Shure SR-109 Service manual

SR109

Professional Mixer

OPERATION AND SERVICE MANUAL

Manufactured

SHURE BROTHERS

222

Hartrey Avenue

Evanston, Illinois

60204

INC.

U.S.A.

WARNING

To reduce the risk of fire or electric shock, do not

expose this appliance to rain or extreme moisture.

Printed in

U.S.A.

SR109

Professional Mixer

SPECIFICATIONS

Equipment Type

Number of

lnput Channels Power Output Voltage Gain

Program

Headphones

Link

Accessory

Frequency Response

lnput Sensitivity

Distortion

Noise

(300 Hz-20 kHz)

Hum and Noise

(20 Hz-20 kHz)

'Measurement

kilohms

LINK INPUT

600

oh&,

up; all

PROGRAM

ohms:

other

nated

full

. . . . . . .

. .

. . . . . . .

. .

. . . . .. .

. . . . .

. . . . . .

. . . . . . . . . .

. . .

conditions:

through

MIC

MASTER

controls

All silicon transistor mixer/pre-

amplifier

. .

+19 dBm (program line level)

. .

.87 -13 dB MIC input to LlNE

LEVEL out

-+3 dB LlNE input to LlNE

LEVEL out

-13 dB MIC input to MIC

LEVEL out

. .

.69 -13 dB MIC input to PHONES

out

. .

.54.5 k3 dB MIC input to LlNK

OUTPUT (with 600-ohm termination)

k2 dB LlNK INPUT to LlNE

LEVEL output

.59 t3 dB MIC input to ACCES-

SORY output (via pins PUTS)

54.5

k3 dB MIC input to ACCESSORY output (via pin 9/PROGRAM) (terminated with 600 ohms)

. .

k3 dB, 20 Hz-20 kHz (150-ohm

source; 600-ohm load)

.0.1 mV max. for

output

.THD less than 1% at +12 dBm,

30 Hz-20 kHz; IM distortion less than

1% at +12 dBm

. .

128 dBV (equivalent input noise at full gain)

dBm output noise (MAS-

TER Volume Control down)

dBm output noise (MASTER and one channel Volume Control up)

125 dBV (equivalent input hum and noise at full gain)

dBm output noise (MASTER Volume Control down)

dBm output noise (MASTER and one channel Volume

Control up)

through

ohms

PROGRAM

terrhinated

Channel

out.

. .

MIC

LEVEL Volume,

and

-72.8

-38.8

-61.8

-34.8

input

600

switches

150

Volume

ohms,

LlNE

150

dBm program

LINE

input

LEVEL

ohms,

PHONES

and

PHONES

1-8/IN-

through

terminated

termi-

Controls

Signal to Noise

(20 Hz-20 kHz)

lnput Attenuation lnput Clipping Level

at 1 kHz:

MIC lnput

LlNE lnput

lnput Common

Mode Rejection

Low-Frequency

Equalization

High-Frequency

Equalization

Tone Oscillator

lnput Impedance at

1 kHz:

Microphone Line (channels

and 8) Link lnput

Output Impedance:

Program

. . .

. . . .

. . . . . . .

. . . . . .

. . .

. . . . . . .

. .

. . . . .

. . .

. . . .

. . .

. . . . .

.Typically 83 dB at maximum out-

put with one channel Volume Control and MASTER Volume Control set at 8 (approximately 58 dB gain)

0, 15 dB (switch-selected)

100 mV (ATTENUATOR out; Ch.

Volume at 2)

4.5

mV (ATTENUATOR out; Ch.

Volume at 12)

0.56V (ATTENUATOR in; Ch. Volume at 2)

mV (ATTENUATOR in; Ch. Vol-

ume at 12)

.33V (ATTENUATOR out; Ch. Vol-

ume at 2)

1.35V (ATTENUATOR out; Ch. Volume at 12)

90V (ATTENUATOR in; Ch. Vol-

ume at 2)

8.OV (ATTENUATOR in; Ch. Vol-

ume at 12)

.I00 dB at 100 Hz

213 dB at 100 Hz with respect to

0 (flat) setting

212 dB at 10 kHz with respect

0 (flat) setting

1 kHz; less than 1% distortion;

variable level

. .

.2.1 kilohms balanced (for use with

25- to 600-ohm microphones)

. . .

66 kilohms balanced bridging

.35 kilohms unbalanced

Balanced line level: 120 ohms ac-

tual (for use with 25- to

ohm inputs)

Microphone level: 0.5 ohms ac-

tual (for use with 25- to ohm inputs)

600-

SR109

Professional Mixer

SPECIFICATIONS

Headphones

..........

Link Accessory

Limiter

Threshold

(adjustable)

Range

Link Jack System

VU Meter Calibration

Phasing (polarity) .Pin 3 of INPUT connectors in

............

...

.3.5 ohms actual (for use with 4- to

16-ohm headphones)

.600 ohms (actual)

......

Unbalanced aux level: 33 ohms

actual (for use with 4K or higher loads)

.....

.Typically -20 to +20 dBm (at

LlNE LEVEL output)

.Approximately 30 dB

......

External signal conditioning out-

put/input; high-level auxiliary amplifier and tape recorder signal output; multiple Mixer con-

nection (common mix); remote master volume control

...

