User Guide
Issue 1, December 2015
This User Guide is applicable for serial numbers:
M211-00151 and later
Copyright © 2015 by Studio Technologies, Inc., all rights reserved
www.studio-tech.com
50616-1215, Issue 1
This page intentionally left blank.
Table of Contents
Revision History ............................................................ 4
Introduction ................................................................... 5
System Features .......................................................... 5
Installation and Setup ................................................... 9
Configuration ................................................................ 13
Operation ...................................................................... 21
Technical Notes ............................................................ 24
Specifications ............................................................... 29
Appendix A ................................................................... 30
Appendix B ................................................................... 31
Block Diagram
Model 211 User Guide Issue 1, December 2015
Studio Technologies, Inc. Page 3
Revision History
Issue 1, December 2015:
1. Initial release.
Issue 1, December 2015 Model 211 User Guide
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Introduction
What This User Guide Covers
This User Guide is designed to assist
you when installing, configuring, and using Model 211 Announcer’s Consoles with
serial numbers 00151 and later. Additional
background technical information is also
provided. A product block diagram is included at the end of this guide.
System Overview
The Model 211 Announcer’s Console is
designed to serve as the audio control
center for announcers, commentators, and
production talent. The tabletop unit is suited
for numerous applications including on-air
television sports broadcasting. The Model
211 integrates all on-air, talkback, and cue
audio signal routing into one compact system. Ease of use, configuration flexibility,
and sonic excellence are some of the unit’s
highlights.
The Model 211 is compatible with many
broadcast and audio system environments.
Standard connectors are used to interface
microphone, headphone, talkback, and
talent cue signals. Whether it’s microphone
switching, talkback output, or headphone
cue feed, superior audio quality is maintained. A microprocessor provides the
Model 211’s logic power, allowing exacting control of the unit’s operation. A range
of configuration choices allow the desired
operating parameters to be easily selected.
While flexible, the user is presented with an
easy-to-use set of controls and indicators.
A truly next-generation product, extensive
research into the needs and desires of field
production personnel was integral to the
Model 211’s creation. Target applications
include on-air television, radio, streaming,
Figure 1. Model 211 front and back views
and production applications. Specialized
features are included to allow the Model 211
to be used in a variety of other audio applications
ment and voice-over/narration booths.
. These include stadium announce-
System Features
Microphone Input
A high-performance microphone preamplifier circuit provides low-noise/low-distortion
amplification over a 20 to 60 dB gain range.
The gain is adjustable in 10 dB steps. The
input is compatible with balanced dynamic
Model 211 User Guide Issue 1, December 2015
Studio Technologies, Inc. Page 5
or condenser-type microphones. The
microphone power source meets the
worldwide P48 phantom power standard.
The preamplifier’s gain can also be set
for 0 dB, allowing a line-level audio signal
to be connected. This could prove useful
in special applications such as when an
external preamp or mic processor is being
used. An LED indicator serves as an aid
for optimizing the setting of the preamplifier’s gain. The output of the microphone
preamplifier is used by the main output as
well as being routed to the compressor
circuit that supports the talkback function.
Main and Talkback Outputs
The Model 211 provides one main and
one talkback output. The main output is
designed to serve as the on-air, stadium
announcement, or other primary audio
feed. With a nominal level of –2 dBu, it is
designed as a fully professional interface
with high output capability, low distortion,
and low noise. It features a high-quality
transformer expressly designed for driving
long broadcast cable runs. The talkback
output is intended to provide production
trucks, control rooms, or support personnel with a talent-originated cue signal. The
talkback output is transformer-coupled
with a +4 dBu nominal signal level. It
contains resistors in series with its output
connections, allowing the talkback output
from multiple units to be directly summed
(combined).
For non-on-air applications, a specialModel 211 feature can be enabled, placing the
unit in a “production” mode. This allows the
main output to be used as a second talkback output. In this configuration the unit
can be even more powerful when used in
a live-event application, such as serving as
a master console for a production director.
Dynamic Range Control
A studio-quality compressor circuit is
provided to control the dynamic range of
the signal coming from the microphone
preamplifier. Far from a simple “clipper,”
the circuit utilizes a sophisticated lasertrimmed voltage-controlled-amplifier (VCA)
integrated circuit for quiet, low-distortion
level control. The signal from the compressor is always used by the talkback output.
In addition, the audio source for the main
output can be selected to be either the output of the microphone preamplifier or the
output of the compressor. While possibly
inappropriate for major on-air situations,
having dynamic range control of the main
output can offer increased effectiveness
for many applications. These could include
stadium announcement positions, sports
events using non-professional on-air talent,
and situations where cable crosstalk is of
concern.
User Controls and Status
Indicators
Two pushbutton switches, three LED indicators, and two rotary controls provide
the user with a clear, easy-to-use interface.
One pushbutton switch controls the status
of the main output. This is the audio output intended for on-air, announcement, or
other primary uses. Two LEDs display the
on/off status of the main output. A second pushbutton switch controls the status
of the talkback output. This is the audio
output used to communicate with producers, directors, spotters, or other behindthe-scenes production personnel. A status
LED is associated with the talkback button.
Two rotary controls allow the user to adjust
the level of the headphone output.
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Flexibility
A large part of the Model 211’s unique
power is the ability to configure the operation of the main output and talkback
functions. To meet the needs of the many
specific broadcast and production applications, a variety of button operating modes
is available. The main output button can
be selected to operate from among four
modes. In the “push-to-mute” mode the
button performs a momentary mute of the
main output. In this way a “cough” button
function is created, something typically
required for television sports broadcasting. In the “push-to-talk” mode the button
provides a momentary active function
for the main output. This mode would be
appropriate for applications such as stadium announcement. An alternate action
“latching” configuration allows the button
to enable or disable the main output as
desired. This is useful in radio broadcasting, announce-booth, or voice-over applications. The fourth mode provides a hybrid
function, supporting both push-to-talk and
tap-to-enable/tap-to-disable operation. This
operation is similar to that found in many
broadcast intercom system user stations.
The button associated with the talkback
function can be configured to operate
from either of two modes. One of the
modes supports a “push-to-talk” function.
This is typically used for on-air broadcast
applications. The other mode provides a
hybrid function, the operation of which is
discussed in the previous paragraph. The
hybrid mode is especially useful when the
Model 211 is used in a production-support
application.
Cue Sources
Two line-level audio sources can also be
connected to the Model 211. Possible signal sources include audio consoles, matrix
intercom systems, and off-air receivers.
The connected signals can be from two
independent sources or could be a stereo
audio feed such as would be associated
with a broadcast music event. Two trim
potentiometers, located on the bottom of
the unit, allow signals with wide nominal
audio levels to be cleanly interfaced. Each
source can be individually assigned to the
left channel, right channel, or both left and
right channels of the headphone output.
This allows a wide variety of stereo and
mono headphone mixes to be created.
Using the optional IFB Input Card Kit
broadcast-standard 2-channel powered
(“wet”) IFB circuits can also be connected
to the Model 211. In this way an IFB (“interruptable foldback”) audio signal can
be used as a source of headphone cue
audio signals. (But note that the connected
IFB circuit will not be able to power the
Model 211; only the audio signals will be
interfaced!) The two audio signals associated with the IFB input can be assigned
to either or both of the headphone output
channels. Originating in production trailers,
control rooms, or remote locations, an IFB
source typically provides DC power and
program-with-interrupt audio on one channel and program-only audio on the other.
The IFB Input Card Kit also allows direct
connection to single- and dual-channel
party-line (PL) intercom circuits. This can
be useful when applications will benefit
from intercom audio channels being used
for headphone cue signals. But be aware
that no talkback into the PL circuits is possible, nor is it possible to power the Model
211 from the party-line circuit.
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Headphone Output
Two rotary controls are provided for user
adjustment of the headphone output
levels. For application flexibility the actual
function of the two “pots” is configurable.
For traditional on-air sports applications
they can be selected to the dual-channel
(“level/level”) mode which provides independent control of the left- and rightchannel volume. For use with dual-channel
cue signals, or to support user preference,
the stereo (“level/balance”) mode can be
selected. In this mode one control adjusts
the overall level of both the left and right
channels, while the other allows adjustment of the left/right level balance. To
help minimize the chance of broadcast
cues being missed, both level control
modes can be configured so that a minimum headphone output level is maintained. Alternately, the headphone output
can be set to fully mute when the controls
are at their minimum position.
