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

The outputs of the power amplifiers in a biamplifica­tion system may be connected to any high-power,
two-way speaker system with separate driver connec-

tions such as the Shure

restriction placed on speaker systems is that the
crossover frequency of the speaker system must match

the crossover frequency selected on the back of the
SR106. Damage to the high-frequency drivers may

result if the crossover frequency of the SR106 is set
below that recommended for the speaker system.

For three-way speaker systems, a second SR106
may be used to split the high-frequency output of the
first SR106 into mid-range and high-frequency outputs.

The two

into three components for routing to three power am-

plifiers and into the three-way speaker system (see

Figure
used with any three-way speaker system with cross­over frequencies matching those of the

Certain three-way speaker systems are designed for

biamplified operation only, and use their internal cross­over networks to separate the mid- and high-frequency
signals. When using a speaker system of this type,
follow the instructions under
speaker system manufacturer's instructions.

SRlO6's thus separate the line level signal

G). This is called triamplification, and may be

SR108. The only important

SR106. NOTE:

Biamplification and the

Crossover Frequencies

The three crossover frequencies available (500, 800

and 2600 Hz) on the SR106 rear-panel selector switch

(7)

are designed for use with the Shure SR108 Ex-

tended Range Speaker System (2600 Hz) and other

popular speaker systems. In connecting the
it is imperative that the crossover frequency of the
speaker system be known and the
OVER FREQUENCY Switch be set before operating the
system.

SR106 CROSS-

SR106,

CAUTION

High-frequency drivers may be damaged or
destroyed if the electronic crossover is not
set to match the speaker system crossover
frequency.

Phasing

The SR106 high- and low-frequency output signals

are intentionally wired out of phase (opposite polarity).

The low-frequency output is in phase with the input,

and the phase of the high-frequency output is re-

versed. This phase relationship is consistent with the

requirements of the passive 12

networks used in most popular speaker systems. The
Shure
ternally wired out of phase and provides the correct
acoustic output when operated in the

speakers in the crossover region. Failure to maintain
characteristics in the critical mid-range frequencies.

The speaker system instruction manual should be con­sulted for information on proper phasing when con-

Shure Model
and low-frequency power amplifiers may be used

system while listening to the same program material.

SR108 Extended Range Speaker System is in-

mode.

Proper wiring is necessary to maintain the correct

phase relationship of the high- and low-frequency

proper phasing may cause incorrect overall response

necting the speakers to the power amplifiers.

The following considerations should be given to
phasing: When using the
amplifiers (Shure SR105 or equivalent) to power a

SR108 Speaker System, the phasing is

correct. Different speaker systems or dissimilar
long as all low-frequency sections are in phase with

one another and all high-frequency sections are in

phase with one another, as well as maintaining proper
high- to low-frequency phasing.

To check for a possible out-of-phase condition in
a single speaker system (high- to low-frequency phas-

ing), the following listening test should be performed.
Connect the
power amplifiers to a single speaker system. Feed the
system with program material (vocal or instrumental)
and adjust for a moderate level. Listen carefully to
the speaker system output and
either the high- or low-frequency section of the speaker

Choose the connection that produces the most uni­form sound quality.

SR106, program input equipment, and

dB/octave crossover

biamplification

SR106 and identical power

high-

as

reverse the phase of

If a crossover frequency other than the three pro-

vided (500, 800, and 2600 Hz) is desired a qualified

service technician can change the crossover frequency
to a new desired frequency. Refer to the section on
Alternate Crossover Frequencies.

ELECTRONIC

CROSSOVER

(2600

AUDIO CONSOLE

OR MIXER-PREAMP-

OR MIXER

-

SR106

CROSSOVER

HZ)

(500

HE

-

-

FIGURE G.

TRl AMPLIFIED OPERATION

SRlO6

HZ)

LOW

CAUTION

Do not interchange high- and low-frequency
speaker cables. Damage to high-frequency
drivers from high level, low-frequency sig­nals may result.