0, f4, +8 dBm, switch-select-

able (0.775, 1.23, 1.95 Vrms) at 1 kHz to 600-ohm load. [VU

RANGE Switch in provides (0.775 Vrms) to 600-ohm load1

0 VU reading of 0 dBm

....

phase with pin 9 of ACCESSORY OUTPUT, tips of OUTPUT and PROGRAM LlNE LEVEL OUTPUTS, and pin 3 of

PROGRAM

MIC LEVEL OUTPUTS (PHASE Switch in of ACCESSORY OUTPUT out of phase with the above.

LlNE LEVEL and

0" position). Pins 1-8

0 position

LINK

Phase Switch Output polarity-reversing switch

30 Vdc Bus .Pin 10 on ACCESSORY OUTPUT

Operating Voltage

Power Consumption

Temperature Range:

Operating Storage

Dimensions..

Installation

Weight 7.7 kg (17 Ib) Finish

Certifications Listed by Underwriters' Labora-

...............

................

.........

.90-132 Vac, 50/60 Hz (SR109)

....

90-132, 180-250 Vac, 50/60 Hz

...

20 watts max. (Mixer only). 500

-7O to 54OC (20' to 130°F)

......

.......

.........

...........

.........

.-29O to 71°C (-20' to 160°F)

133 mm H

Equipped for standard 19 in. (483

Matte black, with beige write-on

(0°, 180') (reverses phase of all program outputs)

connector is regulated +30

k3.5 Vdc supply; pin 11 is ground (earth). May be used to power accessories up to 50

mA.

(SR109-2E)

watts max. (SWITCHED AC re-

ceptacle)

mm D (See Page 4.)

(51/4 in. x 19 in. x 9% in.)

mm) rack mounting; (133 mm) height; may be oper-

ated in accessory

rying Case or in custom control center.

trim strip

tories, Inc.; listed by Canadian

Standards Association as cer-

tified

(SR109 only)

483 mm W X 232

(SR109 only)

5% in.

A105A Car-

SR109

Professional Mixer

TABLE OF CONTENTS

Section

SPECIFICATIONS

DESCRIPTION OPERATING INSTRUCTIONS

Functional Identification General Operating Instructions 3 Mounting and Ventilation 4 Power Supply 5 Functional Circuit Description Inputchannels Monitor Mixer System Program Mix Amplifier 7 Link Jacks Program Output

VU Meter Circuit 7

Limiter Tone Oscillator Basic Operating Hints

SPECIAL OPERATING INSTRUCTIONS

High-Impedance Microphones Musical Instruments Tape Recording 9 Record Playback Tape Playback Additional Mixer Inputs Additional Mixer Inputs (Two SRlO9s) Redundant Mixer Set-up (Two Stereo Operation Remote Volume Control Telephone Line Surge Protection

.......................................

.............................

...................................

.........................

...................

........................

..................................

....................

.................................

...........................

..........................

....................................

...............................

................................

.................................

..........................

....................

............................

................................

...............................

.........................

............

SRIO9s)

............

...............................

.........................

.................

Page

ii.

Section

iii

SERVICE INSTRUCTIONS

1 Mixer Service 14

Replacement Parts Fuse Replacement

Knob Replacement Service Access Lamp Replacement Board Removal

Limiter Internal Adjustment

Overload Indicator Check

VU Meter Removal VU Meter Calibration

Parts Removal

Transistor and Diode Removal Active Component Checking

Service Illustrations

Optional Accessories

REPLACEMENT PARTS LIST 19 NOTES TO CIRCUIT DIAGRAM

General 29

Troubleshooting 10 11 11 12 12 12 13 14

Ac Voltage Measurements

Dc Voltage Measurements

Resistance Measurements

CONDENSED OPERATING INSTRUCTIONS 35

ARCHITECTS' AND ENGINEERS' SPECIFICATIONS GUARANTEE 35 SHIPPING INSTRUCTIONS 35

..................................

.............................

................................

.............................

................................

......................

.......................

.............................

...........................

.................................

....................

.....................

............................

...........................

......................

.......................................

...............................

.......................

..........

....................................

........................

Page

14 14 14 14 14 15 16 16 16 16 17 17 17 18 18

29 29 30 30

. .

SR109

Professional Mixer

LlST OF ILLUSTRATIONS

Figure Page

1 SR109 Professional Mixer Front Panel 2 2 SR109 Professional Mixer Rear Panel 2

3 Overall Dimensions 4 Block Diagram 5 SR110 Monitor Mixer Applications 7

Tone Oscillator Applications 7 Preamplifier-Mixer Connections 8 Tape Recording 9 Record Playback

10 Tape Playback 11 Additional Mixer Inputs 12 Additional Inputs: Two

........................

.............................

................

............................

...........................

.............................

.....................

SRIO9s

...............

.........

..........

............

..............

9 10 10 11 11 12

Figure Page

13 Redundant Mixers 13 14 Stereo Tape Recording 13 15 Remote Volume Control

16 Printed Circuit Board and Parts Location 16

17 Opto-Isolator Test 18 Board

19 Board 2: Channel Equalizer 20 Board 3: Main Board 21 Board 9: Power Supply 22 Board 23 Lead Codes 24 SR109-2E Power Supply Circuit Diagram 30 25 SR109 Professional Mixer Circuit Diagram .3 2-33

1: Preamplifier

0: Program Mute

..........................

......................

.....................

.......

..........................

......................

................