Provision has been made to support
applications where a monaural cue feed
is desired. A configuration switch allows
the summing (combining) of the selected
left and right headphone sources. In addition to creating a dual-channel mono
output it also allows the level controls to be
configured as a simple 2-channel mixer.
The headphone output was designed to
meet the needs of contemporary headphones and headsets. Specifically, the
output circuits act as voltage, rather than
power, drivers. In this configuration they
can provide high output levels with very
low distortion and noise, along with minimal current consumption. The output circuits are configured to safely drive stereo
or mono loads. This ensures that all types
of headphones, headsets, and earpieces
can be directly connected.
Audio Quality and Protection
The Model 211’s circuitry is carefully
tailored to provide excellent audio performance. Professional-quality components
are featured throughout. For reliability all
audio routing is performed using solidstate devices. In all critical audio paths,
“clickless” electronic switches provide
noise-free control. All audio inputs and
outputs make extensive use of protection components. This limits the chance of
damage from ESD and other undesirable,
yet real-world, hazards.
Power Source
The Model 211 derives its operating power from an external nominal 24 volt DC
source. Internal switch-mode power supply
circuitry uses the incoming 24 volt source
to generate the various voltages required
by the Model 211’s circuitry, including
P48 phantom. A universal input/24 volt DC
external power supply is included
with each Model 211 unit.
Relay Contacts
The Model 211’s circuitry includes two
general-purpose relay contacts to allow
specialized configurations to be created.
Under software control, the form-A (normally open) solid-state relay contacts
follow the state of the main and talkback
output functions. Taking advantage of the
locations provided for additional XLR connectors, a technician may easily implement
a variety of functions such as a mic active
indication, audio muting during talkback,
or audio insertion control.
Configuration
Model 211 configurations are made using
a number of DIP switches. One 8-position
switch assembly is used to set the gain of
Issue 1, December 2015 Model 211 User Guide
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the microphone preamplifier, the on/off status of phantom power, and the headphone
stereo/mono mode. A second 8-position
switch assembly configures which of the
line-input and optional auxiliary input audio
sources are routed to the headphone
output. A third 8-position switch assembly communicates the desired operating
modes to the microprocessor. All switches
are accessible via the bottom of the Model
211’s enclosure; the unit does not have to
be disassembled. Changes made to any
of the configuration parameters become
active immediately. To prevent unwanted
access to the configuration switches a
security plate, included with each unit, is
attached to the bottom of the enclosure.
Connectors
The Model 211 uses standard connectors
throughout. The microphone and line-level
inputs use 3-pin female XLR connectors.
The main and talkback outputs use 3-pin
male XLRs. A ¼-inch 3-conductor jack is
used for the headphone output. The external source of 24 volt DC power is connected by way of a 2.1 x 5.5 mm “locking”
coaxial power jack.
In the world of broadcast and production
audio it’s fair to say that applications vary
widely. To this end, one or two additional
XLR connectors can easily be mounted
into the Model 211’s back panel. Multiple
3-position headers located on the Model
211’s circuit board provide technician access to all input and output connections.
Using a factory-available interface cable
kit allows a Model 211 to be optimized to
meet the exact needs of specific applications. For example, some applications may
prefer to use a multi-pin XLR connector to
interface with a headset. This can easily be
accomplished by adding the appropriate
5-, 6-, or 7-pin XLR connector and making a f
plications may benefit from having “mult”
or “loop-through” connections, something
easily incorporated into a Model 211.
An optional IFB input card, as previously
discussed, can also be mounted in one
of the spare XLR connector positions.
ew simple connections. Other ap-
200-Series Announcer
Console Products
The Model 211 is just one in a series of
announcer console products available from
Studio Technologies. For applications that
require an alternate set of features the
other products in the 200-Series should
be reviewed. Complete information is available on the Studio Technologies website.
Installation and
Setup
In this section interconnections will be
made using the input and output connectors located on the Model 211’s back
panel. Microphone, cue audio, main output,
and talkback output signals are interfaced
by way of 3-pin XLR connectors. A ¼-inch
3-conductor phone jack is provided for the
headphone output. A 2.1 x 5.5 mm coaxial
jack allows connection of an external
24 volt DC power source.
System Components
Included in the shipping carton are the
following: Model 211 Announcer’s Console,
user guide, button label sheet, and 24 volt
DC power supply.
Model 211 User Guide Issue 1, December 2015
Studio Technologies, Inc. Page 9
Microphone Input
The Model 211 is compatible with balanced dynamic and condenser microphones. Depending on the application,
the microphone may be part of a headset,
or be an independent handheld or standmounted model. The Model 211’s P48
power source will support essentially all
phantom-powered microphones. The quality of the Model 211’s microphone preamplifier and associated circuitry is such that
special applications may benefit from using
“high-end” microphones. If selected appropriately, models from manufacturers such
as AKG, Beyerdynamic, DPA, Neumann,
Sennheiser, and Shure will perform very
well in Model 211 applications.
Microphone interconnection is made by
way of a 3-pin female XLR connector
which is located on the Model 211’s back
panel. The mating connector (male) should
be wired so that pin 2 is signal high (+ or
hot), pin 3 is signal low (– or cold), and
pin 1 is shield. It’s possible that an unbalanced microphone will also work correctly.
In this case, the mating connector (male)
should be wired so that pin 2 is signal high
(+ or hot), and signal common/shield is
connected to both pins 1 and 3.
As of the writing date of this user guide,
the Sennheiser HMD 26 headset is very
popular for on-air sports broadcasting
use. A fine product, it works very well with
the Model 211. Note that adding the suffix “-XQ” to the headset’s full part number
(HMD 26-600-XQ) specifies a 3-pin male
XLR connector for the dynamic microphone and a ¼-inch 3-conductor plug for
the stereo headphones. This configuration
is very useful, allowing the headset to work
directly “out of the box” with the Model 211.
If the writer may digress for a moment to
recount a story… an audio dealer once
shared a secret with me concerning headsets. He loved selling the “lower-end” (less
expensive) models of name-brand headsets,
which he did by the veritable “boatload.”
Why? Because these usually broke soon
after going into service! He knew that on a
regular basis he’d receive orders for more of
them. Had these users, from the beginning,
purchased only premium-quality headsets,
their total cost of ownership would have
been much less. Enough said…
Headphone Output
The Model 211’s headphone output is compatible with stereo or mono headphones,
headsets, or earpieces. Connecting devices
with a nominal impedance of 100 ohms
or greater is preferred. This shouldn’t be
an issue as essentially all contemporary
devices meet this condition.
Devices are connected to the headphone
output by way of a ¼-inch 3-conductor
phone jack located on the Model 211’s
back panel. As is standard for stereo headphones, the left channel is connected to the
“tip” lead of the ¼-inch headphone jack. The
right channel is connected to the “ring” lead
of the jack. Common for both channels is
connected to the “sleeve” lead.
Devices with ¼-inch 2-conductor “monaural”
plugs can also be used with the Model 211’s
headphone output. In this arrangement
only the tip lead (left channel) will be active.
The 2-conductor plug will physically connect
(“short”) the ring lead (right channel) to the
sleeve lead (common). Technically this won’t
damage the circuitry associated with the
right-channel headphone output since 100
ohm protection resistors are electrically in
series with the headphone output circuits.
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Main Output
The main output is intended to be the “onair” signal that connects to the input of an
audio console. The output is transformer
balanced with a nominal signal level of
–2 dBu. The actual level will depend on the
gain setting of the microphone preamplifier, sensitivity of the microphone, and how
loudly the talent speaks into the microphone. The transformer used in the main
output is intended for professional broadcast applications. It has a low output impedance and can drive lengthy cable runs
with no difficulty. It is capable of driving 600
ohm loads but performs best with loads of
2 k ohms or greater. (This should not prove
to be an issue as virtually all contemporary
audio equipment has a relatively high input
impedance.) As the secondary winding of
the output transformer connects directly to
the main output connector, care should be
taken so that DC voltage is never present
on the interconnecting cable.
