Shure SR-106, SR-1062-E Service manual

222

HARTREY

AREA CODE 312/866-2200 . CABLE: SHUREMICRO

TWX: 910- 231-0048 TELEX 72-4381

AVE..

EVANSTON,

IL.

60204 u.S.A.

MODEL SR106

AND SR106-2E

SHEET ELECTRONIC CROSSOVERS

1

DATA

I

OPERATION AND

The Shure Model SR106 Electronic Crossover is a
selectable-frequency dividing network, designed for
use with two- or three-way speaker systems such as
the Shure
high-quality sound systems. It utilizes the principle
of biamplification to separate an audio console or
mixer-preamplifier output into two frequency bands for
distribution to separate power amplifiers. In this man­ner, the advantages of low distortion, increased
frequency power, wide dynamic range, and maximum
efficiency are obtained.

SR108 Extended Range Speaker System in

high-

DESCRIPTION

The SR106 provides crossover frequencies of 500

Hz, 800 Hz and 2600 Hz. It can be used to provide two

output frequency bands or, in conjunction with a
second
bands, with each output routed to a separate power
amplifier (triamplification). The
professional three-pin and phone jack input and out­put connectors, and can be operated in line level bal-

anced and unbalanced systems.

operation and maintenance. A frequency-selector
switch and a power on-off switch are the only con­trols. Silicon transistors and other solid-state devices
are
est quality and are operated well within their re­spective ratings to assure maximum reliability under
normal use conditions.

the
SR106-2E operates from either 105-125 or 210-250 Vac
(switch-selectable).

mounting screws for mounting in 483 mm (standard 19
in.) audio equipment racks or in optional Shure
or A105A Carrying Cases. In addition, the SR106 is
supplied with a protective power switch cover and the
SR106-2E is supplied with an ac line cord (without

power plug). The
writers' Laboratories, Inc., and is listed by Canadian
Standards Association as certified.

SR106, to provide three output frequency

SR106 contains both

SR106 is designed for maximum simplicity of

The

used throughout. All components are of the high-

SR106 and SR106-2E are identical except that

The

SR106 operates from 108-132 Vac, and the

All

SR106 Series units are supplied with four rack-

A30A

SR106 (only) is listed by Under-

SPECIFICATIONS

Type

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

Crossover

Frequency

Copyright

27A1145

1979,

(SF)

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

Shure

All silicon transistor electronic

crossover network

500 Hz, 800 Hz or 2600 Hz

(selectable)

Brothers

Inc.

SERVICE MANUAL

Voltage Gain

Input Sensitivity

Frequency

Response

Phase

lnput Common

Mode Rejection

Input Impedance

Total Harmonic

Distortion

Hum and Noise

Noise

Clipping Level

Recommended Output

Load Impedance

Power Supply

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

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

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

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

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

........

..Input and low frequency output

......

........

..........

...

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

....

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

0 2 1 dB (low or high frequency

output) with 47-kilohm output
termination

-

1.5 + 1 dB with 600-ohm
output termination

1-volt input produces I-volt

output (unity gain) with
47-kilohm output termination

I-volt input produces 0.84-volt

output with 600-ohm output
termination

Electrical sum of outputs (phase

reversed): flat
20-20,000 HZ

High-frequency output: 12 dB/

octave

Low-frequency output: 6 dB/

octave
(see Figure E)

connectors in phase, high
frequency output reversed
phase

92 dB minimum at 100 Hz
47 kilohms

1 % max. (I-volt input; low

frequency: 20-2,600 Hz; high

frequency: 500-20,000 Hz)

-

96 dBV max. low or high
frequency output (through
20,000 Hz noise-bandwidth
filter with 20 Hz lower cut-off;
600-ohm source, 47-kilohm
output terminations)

-

98 dBV max. low or high
frequency output (through
20,000 Hz noise-bandwidth
filter with 300 Hz lower cut-off;
600-ohm source, 47-kilohm
output terminations)

+

18 dBm (6.2V) min. input from
30-20,000 Hz with 600-ohm or
greater output loads.