......................

....................

...............................

13 17

24 25 26 27 27 29

......

SR109

Professional

DESCRIPTION

Mixer

The Shure Model SR109 Professional Mixer is a solidstate, eight-channel microphone mixer-preamplifier that enables the operator to mix as many as eight microphones with individual control over input attenuation, volume and high- and low-frequency equalization. The Mixer has three outputs: a program output, an accessory output and a headphone output. In addition, channels

switch-selectable inputs for use with either low-impedance microphones or line level sources. A master volume control regulates program output.

The program output has both a 600-ohm, balanced line

level output and a low-impedance, balanced, microphone output. The with separate volume control. A pair of link jacks facilitate connection to an additional mixer, or external equipment such as compressors, limiters or equalizers.

The

to one or more Shure The mixer designed to provide a separate stage monitor mix that follows the program mix levels. In addition, it may be used in multi-track recording as a submaster mix panel or mixdown panel.

The

put limiter with an in-out switch and an indicator lamp

that flashes when the limiter is operating. The front panel

also contains an overload indicator lamp that signals when

headphqne output is an &ohm balanced output

SR109 rear panel contains provisions for connection

SR110 Professional Monitor Mixers.

SR110 is a self-contained, eight-channel, line level

SR109 contains a peak-responding, adjustable out-

and 8 contain

the output is clipping in the non-limiting mode.

The Mixer contains a switch to adjust sensitivity to indicate program output level. A built-in 1 kHz tone oscillator facilitates synchronization of all meters in a system. space for pencilled notations.

The regulated power supply is designed to operate over a wide range of ac line voltages, permitting the use of extremely long ac extension cables without performance degradation. Accessory equipment drawing up to 500 watts may be connected to the rear-panel switched ac receptacle

The solid-state components in the Mixer are protected against damage as a possible result of open-circuit or short-circuit conditions on the inputs or outputs. All components are conservatively rated and are operated well within their respective ratings to assure long life and trouble-free performance.

The Mixer is supplied with rack-mounting screws and spare fuses.

The Mixer is Underwriters' Laboratories, Inc., listed,

and is listed by the Canadian Standards Association as

certified

The following are designed for use with the

fessional Mixer:

(SR109 only).

SR110 Professional Monitor Mixer

A1 05A Carrying Case

meter and a meter sensitivity

front-panel trim strip provides

SR109 Professional

SR109 Pro-

FIGURE 1. SR109 PROFESSIONAL MIXER FRONT PANEL

15 16 17 18

FIGURE

(SR109-2E

SR109 PROFESSIONAL MIXER REAR PANEL

Only)

SR109

Professional Mixer

FUNCTIONAL IDENTIFICATION (Refer to Figures 1 and 2,

Page 2.) NOTE: All front panel controls are numbered for ref-

erence only.

Individual Channel Volume Controls (Eight) trol volume and input clipping level of each channel separately. Channel 1 contains TONE

push-pull Switch - Pulling switch outward turns oscillator on, and rotating control adjusts level of 1 kHz tone generated internally for set-up purposes.

Individual Channel tary Controls (Eight) -Adjust low-frequency signal equalization for each channel.

Individual Channel Rotary Controls (Eight) -Adjust high-frequency sig-

nal equalization for each channel. LIMITER Indicator Lamp

when LIMITER Switch (11) is turned on (IN).

OVERLOAD Indicator Lamp load condition (output clipping) when LIMITER Switch (11) is turned off (OUT).

True VU Meter

output. (Meets all current standards for VU Meters.) PHONES Rotary Control PHONES Jack (8). PHONES Output Jack- Provides for connection of

stereo or monophonic headphones for monitoring.

9. MASTER Volume Rotary control and POWER

-Adjusts level of totai program output, and applies ac power to power supply and SWITCHED AC Receptacle. THRESHOLD

Control -Sets threshold level of limiter function. LIMITER IN-OUT Slide Switch -Turns program output limiter on and off. Ac Grounded Line Cord to Mixer power supply 3AG-3/16A SLO-BLO Ac Fuse - Protects Mixer ac input line against overload

SWITCHED AC Grounded Receptacle to 500 watts of unfused switched ac power to accessory equipment

PROGRAM

verses phase (polarity) of

PHONE LEVEL program outputs with respect to

inputs. VU METER RANGE Slide Switch

(6) sensitivity for three ranges of program level indication in ACCESSORY OUTPUT/AUX LEVEL 1 1-Pin Connector

Monitor Mixer. 15

dB ATTENUATORS/IN-OUT Slide Switches (Eight)

Provide choice of input signal attenuation for each

channel.

INPUTS/MICROPHONE LEVEL LOW IMPEDANCE Three-Pin Jacks (Eight) nection of low-impedance sources to channels 1

OUTPUTS/PHASE Slide Switch - Re-

dBm.

Provides output connection to Shure SR110

FREQuency EQualizer-LOW Ro-

FREQuency EQualization-Hlgh

lndicates limiting action

lndicates Mixer over-

lndicates volume level of program

Controls volume level to

ADJustment Screwdriver-Adjustable

Connects ac power source

(SR109 only).

Provides up

(SR109 only).

LINE LEVEL and MICRO-

Selects VU meter

Provide for balanced con-

Con-

OSCillator

switch

through 8 inputs, or line level sources to channels and 8.