The main output is interfaced by means
of a 3-pin male XLR connector located on
the Model 211’s back panel. The interconnecting cable’s mating connector (female)
should be wired so that signal high (+ or
hot) is on pin 2 and signal low (– or cold)
is on pin 3. The cable’s shield can be connected to pin 1, but it will have no function.
To limit the chance of grounding interaction
between the Model 211 and connected
equipment, pin 1 on the main output’s
connector is isolated from any point in the
Model 211. The fact that pin 1 “floats” will
minimize the chance of hums, noises, or
buzzes being present on the equipment
connected to the main output.
Talkback Output
The talkback output is intended for connection to control rooms, production trailers,
or other locations where talent- originated
voice cues are required. The talkback output is tr
ansformer balanced with a nominal
level of +4 dBu. To enhance talkback audio
quality, the compressor circuit controls the
dynamic range of the signal coming from
the microphone preamplifier.
For protection against accidental connection to cables that have DC power present,
the talkback output is capacitor coupled.
Also in series with the talkback output connections are 300 ohm resistors, making
the effective output impedance approximately 600 ohms. These resistors create
a passive summing network, allowing talkback outputs on multiple Model 211 units
to be connected together.
The talkback output is connected by way
of a 3-pin male XLR connector which is
located on the Model 211’s back panel.
A mating connector (female) should be
prepared so that signal high (+ or hot) is
expected on pin 2. Signal low (– or cold)
should be expected on pin 3. The cable’s
shield can be connected to pin 1. But, as
with the main output, in order to minimize
the chance that ground-interaction problems will arise, pin 1 of the talkback output
connector is isolated from the Model 211’s
chassis and circuitry. By making pin 1
“float,” the often-feared “ground loop”
problem shouldn’t arise.
The talkback output is intended to drive
lengthy cable runs that are frequently part
of a remote broadcast application. While
the talkback output circuitry is not intended
to be “on-air” quality, overall audio performance should be very good. Devices
connected to the talkback output include
amplified loudspeakers, analog inputs on
intercom systems, and input channels associated with audio consoles. Connecting
Model 211 User Guide Issue 1, December 2015
Studio Technologies, Inc. Page 11
the talkback output to devices that allow
easy control of the signal level can be
helpful. For example, connecting to a spare
input channel on an audio console will provide the flexibility to add gain or attenuate
as required. A talkback-associated output
connection on the audio console can then
connect to the final destination(s).
As previously mentioned, the talkback
outputs on multiple Model 211 units can
be directly connected together. Using a
simple “Y” or “W” cable, this passive summing (adding together) of talkback signals
allows one audio cable to serve as a master talkback path. A side effect when using
this passive summing technique is that signal attenuation will occur. The audio quality
won’t suffer appreciably, but an audio “pad”
is created. If two talkback outputs are
connected together, a signal attenuation
of 6 dB can be expected. Connecting three
talkback outputs together will result in
9.5 dB of attenuation. And four talkback
outputs “multed” together will lead to 12 dB
of attenuation. In most cases this attenuation won’t pose a problem. Typically a device that receives the talkback signal, such
as an amplified loudspeaker, will have a
method of adjusting its input sensitivity.
Line Inputs
The Model 211 allows two line-level audio
sources to be connected. These sources
can be individually routed to the left channel, right channel, or both the left and right
channel of the headphone outputs. The
inputs are balanced, transformer-coupled
with a nominal impedance of 10 k ohms.
Capacitors, in series with the transformer’s
input leads, prevent a DC voltage present on a connected source from impacting
performance. The line inputs are compatible with signals that have a nominal level
of –12 dBV to +6 dBu. Two trim potentiometers
, located on the bottom of the Model
211’s enclosure, allow signals over this
wide nominal level range to be effectively
utilized. Audio sources are connected to
the line inputs by way of 3-pin female XLR
connectors which are located on the unit’s
back panel. Prepare the mating connectors (males) so that pin 2 is signal high
(+ or hot), pin 3 is low (– or cold), and pin
1 is shield. If connecting a source in this
manner results in hum or noise, it’s possible that removing the shield connection
from pin 1 can eliminate the issue. With an
unbalanced source connect pin 2 to signal
high (+ or hot) and both pins 1 and 3 to
shield. If connecting an unbalanced source
in this manner results in hum or noise,
connect pin 2 to high (+ or hot) and pin 3
to shield; leave pin 1 not terminated
DC Power Input
An external source of nominally 24 volt DC
power must be connected to the Model
211 by way of a 2.1 x 5.5 mm coaxial power jack which is located on the back panel
of the unit. The center pin of the jack is the
positive (+) connection. While the requirement for the external source is nominally
24 volts, correct operation will take place
over a 20 to 30 volt range. The Model 211
requires 70 milliamperes at 24 volts DC
for correct operation.
Included with each Model 211 is a 24 volt
DC external power supply. The power supply’s DC output cable has been terminated
with a Switchcraft® S760K coaxial power
plug. This “locking” type of plug correctly
mates with the Model 211’s 24 volt DC
input jack. The locking feature is important,
allowing the external power source to be
securely attached to the Model 211.
Issue 1, December 2015 Model 211 User Guide
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Pushbutton Labeling
The two pushbutton switches used in the
Model 211 were selected for several reasons. Foremost was the fact that they are
highly reliable, using gold-plated contacts
for long life in less-than-ideal environments. A second reason was that applying
customized labels to the button caps would
be very simple. The labels, text printed on
clear material, are placed under the clear
caps on the top of the buttons.
From the factory the left button is labeled
COUGH and the right button is labeled
TALKBACK. This was selected to be appropriate for many on-air applications in
English-speaking locations. But it’s expected that these may need to be changed to
meet the needs of specific applications.
As a “head start” for some applications,
a clear sheet with a number of commonly
used English-language button designations printed on it is included in the shipping carton. These were created at the
factory using a standard personal computer graphics program and laser printed onto
3M CG3300 or equivalent transparency
film. The desired button labels can be cut
out with a pair of scissors or an X-ACTO®
knife following the printed guide lines that
indicate the required size.
The clear lens on top of each button cap
can be removed with a fingernail or small
screwdriver. Be certain not to scratch the
button if a screwdriver or other small tool is
used. The clear label can be removed and
replaced. The button cap is then snapped
back into the top of the button housing using finger-pressure only. No tool is required
to replace the button cap.
If you need to make your own labels the
process is quite simple. Use a personal
computer to create the desired text. The
finished label size should be 0.625-inches
(15.8 mm) square. The completed artwork
can then be printed on transparency film
sheets using a laser or inkjet printer. These
sheets are readily available from most office supply stores. A pair of scissors or an
X-ACTO knife will complete the task.
Configuration
For the Model 211 to support the needs
of specific applications a number of
operating parameters must be configured.
These include microphone preamplifier
gain, phantom power on/off, headphone
source selection, headphone stereo/mono
mode, and operating modes. Three
8-position DIP switch assemblies are
used to establish the desired configuration.
These switch assemblies are referred to
as SW1, SW2, and SW3, with individual
switches designated as SW1-1, SW1-2,
etc. The switch assemblies are accessed
through openings in the bottom of the
Model 211’s enclosure. The enclosure
does not have to be disassembled to gain
access to the switches.
To prevent unauthorized personnel from
changing the configuration settings, a
security plate is attached to the bottom
of the Model 211’s enclosure. For convenience, the security plate provides a
summary of the configurable parameters
and related information. Refer to Appendix
A for a representative view. The security
plate is held in place by means of four
rubber bumpers (“feet”) that have built-in
screws. Using your fingers, remove the four
bumpers so that the plate can be removed.
Refer to Figure 2 for a detailed view of the
configuration switch assemblies.
Model 211 User Guide Issue 1, December 2015
Studio Technologies, Inc. Page 13
Figure 2. Bottom view of Model 211 showing
configuration switches and trim pots
Microphone Preamplifier Gain
and Phantom Power
Five switches are used to set the gain of
the microphone preamplifier. One switch
is used to select the on/off status of the
phantom power supply.
Microphone Preamplifier Gain
Switches SW1-1 through SW1-5 are used
to select the gain of the microphone preamplifier
and 60 dB; 0 dB (no gain) is also available.
