Shure SM15 User Guide

MODEL SM15
UNIDIRECTIONAL HEAD-WORN CONDENSER MICROPHONE
MODEL SM15
UNIDIRECTIONAL HEAD-WORN CONDENSER MICROPHONE
The SM15’s smooth, natural voice frequency response makes it ideal for drummers, keyboard art­ists and other musicians requiring a vocal microphone with all the qualities of a hand-held unit-the SM15 can be used under noisy conditions without loss or masking of voice signals.
A small, lightweight, rugged and reliable unit, the SM15 has provisions for mounting to a supplied head­band with cushioned arms. The dual steel headband holds securely without causing discomfort for active microphone users. A pivot housing permits the micro­phone boom to be moved 20° in any direction, and the distance between the microphone and pivot can be changed by up to 89 mm (3-1/2 in.).
The SM15’s amplifier is constructed of high-impact ARMO-DUR®, making it compact, lightweight, and extremely rugged. It can easily be clipped to a belt or waistband, or slipped into a pocket. It is powered by a readily available 9-volt battery or by phantom power from an external source providing 5-52 Vdc (such as a Shure PS1A power supply or M267 or M268 micro­phone mixer). The amplifier incorporates extensive RF and hum shielding to reduce the effects of electro­magnetic and electrostatic interference. Connections between the microphone and amplifier are made through a miniature 3-pin connector.
The SM15 is supplied with a windscreen to protect against wind noise and explosive breath sounds, and a foam-lined carrying/storage case.
Features
Close-talk operation and unidirectional polar pat­tern for effective noise reduction
High sound pressure level capacity
Smooth, natural frequency response, tailored for
voice
Low distortion and wide dynamic range characteris­tics under various load impedances
Wide-range phantom powering accepts all commonly used voltages; can also be battery-powered
Acoustically isolated for maximum feedback freedom
Locking adjustment knob permits 20° boom pivot
in any direction. Boom mounts on either side of headband
Boom length adjustment through 89 mm (3-1/2 in.)
Dual headband design plus serrated arms minimize
accidental movement
Lightweight design prevents user fatigue
No interference with eyeglasses
Ruggedly constructed of stainless steel, aluminum
and high-impact thermoplastic
Usable over wide range of temperature and humid­ity conditions
Amplifier assembly can be pocketed, strapped to body, or clipped to belt or waistband
ASSEMBLY
Assemble the SM15 for use as follows:
1. Twist the lower headband arms 90° so they are
perpendicular to the headband. As supplied, the retaining clip is positioned for left side operation as shown in Figure 1. For right side usage (see photo), remove the retaining clip and attach it to the other (unused) hole in the headband arm so the screw is at the top.
2. Snap the microphone pivot housing into the retaining
clip with the pivot adjustment knob upward and the microphone toward the front. Loosen the pivot adjust­ment knob, position the boom so that the micro­phone is near where the side of the mouth will be, and tighten the pivot adjustment knob.
3. Place the assembled microphone on the user’s head
and pull the headband arms downward until they rest against the head just over the ears.
4. Loosen the pivot adjustment knob and position the
microphone as close as possible to the corner of the mouth. IMPORTANT: For optimum close-talking operation, the microphone should be less than 25mm (1 in.) from the corner of the mouth. Be sure to position the microphone at the corner (not the cen­ter) of the mouth to eliminate explosive breath sounds (“pop”). Tighten the adjustment knob.
222 HARTREY AVE., EVANSTON, IL 60202-3696 U.S.A. PHONE (312) 866-2200 TELEX: 4330191 FAX (312) 866-2279
Copyright 1987. Shure Brothers Inc. Printed in U.S.A. 27A2371 (GB) U.S. Patent 4,039,765
5. Connect the SM15 microphone cable to the ampli­fier assembly.
6. Insert a fresh 9-volt battery in the amplifier battery compartment (see Batteries section) and connect the amplifier 3-pin XLR connector to the mixer input connector, or phantom-power the SM15 by con­necting the amplifier (without battery) to a micro­phone powersupply providing 5 to 52 Vdc phantom voltage. This can be a separate phantom power supply, or a mixer or amplifier with provisions for phantom powering (see Phantom Powering section).
