Studio Technologies 93 User Manual
User Guide
Generation II
Stereo Simulator
Issue 3, July 1991
© 1994 Studio Technologies, Inc.
5520 West Touhy Avenue
Skokie, Illinois 60077 U.S.A.
Telephone (847) 676-9177
Fax (847) 982-0747
www.studio-tech.com
50016-791, Issue 3
Table of Contents
Introduction.................................................................................. 5
Installation.................................................................................... 5
Operation..................................................................................... 8
Technical Notes...........................................................................10
Circuit Description........................................................................11
Troubleshooting...........................................................................15
Specifications...............................................................................18
Studio Technologies Limited Warranty........................................19
Schematic Diagrams ........................................Not included in PDF
Generation II User Guide Issue 3, July 1991
Studio Technologies, Inc. Page 3
Introduction
General Description
The Studio Technologies Generation II
Stereo Simulator is designed to create a
simulated stereo signal from a monaural
input. It is intended for use in applications
such as television and radio broadcasting,
film production, and audio restoration.
Specialized circuitry converts the incoming
signal into a time-domain randomized audio
field which provides an excellent stereo
“feel.”
In television applications, the Generation II
is appropriate for both on-air and production
use. The MTS television broadcaster is
faced with the reality of having a large
amount of mono audio material to broadcast. Using the Generation II Stereo Simulator can greatly improve the listener’s
appreciation of “stereo” TV. The output is
mono-compatible, ensuring that monaural
(L+R) listeners are not negatively impacted
by the use of the Generation II.
status to be set. In the fixed—music setting,
the music mode is activated, the front panel
controls are disabled, and the stereo intensity trim potentiometer is active. In the
fixed—music & voice setting, the music &
voice mode is activated, the front panel
controls are disabled, and the stereo intensity trim pot is active.
Careful circuit design provides excellent
audio performance and operational characteristics to match the special requirements
of most facilities. The line input stage is
electronically balanced, maintaining excellent common-mode rejection, low noise,
and low distortion. The audio output stages
use advanced circuitry to provide high
output level, low noise, and low distortion.
Two switches allow the input and output
levels to be set for nominal 0, +4, or +8dBu
operation. Two 3-section LED meters, along
with a meter select switch, provide monitoring of the input and output levels.
Installation
In film and video production use, the Generation II is invaluable in converting mono
audio into realistic stereo. The two modes of
operation, music and music & voice, allow
for correct processing in all audio scenarios.
In the music & voice mode, a specialized
filter is used to give greater simulation to all
frequencies
This ensures that excellent voice centering
is maintained.
In some cases, it is desirable to disable the
front panel controls. An authorized person
may want to optimize the “sound” of the
Generation II, and then restrict the changing
of those settings. A 3-position switch, located inside the unit, allows the operating
Generation II User Guide Issue 3, July 1991
Studio Technologies, Inc. Page 5
except those in the voice band.
Overview
In this section you will:
• Remove the top and, if required, the
bottom cover
• If required, install an input load resistor
• Set the input, output, and system status
switches
• Replace the cover(s)
• Mount the Generation II
• Connect the audio signals
• Connect power
• Adjust the input level
Remove the Cover(s)
The following procedures must be
performed by a qualified technician.
Operating the Generation II with
the top and/or bottom cover removed exposes the technician to points in the power
input section with hazardous voltages.
3-position switch located on the left side,
toward the back of the circuit board.
The Generation II is designed to produce
nominal audio signal levels of 0, +4, or
+8dBu. Set the desired output level using
the 3-position switch located in the center,
toward the back of the circuit board.
Ensure that the power cord is removed from
the power connector on the back panel.
Remove the top cover. Four Phillips head
screws hold the top cover to the side rails.
If an input load resistor is going to be installed, remove the bottom cover. Four
Phillips head screws hold the bottom cover
to the side rails.
Please Note: Do not touch any potentiometer on the circuit board or factory calibration may be required.
Input Load Resistor
The input impedance of the Generation II is
25k ohms. In some cases, an input termination resistor, with a value such as 150 ohms
or 600 ohms, may be desired. Provision has
been made for an input resistor to be installed in the Generation II’s circuit board.
The resistor is shown on the schematic
connected to pins 2 and 3 of the input
connector. It is labeled R2 on the circuit
board’s legend. Carefully insert the desired
resistor into the circuit board and solder the
connections. Using diagonal cutters, trim
the excess resistor lead. You may want to
label the back panel with the revised input
impedance.
Configuration Switches
The Generation II is designed to accept
nominal audio signal levels of 0, +4, or
+8dBu. Set the desired input level using the
The system status switch sets the way the
Generation II operates. This switch is located on the left side, near the front of the
circuit board.
In the front panel position, the front panel
controls are enabled.
In the fixed — music position, the front
panel controls are disabled, and the unit
operates in the music mode.
In the fixed — music & voice position, the
front panel controls are disabled, and the
unit operates in the music & voice mode.
Replace the Cover(s)
Carefully replace the top and, if removed,
bottom cover using the screws that were
previously removed.
Mounting
The Generation II Stereo Simulator is rackmountable, requiring one standard rack
space (1.75 inches) in a standard EIA 19.00
inches rack. Keeping the Generation II
relatively cool will enhance operating life.
Most electronic equipment failures are
power-supply related. Power supplies tend
to generate heat which, when not adequately controlled, toast the power supply,
dry out electrolytic capacitors, etc. Keeping
all equipment relatively cool will reduce the
likelihood of problems occurring.