600 ohms minimum

(115 ohms actual output im­pedance)

SR106: 120 volts t lo%, 50/60

Hz ac only. SR106-2E: 105-125
or 210-250 volts,
only. Power consumption:
3 watts maximum.

rolloff below crossover
rolloff above crossover

t

2 dB,

50/60 Hz ac

Printed

in

U.5.A

FIGURE A.

SR106 FRONT PANEL

Temperature Range:

Operating

Storage

Dimensions

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

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

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

-

7" to 57°C (20" to 135°F)

_

-

29" to 71 "C (-20" to 160°F)

44.5 mm height x 483 mm width

x

216 mm depth (1% in.

19 in. x 8% in.)

Weight

Finish
Installation

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

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

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

3 kg (6

Ib, 8.8 oz)

Matte black

Equipped for standard 483 mm

(19 in.) audio rack mounting;
may be operated in optional
A30A or A105A Carrying Case
(with other equipment)

Certifications

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

~isted by Underwriters' Labora-

tories, Inc.; listed by Canadian
Standards Association as cer-

(SR106 only)

tified

OPERATING

Functional Description

INSTRUCTIONS

(Refer to Figures A and

1. Power-On Indicator Lamp-Indicates ac power
is being applied to unit.

2.

POWER ON-OFF Switch-Controls ac power to
unit.

3. LlNE LEVEL

OUTPUTS/LOW FREQUENCY
Pin Male Connector-Provides low-frequency
balanced output connection to power amplifier.

May be unbalanced externally.

4. LlNE LEVEL

OUTPUTS/LOW FREQUENCY

Phone Jack-Provides low-frequency balanced

or unbalanced output connection to power am-

plifier.

5. LlNE LEVEL

OUTPUTS/HIGH FREQUENCY
Phone Jack-Provides high-frequency balanced
or unbalanced output connection to power am-

plifier.

6. LlNE LEVEL

OUTPUTS/HIGH FREQUENCY 3­Pin Male Connector-Provides high-frequency
balanced output connection to power amplifier.

May be unbalanced externally.

7.

CROSSOVER FREQUENCY Slide Switch­Selects crossover frequency of 500 Hz, 800 Hz

B)

or 2600 Hz for separation of high- and

low-

frequency signals to power amplifiers.

8. LlNE LEVEL INPUT 3-Pin Female

Connector-

Provides balanced bridging, high-impedance in-

x

put connection from audio console or mixer-

preamplifier. May be unbalanced externally.

9. LlNE LEVEL INPUT Phone Jack-Provides ba­lanced or unbalanced bridging, high-impedance
input connection from audio console or mixer­preamplifier.

10. Ac Grounded Line Cord-Connects unit to ac
power source

(SR106 only).

11. AC (MAINS) POWER 3-Pin Connector-Con­nects unit to ac (mains) power source via
supplied line cord

(SR106-2E only).

12. VOLTAGE SELECTOR Slide Switch-Selects
115V or 220V input power

(SR106-2E only).

General Operating Instructions

WARNING

To reduce the risk of fire or electric shock,
do not expose this appliance to rain or
extreme moisture.

3-

Using hardware provided, install

1.

SR106 securely

in 483 mm (standard 19 in.) rack or optional

A30A or A105A Carrying Case prior to making

electrical connections.

Connect SR106 LlNE LEVEL OUTPUT/LOW FRE-

2.
QUENCY 3-pin connector or phone jack (3,

4)

to (low frequency) power amplifier line level
input.

3. Connect

SR106 LlNE LEVEL OUTPUT/HIGH
FREQUENCY &pin connector or phone jack
(5, 6) to second (high frequency) power amplifier

line level input.

Connect audio console or mixer-preamplifier line

4.
level output to
connector or phone jack (8,

SR106 LlNE LEVEL INPUT &pin

9).

5. Make sure speaker systems are properly con­nected to power amplifiers and are adjusted
for biamplified operation.

II

rr

SR106-2E

rolula

ONLY

MTIM

if(TOR

3

whr

\

12

t

10

FIGURE

B.

