User manual ALESIS MEQ230

[. . . ] 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. [. . . ] OUTPUT JACKS (Left & Right) Line level output of the M-EQ 230 for 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 A lesis 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 MAIN OUT LEFT MAIN OUT RIGHT LEFT INPUT RIGHT INPUT M-EQ LEFT OUTPUT LEFT INPUT STEREO POWER AMP RIGHT INPUT 230 RIGHT OUTPUT 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 AUX SEND OUT or MONITOR OUT MAIN OUT RIGHT OR LEFT LEFT INPUT RIGHT INPUT M-EQ 230 LEFT OUTPUT INPUT MONITOR POWER AMP RIGHT OUTPUT INPUT HOUSE 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 INSERT SEND INSERT RETURN RIGHT INPUT RIGHT OUTPUT M-EQ 230 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. 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. PLEASE NOTE: A) In many cases, room acoustics, uneven frequency response in speaker components and microphones, excessive gain due to poor microphone technique, poor placement of speaker systems, or many open microphones in the sound system will all contribute to feedback which can only be mildly controlled but not totally eliminated. If excessive EQ is being used it's best to try to correct some of the reasons for feedback first before resorting to EQ. 7 B) For feedback control, the sliders of the M-EQ 230 should always be operated in the downward or cut position. FIGURE 4 CONTROLLING FEEDBACK A. Find the 2 major feedback frequencies (1 high, 1 low frequency) B. [. . . ] Although it is a wonderful device and will help your sound a lot, remember that a little goes a long way. If you're using the M-EQ 230 for tonal contour of an instrument or voice, Figure 5 will help you zero in on the key frequencies of some popular instruments. Remember: The chart serves only as a starting point. you must use your ears as a guide. Ultimately, 10 SECTION 4 SPECIFICATIONS ELECTRICAL CHARACTERISTICS FREQUENCY RESPONSE HARMONIC DISTORTION INPUT NUMBER OF CHANNELS NOMINAL LEVEL MAXIMUM LEVEL IMPEDANCE OUTPUT NUMBER OF CHANNELS MAXIMUM LEVEL IMPEDANCE FRONT PANEL CONTROLS INDICATORS SWITCHES REAR PANEL JACKS 2 0dBV +18dBV 1M 2 +18dBV 240 25Hz to 20kHz in 1/3 octave increments . 004% @ 1KHz @ 0dBV 30 Band, 1/3rd octave , ±12dB, center frequencies set to ANSI and ISO standards. [. . . ]