SPEAKER SYSTEM

r-------

-

HIGH

-

POWER

AMPLIFIER

HIGH-FREQUENCY

I

,

I

SPEAKERS

I

I

MID

(LOW)

-

POWER

AMPLIFIER

MID-FREQUENCY

I

SPEAKERS

I

I

POWER

AMPLIFIER

LOW-FREQUENCY

I

I

SPEAKERS

I

L

-------

7

J

I

I

I

I

I

I

I

I

I

I

The second test should be made feeding two

speaker systems at a time with the same vocal or

instrumental program material or noise (pink or white).
Connect the

SR106, power amplifiers, speaker systems,

and program input equipment.

Turn on the sound system and adjust for a moderate

level. Disconnect the high-frequency driver input ca-

bles. Stand approximately mid-way between the two
speaker systems and listen to the program material
while reversing the "hot" and common leads to one
of the low-frequency speaker sections. (This may be
accomplished by wire-reversing or by a simple

cross-

wired, double-pole, double-throw switch.) Use the con-

nection that gives a localized sound, centered between

the speaker systems; this is the correct phase connec-

tion.

A

diffuse, directionless sound indicates improper

phasing.

Reconnect the high-frequency speaker sections and
disconnect the low-frequency sections. Perform the
same test as above. Correct phasing will provide a
localized sound, centered between the speaker sys-

tem; incorrect phasing is indicated by the sound ap-

pearing to come predominantly from one speaker
system, and to shift from one speaker system to
another as the listener moves around the audience
area.

If it becomes necessary to invert the phase of the

SR106 output signal without changing any wiring, a

A15PR Phase Reverser may be inserted in the

Shure
LINE LEVEL OUTPUTS/HIGH FREQUENCY or /LOW
FREQUENCY three-pin connector (6, 3) of the

SR106.

+

10

-

m

-

W

p

0

W

W

z

-I0 20 50 100 200 400 600 IK 2K 4K

FREWNCY

(HZ)

FIGURE

J.

TYPICAL SHELVING EFFECT:

LOW TO

HlGH FREQUENCY

SPECIAL OPERATING INSTRUCTIONS

The following information is supplied to enable the

user to utilize the

SR106 Electronic Crossover in spe-

cial or custom installations.

WARNING

Voltages in this equipment are hazardous

to life. Make all circuit changes described

in this section with ac power disconnected.
Circuit changes should be referred to quali­fied service personnel.

6K

IOK 2OK

Shelving

In normal operation the flat portions of the

pass­bands of the SR106 high- and low-frequency outputs
are at equal levels (see Figure E). However, because
of the wide variance in acoustically "live" and

"dead"
rooms, it is often necessary to "shelve," or adjust,
relative to one another, the high- and low-frequency

signals in order to compensate for room reflection or
absorption. This is done by decreasing the volume or
output level setting on the desired power amplifier

(high- or low-frequency) to some arbitrary position be-

low that of the other power amplifier, and performing
a listening test to establish that the desired compen-

sation has been achieved.

The effects of shelving the high- and low-frequency

H

and

J,

outputs are shown in Figures

+I0

-

m

0

U.

g

0

W

Y

-

L?

W

z

-

10

20

50

100

200 400 600 IK 2K 4K

FREWENCY

FIGURE

[HZ)

H.

respectively.

6K

IOK ZOK

TYPICAL SHELVING EFFECT:

HlGH TO LOW FREQUENCY

Alternate Crossover Frequencies

The crossover frequency is determined by a single

two-pole, 12

dB/octave, high-pass, active filter. Trans­sistors Q3 and Q4 and associated circuitry, including
capacitors C4 to C13, comprise this filter. In the 2600
HZ position of switch

S1 capacitors C4 and C13 deter­mine the crossover frequency. In the 800 and 500 HZ
switch positions capacitors C5 to C12 are selectively
added in parallel to produce a lower crossover fre­quency.

Should a different crossover frequency than those
provided be desired for use with a special custom
speaker system, capacitors C4 and C13 may be re­placed. The two capacitors have the same value; to
determine the new value capacitor required in micro­farads, divide 7.02 by the desired crossover frequency.

Example: If the new crossover frequency is to be

1500

Hz,

Use + 5% tolerance, 50-volt or greater capacitors.

Stable film-type capacitors, matched within 10% or

better, are recommended.

The new crossover frequency is 1500 Hz with the

switch in the 2600

HZ

switch position. Note that the

crossover frequencies corresponding to the 500 HZ

HZ

and 800

switch positions are also different due

to the change in capacitors C4 and C13.

