OPERATION MANUAL
SA601F & SA601FX
INFRARED TRANSMITTER
SOUND ASSOCIATES, INC.
424 West 45th Street, New York, NY 10036
Tel: (212)757-5679
Fax: (212)265-1250
Toll free: (888)772-7686
Home Page: www.soundassociates.com
TABLE OF CONTENTS
INTRODUCTION ......................................................................................................... 2
INFRARED LISTENING SYSTEM 600 FEATURES..................................................... 2
UNPACKING UNIT ...................................................................................................... 3
RACK MOUNTING ...................................................................................................... 3
Rack Mounting One Transmitter............................................................................. 3
Rack Mounting Two Transmitters or
Transmitter and Emitter Power Supply (Side by Side)........................................ 4
FRONT PANEL CONTROLS ....................................................................................... 5
REAR PANEL CONTROLS.......................................................................................... 5
POWER CONNECTION .............................................................................................. 6
AUDIO/CHASSIS GROUND LINK ............................................................................... 6
INPUT CONNECTION ................................................................................................. 6
OUTPUT CONNECTION ............................................................................................. 7
THEORY OF OPERATION .......................................................................................... 7
LEVEL CONTROL……………………………………………………………………………..8
TROUBLESHOOTING....................................................................................................8
TECHNICAL SPECIFICATIONS .................................................................................. 9
SERVICE OR REPAIRS.................................................................................................9
ACCESSORIES ......................................................................................................... 10
WARRANTY .............................................................................................................. 10
TYPICAL SYSTEM SCHEMATIC............................................................................... 11
INTRODUCTION
The Infrared Listening System 600 is a wireless assistive listening device which can be used as
either an aid for the hard of hearing, sight description, or simultaneous translation. As an
assistive listening device, the Infrared Listening System 600 meets the Americans with
Disabilities Act standards to aid the hearing impaired. Also, infrared technology meets
international standards for wireless interpretation equipment. The System 600 consists of three
major components: the transmitter, the emitter, and the receiver.
The transmitter modulates an audio signal that is converted into infrared light by the emitters.
This light carries the modulated audio on its back, fills the room, and is converted back into
audio by the receiver. The infrared light is amplitude modulated with a 95 kHz or 250 kHz
frequency-modulated sub-carrier. Both 95 kHz and 250 kHz are industry standard frequency
carriers, therefore other manufacturer’s receivers can be used with our system and our
receivers used with other home or large area systems. For the purposes of this manual, the
only difference between F series transmitters and FX series transmitters is frequency (F
series=95 kHz; FX series=250 kHz).
To ensure proper set up and use of the system, the following instructions should be read
completely before attempting to install any equipment. If you require further assistance, please
call our Customer Service Department Monday-Friday 10:00 am - 5:30 pm at (888) 772-SOUND
(7686).
INFRARED LISTENING SYSTEM 600 FEATURES
Infrared Technology
Feature
Wireless Receivers
Wireless signal transmission by Infrared light
as compared to RF transmission
The audio signal is frequency modulated at 95
kHz or 250 kHz
Advantage
No pre-registered seating
No “deaf section”
Easy distribution
Confidentiality; signal will not pass through walls or
curtains
No interference from common radio signals
Superior audio quality
Industry standard
Headsets are interchangeable with other home and
large area systems
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SA601F & SA601FX Transmitter
Feature
Advanced pre-amp and limit/compressor
circuit
Phantom Power
Infrared test diodes on front panel
Neutrik NCJ series audio input connector
BNC modulated audio output
Advantage
Signal to noise ratio 60 dBC weighted
Gain control on back of unit gives user more flexibility
in setting an optimal audio level from a variety of
audio sources
Limits output before distortion
Fast response time
Can be used in conjunction with condenser
microphone without the need of an external mixer
Ability to monitor the output using a receiver without
being in the seating area
Excepts both 3-pole XLR (microphone level signal) or
¼” phone connectors (line level signal)
Can drive Sound Associates and other manufactured
emitters
UNPACKING UNIT
As soon as the shipment is received, inspect the unit and all components for damage incurred
by shipping. Also, check to see if all components are enclosed.
Equipment enclosed:
1
SA601F or SA601FX Infrared transmitter/base station
1
AC power cord
1
Instruction manual
If the unit is damaged due to shipping, please keep all packing material and contact the shipping
company as soon as possible. Only the consignee may institute a claim against a carrier if
damage has occurred in shipping, however, Sound Associates will assist the client in any such
event.