MIC/LINE Slide Switches (Two) -Select low-impedance (MIC) or line level (LINE) input connections for channels LlNK OUTPUT Phone Jack - Provides output connection to external equipment or common mix bus to combine two or more Mixers.

LlNK INPUT Phone Jack - Provides input connection from external equipment (compressor, limiter, equal-

izer, etc.). PROGRAM

nector power amplifier. PROGRAM (Two) nection to power amplifier. PROGRAM Pin Connector phone-level program output. VOLTAGE SELECTOR Slide Switch -Selects operating voltage range of 90 to 132 or 180 to 250 50/60 Hz (SR109-2E only). AC (MAINS) POWER 3-Pin Connector line cord to Mixer power supply 180-250V 0.1 Protects Mixer ac input line against overload (SR109-2E only).

GENERAL OPERATING INSTRUCTIONS

and 8.

OUTPUTS/LINE LEVEL Three-Pin Con-

Provides balanced output connection to

OUTPUTS/LINE LEVEL Phone Jacks

Provide balanced or unbalanced output con-

OUTPUTS/MICROPHONE LEVEL Three-

provides low-impedance micro-

Connects ac

(SR109-2E only).

AT/90-132V 0.2AT SLO-BLO Ac Fuse

Vac,

WARNING

Voltages in this equipment are Make all input and output connections before ac power is connected. Refer servicing to qualified

service personnel.

Using hardware provided, install Mixer securely in standard 19 in. (483 mm) rack or optional rying Case prior to making electrical connections.

Set front-panel switches to off or OUT and all controls to

Set rear-panel PHASE Switch (15) to

3. Connect desired PROGRAM OUTPUT/LINE LEVEL Connector (23, 24) to

ing cable. (NOTE: Shure

supplied with audio connecting cables.) If Mixer out-

put is to be fed to another mixer or tape recorder microphone input, use PROGRAM PHONE LEVEL Connector (25). If desired, connect monophonic or stereo headphones to front-panel PHONES Jack (8). Connect speakers to power ampli-

fier.

Connect one or more low-impedance microphones to rear-panel PEDANCE Connectors (19). Any high-quality dynamic,

INPUTS/MICROPHONE LEVEL LOW IM-

power amplifier input connect-

hazardous to life.

A105A Car-

OO.

SR105 Power Amplifiers are

OUTPUT/MICRO-

ribbon or condenser low-impedance microphone may be used. Connect line level sources to channel 7 or 8 connectors only. If line level inputs are used, set

corresponding

If external signal-processing equipment such as an

MICILINE Switch (20) to LINE.

equalizer, compressor or limiter is to be used, con-

nect Mixer

equipment input and external equipment output. (See 7, for detailed information.) If a Shure

LlNK OUTPUT Connector (21) to external

LlNK INPUT Connector (22) to

Link

Jacks,

Page

SR110

Monitor Mixer is to be used with the SR109, connect multi-pin plug of Connector (17) of

SR110 to ACCESSORY OUTPUT

SR109.

6. SR109: Connect ac line cord (12) to grounded 90- to 132-volt, 50160 Hz ac source. Line cord is a

2.4m

(8 ft), 3-conductor cord with 3-pin grounding plug.

If extension cords are required, use high-quality, rubber-jacketed cable with 18 gauge (0.8 mm2) or heavier wire.

SR109-2E: Obtain suitable &pin male ac connector

and attach to line cord: brown lead to "hot" or "live"

terminal, blue lead to neutral terminal, and

green1 yellow lead to ground or earth terminal. (Connector should be installed by qualified service personnel.) Select proper operating voltage (90-132V or

180250V) using VOLTAGE SELECTOR Switch (26). Note that switch positions are marked 115 and 220 volts. Make certain proper fuse is installed in fuseholder (28):

O.1AT with switch set to 220, or 0.2AT with

switch set to 115. Insert female end of line cord into

chassis power connector (27) and connect male plug

to 3-wire grounded ac power receptacle providing

proper operating voltage.

7. Turn on front-panel MASTER Volume

ControllPOW-

ER Switch (9) and allow one to two minutes warmup time. This warmup time allows the supply voltages to stabilize and capacitors to charge to provide opti-

mum performance. Set 15 dB ATTENUATOR Switch

(18) initially to OUT for normal PA use, to IN for

"hard" rock music. For nels 7 and 8), set

LINE INPUT sources (chan-

MICILINE switch (20) to LINE.

8. Set Master Volume Control (9) to 6. Set VU METER RANGE Switch (16) to (when using a Western Electric

0 for PA or telephone line use

308 Voice Coupler), +4 for recording, or +8 for broadcast use. Have someone sing or talk into microphone and raise channel Volume Control (1) to achieve desired sound level. If meter reads low at proper sound level, reduce power amplifier volume level and increase channel volume level. For single microphone set-up, if meter

indicates excessively high level ("pinning" or "pegging" needle), decrease MASTER Volume Control to obtain good meter reading and increase power amplifier volume level or input sensitivity to obtain proper sound level. In multiple microphone set-up, it may be necessary to decrease MASTER Volume Control in order to maintain channel Volume Control setting. Ideally, set the channel Volume Controls as high as possible (consistent with an adequate mixing range), and increase the MASTER Volume Control to obtain a

0 VU Meter reading. Then increase the power amplifier level control to the desired level. Using the 15 dB ATTENUATORS (18) may aid in maintaining this setting if the channel Volume Control is consistently set low.