3

7

8

9

SR106 REAR PANEL

6. Move CROSSOVER FREQUENCY Switch

(7)

to
select proper crossover frequency (see Speaker
Operating Instructions).

7.

(SR106-2E only) Move VOLTAGE SELECTOR
Switch (12) to 115V or 220V position as desired.

8. Connect ac line cord to grounded 108- to

132­volt (SR106), or 105-1 25V or 210-250V (SR106­2E), 50/60

Hz

ac source.

9. Turn on front-panel POWER ON-OFF Switch (2).
Red indicator lamp (1) will go on, indicating
power application. The

1

@.

Adjust audio console or mixer-preamplifier and

SR106 is now operating.

power amplifier controls for desired operating
levels.

Mounting and Ventilation

The SR106 Electronic Crossover is designed for

rack-mounting in a 483

mm (standard 19 in.) audio
equipment cabinet rack and is supplied with the nec­essary mounting hardware (see Figure C). If possible,

SR106 should be rack-mounted below its asso-

the

ciated power amplifiers.

SR106 may also be operated while mounted in

The
a Shure A30A or A105A Carrying Case. The A30A has
a panel height capacity of 88.9

mm (3Y2 in.), pro­viding space for two SRlOG's, or one SR106 and
one other unit of 44.5 mm

(1% in.) height. The
A105A has a panel height of 178 mm (7 in.), providing
space for up to four

SRlO6's, or one SR106 and

other equipment totaling 133.4 mm (5Y4 in.) in height.

No special precautions are required for ventilation.

The

SR106 may be operated over a temperature range

-

7"

of

to 57°C (20" to 135°F) in continuous duty with-

out derating.

483

mm

(19

1N!

-44

4

mrn(1-3/4 IN,

'NOT

lNCLUDlN6 CABLE/CONNECTOR CLEARANCE DEPTH

FIGURE C.

OVERALL DIMENSIONS

Power Supply

The SR106 is furnished with a three-conductor power

cable and three-prong grounded plug (10). Connect

SR106 to an outlet which supplies 108 to 132 volts

the
ac,

50/60

Hz

power. Maximum power consumption at
120 volts under normal operating conditions is 3 watts
(0.025 amperes at 120 volts). If extension cords are
required, a high-quality, 18-gauge or larger cord should
be used.

SR106-2E is furnished with a three-conductor

The

line cord without a power plug. Obtain a suitable 3-pin

male power plug and attach it to the line cord. The

plug should be installed by qualified service personnel.
(Brown lead goes to "hot" or "live" terminal, blue lead
to neutral terminal, and

greenfyellow lead to ground
or earth terminal.) Select proper operating voltage
(115V for 105-125V supply or 220V for 210-250V supply)
using the VOLTAGE SELECTOR Switch (12).

A

POWER ON-OFF toggle switch on the front panel

(2) controls the application of ac power to the

SR106,
and a red indicator lamp (1) indicates the power-on
condition. The tamper-proof cover supplied

(SR106
only) may be used to eliminate accidental movement
of this switch.

Functional Circuit Description

The inputs of the SR106 Electronic Crossover con-

sist of one phone jack (9) and one three-pin female

D).

audio connector (8) (see Figure

The phone jack is
a three-circuit (stereo) type and is wired in parallel
with the three-pin connector to provide a balanced in-

put with either connector. The input signal then passes

through a 6 dB

stepdown input isolation transformer

to a unity-gain buffer amplifier.

The next stage is a 12

with an operating frequency of 500 Hz, 800

Hz.

All frequencies above the selectable operating fre-

dB/octave high-pass filter

Hz

or 2600

quency are routed to a unity-gain filter amplifier stage.

One output of this stage goes to a 6 dB gain, 600-ohm

line driver, which drives the high-frequency output
transformer to
a differential

+I8 dBm. The other output goes to

amplifier/line driver stage, which also

receives an input from the first buffer amplifier stage.