RACK MOUNTING
Rack Mounting One Transmitter:
To mount a single transmitter in a standard 19” rack, use a RK1 single rack mount kit. Fix the
blank half space bracket to the side of the transmitter with the four enclosed flat head 8/32
screws (see figure). Attach the rack ears to the transmitter and to the blank panel with the four
enclosed flat head 8/32 screws. All screw lengths should not exceed 1/2 inch. The unit will
mount in a 2-space rack.
(See diagram on following page)
-3-
Rack Mounting Two Transmitters or Transmitter and Emitter Power Supply Side by Side:
To mount two infrared transmitters or a transmitter and emitter power supply side by side in a
standard 19” rack, use a RK2 double rack mount kit. Place the transmitters or transmitter and
power supply side by side on a flat surface. Fix the top support plate to the units with four flat
head 8/32 screws (see figure below). Once the support plate is tightened, flip the units and
attach the bottom support plate with four flat head 8/32 screws, then attach the rack ears to the
units with four 8/32 screws enclosed. All screw lengths should not exceed 1/2 inch. The unit
will mount in a 2 space rack. When racked with an emitter power supply, be sure to separate by
one rack space for ventilation.
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FRONT PANEL CONTROLS
1 - Power Switch:
Applies line power. Rocker switch
with LED to indicate on/off modes.
1
sound
a ssocia te s, inc.
POWER
2 - Infrared Test Diodes:
Infrared diodes that emit
modulated infrared signal. Gives
operator/installer the ability to
monitor infrared output using a
receiver without being in seating
area.
4
IR HEADSET TEST
LEVEL
0
10
INFRARED TRANSMITTER
2
3
3 - Level indicator: 10-segment
level indicator. Indicates premodulated audio level. Each LED represents approximately a 3 db
gain/loss.
4 - Volume Control: Adjusts audio level prior to modulation stage.
REAR PANEL CONTROLS
1 - Balanced audio input: Inputs
audio source via XLR connector
(pin 2 hot) for a microphone level
signal or ¼” phone connector for a
line level signal
2 - Pre-amp gain control: Controls
the audio signal gain of the input
channel’s pre-amp. Used to
optimize the input signal level for
the best signal-to-noise performance.
3 - Modulated Audio Output: Supplies modulated audio to emitter panels or emitter power
supply via RG58u coax cable terminated with BNC connector.
4 - AC Fuse: AC Fuse prevents excessive current flow. Timed 500 mA 5 x 20 mm European
fuse at 115 VAC or timed 250 mA at 230 VAC
5 - AC Power: Connects to power source via AC line cord
-5-
POWER CONNECTION
The transmitter is shipped with the input voltage set to 115 volts 50-60 Hz unless otherwise
specified. The transmitter is furnished with a detachable AC power cord rated for 10 A at 120
volts that plugs into a 15 A plug. The input voltage may be changed internally from 115 volts
AC to 230 volts AC. To change the voltage, first disconnect power and remove the top chassis
cover. The input voltage switch is located in the back left-hand corner near the transformer.
Simply slide the switch from 115-volt position to the 230-volt position. In the 115-volt position,
the Mains fuse should be a T500 mA fuse. In the 230-volt position, the Mains fuse should be a
T250 mA fuse. Voltages over 135 volts in the 115 volt position or over 255 volts in 230 volt
position are potentially damaging to the transmitter’s power supply circuit.
AUDIO/CHASSIS GROUND LINK
In some installations, it might be necessary to separate the electronic 0 v from the chassis and
Mains power ground to help avoid ground loops around unbalanced connections. Should this
become necessary, it is easily accomplished by removing the header link (marked “chassis
link”), located internally next to the power transformer.
INPUT CONNECTION
The SA601 Series infrared transmitters have one audio input.
The Neutrik Combo connector accepts a balanced XLR line connector or a ¼” phone plug. The
XLR connector is wired with pin 1 as ground, pin 2 as positive (+), and pin 3 as negative (-).
The ¼” phone plug is wired with the sleeve as ground, the ring as negative (-), and the tip as
positive (+). Use the pre-amp gain control to best match the audio level of the source.