9. Set

HI and LO FREQ EQ Controls use. Vertical position response. Clockwise

(0) indicates "flat" frequency

(+)

(3,

2) for channel in

settings increase highfrequency (treble) or low-frequency (bass) level and counterclockwise

(-)

settings decrease the high- or

low-frequency level.

10. With LIMITER Switch (11) in OUT position, OVERLOAD Indicator Lamp (5) will flash when Mixer output clipping level is exceeded. If limiting is desired,

adjust limiter as follows: Operate Mixer with program

material and adjust the channel and MASTER Volume

Controls (1, 9) for desired sound level. With small screwdriver, turn THRESHOLD ADJ Control (10) full counterclockwise. Set LIMITER

INIOUT Switch to

IN. Slowly increase (clockwise) THRESHOLD ADJ

Control until LIMITER Lamp

(4)

flashes intermittently,

indicating limiting action on program peaks. A con-

tinuous glow indicates an undesirable excess of lim-

iting: MASTER

andlor channel Volume Controls should be reduced. Increasing channel or MASTER Volume Controls will not increase mixer output above the level just set. Should higher or lower maximum output level be desired, increase or decrease THRESHOLD ADJustment. (An alternate set-up pro-

cedure uses the TONE

OSCillator to produce a maximum desired VU level. The THRESHOLD ADJustment is slowly increased (clockwise) until the VU Meter reading just set is reduced by 1 dB. Note that with this set-up, the program material level displayed on the VU Meter will be lower because of the difference between peak and average levels. However, limiting action will take place at the same peak level. This effect will be more evident on speech than on music.)

11. Monitor output is available at front-panel PHONES Jack (8). Adjust PHONES Control (7) for comfortable

listening level.

12. NOTE: During temporary shutdown (break, intermission), do not turn off Mixer power. It is designed to operate continuously, and optimum performance is

maintained after internal voltages are allowed to stabilize. Also, do not turn down all microphones. Leave the master or announcer's microphone on so that if

the Mixer is left unattended, announcements may be

made, and the operator will be alerted that the next performance is about

to begin.

MOUNTING AND VENTILATION

The Shure

SR109 Professional Mixer may be operated

in a standard 19 in. (483 mm) audio equipment rack (see

Figure 3, Page

5),

or in a Shure A105A Carrying Case.

Four rack-mounting screws are provided with the Mixer.

The Shure rack-mounting space. When the case, an additional rack-mounted unit such as the

A105A Carrying Case has a 7 in. (178 mm)

SR109 is mounted in this

SR110 Monitor Mixer may be mounted in the remaining 1% in. (44.4 mm) space.

In rack-mounted installations, consider rear-panel ac-

cess before installation is made. Although most installa-

tions will not require frequent access, it should be re-

membered that input and output changes, and some switch movements, will necessitate rear-panel access.

FIGURE

OVERALL DIMENSIONS

POWER

SUPPLY

SR109: The Mixer regulated power supply is designed

to operate from 90 to 132 volts ac,

50/60

without adjustments, allowing the Mixer to meet all specifications over this wide range of ac input voltages.

three-conductor, grounded line cord (12) supplies ac power to the Mixer through the front-panel POWER Switch (9). The Mixer consumes 20 watts maximum (0.2 amperes) and the

ac line input is protected by a

(13) and a wired-in

3/10-ampere slow-blow fuse in series.

3/16-ampere slow-blow fuse

'(TYPICAL

-50 DB -1100 XFMR

ATTENUATOR ATTENUATOR

NOTE I

600A

RESISTOR

CHXNELS

23DB CHANNEL

200x~:HGH VOLUME CHANNEL

1-8)

PHONES

LEVEL

FIGURE

METER

SR109 BLOCK DIAGRAM

NOTES I MIC-LINE SWITCHES ON CHANNELS

2 TONE GENERATOR ON CHANNEL I ONLY

AND 8 ONLY

These fuses should not be replaced with

CAUTION

any other size or type of fuse.

Accessory equipment may be connected to the panel SWITCHED AC Receptacle (14). The accessory equipment may consume up to 500 watts maximum, which provides for use with high-power amplifiers such as the

SR105. Note that the receptacle is switched but not

Shure fused; all accessory equipment used with the Mixer should contain its own fuse.

SR109-2E: The SR109-2E regulated power supply is designed to operate from either 90 to 132 volts ac or 180 to 250 volts ac, VOLTAGE SELECTOR Switch (26). A three-conductor, grounded line cord supplies ac power to the Mixer through the front-panel POWER ON-OFF Switch (9). The

SR109-2E line cord does not have a connector on the

power source end of the cord. Obtain a suitable male ac connector and install it on the line cord: brown to "hot" or "live" terminal, blue lear to neutral terminal,

green/yellow lead to ground or earth terminal. (Con-

and nector should be installed by qualified service personnel.) The ac line is protected by a 0.1-ampere Slo-Blo fuse (for 180- to 250-volt operation) or a 0.2-ampere Slo-Blo fuse (for 90- to 132-volt operation. A wired-in fuse also protects the ac line.

FUNCTIONAL CIRCUIT DESCRIPTION (See Figure 4, Page 5)

Each three-pin professional audio input MICROPHONE LEVEL Connector (19) feeds its own low-impedance bal-

anced lnput Transformer, which provides gain of 23 dB.