7. Place the amplifier assembly in the desired position (see Amplifier Mounting section).
Polar Pattern
Cardioid (unidirectional) response–uniform with frequency, symmetrical about axis (see Figure 3)
TYPICAL POLAR PATTERNS
FIGURE 3
Output Impedance
Rated at 150 ohms (95 ohms actual) Recommended minimum load impedance: 800 ohms (may be used with loads as low as 150 ohms with reduced clipping level)
SM15 POSITIONED FOR LEFT SIDE OPERATION
FIGURE 1
SPECIFICATIONS
Type
Condenser (electret bias)
Frequency Response (at 76 mm–3 in.)
50 to 15,000 Hz (see Figure 2)
Output Level (close-talked at 1,000 Hz)
Open Circuit Voltage
–40.5 dB (0.9 mV) at 610 mm (24 in.) –39 dB (1.1 mV) at 10 mm (0.39 in.)
(0 dB = 1 volt per 100 microbars)
Clipping Level (at 1,000 Hz)
800-ohm Load................. –13 dB (0.22V)
150-ohm Load................ –27 dB (0.045V)
Total Harmonic Distortion
Less than 1% (138 dB SPL at 1,000 Hz into 800-ohm
load)
Maximum SPL
141 dB with 800-ohm load
130 dB with 150-ohm load
Hum Pickup
Less than or equal to 0 dB equivalent SPL in a 1
millioersted field (60 Hz)
Output Noise (equivalent sound pressure levels; meas­ured with true rms voltmeter)
32 dB typical, A-weighted
38 dB typical, weighted per DIN 45 405
Dynamic Range
109 dB (maximum SPL to A-weighted noise level)
TYPICAL FREQUENCY RESPONSE
FIGURE 2
Signal-to-Noise Ratio
62 dB (IEC 651) at 94 dB SPL
Phasing
Positive pressure on diaphragm produces positive
voltage on pin 2 relative to pin 3
Power
Battery: 9 Vdc (type 1604A, alkaline recommended);
0.33 mA current drain; approximately 1600 hours
continuous use with fresh battery
Phantom Voltage: 5 to 52 Vdc; 0.33 mA current drain Protected against reverse voltage application
Environmental Conditions
Operating Temperatures ... –18° to 60°C (0° to 140 °F) Storage Temperatures .. –29° to 66°C (-20° to 150 °F)
Cables
Microphone: 1.2m (4 ft) attached, two-conductor, shielded with miniature 3-pin connector designed to mate with Switchcraft TA3 series or equivalent. Amplifier: 3m (10 ft) attached, two-conductor, shielded with 3-pin XLR audio connector designed to mate with Cannon XL series, Switchcraft A3 (Q-G) series or equivalent connectors
Case
Microphone: Black thermoplastic microphone and pivot housing, anodized aluminum end caps, stain­less steel grille and boom Amplifier: Black molded high-impact ARMO-DUR with detachable belt clip
Dimensions
See Figure 4
To insert the battery, depress the ridged area of the
case and swing the hinged door outward. Insert the battery in the compartment, battery terminals toward the hinge and positive terminal inward (the negative contact is marked inside the compartment). Depress the battery slightly and hook it under the “ledge” in the compartment. The ledge and spring contacts will retain the battery even if the door or hinges are damaged. Close and lock the door. Note that the door will not lock if the battery is incorrectly inserted; the positive and negative contact areas accept only the corres­ponding battery terminals.
To prevent battery drain when the unit is not in use,
the battery should be removed or stored in the battery compartment upside down (battery terminals facing in the opposite direction from the amplifier contacts) and positive battery terminal inward. If the unit is not to be used for a prolonged period, the battery should be removed to prevent possible damage from leakage.
Note that no current is drawn from the battery when
a phantom voltage higher than the battery voltage is applied. Phantom power can be used whether or not a
®
battery is in the amplifier.
PHANTOM POWERING
The SM15 is designed for phantom powering by
virtually any microphone power supply providing 5 to 52 Vdc phantom voltage. The Shure PS1A power sup­ply will provide phantom power to one or two SM15 microphones. Phantom powering uses the balanced audio cable pair to carry the supply current to the microphone, and the cable shield as a ground return.
Use only high-quality extension cables, as intermit-
tent shorts between broken shield wires and balanced conductors will cause objectionable noise transients in the system. A reliable ground path is essential for the same reason.
