Specifications

ManualsBrandsShure ManualsMicrophones and systemsAMS4000

Shure Brothers lncorporated

222 Hartrey Avenue

Evanston,

60202-3696 U.S.A.

AMS4000 AND AMS8000 Installer's Manual

The Shure Automatic Microphone System [AMS] turns

microphones on and off [with automatic gating], greatly

reducing the reverberant sound quality and feedback prob-

lems often associated with the use of multiple microphones.

The special AMS microphones are gated on only by sounds

arriving from the front within their acceptance angle of

20°. Other sounds outside the 120° angle, including

background noise, will not gate the microphones on, regard-

less of level. In addition, the AMS adjusts gain automatically

to prevent feedback as the number of "on" microphones

increases.

The resulting sound is clearer than that of conventional

multiple microphone speech reinforcement and recording

systems-and free of the clipped and missed words, clicks

and pops, and noise pumping often associated with other

"automatic mixer" systems. Besides its major advantages

of simple setup and unmanned operation, the Automatic

Microphone System operates over an extremely wide

dynamic range without the possibility of threshold-setting

misadjustments.

AMS Mixers are supplied in 4- and

Schannel configura-

tions [Models

AMS4000 and AMS80001, each housed in a

single

3lh-inch rack-mount package. Both contain logic ter-

minals [for channel muting, override functions, and gating in-

dications], and link circuitry for expansion to as many as 200

linked channels.

AMS

Features:

Reliable, quick-acting, noise-free gating-virtually insens-

itive to changes in sound source loudness or distance

Smooth pleasant-sounding turnon and turnoff

characteristics

No threshold settings to misadjust

Front-panel microphone channel gain controls and

Master control operate as in conventional mixers

Selectable hold time keeps microphones on during short

pauses

Preset or adjustable Off-Attenuation control for unob-

trusive gating

Automatic gain adjustment as additional microphones

gate on

Wide, flat frequency response and low distortion up to

dBm output

Logic inputs and outputs enhance system versatility

Linking capability for systems of as many as 200

microphones and 25 mixers

LED indication of gating operation and output level

Automatic muting prevents annoying thumps and

loudspeaker damage when unit is turned on and off

Four or eight special microphone inputs [for use

only

with

AMS microphones] use standard two-conductor shielded

cables and three-pin connectors

Balanced output switchable to line or microphone level

Front- and rear-panel unbalanced Aux inputs and outputs

Front-panel headphone monitor jack

Direct [non-gated] outputs available from individual

microphones

Underwriters Laboratories Listed and Canadian Stan-

dards Association listed as Certified

.....

......

Shure AMS4000 and AMS8000 Mixers are designed for use only with Shure AMS Condenser Microphones. Conventional condenser or

other microphones will not operate properly with the

AMS4000 and AMS8000.

OCopyr~ght 1997, Shure Brothers lncorporated

27A8273(QC)

Printed in U.S.A.

U.S. Patent 4,489,442; other patents pending

Summary of content (20 pages)