Channels 7 and 8 also contain

which switch in a 50 dB bridging line-to-microphone

level Attenuator to accept line-level inputs. The lnput Transformers (and, on channels 7 and 8, the Switch) are fed to 15 dB ATTENUATOR Switches (18) and then to the Preamplifier, which provides gain. The amount of voltage gain provided by the Preamplifier (7 to 42 dB) is controlled by the Channel Volume Control as gain is reduced. The Preamplifier circuits contain the individual Channel Volume Controls and feed the individual Channel Equalizer (HI and LO FREQ EQ) Controls (3,2) which decrease the signal approximately 3 dB when set to the 0, or "flat," setting.

fier and the ACCESSORY OUTPUT Connector (17) for interconnection with Mix Amplifier feeds through a 560-ohm resistor to the LlNK jacks (21, 22). When accessory equipment is not connected to the the program signal is fed to the MASTER Volume Control (9) and back to the ACCESSORY OUTPUT Connector.

a The attenuated signal feeds a limiter, which is connected to a Lamp Driver (for driving the LIMITER and OVERLOAD lamps) and a Limiter THRESHOLD ADJ Control (10) for setting the threshold of Limiter operation. Note that when the LIMITER Switch (11) is turned off (OUT), the LIMITER Lamp (4) will not light, but the OVERLOAD Lamp flash whenever the output clipping level is exceeded. The Limiter Attenuator also feeds a Amplifier, also controlled by the MASTER Volume Control.

(I), providing an increase in input clipping level

The Equalizer outputs are fed to the Program Mix Ampli-

The output of the MASTER Volume Control, after feeding

0 dB gain Amplifier, is sent to a Limiter Attenuator circuit.

50/60 Hz, as selected by the rear-panel

3/10-ampere

MIC/LINE Switches (20)

+7 to +42 dB

SR110 Monitor Mixers. The Program

LlNK jacks, the jacks are bypassed and

+7 to +35 dB output

rear-

three-'pin

MIC/LINE

(5)

will

The signal then goes through a

and into the Program Output Transformer. The Trans-

former feeds three

24) and a MIC LEVEL Output Connector 50 dB below line level. The

fier also feeds the VU METER RANGE Switch

goes to a +22 dB Meter Amplifier and then to the VU

(6), and a PHONES Level Control (7), Headphones

Meter

Transformer and PHONES Output Jack (8).

The Mixer also contains a in set-up and check-out. The Generator is activated and controlled by the channel 1 Volume Switch

and their uses is provided in the following paragraphs of this section.

INPUT CHANNELS LEVEL lnput Connectors (19) are provided on the rear

panel of the Mixer. The Mixer is designed to operate with high-quality, low-impedance dynamic, ribbon or condenser microphones. Each low impedance microphone input connected to a low-impedance, balanced-input transformer through a 15 dB input ATTENUATOR (18). Two Slide Switches (20) are provided for channels 7 and 8. These switches allow the user to select between either low-impedance MICROPHONE or additional line level inputs are required, Shure lnput Adapters may be used in each microphone level input.

vides input attenuations of the user to compensate for the differences in levels due to

different sources, such as close talking or distant microphone placement, and to compensate for high output levels from condenser microphones.

section, in a feedback circuit, sets the gain of the preamplifier; the second section is a preamplifier output tenuator. This circuit configuration increases the preamplifier input clipping level as the Volume Control is reduced to lower settings. Ideally, the control should operate in the middle range, between 4 and be accomplished by proper 15 dB ATTENUATOR Switch

(18) setting.

equalizer circuit. Individual HI and LO FREQ EQ controls

(3,2) allow the user to shape the sound of each input channel without affecting the other channels of the Mixer. The HI FREQ controls provide up to 13 dB of boost or cut at 10 kHz with a 1 kHz hinge point. The LO FREQ controls provide up to 13 dB of boost or cut at 100 Hz with a 1 kHz

bin-ge

cate boost, and minus (-) markings denote cut. A ting provides a normal or "flat" frequency response.

PUT/AUX LEVEL Connector (17) and the Program Mix Amplifier.

MONITOR MIXER SYSTEM nector (17) of the

one or more Shure The output of each individual channel after all channel controls (volume, equalization and attenuation) appears

(I), and the Control output is fed to the Preamplifier.

A detailed description of the Mixer circuits and controls

Eight professional, three-pin, audio MICROPHONE

The 15 dB ATTENUATOR (18) two-position switch pro-

The Channel Volume Control

The output of the Channel Volume Control (1) feeds the

point. Control settings with plus

The output of the equalizer feeds the ACCESSORY

The rear-panel ACCESSORY

LlNE LEVEL Output Connectors (23,

SR109 provides for interconnection to

SRl10 Professional Monitor Mixers.

0'-180' PHASE Switch (15),

(25), which is at

+7 to +35 dB output Ampli-

(16), which

1 kHz Tone Generator for use

Control/TONE OSC

MIC/LIINE

LlNE LEVEL inputs. If

0 or 15 dB. This switch allows

(1) is a dual control: one

(+)

OUTPUT/AUX LEVEL Con-

A15LA Line

This can often

markings indi-

at-

0 set-

OUT-

on this connector as do the LlNK INPUT total mix signal and the power supply connections. The

SR110 is a selfcontained, eight-channel, line level mixer designed for use with the

SR109 or similar equipment. The SR110 can provide a separate stage monitor "mix" that follows the program "mix" levels coming from the eight channels of

SR109. In addition, it may be used in multi-track re-

the cording as a submaster mix panel or as a "mixdown" panel.