The differential

amplifier/line driver stage thus de­rives the low-pass signal by responding to the differ­ence between the buffer amplifier signal (all-pass) and

the filter circuit signal (high-pass). The difference
signal

ampli.tude rolls off at 6 dB/octave. The differ­ence signal is amplified and drives the low-frequency
output transformer. The resulting frequency response
curves are shown in Figure E. Adding the two outputs
out-of-phase provides a flat output response from 20

Hz.

to 20,000

High- and low-frequency outputs appear

on both phone jacks and three-pin, professional, male

audio connectors.

LlNE

LEVEL

INPUT

- - - - - -

HIGH-PASS FILTER

FIGURE D.

BLOCK DIAGRAM

- - -

-

- - - - - - -

HIGH

1

LINE

LOW

LlNE

FREQUENCY

LEVEL

OUTPUTS

FREQUENCY

LEVEL

OUTPUTS

+

10

-

m

P

0

w

0

B

-10

W

W

:

-20

w

-30
20 50 100 200 400 600

CROSSOVER FREQUENCY:

CROSSOVER FREQUENCY:

+I0

m

a

0

I

0

-10

Y

",

5

-20

W

-30
20 50 100 200 400 600

CROSSOVER FREQUENCY: 500

FIGURE E.

FREQUENCY RESPONSE

FREQUENCY (HZ

1K 2K 4K

)

1K 2K 4K 6K IOK 20K

2600

800

Hz

Hz

6K

IOK 2OK

Hz

Input and Output Connections

Two

LlNE LEVEL INPUT Connectors are located on
the rear panel of the
female audio connector

SR106. A professional, three-pin

(8)

provides a balanced con­nection from the audio console or mixer-preamplifier.
A

standard

1/4

in. three-circuit (stereo) phone jack

(9)

provides either a balanced or unbalanced input con­nection.

The

SR106 is a unity gain device, that is, a 1-volt

input signal provides a 1-volt output signal. The

SR106
may be driven by virtually any mixer, audio console
or mixer-preamplifier. When connecting the source
output to the

SR106, follow the instructions supplied
with the source equipment with regard to connectors
and cabling. Note that if a two-circuit phone plug is
used, the

SR106 input will automatically become un-

balanced.

HlGH FREQUENCY and LOW FREQUENCY LlNE

LEVEL OUTPUT connectors consist of both profes-

(3,

sional, three-pin, male audio connectors

6) for bal-

anced connection to power amplifiers, and standard

1/4

in. three-circuit (stereo) phone jacks

(4,

5)

provide

balanced or unbalanced connections.
Biamplification

The principle of biamplification is to separate the

high- and low-frequency signal components ahead

of the power amplifier, and to use separate power
amplifiers for each section of a two-way speaker sys­tem (see Figure F). Proper matching of amplifiers and
speakers, increased system power, and reduced dis­tortion may be realized.

With biamplification it is possible to power-match
each speaker system section to a power amplifier for
maximum efficiency, whereas if a single equivalent
high-power amplifier were used it would exceed the
speaker system power rating. The improved system
performance using separate power amplifiers for each

speaker section may be that of a single high-power
amplifier whose rating is up to twice the sum of the

individual power amplifiers. In addition, the power
amplifier overload caused by high-level, low-frequency

signals severely degrades high-frequency signals in
a single-amplifier system. This overload, a form of

intermodulation distortion, is eliminated by the use of

separate power amplifiers. Biamplification also elimi­nates low-frequency distortion produced by saturation
of iron cores used in some passive speaker crossover
networks.

AUDIO CONSOLE SR106

OR MIXER-PREAMP ELECTRONIC

OR MIXER CROSSOVER

H

BlAMPLlFlED OPERATION

HIGH

LOW

-

FIGURE F.

POWER

AMPLIFIER

POWER

AMPLIFIER

TWO-WAY

SPEAKER SYSTEM

r-------

HIGH-FREQUENCY

i

I

I

I

I
I

SPEAKERS

-

LOW-FREQUENCY

SPEAKERS

I

1

I

I
I

I

I

I