PAGE 1
Shure Brothers lncorporated 222 Hartrey Avenue Evanston, IL 60202-3696 U.S.A. AMS4000 AND AMS8000 Installer's Manual The Shure Automatic Microphone System [AMS] turns microphones on and off [with automatic gating], greatly reducing the reverberant sound quality and feedback problems often associated with the use of multiple microphones. The special AMS microphones are gated on only by sounds arriving from the front within their acceptance angle of 1 20°.
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TABLE OF CONTENTS General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 . Connections. Controls and Indicators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 MicrophonePlacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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SPECIFICATIONS Output Level [at full galn, 1 kHz, one channel gated On, Off-Atten a t -1 5 , wlth AMS26 probe mtcrophone, output terrnlnatlons: Llne 6000, MIC1500. Aux 50k.
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CONNECTIONS, CONTROLS, AND INDICATORS [Paragraph numbers that follow refer t o pictorial views on inside back cover .] 1 . Microphones: The Shure A M S Condenser Microphones are designed specifically for use with Shure Automat~c Microphone Systems, A M S 4 0 0 0 or AMS8000 mixers Do not attempt to connect AMS microphones to standard phantom-powered or standard non-phantom-powered inputs; they will not function properly.
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LineIMic, Aux, and Phones outputs approach clipping. If this light flashes on, turn down the Microphone Channel controls of the channels in use or turn down the Master control until the light stays out. 13. Aux Input: A l/4 -inch unbalanced phone jack input on both the front and rear panel of the AMS mixer, suitable for Aux level and line level sources, such as tape recorders or players or conventional mrxers.
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linked mlxers, connect the Channel 8 Logic Ground terminals of each unit together. Switching clicks may result if thts is not done. When mixers are linked, the combined signals of all the mlcrophones appear at the outputs [MicILine, Aux, and Phones] of ALL the linked mixers. Thus, you can take outputs from several mixers for a multiple feed. Use as few microphones as necessary to pick up everyone.
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ALTAR oMUTING l SWITCH 0 CHAIRPERSON*^ CHANNEL ma RECORDER CHURCH SETUP FIGURE 6 LEGISLATURE SETUP FIGURE 8 LOGIC FUNCTIONS Cough Button The user can turn off his or her microphone [to the selected Off-Attenuation level] during coughing or private conversations. To establish this function, wire an SPST pushbutton switch between the Mute In and Logic Ground terminals on each channel requiring a cough button. See Figure 9.
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0/ 0 0 1 GATE OUT LOGIC GROUND M U T E IN OVERRIDE IN CcHAIRPERsoN7.s CHANNEL CHAIRPERSON-CONTROLLEDMUTING FIGURE 10 Disabling the Gating Function [Bypass) To keep all the microphones on, wire all the Override In terminals together to a Logic Ground terminal [see Figure 1 I ] . This is useful if i t is desired t o bypass the automatic functioning and use the AMS mixer as an ordinary mixer.
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NOTE: To prevent high-frequency oscillation, do not wire a channel's Gate Out terminal to its own Mute In terminal until the Mute to Inhibit change has been made. GATE OUT LOGlC GROUND Preventing Room Noise Modulation This connection keeps at least one microphone on to eliminate varying background noise or "pumping" [see Figure 151. The channel to which the transistor collector is connected will be turned on whenever all other microphones are gated off [see AMS Theory section].
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15-Volt CMOS The logic terminals can be used with 15-volt CMOS if a pullup resistor is used with each Gate output [see Figure 191. LOGIC GROUND The logic circuit for direct' out gating is shown in Figure 21 . IG I All resistors are 114 watt, and the opto-isolator can be a Vactec VTL5C2 or VTL2C2, or a Shure 86A8900. The 50k to 100k resistor is optional; it will provide a finite OffAttenuation capability.
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microphone features: it will not sense ambient room noise, gating will not be direction-sensitive, and gating threshold adjustment will be necessary. Figure 2 3 describes the re] microphone-on sensitivity and quired circuit.
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I WARNING No user-serviceable parts inside. Refer all servicing, including modifications, t o qualified service personnel. I AMS mixers can be disassembled for modification as follows: 1 . Remove line cord from ac power source. 2. Remove screws securing top cover t o chassis. 3. Remove individual Channel boards by removing: [a] Channel board bottom screw; [b] Channel Level control knob and nut; [c] Channel-On LED leads; and [dl ribbon cable connector. 4 .
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Channel board near integrated circuit U105 [see Figure 271. 3 . ~nsolderthe jumper at X I 04 and solder it or a new jumper in the holes of X I 03. 4. Reassemble the Channel board and top cover as described above. Mute Action to Inhibit Action As supplied, a channel will mute when the Mute In terminal is grounded. After this modification, grounding the Mute In terminal will not affect the channel if it is already "on", but it will prevent the channel from gating "on" from the "off" condition.
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are the two terminals on the opposite side of the jack body from R l O l and R104.] Wiring can be made at the top [component] side of the board, or to the foil side after the bottom plate is removed. Note that the jumper should be run around the area that will be covered by the bottom plate t o assure proper bottom plate fitting. Replace the bottom plate after wiring.
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TROUBLESHOOTING Symptom Probable Cause To Diagnose or Correct No sound Channel control or Master control turned too far down; microphone not connected; mixer not connected to power source; Power switch not on. Make indicated correction. Defective microphone, cable, channel input module Listen to headphones plugged into the AMS front-panel Phones jack. To check microphone: replace suspect microphone with another.
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EFFECTS OF ACOUSTIC ENVIRONMENT ON GATING Room Noise: The louder the room noise, the greater the talker's sound pressure level must be at the microphone for it t o gate on reliably. Generally this is not a problem because people tend t o talk louder in noisy environments. In addition, the sensing circuitry has been equalized t o reduce sensitivity t o room noise. If room noise is causing erratic gating, instruct the talker to stand or sit closer to the microphone.
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With a single microphone fully "on", the increase in system gain due t o incomplete attenuation in the " o f f microphones is given by: installer to check different combinations of "on" microphones before declaring the system to be free of feedback. APPENDIX Ill Where: G' is the system gain increase in dB compared to full attenuation, Att is the Off-Attenuation in dB, and m is the total number of microphones.
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MODELS AMS4000AND A M S 8 0 0 0 FRONT PANEL I OFF-ATTEN o "oLoki;a 0.5 SEC 1.0 O mMIC0 LINE 8 OUTPUT GATE OUT LOGIC GND MUTE I N OVERRIDE I N 0 ..- MODELS A M S 4 0 0 0 AND A M S 8 0 0 0 REAR PANEL -.
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The Sound of Professionals...Worldwidem Shure Brothers Incorporated 222 Hartrey Avenue Evanston, IL 60202-3696U.S.A.