Only one switch should be enabled at a
time. There’s no problem changing the gain
setting while the unit is operating. Audio
clicks or pops might occur during gain transitions, but this shouldn’t be a major issue
. The choices are 20, 30, 40, 50,
Figure 3. Microphone preamplifier gain switch
settings
as long as associated monitor loudspeakers
are temporarily attenuated or muted.
Selecting the correct amount of gain for an
application might take a little experimentation. The goal is to bring the mic’s signal
up to line level, nominally –2 dBu for the
Model 211’s main output. Operating at this
signal level will help to ensure the delivery
of “clean” audio to the connected device.
It’s also acceptable to connect a line-level
audio source to the microphone input. In
this case selecting 0 dB (no gain) would
be appropriate.
The output of the Model 211’s microphone
preamplifier is used by the main output and,
by way of the compressor circuit, the talkback output. So creating a nice “hot” signal
will help to maintain the audio quality, specifically a high signal-to-noise ratio, when
driving lengthy cable runs.
Unfortunately, there’s no “perfect” gain setting that this guide can recommend. The
o issues that impact the setting are
tw
output sensitivity of the connected microphone and the acoustical output le
vel of
Issue 1, December 2015 Model 211 User Guide
Page 14 Studio Technologies, Inc.
the microphone’s user. With some headset
microphones, such as the Sennheiser HMD
26, selecting an initial setting of 40 dB is
appropriate. Users who speak loudly might
need to have the gain reduced to 30 dB.
Quiet users might need 50 dB of gain.
An LED indicator is provided as an aid
in correctly setting the gain of the microphone preamplifier. Red in color, this LED
is located on the back panel adjacent to the
mic input connector and is labeled COMP.
Technically, this red LED lights whenever
the compressor circuitry is controlling the
dynamic range of the signal coming from
the microphone preamplifier. The threshold
is set to be 2 dB above the Model 211’s
nominal internal operating level. So a good
“rule of thumb” is to adjust the gain of the
microphone preamplifier such that the compressor active LED lights (“flashes”) when
the connected microphone is sending signal
peaks. During normal operation the LED
should not remain fully lit when audio
is present on the mic input.
Note that if no gain switch is set to its active (on) position the preamplifier will operate at unity (0 dB) gain. This is provided for
compatibility when line-level signals need
to be connected to the microphone input.
However with a microphone connected as
the input source the 0 dB setting should
never be used. The issue is that with no
gain added to the microphone input signal,
the relative noise floor on the main and
talkback outputs will be much too high.
Phantom Power On/Off
The Model 211 can provide P48 phantom po
wer to the connected microphone.
Switch SW1-8 controls whether or not
phantom power is active. By phantom
power’s very nature it could be left applied
to the microphone input at all times. But
generally people prefer to turn it off unless
required for a specific microphone.
It’s important to remember that the compressor active LED is used to assist in setting
the gain to the optimal value. It doesn’t
necessarily indicate that the main output’s
Figure 4. Phantom power switch settings
signal is being compressed. Unless specifically configured to perform otherwise, the
output of the compressor is only used for
the talkback output.
Headphone Source Selection
Switch assembly SW2 is used to configure
the source or sources that are routed to the
stereo headphone output. The headphone
It’s expected that the 20 and 60 dB gain
settings will not often be used. But there are
always exceptions and that’s why they were
included. It’s possible that with a very “hot”
microphone, such as a phantom-powered
condenser, 20 dB of gain could be correct.
It’s also possible that a microphone with a
very low-level output, such as a ribbon-type,
would need 60 dB of gain. But in general,
sources are line input 1, line input 2, auxiliary input 1, and auxiliary input 2. The line
inputs are provided by way of the XLR connectors located on the Model 211’s back
panel. The auxiliary inputs are available on
the Model 211’s main circuit board and are
only accessible if an optional IFB input card
has been installed or a special Model 211
configuration has been implemented.
the 30, 40, and 50 dB gain settings will
serve most applications.
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Each of the available input sources can be
assigned to the headphone output’s left
channel, right channel, or both the left and
right channels. The Model 211’s circuitry allows any combination of input assignments
to be made.
Note that in some cases a user may wish
to wear a headset or a pair of headphones
in a left/right orientation opposite of what is
usual. In this situation the transducer designated for the left ear would actually supply
audio to the user’s right ear, and vice versa.
A specific application when this occurs is
where on-air talent needs to have a headset’s boom microphone come across the
right side of their face, rather than the moretypical left side. In this case it’s important to
select the left- and right-channel headphone
source assignment accordingly. With the
Model 211’s flexible source selection there’s
no reason why users, such as on-air talent,
shouldn’t have their cue sources assigned
correctly.
There may be cases where a monaural
“single-muff” headset or headphone will
be connected to the Model 211’s headphone output. In this case the desired
source(s) should be routed only to the left
channel. No sources should be assigned
to the right channel. This will eliminate the
short-circuit current that could occur when
a 2-conductor (monaural) plug is mated
with the Model 211’s 3-conductor (stereo)
headphone output jack.
Headphone Output Mode
Switch SW1-6 allows a monaural headphone output to be created. This is accomplished by summing (adding) the selected
left- and right-channel cue signals. The
combined signals are sent to both the leftand right-channel headphone output driver
circuits. The outputs of these circuits connect, by way of 100 ohm series protection
resistors, to the headphone output jack.
The headphone output monaural mode feature was specifically included so that a special 2-channel headphone mix mode can be
created. By enabling the mono mode, the
two front-panel user level controls (“pots”)
can be used to create the desired “mix” of
signals being sent to the headphone output.
Many applications, especially in production
settings, can benefit from this capability.
The desired cue sources must be carefully
assigned to take advantage of the monaural mode. The first cue source should be
assigned, using the appropriate configuration switch, to the left channel. Its output
level will be adjusted by the left control. The
second cue source should be assigned to
Figure 5. Left and right channel headphone
source selection settings
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the right channel. Its output level will be
adjusted by the right control.
Figure 6. Headphone output mode settings
There is one limitation related to the
headphone mono output mode. It’s the
fact that the output will be 2-channel monaural. Whatever signal is present on the
headphone output’s left channel will also
be present on the right channel. A stereo
headphone mix can’t be created. But in
most cases this limitation won’t overshadow the benefit of being able to create the
mix. For signal-flow clarification please
review the block diagram located at the
end of this user guide.
Operating Modes
The eight switches associated with switch
assembly SW3 are used to configure the
Model 211’s operating modes. Technically,
these switches “talk” to the microcontroller
integrated circuit and associated software
that give the Model 211 its “smarts.” The
software has been carefully designed
to provide a number of different ways in
which the unit can function. It’s critical to
carefully review the available options and
choose the ones that best meet the needs
of a specific application. Note that switches
can be changed even while the Model 211
is powered up and operating. The unit’s operating characteristics will change in “realtime” in response to configuration changes.
Main Output Button Mode
Switches SW3-1 and SW3-2 configure
w the main output button functions.
ho
Figure 7. Main output button mode settings
There are four available modes:
• Push to mute: In this mode the main out-
put is normally active. The main output
will mute whenever the button is pressed
and held. This is the “cough” mode typically used for on-air sports broadcasting
applications.
• Push to talk: In this mode the main out-
put is normally muted. The main output
will become active whenever the button
is pressed and held.
• Alternate action: In this mode the main
output will change between its active
and muted state whenever the button is
pressed. Upon power up the main output
will be in its muted state.
• Hybrid: This mode is a combination of
push to talk and alternate action. It’s
similar to the way talk buttons function
on user stations associated with broadcast and production intercom systems. If
the button is pressed and held, the main
output will become active until the button
is released. If the button is momentarily
“tapped” the main output will change
state. Upon power up the main output
will be in its muted state.
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Talkback Output Button Mode
Switch SW3-3 configures the way the talkback output button functions.
Figure 8. Talkback output button mode settings
Two modes are available:
• Push to talk: In this mode the talkback
output is normally muted. The talkback
output will become active whenever the
button is pressed and held.
• Hybrid: This mode is a combination of
push to talk and alternate action. If the
button is pressed and held, the talkback
output will become active until the button
is released. If the button is momentarily
“tapped” the talkback output will change
state. Upon power up the talkback output
will be in its muted state.