Be sure to note the new crossover frequency on
the switch position to avoid damage due to accidental
connection to another speaker system.

Adding Level Controls

If the power amplifiers in use do not have volume
controls, or if volume controls are desired at the
SR106 location, external controls may be added to

SR106 outputs. Obtain two 1,000-ohm linear taper

the

J

potentiometers (Allen-Bradley Type

44.5

and mount them in a
the potentiometers to the
Figure

mum volume position (full clockwise) and reduce one
control for the desired effect.

K.

For shelving adjustments, set the controls to maxi-

FROM SR106 TO POWER AMPLIFIER

OUTPUT INPUT

T

mm (1% in.) rack panel. Wire

SR106 output as shown in

-

ONE-HALF OF CIRCUIT

FIGURE

K.

or equivalent)

SHOWN

LEVEL CONTROL WIRING

WARNING

Voltages in this equipment are hazardous
to life. Refer servicing to qualified service
personnel.

Replacement Parts

Parts that are readily available through local elec­tronic parts distributors are not shown on the accom­panying Parts List. Their values are shown on the

P).

Circuit Diagram (Figure

readily available and unique parts are shown on the
Parts List and may be ordered directly from the fac-

tory.

The commercial alternates shown on the Parts List

are not necessarily equivalents, but are electrically and

mechanically similar, and may be used in the event
that direct factory replacements are not immediately
available. To maintain the highest possible perform­ance and reliability, Shure factory replacement parts
should be used. When ordering replacement parts,
specify the Shure Replacement Kit Number, descrip­tion, product model number and serial number.

Commercial parts not

Telephone Line Surge Protection

When using the SR106 to feed a telephone line sub-

ject to lightning-induced voltage surges, the following

part (commercially available) can be installed across

LINE LEVEL OUTPUTSIHIGH FREQUENCY and

the
/LOW FREQUENCY three-pin jacks (6,

(5,

4)

jacks

circuit components: Thyrector, General Electric Co.,
Part number

to provide additional protection for output

6RS20SPl B1.

3)

or phone

SERVICE INSTRUCTIONS

Service

of the highest quality, operating well within their re­spective ratings to assure long life.

(See Guarantee)

SR106 Electronic Crossover uses components

The

CII

CIO

T4

Cover Removal

To service components inside the chassis, the pro­tective top cover must be removed. This is done by
removing
the cover off.

10 screws from the top surface and lifting

Printed Circuit Board Removal

The SR106 chassis contains a printed circuit board
assembly. The foil side of the board may be made ac­cessible for servicing, without disconnecting any leads,
by removing the four Phillips head screws securing

the board. The board may be completely removed as

14

follows (see Figure L). Remove all

leads from the push-on board terminals, noting con­nections as listed in the table below.

A

I

T

2

interconnecting

T

3

D2

C6

J5

J6

C5

RI

FIGURE

L.

J

3

SR106 TOP VIEW, COVER REMOVED

TI

S

I

CI

C

2

CAUTION
Similar wire colors are used in different cir­cuits; make sure proper re-connections can
be made. Take care not to bend or break
the push-on terminals.

Letter

A
B

C
D
E

F

G

NOTE:

CIRCUIT BOARD

Wire Color
Red

Black
Purple
Yellow/Purple
Yellow/Black
Yellow/Red
Black

Production variations
ing from those in the table.

WIRE COLORS

Letter

H

J

K

L

M

N
P

may

result in wire colors differ-

Wire Color
Red

Red
Blue
Red
Blue
Black
White

Remove the four Phillips head screws from the board

and remove the board from the chassis.

Replace cover after servicing board.

Transistor and Diode Removal
All transistors and diodes used in the

chanically supported

by their leads. When replacing

SR106 are me-

these devices, proper lead configurations must be
followed. Minimum soldering heat (preferably with a

low-wattage soldering iron) should be used to avoid
damage to the device. Transistor lead codes are in­cluded in the Notes to Circuit Diagram (Figure N).

Transistor and Diode Checking

Defective transistors and diodes may be located by

use of a standard ohmmeter such as a

Simpson 260.

Polarity of the ohmmeter must be verified before
these checks are made.