Issue 3, July 1991 Generation II User Guide
Page 6 Studio Technologies, Inc.
Signal Connections
All signal connections to and from the
Generation II are made via 3-pin XLR-type
connectors located on the back panel; one
female for line input, and two male for left
and right line output. For hum, noise, and
radio frequency pickup rejection, shielded
cable must be used. The shield should be
connected to pin 1 of the input and output
connectors. Pin 1 is electrically in common
with the Generation II’s power supply
ground, chassis ground, and power cord
ground leads. Following the European
convention, pin 2 is audio high and pin 3
is audio low. Maintaining consistent audio
input and output polarity is important for
correct performance. Failure to maintain
consistent left and right output polarity
will make the output audio not monocompatible.
The Generation II uses electronically balanced input and output circuitry. Best performance is achieved if the equipment
sending signal to and receiving signal from
the Generation II is operating in a balanced
mode. The input and output stages will
operate correctly in an unbalanced mode,
but selected performance characteristics
will be sacrificed. On the input side you will
lose the ability to reject common-mode
signals that balanced operation affords. On
the output side, you will lose 6dB maximum
output level. This is not a technical fault but
is inherent in electronically balanced output
stages. If unbalanced input operation is
required, strap the audio low to ground (pin
3 to pin 1). Connect input audio high to pin
2 and signal ground to the combined pins 1
and 3. If unbalanced output operation is
required, strap pin 3 to pin 1. Connect the
output audio high lead to pin 2 and signal
ground to the combined pins 1 and 3.
In broadcast settings, it is recommended
that the Generation II’s input and output
signals be connected via patch points.
Installation, testing, and servicing procedures will be greatly improved if the unit can
be easily taken off line. Make sure that the
Generation II can be “patched around”
during testing and maintenance.
The Generation II’s line outputs are low
impedance, electronically balanced, line
level. They are capable of driving virtually
all line inputs (low or high impedance,
transformer or transformerless).
In most cases, transformer coupling between audio equipment is neither required,
nor desirable. If the equipment sending
signal to, or receiving signal from the
Generation II requires the isolation given
by a transformer, but does not contain
internal transformers, external transformers
can be added. Refer to the Technical Notes
section of this manual for recommended
transformers.
Connecting to Power
The Generation II may be operated from
either nominal 115Vac or 230Vac, 50/60Hz.
Units shipped to North America and Japan
are factory selected for 115V operation and
are supplied with a 0.50A 3AG fuse. Units
shipped outside North America or Japan are
selected for 230V operation and are supplied with a 0.25A 5x20mm fuse. Before
connecting the unit to power, determine the
actual line voltage and check to see that the
voltage selector switch located on the back
panel is set to the appropriate voltage. If the
voltage selector switch is set for 230V, a
0.25A fuse is required; 115V requires
0.50A.
Generation II User Guide Issue 3, July 1991
Studio Technologies, Inc. Page 7
Caution: An incorrect voltage setting and/or
incorrect fuse could seriously damage the
unit.
The Generation II uses an IEC standard
connector to mate with the line cord. The
line cord supplied has a North American
standard plug at one end and an IEC connector at the other. In non-North American
applications, the plug must be cut off and an
appropriate plug attached. The wire colors
in the line cord conform to the internationally recognized CEE color code and should
be wired accordingly:
use a sine wave input signal when attempting to perform this, or any other Generation
II adjustment. A single frequency input
signal produces output signals that have
level characteristics very different from
those produced by normal audio input
signals. When testing, it is best to use
normal program audio or pink noise.
Operation
Using the Controls
Connection Wire Color
Neutral (N) Light Blue
Live (L) Brown
Protective Earth (E) Green/Yellow
The Generation II does not contain a power
switch. The unit will start to operate as soon
as power has been connected.
Input Trim Adjust
Once the unit has been installed and is
operating, the input trim potentiometer may
be adjusted. This control is accessible from
the back panel, directly next to the input
connector. The trim pot allows the input
level to be adjusted over a small range,
approximately ±0.75dB. Use this control
only if you need to precisely match the
signal levels in your audio chain. In most
installations, the pot can be set at 50 percent rotation, and then forgotten about. The
Generation II’s electronically balanced
output stages have slight output level
changes as a function of load impedance. It
is normal to find a 0.35dB drop in output
level when driving a 600 ohm load, versus
driving a 20k ohm load. The input trim pot
can be set to “make up” this loss. Do not
There are two switches and one potentiometer on the front panel of the Generation II.
In addition, there is a trim potentiometer
accessible via an opening in the front panel.
There is no power switch; the Generation II
is designed for continuous operation. Not
having a power switch means that the unit
cannot be accidently turned off.
Mode Switch
The mode switch controls the overall sound
of the Generation II. The mode switch is
active only when the internal system status
switch is set to the front panel position. In
the music position, the full audio bandwidth
of the input signal is simulated. This mode
is appropriate for audio material with little or
no voice only content. In the music & voice
position, the input signal is sent through a
band-reject filter prior to getting sent to the
simulator circuits. This creates stereo simulation over the low and high frequency
range, while limiting simulation in the voice
band. This mode is appropriate for audio
material that contains voice only content,
such as a film track or television show.
Issue 3, July 1991 Generation II User Guide
Page 8 Studio Technologies, Inc.
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