Headphone Output Operating
Modes
The user is provided with two rotary level
controls (“pots”) that are associated with
the stereo headphone output. Switches
SW3-4, SW3-5, and SW3-6 are used to
configure the way the controls function.
With just these three switches a wide
range of operating modes can be configured. Carefully reviewing the capabilities
of the available functions may prove
worthwhile.
Dual-Channel or Stereo Mode
Switch SW3-4 is used to select whether
the controls pro
level”) or stereo (“level/balance”) mode of
vide a dual-channel (“level/
Figure 9. Headphone control mode settings
operation. In the level/level mode the two
controls operate independently, each controlling the level of one of the headphone
output channels. This mode is generally
used for on-air broadcast applications
where independent cue signals are provided to the left- and right-headphone
channels. In the level/balance mode the
left rotary control sets the overall output
level for both headphone channels. The
right rotary control is used to adjust the
balance (the relative levels) of the left and
right channels. This mode is generally best
suited for applications where a stereo cue
source is being provided.
Reverse Left/Right Mode
Switch SW3-5 is used to select whether
the rotar
y controls are in the normal or
reverse left/right mode of operation. When
set to the normal mode, and level/level
mode is also selected, the left control
adjusts the level of headphone output’s left
channel. (This is the signal that appears
on the tip lead of the ¼-inch 3-conductor
jack.) The right control adjusts the level
of the right channel. When selected to
the normal mode, and the level/balance
mode is also selected, turning the balance
control in the counterclockwise direction
increases the perceived level of the left
channel, and vice versa.
As you may have already guessed, when
selecting the reverse left/right mode of operation everything is reversed! To be more
specific, when selected for reverse mode,
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Figure 10. Headphone control operation
settings
and the level/level mode is also selected,
the left control adjusts the headphone output’
s right channel (output jack’s ring lead)
while the right control adjusts the left channel. When set to the reverse mode, and the
level/balance is also selected, turning the
balance control in the counterclockwise
direction increases the perceived level of
the right channel, and vice versa.
The reverse mode is provided specifically
for cases where a headset’s left and right
earpieces are placed on a user’s head
in a reverse orientation. This ensures that
the user is provided with a consistent
and easy-to-use set of headphone level
controls.
Minimum Level Mode
Switch SW3-6 is used to configure the
headphone output’s minimum level. In the
–40 dB mode the minimum headphone
output level is 40 dB below maximum. The
headphone output channels will never fully
mute. This ensures that any audio signal
present on the selected Model 211 inputs
will alw
ays be present on the headphone
output. In most on-air broadcast applications this is the appropriate setting.
When the full mute mode is selected,
and the level/level mode is also selected,
moving either control to its fully counterclockwise position will cause its associated
channel to fully mute.
Figure 11. Headphone output minimum level
settings
When the full mute mode is selected,
and the level/balance mode is also selected, tur
ning the level control to its fully
counterclockwise position will cause both
headphone channels to mute. Turning the
balance control to either its fully clockwise or fully counterclockwise position will
cause the appropriate channel to mute.
Selecting the full mute mode may be appropriate for applications where minimizing
the chance of audio “leakage” is important. This could occur when the connected
headset or headphones are at times
placed on a desk or tabletop.
Main Output Source
Switch SW3-7 is used to select which
audio source is routed to the main output.
The choices are the output of the microphone preamplifier or the output of the
compressor circuit. For most on-air applications the output of the microphone
preamplifier is the desired source. This will
provide the most natural audio quality with
the potential for a large amount of dynamic
range.
In some applications it may be desirable
for the output of the compressor circuit to
be routed to the main output. Appropriate
applications could include on-air broadcast
situations where non-professional talent
is present. Controlling the dynamic range
of the audio signals on the main output
can limit the chance of cable crosstalk and
Model 211 User Guide Issue 1, December 2015
Studio Technologies, Inc. Page 19
Figure 12. Main output source settings
equipment overload. Another typical application where using the output of the compressor would be when the Model 211’s system
mode is selected for production. In this case
the main output would be used as an additional talkback output and dynamic range
control could be beneficial.
System Mode
Switch SW3-8 is used to configure the
verall operating mode of the Model 211.
o
Specifically, it determines how the main
output operates vis-à-vis the talkback output. Understanding how the two modes
impact overall system operation will ensure
that correct operation and maximum usability will occur. When selected to the on-air
mode, the main output will mute whenever
the talkback output is active. The on-air
mode should be selected for all on-air
broadcast applications. It’s imperative that
the main output be muted whenever on-air
talent uses the talkback output to communicate with production personnel.
Figure 13. System mode settings
When the system mode is set for production, the main output is never muted in response to the talkback output being active.
This mode allows the main output to be
used, for example, as an additional talkback
output. In this way the main and talkback
outputs can be used independently, with
neither impacting the other. This also allows
both buttons to be used simultaneously.
When selected for the correct application,
the production mode can prove to be very
useful. But it’s not appropriate for on-air use!
Adjusting the Line Input
Trim Pots
As has been previously mentioned, associated with the two line inputs are trim pots
that allow the input levels to be adjusted.
The two trim pots are accessible by way
of round openings in the bottom of the
Model 211’s enclosure. By adjusting these
trim pots, signals with a nominal level of
–12 dBV to +6 dBu can be effectively used
as cue sources. Unfortunately, there are
no definitive rules regarding how best to
adjust the trim pots, but some suggestions
may prove to be valuable. Depending on
how the line inputs are utilized, the trim pots
can be used to either adjust the absolute
level of each line input signal or to adjust
the relative level of the signals when compared to other sources. The following examples may provide some clarification.
Let’s begin with an application that has a
stereo cue source connected to the line inputs. The cue source selection switches are
configured to create a stereo headphone
output with line input 1 assigned to the left
channel and line input 2 assigned to the
right channel. Begin the trim pot adjustment
process by moving the user level controls
(located on the front panel) to their detent
(50% of rotation) positions. Then, with the
stereo cue source providing signal at its
normal level, adjust the trim pots to provide
a comfortable level to the connected headphones. The user can now, in response to
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changing conditions, adjust the front-panel
level controls as desired. Returning the
controls to their detent positions will always
provide the “reference” level to the headphone output.
Audio signals will not be present on the
outputs if correct power has not been supplied.
Specifically, the microphone does not
passively “cut through” to the main output
connector!
A second example has line input 1, line input 2, and auxiliary input 1 all providing cue
sources. Line input 1 might supply programwith-interrupt audio that is routed to the
headphone output’s left channel. Line input
2 might supply program-only audio that is
routed to the right channel. And auxiliary input 1, interfaced using a line-input card kit,
is connected to an audio source associated
with a sports event “spotter” position. This
source is routed to the headphone output’s
right channel. The input trim pot associated
with line input 1 can now serve a critical
role—adjusting the relative level of the
“spotter” audio as compared to the level of
line input 2. The trim pot allows the desired
“mix” to be created, providing the user with
an effective cue signal.
Conclusion
Once the switches have been set to the
desired configuration and the line input
controls adjusted as desired, the security
plate should be reattached. The four rubber
bumpers should be hand-tightened only. No
tools should be used.
Operation
At this point the desired input, output, and
power connections should have been made.
The button labels may have been revised.
Finally, the configuration switches should
have been set and the line input trim pots
adjusted as required. Normal operation
of the Model 211 can now begin. The unit
will begin functioning a few seconds after
the 24 volt DC power source is connected.
Upon Model 211 power up, the three
status LEDs will light in succession as a
firmware “boot up” indication. The unit will
then begin normal operation. Depending
on the selected configuration, one LED associated with the status of the main output
may be lit. The user is now presented with
two buttons, three LEDs, and two rotary
controls. These are simple to operate and
understand, as will be described in the following paragraphs.
Pushbutton Switches and
Status LEDs
Two pushbutton switches are used to
control the main and talkback outputs. The
way each operates depends on the selected configuration. Three LED indicators
are located adjacent to the buttons. They
reflect the status of the main and talkback
output functions.
Main Output Button and LED Indicators
The button on the left, factory labeled as
COUGH, functions according to the selected configur
located directly above the button, are associated with the status of the main output.