With a known diode orientation, measure the diode

resistance in the forward and reverse directions. The
lowest meter reading will establish the probe at the
cathode end (schematic symbol arrow points to ca­thode) as the "minus" probe while the other probe
will be "plus." Some ohmmeters are not polarized in
this manner with relation to "volts plus probe" and

"volts minus probe." With the ohmmeter "plus" probe
on the anode end of a diode, and the "minus" probe
on the cathode end, the ohmmeter should read ap­proximately 2000 ohms or less. With the meter probes
reversed, a reading of about 10,000 ohms or more
should be obtained. If either of these conditions is

not met, the diode should be replaced.

To check transistors, the ohmmeter should be set
to the 100- or 1,000-ohm scale. Transistors and diodes
must be removed from the circuit before testing. If
all conditions in the following table are met, the tran­sistor may be considered free of any major defect; if
any of the following conditions are not met, the tran­sistor should be replaced. See Notes to Circuit Di-

N)

agram (Figure

for transistor lead codes.

Ohmmeter Connections Ohmmeter Reading

NPN PNP

"Plus" Lead "Minus" Lead Transistor Transistor

Collector Emitter High High

Emitter Collector High High
Collector Base High Low
Emitter Base

Low
Base Collector Low High
Base Emitter Low

*Not a significant measurement.

Replacement Parts List

The commercial alternates shown in the following
parts list are not necessarily equivalent parts, but are
electrically and mechanically similar, and may be
used if direct factory replacements are not imme­diately available. To maintain highest possible per-

formance and reliability, Shure Factory Replacement

Parts should be used.
Service Illustrations

The pages that follow contain a Parts Location

M)

Drawing for the printed circuit board (Figure

and

an overall Circuit Diagram (Figure P). Foil circuit paths

M.

are shown as shaded areas in Figure

Diagram shows all printed circuit board and

The Circuit

chassis-

mounted parts.
GUARANTEE

This Shure product is guaranteed in normal use to
be free from electrical and mechanical defects for a
period of one year from date of purchase. Please
retain proof of purchase date. This guarantee includes

all parts and labor. This guarantee is in lieu of any
and all other guarantees or warranties, express or

implied, and there shall be no recovery for any con­sequential or incidental damages.

SHIPPING INSTRUCTIONS

Carefully repack the unit and return it prepaid to:

Shure Brothers Incorporated
Attention: Service Department
1501 West Shure Drive

Arlington Heights, Illinois 60004
If outside the United States, return the unit to your
dealer or Authorized Shure Service Center for repair.
The unit will be returned to you prepaid.

REPLACEMENT PARTS

I I

Reference

Designation

CHASSIS-MOUNTED

Replacement

Kit No.*

PARTS

LIST

Qty. Part No. Description

AND

(See

ASSEMBLIES

Figures

Replacement Kit Consists

L

and

P)

Of:

I

Commercial

Alternate

A1
C10

C11

Dl, D2

F1

J 1

J2, J4, J6

J3, J5

J7

L1-L4

MP1

MP2
PL1
S1
S2

S2

S3

T1

T2,

T3

T4

T4

W1

W1

-

-

-

RKC21

-

RKC83

-

RK122P

-

-

-

-

RKC45

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

4

2

1

-

-

1

-

-

-

-

-

-

-

-

-

-

90A2058

86L628

86B632

86A404
80A297

95A482

95D446

95A198

95A689

80A250

39A418

31A1144A

80A79

55A105

55A96

55A117

55A116

90C2150

51 8229

51 A253

51 A259

95A632

90A1888

Printed Circuit Board Assembly
Capacitor, Electrolytic,

,F, 40V

250

Capacitor, Electrolytic,

1000

,F, 40V

Silicon Rectifier,

Fuse, SLO-BLO, 1
Pigtail (SR106-2E)

Connector, Female, 3-Pin
Audio,

Connector, Phone Jack,

3-Conductor, Open Circuit,
LlNE LEVEL INPUT and LOW
and

Connector, Male, 3-Pin

Audio, LOW and
OUTPUT

Connector, 3-Pin,
AC (MAINS) POWER (SR106-2E)

Ferrite Bead Ring

Nameplate, Front-Panel
Cover, Switch, POWER

Lamp, Indicator

Switch, Slide,
Switch, Toggle, SPST,

POWER ON-OFF

Switch, Toggle, SPST,
POWER ON-OFF

Switch, Slide, DPDT,
VOLTAGE SELECTOR
(SR106-2E)