OVERALL DIMENSIONS
Figure 4
Net Weight
Microphone: 78 grams (2.8 ounces) Amplifier: 270 grams (9.45 ounces)
BATTERIES
The SM15 is normally powered by a 9-volt battery (alkaline types are recommended). Under normal operating conditions, a fresh alkaline battery should provide approximately 1600 hours of operation. Recommended battery types are:
Duracell MN1604 NEDA 1604A
Eveready 522 IEC 6LR22
Bright Star 7590 Japanese 6AM6
Ray-O-Vac A1604 Varta 4022
Radio Shack 23-553 U.S. Military BA3090
Note that the SM15 is designed without an on-off switch; the amplifier is on whenever a “good” battery is inserted or phantom power is applied. The highly efficient circuit can operate for two months contin­uously with a fresh alkaline battery.
MICROPHONE LOADING
A minimum load impedance of 800 ohms should be used for maximum signal handling and minimum dis­tortion. The load can be as low as 150 ohms, but a reduction in output clipping level will result. It should be noted that the power supply itself may add loading (3300 ohms in the Shure PS1A) to the microphone.
WIND NOISE
A head-worn microphone generally needs a wind­screen for proper operation. When used outdoors under windy conditions, the SM15’s acoustic foam windscreen helps eliminate the unpleasant “rushing” noise asso­ciated with outdoor miking.
AMPLIFIER MOUNTING
Most SM15 applications require that the amplifier be worn on the body. The spring-loaded belt clip holds the amplifier to a belt, skirt or trouser waistband, or inside pocket.
The belt clip can be removed from the case and the amplifier placed on a nearby horizontal surface or worn in an inside pocketwithoutany retention method. Clip removal requires disassembly of the case (two Phillips head screws in the case and two slotted head screws in the connector collar).
BLOCK DIAGRAM
Figure 5
Note that the “W-shaped” belt clip permits the power supply to be worn with the cable end either upward or downward, depending on the speaker’s comfort and the particular application.
CIRCUIT DESCRIPTION
A block diagram of the SM15 is shown in Figure 5. The capacitor cartridge is followed by a field-effect transistor impedance conversion stage. The FET out­put is coupled through a two-conductor, shielded cable and miniature three-pin connectors to the amplifier assembly. The first stage in the amplifier is an RFI filter, whose output enters a compound transistor, Class A, emitter-follower amplifier and 12 dB/octave active high-pass filter. The circuit output is transformer­coupled, providing a balanced output. The preamp output is also RFI-filtered.
A constant-current power supply circuit regulates the powering voltage, allowing maximum battery life and operation over the widest range of phantom volt­ages. Reverse voltage protection diodes automati­cally select phantom powering when the applied phan­tom voltage exceeds the battery voltage, and guard against miswired cables and equipment. The circuit provides low noise, low distortion, wide frequency response and dynamic range, low output impedance, and reliable operation over a wide range of working environments.
TROUBLESHOOTING
The following steps should should be taken if prob-
lems arise.
1. Check to see that battery voltage (or external volt­age on pins 2 and 3 of cable output connector) is adequate.
2. If a second SM15 is available, interchange micro­phones and amplifiers to localize the problem.
3. Remove the amplifier case cover (four screws: two Phillips head in the case and two slotted head in the connector collar) and check the voltages against those given in the circuit diagram.
4. Check the microphone and amplifier cables for continuity.
FURNISHED ACCESSORIES
Windscreen.......................... 49A74A
Carrying Case....................... 65A1578
REBLACEMENT PARTS
Microphone Cartridge .................... R145
Headband Assembly .................. 90A3997
Headband Retaining Clip .............. 53A1801C
Battery Compartment Door.............. 65A1536
Belt Clip ............................ 44A279
AMPLIFIER CIRCUIT DIAGRAM
AMPLIFIER PRINTED
CIRCUIT BOARD
AMPLIFIER REPLACEMENT PARTS LIST
Reference
Designation
A1 90A4005 Printed Circuit Board Assembly None C7 86B651
D1 86B429 Diode, Current Regulator,
D2, D3 86A415 Diode, Computer, 75V, 0.4A
J1 95A8077 Connector, Receptacle,
L1, L2 80A253 Ferrite Bead Ring Stackpole 57-0180
P1 90BT2600 Connector, Receptacle,
Q1 86A348 Transistor, PNP Motorola 2N5087
Q2 86A350 Transistor, NPN Motorola 2N5210
T1 51B286 Transformer, Audio None
Part
Number
Description Commercial
Capacitor, Tantalum, 33 µF, 6.3V
100V, 0.33 mA
75V, 0.4A
Miniature 3-pin
3-pin XLR
Alternate
Motorola 1N5287
Motorola 1N5287
TI/GE 1N4148
Switchcraft TB3M
None
W1 90A3792 Cable and Connector Assembly
(incl. P1)
None
Loading...