The green LED, located on the right, is lit
whenever the main output is active. This
could be considered as an “on-air” or mic
active indicator. At the least it should serve
as a “careful what you say” warning! If the
Model 211’s system mode is configured
to on-air, the red LED, located on the left,
will be lit when the main output is muted.
This indicates that it’s safe to speak as one
sees fit.
ation. Two LED indicators,
Model 211 User Guide Issue 1, December 2015
Studio Technologies, Inc. Page 21
If the Model 211’s system mode is configured to production, the red LED will never
light. This is to reflect the fact that the main
output button has now taken on a function
similar to that of the talkback output button.
To clarify, when the Model 211 is set to the
production mode, the red LED will never
light; the green LED will light whenever the
main output is active.
Main Output Button Modes
Push to mute: If this mode is selected
•
the main output is normally active. The
main output will mute whenever the button is pressed and held.
• Push to talk: If this mode is selected the
main output is normally muted. The main
output will become active whenever the
button is pressed and held.
• Alternate action: If this mode is selected
the main output will alternate between
its active and muted states whenever the
button is pressed. Upon power up the
main output will be in its muted state.
• Hybrid: This mode is a combination of
push to talk and alternate action. It’s
similar to the way talk buttons function
on user stations associated with broadcast or production intercom systems. If
the button is pressed and held, the main
output will become active until the button
is released. If the button is momentarily
“tapped” the main output will change
state. Upon Model 211 power up the
main output will be in its muted state.
Main Output vis-à-vis Talkback Activity
This short section applies only in the case
where the Model 211’s system mode is
configured for on-air and the main output
button mode is set to alternate action or
hybrid.
Talkback activity will always cause the
main output to be placed in its off state.
If the main output was in the “latched” on
state when talkback began, once talkbac
k activity ends that state will resume;
the main output will again be in its on
(“latched”) state.
Talkback Output Button and LED
Indicator
The b
utton on the right, factory labeled
TALKBACK, controls the talkback output.
The manner in which the talkback button
functions depends on the way it was configured. One LED indicator, green in color,
is located directly above the talkback button. It lights whenever the talkback output
is active. If the Model 211’s system mode
is selected to on-air, whenever the talkback
function is active the main output will be
placed in the muted state. If the Model 211
is selected to the production mode, the
status of the talkback output will not impact
the main output.
Talkback Output Button Modes
• Push to talk: If this mode is selected the
talkback output is normally muted. The
talkback output will become active when-
ver the button is pressed and held.
e
• Hybrid: This mode is a combination of
push to talk and alternate action. If the
button is pressed and held, the talkback
output will become active until the button
is released. If the button is momentarily
“tapped” the talkback output will change
state. Upon Model 211 power up the
talkback output is will be in its muted
state.
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Headphone Output Level
Controls
Two rotary controls (“pots”) are located on
the Model 211’s front panel and are associated with the headphone output. The
way the controls function depends on the
selected configuration. One configuration
parameter sets the controls to operate in a
level/level or a level/balance mode. Another parameter allows the left/right assignment of the controls to be reversed. A third
parameter selects whether the headphone
output channels will maintain a minimum
output level or can be fully muted.
Level/Level Mode
When set to the level/level mode, the two
controls operate independently. Each control sets the output le
the stereo headphone output. If configured
to the normal mode, the control on the left
side is used to adjust the level of the headphone output’s left channel. The control on
the right is used to adjust the level of the
right channel. If configured to the reverse
left/right mode, the control on the left side
adjusts the headphone output’s right channel. The control on the right adjusts the left
channel.
When in the level/level mode, and the minimum output level is set for –40 dB, turning
each control to its fully counterclockwise
position will place its respective output
level 40 dB below its maximum. This setting ensures that talent will never be fully
“isolated” from potentially important cue
signals. If present on the Model 211’s input
and assigned to the headphone channels,
some audio signal will always be present
on the headphone output. If set to the full
mute mode, turning each control to its fully
counterclockwise position will cause its
respective output to fully mute.
vel of one channel of
Each level control has a mechanical step
(detent) that is located at the halfway
(50%) position of its rotation range. This is
intended to serve as an aid to Model 211
users. In an ideal installation, setting the
controls to their detent position will result
in a comf
ortable headphone output level.
The user, in response to a changing operating environment, can then move the
level controls to get more or less level as
desired. The detent position will always
remain as a useful reference point. To
achieve this condition the audio level on
the connected IFB circuit, or line input, will
have to be calibrated as required. This is
somewhat counter to the usual mentality of
just providing the user with whatever level
comes up by default. Spending a few extra
minutes “trimming” the audio levels can
result in much happier, and more productive, talent.
Level/Balance Mode
When set to the level/balance mode, the
two controls operate together to adjust
the desired headphone output level. The
control on the left adjusts the overall level
of both the left and right channels. The balance control, located on the r
ight, adjusts
the relative left/right level balance. In this
mode the controls operate in a manner
reminiscent of a consumer audio amplifier or receiver. If set to the normal mode,
rotating the balance control in the counterclockwise direction reduces the level of the
right channel providing the user with more
perceived level in the left channel. If set
to the reverse mode, rotating the balance
control in the counterclockwise direction
reduces the level of the left channel providing the user with more perceived level in
the right channel.
Model 211 User Guide Issue 1, December 2015
Studio Technologies, Inc. Page 23
When in the level/balance mode and the
minimum output level is set to –40 dB,
turning the level control to its fully counterclockwise position will place both headphone output channels to 40 dB below
maximum. This ensures that talent will
never be fully “isolated” from potentially
important cue signals. In addition, rotating
the balance control to either its fully clockwise or fully counterclockwise position will
cause the applicable channel to be 40 dB
below its maximum. If set to the full mute
mode, turning the level control to its fully
counterclockwise position will cause both
the left and right channels to fully mute.
In addition, rotating the balance control to
either its fully clockwise or fully counterclockwise position will cause the applicable
channel to fully mute.
Each control has a mechanical step
(detent) that is located at the halfway
(50%) position of its rotation range. The
balance control will typically be set to its
center, detent position, making the level
of the left and right channels equal. In an
ideal installation, the level control can also
be set to its detent position and provide a
comfortable headphone output level. This
will allow the user, in response to their
preference or a changing environment,
to adjust the level and balance controls
as desired. The detent positions will always remain as a useful reference point.
To achieve this condition the audio level
on the connected IFB circuit, or line input,
must be adjusted as required. Spending
a few extra minutes “trimming” the connected audio levels, rather than just providing whatever happens to come up, should
prove worth-while. The result will be talent
that is more relaxed, and an overall production that works more smoothly.
Technical Notes
Grounding and Shielding
As previously discussed in this user guide,
the pin 1 connections on both the main
and talkback outputs’ 3-pin male XLR connectors are “floating,” i.e., not connected to
anything within the Model 211’s enclosure.
Some audio experts might take offense
to this, complaining that this should have
been left to the user or installer to be connected or disconnect as desired. However,
repeated field testing found that floating
pin 1 on the outputs was the key to maintaining quiet audio. From Fenway Park, to
the Orange Bowl, and then northwest to
Husker Stadium, lifting pin 1 did the trick.
A simple solution is available if an application does require that a ground be available on the main and talkback outputs’
interconnecting cables. All Model 211 XLR
connectors have a ground connection
that is made to the interfacing connector’s
metal “shell.” And most XLR connectors
have a pin or connection point available to
access its metal shell. By connecting the
cable shield to the mating connector’s shell
terminal, the common connection typically
found on audio interconnections is created.
Phantom Power
The Model 211 provides a 48 volt nominal
source of phantom power to support condenser-type microphones. It’s designed to
meet the P48 requirements as specified
in the IEC 61938 standard. The circuitry is
very simple: 6.85 k ohm resistors provide a
path from a 45 volt source to pins 2 and 3
of the microphone input connector. The resistors and the power source work together to provide 48 ±4 volts, up to a maximum
current of 10 milliamperes.
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Symptoms of Insufficient
IFB Input Card Kit
Power
A core part of the Model 211’s internal circuitry is a switch-mode power supply that
produces +45 volts, +12 volts, +5 volts,
and –12 volts. This power supply circuit
works very well as long as it is “fed” with
sufficient input voltage and current. “Sufficient” is defined as a minimum of 20 volts
and 70 milliamperes.