Transformer and Shield

Assembly, Line Level Input

Transformer, Low and High

Frequency Line Level Output

Transformer, Power

Transformer, Power (SR106-2E)

Line Cord and 3-Conductor
Ac Plug Assembly

Line Cord and 3-Conductor
Ac Plug Assembly

LlNE LEVEL INPUT

HlGH LEVEL OUTPUT

100V,

/16A, 250V,

HlGH LEVEL

4P3T

(SR106)

(SR106-2E)

(SR106)

(SR106)

(SR106-2E)

Y2

A

(SR106)

None

CDE BR250-50

None

Motorola 1

Littelfuse 315.062

Switchcraft C3F

Switchcraft 12B

Switchcraft C3M

None

Stackpole 57-0181
Ferronics 21-0351 J

None
None

Leecraft 36N1311-6

None
Cutler-Hammer

7501 K13

None

None

None

None

None
None

Belden 17408

None

N4002

;

*Parts listed as RKC Kits should be ordered by that number.

Any orders received for piece parts where RKC Kit number is shown will be shipped in RKC quantities.

"Sprague Type

225P

has a

+lo%

tolerance; select to

&5%

if possible.

REPLACEMENT PARTS LIST-Continued

Reference

Designation

CIRCUIT BOARD ASSEMBLY (Al)

Q2, Q4 06

Q10 Power, PNP

Replacement

Kit No.*

-

Qty.

1 - 1

Replacement Kit Consists Of:

Part No.

Capacitor, Electrolytic,

4.7

,F, 35v

Capacitor, Electrolytic,

p.F,

250

Capacitor, Film,

.0027 ,F, 1OOV & 5%
Capacitor,

.0022 ,F, lOOV t 5%

Capacitor, Film,

.0039 ,F, 10OV
Capacitor, Film,

.0015 ,F, 100V t 10%

Capacitor, Film,

.O1

,F, lOOV t 5%

Silicon Rectifier,

Transistor, Silicon, Low

Power, NPN

86~348

1

Transistor, Silicon, Low

Description

40V

Film,

zk

5%

50V, YzA

Commercial

Alternate

Sprague 30D-TE1303;
CDE NLW-5-50

BR250-50

CDE

Sprague 225P27291*

Sprague 225P22291**

Sprague 225P39291*'

Sprague 225P15291

Sprague 225P10391"

Motorola 1 N4001
Motorola 2N5210

Motorola or
Fairchild

2N5087

*

"

I

Q8, Q12

*Parts listed as RKC Kits should be ordered by that number.

Any orders received

"Sprague Type 225P has a

RKC66

for

piece parts where

I

210%

tolerance; select to

1

1

86A335

RKC

Kit number is shown will be shipped in RKC quantities

25%

1

Transistor, Silicon, PNP

if possible.

FIGURE

PRINTED CIRCUIT BOARD PARTS LOCATION

M.

NOTES TO CIRCUIT DIAGRAM

General 2. Line voltage: 120V, 50/60 Hz (SR106), or 115V

Shure part numbers are not shown in the Parts List
accompanying the Circuit Diagram (Figure P) if parts
are readily available through local electronics parts

suppliers. In these instances, the Circuit Diagram
shows only the reference designation and value of

the standard parts.

All capacitor values are shown in microfarads
less otherwise designated. All non-electrolytic

tors are 100 working volts dc or more unless
wise specified. The capacitor tolerance is shown for

the crossover-frequency-determining capacitors C4 to
C13. Electrolytic capacitors are shown in microfarads The numbers within elliptical symbols

X

volts.

All resistor values are shown in ohms
Resistors are %-watt 10% tolerance unless otherwise
specified. 2. Line voltage:

Transistor lead codes are shown in Figure N.

ceptable replacements are shown in the Parts List.

The following ground symbols denote:

Chassis Ground

Circuit Ground
Printed Circuit Board Ground

Troubleshooting

A

general troubleshooting process is as follows:

SR106 is completely "dead," check the ac power

the

source and power slipply output (36V at pin H of
printed circuit board). If the output is distorted, low
or not present, apply an input signal as described
under Ac Voltage Measurements below, and determine
that the input voltage to the board assembly is correct.

If an incorrect ac voltage is found on the board, per-

form Dc Voltage Measurements as described below to

isolate the problem area.

