Electro-Voice CH230W manual Plate, Application Notes, Architects and Engineering Specifications

CH230/CH230W Condenser Cardioid Hanging Microphone

CH230/CH230W Condenser Cardioid Hanging Microphone

up with “INPUT-OUTPUT”aligned as shown in Figure 3. Start the assembly by inserting the two 11/4-in. screws into the up- per left-hand and lower right-hand holes, drop on the internal toothed lockwashers, thread on the spacer and tighten against the plate with a wrench. Repeat the procedure for the two 3/16-in. screws. Place the fiber washer on each spacer.

3.Position the printed circuit board with the larger terminal block and the transformer over the printed “OUTPUT” label. Align the screw holes in the upper right and lower left corners of the printed circuit board with the

two 11/4-in. screws and push down until the board rests against the four fiber washers.

Take the remaining two 3/16-in. screws and two fiber washers and fasten the board to the

plate.

4.Determine the length of cable required before attaching the microphone cable to the printed circuit board. If the cable must be trimmed, measure the length and add three inches. Trim the cable by removing about 1 in. of the outside jacket, then separate the shield from the red and white wires.

Strip 1/4 in. of insulation from the red and white wires. Push the bare wire ends of mi- crophone cable through the center hole in the plate and the circuit board, then insert the wires into the “INPUT” terminal block. Follow the label instructions printed on the plate. With the small-blade screwdriver, tighten the screws in the terminal block.

5.Use the strain relief to fasten the micro- phone cable to the plate by capturing the

cable about 1/2 in. from the front of the plate, then orient the flats of the strain relief with

the flats of the center hole and squeeze and push the strain relief into the center hole. The strain relief will lock into place.

6.To attach the mixer cable to the circuit

board, trim 1/4 in. of insulation from the cable wires and insert the wires into the “OUT-

PUT” terminal block. Follow the label in- structions and insert the cable shield into “SHLD GND,” and the remaining wires into terminals 2 and 3. Warning: the CH230 and CH230W have terminal 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 roll-off switch to the position desired. The rolloff filter is a two-pole, 12- dB-per-octave high pass with a corner fre- quency of 75 Hz.

8.Position the shield box with the slotted end over the mixer cable and the screw holes

over the two 11/4-in. 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

2or 3 to the shield box. With the wrench, fasten the shield box to the plate with the two split-ring washers and the two hex nuts.

9.Gently push the assembly into the wallbox and fasten the assembly in place with the two remaining 1/2-in. #8-32 screws.

10.To orient the microphone in the proper direction, loosen the holding nut on the back of the microphone and slightly twist the mi- crophone on the wire holder (clockwise ro-

tation moves the microphone to the left; counterclockwise rotation moves the micro- phone to the right). Tighten the holding nut. Note: for fixed installations, allow the mi- crophone cable to hang for at least 24 hours so the cable can completely relax and estab- lish a set. Bend the hanger wire to position the microphone in the vertical plane.

Application Notes

When hanging one or more microphones to provide coverage for a choir, instrumental, or theater group, the best microphone posi- tion for optimum sound quality and feedback control depends on many factors—sound system characteristics, construction of the auditorium or theater, and the size and na- ture of the performing group. Two general rules to observe for the best sound coverage are (1) microphone position and (2) 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 rule, the “3-to-1 rule,” should be applied when more than one microphone is required, and their outputs are combined (as with a mixer). Following the 3-to-1 rule avoids the deep voids and dips in frequency response that occur when two or more mi- crophones “see” the same signal from slightly different distances. The 3-to-1 rule is as follows: when multiple microphones are used, place them at least three times as far apart as any one of them is from the nearest sound source. Figure 6 shows a proper ap- plication of the 3-to-1 rule.

The CH230 and CH230W may also be used to provide coverage for live theater applica- tions (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.

Architects' and Engineering

Specifications

The microphone shall be a back-electret con- denser type with a frequency response of 30 Hz to 20 kHz. The microphone shall have a cardioid polar pattern with a rear response which is typically 20 dB below the front re- sponse at 1.0 kHz. The microphone shall have an output power level of –21.7 dB, where 0 dB = 1 milliwatt per pascal, and output shall not be appreciably affected by the following temperature and humidity ex- tremes: –29° to 74° C (–20° to 165° F) when relative humidity is 0-50%; –29° to 57° C (– 20° to 135° F) when relative humidity is 0- 95%. 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 (CH230) or a low-gloss white finish (CH230W). The cable color shall match the transducer. A switchable, two-pole high-pass filter (f0 = 75 Hz) shall be provided.

The transducer shall have a wire hanger for directing the microphone. Dimensions: the transducer shall be 10.5 mm (0.42 in.) wide and 41.9 mm (1.65 in.) long; the cable shall be 9.1 m (30 ft) long and 2.6 mm (0.106 in.) in diameter. The electronics module shall fit into either a switch box or four-inch electri- cal box, with a rectangular switch-box plate and circular plaster-ring cover provided.

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