It’s worth discussing what will happen if the
power source falls below its specified minimum. Normal operation will continue until
the source falls to somewhere in the range
of 18-20 volts. As the voltage drops below
this range the Model 211’s internal power
supply will have reduced stability, operating in this manner until its low-voltage
shutdown circuit halts operation. Note also
that as the input voltage moves down from
24 volts the input current will rise proportionately to make up for the loss of power.
Travel Case
For portable applications it may be desirable to store and transport each Model
211 in a protective case. After much travel
with prototype announcer console units,
Studio Technologies’ personnel learned to
appreciate the Pelican Model 1450 case.
Purchased with the foam interior option, it
does an excellent job of holding one Model
211 and its associated 24 volt DC power
supply. Some applications may benefit
from selecting a larger case that would
also hold a related headset, cables, etc.
A larger case could also be selected that
would hold multiple Model 211 units. Pelican sells their products through a dealer
network, many of which can be located via
a web search.
The Model 211 is designed to directly
connect with line-level cue signals, also
sometimes referred to as “dry” broadcast
IFB circuits. However, there may be applications where it would be helpful to also be
able to connect to a powered (“wet”) IFB or
party-line (PL) intercom circuit. In this case
the Studio Technologies IFB Input Card Kit
(order code 31212) can be installed.
The IFB input card kit contains a printed
circuit board assembly with 3-pin female
XLR connector, an interconnecting cable,
and hardware. To install the kit is very
simple. The XLR connector is mounted
into one of the spare connector locations on the Model 211’s back panel. This
secures the connector and associated
printed circuit board to the enclosure. The
interconnecting cable is then used to link
the card and the Model 211’s main printed
circuit board assembly. One end of the
cable is plugged into the IFB input card’s
3-position header that is labeled OUT 1/2.
The other end of the cable is plugged into
the 3-position header connector that is
labeled AUX IN 1/2. This is located on the
main printed circuit board.
Several things are worth mentioning when
it comes time to actually using the IFB
input card. The two input channels are
transformer coupled with a nominal input
of –10 dBu and a nominal input impedance
of 10 k ohms. Capacitors in series with the
transformers’ primary windings provide isolation and protection from any DC voltage
present on the connected IFB or party-line
intercom circuit. It’s important to note that
DC power present on either or both pins
of the powered IFB input connector cannot
be used to power the Model 211. An external source of 24 volts DC must always be
connected.
Model 211 User Guide Issue 1, December 2015
Studio Technologies, Inc. Page 25
Note that if an IFB input card is installed
in a Model 211, the audio sources associated with the line-inputs and the powered
(“wet”) IFB circuit can be connected at
the same time. The audio sources will be
routed to the headphone outputs by way
of the headphone source configuration
switches. Each of the four possible audio
sources can be routed to the left-headphone output, the right-headphone output, or both headphone-output channels.
Details on how to use these switches are
provided in the Configuration section of
this user guide.
Additional Connector
Locations
Two spare connector locations are provided on the Model 211’s back panel. They
are labeled A and B. From the factory they
contain blank plates that can be readily
removed and replaced with a variety of
“XLR style” connectors. The spare connector locations are specifically included
so that a Model 211 can be customized to
meet the many specific needs that arise
in broadcast and related audio applications. Expected uses for these locations
include adding a 6- or 7-pin XLR connector
to allow direct connection of a broadcast
headset. Other uses include creating a
“loop through” or “mult” function for the
microphone input or headphone output
connections. A number of interface cable
assemblies, along with some special function kits, are available from Studio Technologies. Please refer to the website for
details on what is available.
The spare connector locations are compatible with the Neutrik DL-series of connectors. For flexibility, XLR versions are
available that provide from three to seven
contacts. For example, a compatible 3-pin
female connector would be Neutrik part
number NC3FD-L-1. The NC6FDS-L-1
is often used to suppor
a 6-pin female connector with the unique
Switchcraft® 6-pin arrangement. Other
connectors, such as the etherCON protected RJ45 and 3-conductor ¼-inch jack,
can also be installed. The 4-40 threadpitch hardware that secures the blank
plates to the Model 211’s back panel are
also intended to secure the replacement
connectors.
If connectors are added to the Model
211’s spare connector locations adding
labels to those connectors can be helpful.
For a great look it is recommended that
Brother® P-Touch ¼-inch (6 mm) labels be
created. Tape material that prints white text
on a black background works out well for
the Model 211. The Brother label cassette
number TX-3151, white on black, is appropriate for use with many of their printers.
t headsets. This is
3-Position Headers
In addition to the spare connector locations on the back panel, provision has
been made to allow easy interconnection
with the Model 211’s printed-circuit-boardmounted input and output connectors. This
was accomplished by including several
3- position male header connectors on the
Model 211’s circuit board. These headers,
on 0.1-inch centers, are wired in parallel
with some of the Model 211’s connectors.
This “no solder” solution makes customizing a Model 211 a simple process. The
headers, located on the Model 211’s printed circuit board, are Molex® part number
22-23-2031. They mate with Molex housing
number 22-01-3037.
To make the interconnection, separate
crimp terminals are attached to three loose
wires and then “snapped” into the housing.
Issue 1, December 2015 Model 211 User Guide
Page 26 Studio Technologies, Inc.
Molex part number 08-50-0114 specifies
crimp terminals that are appropriate for
22 to 30 gauge wires. These terminals are
available worldwide from sources such as
Digi-Key (www.digikey.com).
To make the process of connecting to the
Model 211’s headers a simple task an interface cable kit, order code 31087, is available from Studio Technologies. Each kit
includes five cable assemblies and a length
of heat-shrinkable tubing. Each cable assembly consists of a mating connector with
three color-coded wires attached. These
wires, approximately 12 inches in length,
allow convenient soldering to a connector
selected to be installed in a spare location
on the Model 211’s back panel. For reference, the wire color for pin 1 is gray, pin 2
is yellow, and pin 3 is blue.
The heat-shrinkable tubing is provided
so that the connector terminals or “solder
cups” can be insulated from each other.
It will also provide some strain relief to
the solder joints. Be certain to slip the desired length of tubing over the wire prior
to soldering a connection! (If the writer had
a dollar for every time he forgot to put tubing on a wire (or slip on a connector shell)
before making a solder connection...)
Most of the 3-position headers on the
Model 211’s main circuit board assembly
are located close to their related input or
output connectors. Other headers provide
access to functions such as the relays or
the remote control inputs. For details on the
headers please refer to Appendix B
at the end of this guide.
Remote Control Connections
Provision has been made on the Model
211’s printed circuit board assembly to
allow external switches or contact closures
to control the status of the audio signal
sent to the main and talkbac
3-position headers provide access to the
circuitry associated with the functions. Refer
to Appendix B for connection details. The
input circuitry is “active low,” with a 10 k
ohm resistor connected to +5 volts DC to
act as a pull up. A combination of resistors
and capacitors provide ESD protection.
k outputs. Two
Relay Contacts
The Model 211 provides two normally open
(not shorted) relay contacts for use in specialized applications. One is associated with
the main output and the other with the talkback output. Whenever audio is being sent
to the main output relay contact 1 will close
(short). And whenever audio is being sent to
the talkback output relay contact 2 will close
(short). The two relays operate under software control and are always active, whether
or not connections are made to them. Some
“head scratching” or “brainstorming” should
lead to a number of interesting ways to take
advantage of the relay contacts. Applications could include keying wireless transmitters, activating “on-air” lights, and muting
loudspeaker systems. To utilize the relay
contacts does require the talents of a qualified technician. This is because the Model
211’s enclosure must be disassembled and
the desired wiring scheme implemented.
For detailed information on interfacing with
the relay contacts refer to Appendix B at the
end of this guide.
Pushbutton Backlighting
For special applications, provision has been
made to allow LED illumination (“backlighting”) of the two pushbutton switches. This
may prove useful for applications where adequate room lighting is not available. It can
also serve in custom Model 211 configurations. It’s important to note that the button
Model 211 User Guide Issue 1, December 2015
Studio Technologies, Inc. Page 27
lighting is not intended to serve tally applications. It is strictly intended to provide
a moderate amount of illumination of the
button’s clear lens and associated labeling.
