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ALTEC LANSING INDUSTRIAL PROFESSIONAL SOUND PRODUCTS MICROPHONE LIST

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AL15A/CMB / AL15A/CMW Miniature Hanging Electret Condenser Microphone

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1597B Passive Monitor Panel

insulation from the cable wires and insert the wires into the "OUTPUT" terminal block. Follow the label instructions and insert the cable shield into SHLD GND and the remaining wires into terminals 2 and 3. Warning: terminal is 2 positive with a positive pressure on the diaphragm so be aware of
possible phasing problems if the wires for terminals 2 and 3 are reversed. Tighten the terminal block screws with a small blade screwdriver.

7.Set the rolloff switch either on or off. The rolloff filter is a 2 pole 12 dB/Octave highpass with a cutoff frequency of 75 Hz.

8.Position the shield box with the slotted end over the mixer cable and the screw holes over the two 1 114" screws. Push down the shield box over the circuit board until the shield is sitting on the plate. Inspect the mixer cable connection for any shorts of terminals 2 or 3 to the shield box. With the wrench fasten the shield box to the wallplate with the two #4 split ring washers and the two #4-40 hex nuts.

9.Gently push the assembly into the wallbox and fasten the assembly in place with the two remaining 1/2" #8-32 screws.
lO.To orient the microphone in the proper direction, loosen the holding nut on back of the microphone and slightly twist the microphone on the wire holder (clockwise rotation moves the microphone to the left; counterclockwise rotation moves the microphone to the right). Tighten the holding nut. Note: for fixed installations allow the microphone cable to hang for at least 24 hours so the cable can completely relax andestablish a set. Bend the hanger wire to position themicrophone in the vertical plane.


APPLICATION NOTES:
When hanging one or more AL15A/CMB or AL15ACMW microphones to provide coverage for a choir , instrumental, or theater group, the best positioning for the microphones for the optimum sound quality and feedback control depend on many factors such as the sound system characteristics, the construction of the auditorium or theater, and the size and nature of the performing group. Two general rules to observe for the best sound coverage is microphone positioning and the "3 to 1 rule." The first rule is to suspend the microphone approximately two to three feet in front of the first row of performers and two to three feet higher than the heads of the last row of performers. The microphones are usually aimed to point at the last row of performers (figure 5). The second or "3 to 1 rule" when more than one - microphone is required for coverage simply means that the spacing between adjacent microphones should be at least three times the distance to the nearest performers to avoid phase cancellation and provide the best overall sound coverage and quality (figure 6).
The ALISA/CMB and ALISA/CMW may also be used to provide coverage for live theater applications (figure 7). Most of the action occurs at center stage so the microphone should be positioned above and pointed to the center of the stage.

ARCHITECT'S and ENGINEER'S SPECIFICATION
The choir microphone shall be a back electret condenser type with a frequency response of 30 Hz to 20,000 Hz and a cardioid polar pattern with a rear response which is typically -20 dB from the front response at 1.0 kHz. The microphone shall have an output power level of -21.7 dB where 0 dB =1 milliwatt per Pascal, and whose output shall not be appreciably affected by temperature extremes from -17.8 C (0 F) to 54.4 C (130 F) and /or by humidity extremes. The microphone shall have a nominal balanced output impedance of 150 ohms when connected to its electronics module. The microphone shall have a low gloss black finish (ALISA/CMB) or a white finish (AL15ACMW). The cable color shall match the transducer. A switchable two-pole highpass filter (fo=75 Hz) shall be provided.
Dimensions shall be: the transducer shall be 10.5 mm (.42 in.) wide and 41.9 mm (1.65 in.) long. The transducer shall have a wire hanger for directing the microphone. The cable shall be 9.1 meters (30 feet) long and 2.6 mm (.106 in) in diameter. The electronics module shall fit into a either a single or duel gang switchbox and a rectangular switchbox cover and a circular plaster ring cover shall be provided. Terminations to the electronics module shall be terminal blocks. The microphone shall be of metal construction. The hanging microphone shall be the ALTEC LANSING ALISA/CMB or ALISAICMW.

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