The XLR connection is a balanced 300-ohm microphone level input. The ¼” phone connection
has a 30 dB pad, making it more suitable for line level signals. However, the pre-amp gain
control on the back panel allows for ample reduction of line level signals even in the XLR
connection. Please use the connection that best matches the source signal and adjust the gain
control to better the signal-to-noise ratio.
The XLR input is supplied with +48 V phantom power for use with condenser-type microphones.
The phantom power can be disabled internally by lifting the shunt on link-#3 located in the preamp section of the circuit.
The input is balanced electronically with differential amplifiers. Due to the electronic balancing,
the input may be used with a balanced or unbalanced source.
A balanced line is defined as two conductor shielded cable with each of the two center
conductors carrying the signal but of opposite polarity and equal but opposite potential
difference from ground. An unbalanced line is a single conductor shielded cable with the center
conductor carrying the signal and the shield at ground potential.
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OUTPUT CONNECTION
The SA601 or SA601FX has one modulated output which connects to an emitter panel or to an
emitter power supply via RG58u coaxial cable (RG59u for short cable runs) terminated with a
BNC connector. The SA601 Series transmitters were designed to work in conjunction with
SA611, SA612, and SA613 emitter panels. This transmitter may also be used to drive other
manufactured emitters. The signal voltage is 8 V P-P, therefore, it is high enough to drive most
emitters manufactured at considerable distances. Please check the manufacturer’s instruction
manual to be sure that the emitter will function properly at this signal voltage.
THEORY OF OPERATION
The SA601F or SA601FX transmitter is a frequency modulator that produces an audio signal to
95 kHz or 250 kHz. This process allows the unit to work in conjunction with emitter panels and
receivers that demodulated the signal back to audio. The transmitter consists of four major
circuit stages: pre-amp, limiter, modulator, and output stage. Refer to the block diagram for
signal flow.
+48V
+15V
TP10
TP12
AC V IN
POWER
SUPPLY
GND
TP11
GND
-15V
TEST LED’S
TP1
INPUT 1
INPUT
PREAMP 1
METER
TP9
NOT FITTED IN SA601F
TP2
INPUT 2
TP8
TP4
INPUT
PREAMP 2
SUM
AMP
LIMITER
MODULATOR
OUTPUT
OUT
TP5
INPUT 3
INPUT
PREAMP 3
TP3
NOT FITTED IN SA601F
The pre-amp circuit is designed around an SSM analog low noise pre-amp integrated circuit.
The circuit consists of a 30 dB pad for the line level signal on the ¼” phone connector and an
external potentiometer for pre-amp gain control. The pad is active only in the TRS ¼” phone
connection. The pre-amp gain control is located on the back panel near the audio input
connection (see back panel controls). The sensitivity of the input may be increased or
decreased by this control if the input signal is too low or too “hot”.
The limiter is designed around the THAT 4301 VCA integrated circuit which limits the audio
signal prior to the modulation stage. The limiter restricts the peak modulation swing to <50 kHz
as well as prevents distortion in the modulation stage. The limiter may be taken out of the
circuit if so desired by lowering the limiter sensitivity trim pot at PR7 fully counterclockwise.
-7-
However, if the limit circuit is removed, we suggest that an external limiter/compressor be
utilized.
The modulation circuit frequency modulates the audio signal to 95 kHz (SA601F) or 250 kHz
(SA601FX). The output consists of a push pull driver circuit that has the ability to drive long
cable runs without signal loss.
LEVEL CONTROL
The SA601 Series has one master volume control and one pre-amp gain control. The pre-amp
gain control adjusts the audio level prior to the pre-amp circuit and is used to optimize the input
signal level for the best signal-to-noise performance. The pre-amp gain control should be set
with care. If it is set too low, the signal-to-noise performance will suffer. If it is set too high,
unpleasant signal clipping and distortion may occur. The main volume control located on the
front panel adjusts the audio level after the pre-amp stage and prior to the modulation stage.
The audio level can be monitored visually by the 10 segment LED bar graph on the front of the
unit or audibly with an infrared headset via the five test diodes on the front of the unit. Each
segment of the bar graph represents an approximately 3 dB gain or loss. The limiter will
become active once the level reaches the first red LED on the bar graph. Ideally the input level
should be set to a nominal level, predominately in the yellow section of the bar graph with peaks
occasionally reaching the red.