SR110 provides eight high-impedance, unbalanced,

The line level inputs to its mixing circuity, one high-impedance, unbalanced, line level input to its Output Selector Switch for monitoring the program mix, and one line level,

600ohm, balanced output. Individual channel and master volume controls are provided, as is a switch to choose between monitoring the channels in use (Mixed Inputs) and the total program mix (Program Input). The Mixed Inputs position takes the signal from each channel frequency equalization circuit, and the Program

Input position obtains

the mixed signal at the LlNK INPUT Jack (22).

SR110 has parallel accessory input/output male and

The

female connectors. These connectors permit the connec-

tion of addition tandem or "stacked"

SRllOs. A typical

application is shown in Figure 5, Page 7. PROGRAM MIX AMPLIFIER

The program mix amplifier is an active mixing amplifier in which gain remains constant independent of the individual channel volume control settings. The output of the program mix amplifier is connected through a 560-ohm mixing resistor to the LlNK Jacks (21, 22).

SR1w LINE MIXER LEVEL

ACC

OUT

SRl I0

MONITOR

MIXER

SRllO

MONITOR

MlXER

SRllO

MONITOR

MIXER

FIGURE

POWER

AMPLIFIER

POWER

AMPLIFIER

STEREO

TAPE

RECORDER

SRllO MONITOR MlXER APPLICATIONS

SPEAKERS

STAGE

MONITOR

SPEAKER

LlNK JACKS

The LlNK Jacks

(21,22) on the rear panel of the Mixer enable the user to interconnect more Mixers for additional inputs or add external equipment, such as equalizers, compressors, or limiters. When connecting two or more SR109 Professional Mixers together to provide many channel inputs, connect the LlNK OUTPUT Jacks (21) of all the units together. It should be noted that the LlNK OUTPUT Jack is actually a two-way jack; the impedance at this point is actually 600 ohms, and any number of units may be tied together at this point. The LlNK INPUT Jack

(22) is an input-only jack and has switching contacts that

disconnect the LlNK OUTPUT signal from the MASTER Vol-

ume Control (9). Note that the

SR109 and the Shure SR101

Audio Console may be interconnected in the same manner.

If an equalizer, limiter or compressor is connected to the Mixer, the LlNK OUTPUT Jack (21) is connected to the input of the external unit and the output of the external unit is connected to the LlNK INPUT Jack (22).

The signals at the LlNK Jacks are typically at a level 10 dB below line level. These jacks will accommodate signal levels in the range between LlNK INPUT impedance is greater than 20

30 to +10 dBm. The

kilohms and

may be considered a bridging impedance. The output of

the LlNK Jacks feeds the MASTER Volume Control (9)

which is a two-section control similar to those used in the individual channels. The LlNK INPUT Jack is connected to the ACCESSORY

OUTPUT/AUX LEVEL Connector (17).

PROGRAM OUTPUT

The signal from the LlNK Jacks (22, 21) drives the program output amplifier. The gain of this amplifier is controlled by one-half of the MASTER Volume Control (9) (the other half is an input attenuator for the output amplifier). In addition to the limiter circuitry, the program output amplifier also contains the front-panel OVERLOAD Indicator Lamp (5). This indicator will flash when the output clipping level is exceeded, and only when the LIMITER Switch (11) is in the OUT position. The output of the program amplifier is sent to the PHASE Switch (15) mounted on the rear panel of the Mixer. This switch allows the user to change the phase of the program output, which may be helpful in eliminating or reducing low-frequency acoustic feedback. Generally, this switch is adjusted to the position which either gives the most gain before feedback or, if both positions give the same gain before feedback, use the position that produces the highest pitch feedback. The program signal, after leaving the PHASE Switch, is routed to the output transformer which provides both LlNE LEVEL and MICROPHONE LEVEL outputs. The LlNE LEVEL output is connected to one professional three-pin, male, audio output connector (23) and two three-circuit phone jacks (24). The MICROPHONE LEVEL output is a low-impedance, balanced output, 50 dB below the LlNE LEVEL output, and is connected to a professional three-pin, male, audio output connector (25).

Note that all of the program outputs are balanced with respect to ground. If a two-circuit type phone plug is used to connect the mixer line level output to an amplifier or tape recorder, the line outputs will automatically become unbalanced. If the three-pin unbalanced output is used and a phone jack output is also to be used, obtain a stereo phone plug and

corrnect the tip and ring of the plug only.

(The sleeve is a shield and would cause a ground loop.)

If it becomes necessary to use the MICROPHONE LEVEL Output Connector (25) to feed a high-impedance microphone input, use a line matching transformer such as one of the Shure A95 Series at the high-impedance microphone input.

The output of the program output amplifier is also fed

to the VU Meter (6) circuit. VU METER CIRCUIT

To allow a wide range of signals to be handled by the

VU Meter

(6), a VU Meter amplifier is provided. The output of the program amplifier is fed to the VU METER RANGE Switch (16) which in turn feeds the VU Meter amplifier and the Meter. The VU METER RANGE Switch provides a

choice of 0, +4 or The

0 setting is usually used for PA applications, +4 is the

standard for recording use, and

dBm output levels for the VU Meter.