AC Voltage Measurements

The numbers within rectangular symbols

the Circuit Diagram denote the ac voltage at that

point under the following test conditions:

1. Voltage measured with respect to chassis un- FIGURE
less otherwise indicated.

*

l

-

un-

capaci-

other-

(k=1000).

Ac-

0

on

If

or 220V

3. Test signal of
5 kHz (high-frequency) applied across connector

J1 through 600 ohms.

4. Measurements made with ac VTVM of 1
or greater input impedance.

5. Loads across LlNE LEVEL OUTPUTS Connectors
J3 and J5: 47 kilohms.

6. Ac voltage measurements may vary t 30% from
values shown.

DC Voltage Measurements

Circuit Diagram denote the dc voltage at that point

under the following test conditions:

1. Voltages measured with respect to chassis un­less otherwise indicated.

or 220V (SR106-2E).

3. No input signal applied.

4. Dc voltage measurements may vary
values shown.

5. Measurements made with VTVM of 11 megohms
or greater input impedance.

Resistance Measurements

With the ac line cord disconnected from the ac

source and the POWER ON-OFF Switch in the OFF

position, the following ohmmeter measurements may
be made:

1. Transformers may be checked for continuity of
each winding.

2. To test transistors and diodes, see Transistor
and Diode Checking.

pK77q

.@

E

-

01

03 07.011

05

p9

(SR106-2E).

l.OV, 200 Hz (low-frequency) or

120V, 50/60 Hz (SR106), or 115V

-1

.a

.Q

E E

-

TRANSISTOR LEAD CODES

.a

E

-

.@

(J.6

E

02,P4 Q8,012

as,

a,o

N.

megohm

o

t

20% from

E E

on the

ARCHITECTS' AND ENGINEERS' SPECIFICATIONS

The Electronic Crossover shall be a rack-mounted
120-volt, 50160 Hz line-operated, all silicon transistor,
active crossover network for separating the output filter with a 300 Hz lower cut-off.
signals from an audio console or mixer-preamplifier
into high- and low-frequency signals for routing to
separate power amplifiers and two-way speaker sys"
tems.

The Electronic Crossover shall be a unity voltage
gain amplifier for either high- or low-frequency output

a

signals, with

the

range
frequency output signals are added electrically out-of­phase. Input impedance shall be 150

and recommended output load impedance shall be
600 ohms (termination for 1.5 dB loss) or 47 kilohms

(bridging for unity gain). The Electronic Crossover leled female professional audio and three-circuit

shall evidence no visible clipping at either output from
30 to 20,000 Hz with a 15.8 dBV (6.2V) input level.
When terminated with a 600-ohm input resistance and
47-kilohm output loads, both high- and low-frequency
output signals shall have a maximum hum and noise

level of -96

*

All spec~ftcat~ons apply to

125~

or

210-250~.

flat f 2 dB frequency response over

of

20

to

207000

dBV through a 20,000 Hz noise-bandwidth above specifications shall be deemed unacceptable

Hz

SR106-2E

when

the

high-

kilohms 2 30%,

except operattng voltage

Or

low-

IS

105-

filter with a 20 Hz lower cut-off, and a maximum noise

level of -98

The Electronic Crossover shall have a POWER
OFF Switch and a three-position CROSSOVER FRE­QUENCY Switch to select crossover frequencies of
500, 800 or 2600

The Electronic Crossover shall be enclosed in a

metal, rack-mounting enclosure housing with a

resistant vinyl-covered front panel. The dimensions
shall be 44.5
in width, and 216

shall be

The

%-inch phone jack connectors. The HIGH and LOW
FREQUENCY
each be paralleled %pin male professional audio and
three-circuit phone jack connectors.

Any Electronic Crossover not meeting all of the

under this

be a Shure Model SR106.

dBV through a 20,000 Hz noise-bandwidth

Hz.

mm

(1%

no

more

LINE LEVEL INPUT connectors shall be paral-

specification'

mm (8V2 in.) in depth. The weight

than

LINE LEVEL OUTPUT connectors shall

in.)

kg

The

(6

*

in

height, 483

Ib,

8.8

oz).

Electronic

mm

(19 in.)

Crossover

ON-

scuff-

11

SR106-2E POWER SUPPLY