Note: If the modulation circuit is overloaded, the red power LED on the bottom of the emitter
and the front panel emitter fault LED will flash with each peak. This will occur only after audio
distortion is reached. Simply lower the audio input gain or main front panel gain control if this
occurs on a regular basis.
TROUBLESHOOTING
Symptom
Cause/Remedy
Only white noise or static is heard in the
headset
No static and no audio in the headset
Headset is not receiving the infrared transmission
Make sure...
...power supply is powered (the red LED on the
emitter panel should light when transmitter is OFF)
...transmitter is powered (the red LED should flicker
out and the green LED on the emitter panel should
light)
...cable is not interrupted or crossed
...the photo cell on the headset is in direct view of the
emitter panel
The headset is not powered or the infrared light is
being received with no audio signal “on its back”
Make sure...
...the audio input is plugged into the transmitter and
functioning properly
...the volume on the transmitter is turned up
...the volume on the headset is turned up
...the headset battery is charged and secured firmly
in place
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Symptom
Cause/Remedy
Signal is received but with some static in theThe infrared signal is too weak or high levels of
infrared light are interfering with the transmission
headset
Make sure...
...all emitters are connected and being powered
...emitters are in direct sight and not blocked
...emitter fault indicator light is not on
...intense light is not shining on the photo cell on the
receiver
...energy efficient fluorescent lights are not in use
TECHNICAL SPECIFICATION
Modulation
Transmitting Frequency
95 kHz (SA601F) or
250 kHz (SA601 FX)
+ 35 kHz nominal, + 50 kHz peak
50 s
Modulation
Pre-emphasis
Phantom Power
Sensitivity at 1 kHz
Input impedance
AF frequency response (-3 dB)
Maximum input level
Microphone – Female XLR;
Line – ¼” phone
1
Pin 1 – sleeve (ground);
Pin 2 – tip (pos); Pin 3 – ring (neg)
+ 24 V
50 mV to 2 V adjustable
Balanced > 50 k ohms/ >2 k ohms
20 Hz to 20 kHz
20 dBm (7.75 V)
Output
Connector
Number of outputs
RF Voltage output
Impedance
BNC
1
approximately 750 mV rms
approximately 50 ohms
Power
Power
120/240 ACV internally switchable
Power consumption with (4) SA611 emitters > 25 W
Fuse
T500 mA (5 x 20 mm) @ 120V;
T250 mA @ 240 V internal
Mechanical
Mechanical dimensions
Weight
Finish/material
Input
Connector
Number of Inputs
Wiring
8.5” w x 3.5” h x 9” d
5 lbs.
Black anodized aluminum
SERVICE OR REPAIRS
Contact Sound Associates’ Customer Service Department at 88-772-SOUND (7686) 10:00-5:30
Monday through Friday for any service or repairs.
-9-
ACCESSORIES
•
•

RK1 - single rack mount unit
RK2 - double rack mount kit
BNC003 – RG59u BNC to BNC cable (3ft.)
SOUND ASSOCIATES
FULL THREE YEAR WARRANTY
We, Sound Associates, Inc., warrant to you the original owner or any
subsequent owner of each new Sound Associates infrared transmitter, emitter
power supply, or emitter panel, that the unit is free of defects in workmanship and
materials for a period of three years from date of original purchase. If the infrared
product fails due to defects in materials or workmanship, or does not meet
specifications enclosed with the product, Sound Associates will repair or replace
the unit, whichever Sound Associates chooses, free of charge. All repairs will be
conducted by trained personnel at Sound Associates’ facility in reasonable time.
All expenses on remedying the defect, including return shipping will be borne by
Sound Associates. All shipping fees, taxes, duties, and other customs fees
incurred by products being shipped between foreign countries will be borne by
the purchaser.
Sound Associates is not responsible for malfunctions due to misuse,
accident, or neglect. This warranty does not cover damage to other products
resulting from Sound Associates product failure. It does not cover defects or
damage caused by unauthorized modifications or service. Sound Associates
reserves the right to change the design of any product without notice and with no
obligation to make corresponding changes in products previously manufactured.
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Typical System Schematic
¼” phone to ¼” phone or XLR audio
SA-601F
PS-24
RG 58U BNC to BNC
RG59U for short runs
2 conductor shielded cable
SA-611
SA-611
SA-611
SA-611
page 12
- 11 -
2 conductor
shielded
cable