+8 is preferred for use

by broadcasters. The calibration of the VU METER RANGE

Switch is internally adjusted at the factory for a 600-ohm load on the program output in the

VU across

+4 dBm switch position. The VU Meter amplifier provides the proper impedance and signal level for correct VU Meter ballistics and calibration. This amplifier also isolates the Meter from the program output and eliminates the distortion normally caused by the nonlinearities of VU meters.

LIMITER

The program output amplifier also contains a

peakresponding, rapid-acting, limiter circuit. When the LIMITER Switch (11) is turned on (IN), and the THRESHOLD

ADJ Control (10) is properly adjusted, the LIMITER Indicator Lamp (4) will flash whenever the limit threshold is exceeded and the limiter is functioning. The dynamic range

of the limiter is approximately 30 dB.

Set the limiter THRESHOLD ADJ Control (10) as fol-

lows. Operate the Mixer with program material, and adjust

the individual channel and MASTER Volume Controls (1, 9) for the desired level. With a small screwdriver, turn

the THRESHOLD ADJ Control full counterclockwise. Set the LIMITER IN-OUT Switch (11) to IN. Slowly increase (turn clockwise) the THRESHOLD ADJ Control until the

LIMITER Indicator Lamp (4) flashes, indicating limiting ac-

tion on program peaks. Note that increasing the channel

or MASTER Volume Controls will not increase the mixed

output above the level just set. Should a higher or lower maximum output level be desired, increase or decrease the THRESHOLD ADJ Control.

An alternate method of limiter threshold adjustment is

to turn on the TONE

Oscillator (1) to produce a maximum reference level on the VU Meter (6). Adjust the THRESHOLD ADJ Control (10) clockwise until the VU Meter reading

just set is reduced by 1 dB. The program material dis-

played on the VU Meter will be lower because of the difference between peak and average levels, but limiting action will take place at the same peak level. This effect

will be more evident on speech than music.

TONE OSCILLATOR

The Mixer contains a built-in 1 kHz tone oscillator for

set-up and check-out purposes. The TONE OSC Control

and On-Off Switch

(1)

injects the 1 kHz tone into the channel 1 preamplifier. The tone is processed through the program channel in the same manner as microphone or line input signals.

The tone oscillator may be used as follows: With the VU METER RANGE Switch (16) set to MASTER Volume Control

until a

VU reading is obtained on the VU Meter. A tone

(9)

and TONE OSC Control (1)

+4,

increase the

reference level has now been established. The Mixer LlNE

LEVEL Output (23,

24)

is now

4-4

dBm (1.23 volts across a 600-ohm load) and the MICROPHONE LEVEL Output (25) is approximately 4 millivolts. These reference signals may be used to set up power amplifiers, tape recorders, or other equipment connected to these outputs (Figure

6A, Page

8). By adjusting the input level (or volume) controls on

the associated equipment, all meters in the audio system

can be made to "track." This allows the Mixer operator to observe only the Mixer VU Meter.

The tone oscillator may also be used to provide a check of cables and equipment connected to the link output. With the

LlNK OUTPUT Jack (21) connected to the input

MIC

LINE LINE

TAPE

RECORDER

GATED

COMPRESSOR

MIXER

6B,

Page 8). Set

(23)

(15)

SLO-BLO

has not

is not be-

SR 109 MIXER

POWER AMPL

109

MIXER

FIGURE

TONE OSCILLATOR APPLICATIONS

POWER

AMPLIFIER

MIC

AUX LEVEL

INPUT JACK

of external equipment, such as a Shure SE30 Gated Compressor/Mixer which in turn feeds a broadcast line, disconnect the Mixer output, either at the back of the Mixer,

power amplifier or speakers (Figure

the MASTER Volume Control

(9)

to 6 or the normal operating position, and increase the TONE OSC Control (1) for a

0 VU reading on the VU Meter (6). Set the MASTER

Volume Control to

Under this set-up condition, the external equipment may now be calibrated or checked out without affecting the Mixer output. After calibrating the external equipment, turn off the tone oscillator, and return the MASTER to the previous setting. Reconnect the power amplifier or speakers.

BASIC OPERATING HINTS

Should any difficulty be encountered in Mixer operation, the problem may often be traced to some simple source such as an error in interconnection. The following is offered as a basic guide to problems of this sort.

Symptom: Mixer is "dead" (no output, VU METER lamps

out)

Check: 1. Check that ac power source is "live" and

that Mixer is plugged in.

2. Check that POWER OFF Switch (9) is on.

3. Check to see that rear-panel Fuse (13, 28) is good.

Symptom:

Mixer is "dead" (no output, VU Meter lamps lit)

Check: 1. Check that cable from PROGRAM OUT

PUT/LINE LEVEL Connector accidentally been connected to PROGRAM

OUTPUT/MICROPHONE LEVEL

Connector (25).

2. Check that PHASE Switch tween positions.

3. If external equipment is connected to LlNK Jacks (21, 22), disconnect external equipment to determine whether fault is in external equipment.

Symptom: One channel is "dead" (other channels oper-

ating properly)

Check:

Check for defective input cable or source. Check that

2. nels

MIC/LINE Switch (20) (chan-

and 8 only) is not between positions

or in the wrong position.

+ 25 hidden pages