCA phono jacks are provided. 3 POWER JACK Accepts the +9VAC power from the M-EQ 230 Power Supply. This external supply keeps hum, noise, and ground loops to a minimum. SECTION 2 SET-UP INSTRUMENTS, MICROPHONES The Alesis M-EQ 230 has high impedance inputs that are ideally suited for use either with instruments or line level signals. Although microphones can be connected directly into the M-EQ 230, it is recommended that for quietest operation they be connected to a mixing console first and then connected to the MEQ 230 as described in Figure 1. STEREO OPERATION For stereo operation of the M-EQ 230, connect the left and right line outputs of the device to be equalized into the left and right inputs of the M-EQ 230. See Figure 1 FIGURE 1 M-EQ 230 STEREO OPERATION Alesis 1622 MIXING CONSOLE M-EQ 230 LEFT INPUT LEFT OUTPUT MAIN OUT LEFT MAIN OUT RIGHT RIGHT OUTPUT RIGHT INPUT STEREO POWER AMP RIGHT INPUTLEFT INPUT 4 INDEPENDENT USE OF LEFT AND RIGHT CHANNELS The M-EQ 230 need not be used in a stereo mode since each channel is completely independent. In Figure 2, the right channel is connected to the house sound system for room tuning while the left channel is connected to the on-stage monitor system for feedback control. FIGURE 2 INDEPENDENT USE OF LEFT AND RIGHT CHANNELS Alesis 1622 MIXING CONSOLE M-EQ 230 LEFT INPUT LEFT OUTPUT AUX SEND OUT or MONITOR OUT MAIN OUT RIGHT OR LEFT RIGHT OUTPUT RIGHT INPUT HOUSE POWER AMP INPUTINPUT MONITOR POWER AMP 5 INTERFACING VIA INSERT SENDS AND RETURNS Another way of interfacing the M-EQ 230 is to connect the unit directly to the insert send and return patch points (if your console has them) of the channel that is to be effected. See Figure 3 FIGURE 3 INTERFACING TO A MIXING CONSOLE VIA CHANNEL INSERTS Alesis 1622 MIXING CONSOLE M-EQ 230 INSERT RETURNINSERT SEND RIGHT OUTPUT RIGHT INPUT 6 SECTION 3 OPERATION POWER-UP When the power is first turned on, the automatic power-up delay circuit will mute the M-EQ 230 for 2 seconds. This is to prevent any possible turn-on transient signal from mixers, power amps, or outboard equipment from possibly damaging speakers. TO CONTROL FEEDBACK 1) Place all microphones in the positions where they will be used. Set mics to approximate levels. 2) Gradually bring up the sound system level until feedback just begins to occur. 3) Feedback will usually occur at two frequencies in each room; one low and one high. Determine which frequency is loudest (or that is feeding back first) by decreasing each slider until one is found that makes the feedback disappear (see Figure 4A). 4) After the feedback frequency is found, gradually increase the slider until just on the edge of feedback. 5) Now gradually decrease the two adjacent sliders until the feedback again disappears (see Figure 4B). 6) Gradually increase the sound system gain until feedback occurs again. 7)...