From the factory, LED lamps are not
installed in the pushbutton housings. The
housing of each pushbutton was designed
for inserting a pluggable T-1 bi-pin incandescent type but more modern leaded T1
LEDs work very well. The Model 211’s 5
volt DC power supply is connected to the
socket in each pushbutton housing by way
of 2.2 k (2200 ohm) resistors. With this
implementation, along with the recommended LED, only 1 milliampere per
LED is consumed.
It’s intended that high-efficiency white
LEDs be installed. They use very little DC
current and have essentially infinite life.
The recommended LED is the Kingbright
WP7104QWC/D which, as of the time of
this writing, is available from sources such
as Digi-Key (www.digikey.com) and Mouser Electronics (www. mouser.com).
The mating socket in each pushbutton
assembly is accessed by removing the
button’s lens cap, graphic label, and back
frosted lens. Once this is done installing
the LED should be very simple, requiring
only lead trimming and careful insertion.
Begin by removing the top clear lens,
label, and frosted under-lens in each pushbutton. Trim the LED leads to 0.25 inches
(6.4 mm) in length and insert into the sockets with the cathode end located nearest
the front of the Model 211. Power up the
Model 211 and observe if the LEDs light.
They are polarity sensitive and if either
or both do not, remove the offending
LED(s), rotate them 180 degrees, and
then re-insert.
Compressor Circuit
In this section some general information
about the Model 211’s compressor circuit
will be provided. As previously discussed,
the output of the microphone preamplifier circuit is connected to a studio-quality compressor circuit. The output of the
compressor is used by the talkback output
and, if configured, the main output. (In
most cases the main output will utilize the
signal coming directly out of the microphone preamplifier.) The gain element in
the compressor circuit is a laser-trimmed
voltage-controlled-amplifier integrated
circuit. It provides accurate, low-noise,
low-distortion performance. The threshold
of the compressor circuit is 2 dB above
the Model 211’s nominal internal operating
level of –2 dBu. A 5:1 compression ratio is
implemented and, like the threshold level,
is not field adjustable. The threshold and
ratio settings were selected so that excellent talkback audio would be provided.
By controlling the dynamic range, intelligibility can be improved and overloading
of connected devices can be avoided. An
LED indicator lights whenever the compressor’s threshold has been reached
and the circuit is actively controlling the
dynamic range. This LED is provided as
an aid when setting the gain of the microphone preamplifier.
Issue 1, December 2015 Model 211 User Guide
Page 28 Studio Technologies, Inc.
Specifications
General Audio:
Frequency Response: 10 Hz-20 kHz, ±0.2 dB, mic
in/main out
Distortion (THD+N): 0.008%, measured at 1 kHz,
mic in/main out
S/N Ratio: 86 dB, referenced to –42 dBu mic in/
–2 dBu main out
Dynamic Rang
Connector
Mic In, Line In 1 & 2: 3-pin female XLR
Main Out, Talkback Out: 3-pin male XLR
Headphone Out: ¼-inch 3-conductor phone jack
24
Vdc Power In: coaxial power jack, 2.1 x 5.5 mm,
locking bushing, compatible with Switchcraft S760K
plug
Spare Connector Locations: 2
Allo
ws one or two Neutrik NC*D-L-1 connectors to
be installed (*=3F, 3M, 5F, 5M, 6F, 6FS, etc.)
Microphone Input/Preamplifier:
Type: electronically balanced
Input Impedance: 2 k ohms, nominal
CMRR: >80 dB, 20 Hz-20 kHz, 40 dB gain
Gain Rang
10 dB steps;
Compatibility: dynamic or phantom-powered mics
Phantom P
61938 P48 standard
Line Inputs: 2
T
ype: balanced, transformer-coupled
Impedance: 10 k ohms
Nominal Le
2-Channel Auxiliary Input:
Implementation: optional IFB Input Card Kit (Studio
T
echnologies order code 31212) can be installed
into back panel
Type: 2-channel, unbalanced, transformer-coupled
Impedance: 10 k ohms, nominal
Nominal Le
Compressor:
Threshold: 2 dB above nominal level
Attac
k/Release Time: 2 mSec/100 mSec, nominal
Slope: 5:1, nominal
Status LED: compressor active
e (A-weighted): 108 dB
s:
e: 20 to 60 dB, nominal, adjustable in
0 dB (no gain) also available
ower: 45 volts DC nominal, meets IEC
vel: –12 dBV to +6 dBu, adjustable
vel: –10 dBu
Main Output:
Type: balanced, transformer-coupled
Nominal Level: –2 dBu
Maxim
Impedance: 100 ohms, nominal
Sour
output of compressor
Talkback Output:
Type: transformer-coupled with series capacitors
and isolation resistors
Impedance: 600 ohms, nominal
Nominal Le
Maxim
maximum)
Headphone Output: 1, stereo
Compatibility: intended for connection to mono or
stereo headphones or headsets with nominal impedance of 100 ohms or g
Type: voltage driver
Maximum Output Voltage: 12 Vpp, 150 ohm load
Relay Contacts: 2
Functions: follows status of main and talkback
outputs
T
state relay contact
Rating: 100 mA, 60 volts AC/DC, maximum
Contact Resistance: 16 ohms, maximum
Access: requires user-implemented connection
method
P
24 v
unit shipped with a universal input/24 volt DC output
power supply.
Dimensions (Overall):
5.6 inches wide (14.2 cm)
3.3 inches high (8.4 cm)
8.5 inches deep (22.4 cm)
W
Specifications and inf
Guide subject to change without notice.
um Level: +20 dBu into 2 k ohms
ce: output of microphone preamplifier or
, selectable
vel: +4 dBu
um Level: +11 dBu (compressor restricts
reater
ype: form-A (normally open, not-shorted) solid-
ower Source: 24 volts DC nominal, 70 mA @
olts DC; acceptable range 20-30 volts DC. Each
eight: 3.4 pounds (1.6 kg)
ormation contained in this User
Model 211 User Guide Issue 1, December 2015
Studio Technologies, Inc. Page 29
Appendix A
Attached to the bottom of the unit is a security plate with text that provides a summary
of the configurable parameters and related information.
Issue 1, December 2015 Model 211 User Guide
Page 30 Studio Technologies, Inc.
Appendix B
The following list provides details on the 3-pin header connectors located on the Model
211’s printed circuit board. Shown are reference numbers, reference text, and function
descriptions.
P3 PHONES: Headphone Output
Pin 1 common
Pin 2 tip (left)
Pin 3 ring (right)
P4 MIC IN: Microphone Input
Pin 1 shield
Pin 2 high
Pin 3 lo
(Follows back-panel 3-pin female XLR pin
assignment)
P5 MAIN OUT: Main Output
Pin 1 shield
Pin 2 high
Pin 3 lo
Careful! Back-panel 3-pin male XLR has pin 1
floating, pin 2 high, pin 3 low
P6 TALKBACK OUT: Talkback Output
Pin 1 shield
Pin 2 high
Pin 3 lo
Careful! Back-panel 3-pin male XLR has pin 1
floating, pin 2 high, pin 3 low
P7 LINE IN 1: Line Input 1
Pin 1 common
Pin 2 high
Pin 3 lo
P8 LINE IN 2: Line Input 2
Pin 1 common
Pin 2 high
Pin 3 lo
P9 DC IN 1: 24 Volt DC Input (used by
Model 211’
Pin 1 common
Pin 2 +24 Vdc
Pin 3 not used
w
w
w
w
w
s back-panel connector)
P10 DC IN 2: 24 Volt DC Input
Pin 1 common
Pin 2 +24
Pin 3 not used
P11 AUX IN CH 1/2: Auxiliary Audio Inputs
Pin 1 common
Pin 2 channel 1 unbalanced audio @ –10 dBu
nominal
Pin 3 channel 2 unbalanced audio @ –10 dBu
P12 RELA
open, not-shorted) Solid-State Relay
Contact
Pin 1 common
Pins 2 & 3 rela
common)
P13 RELAY OUTS TALKBACK: Form-A
(normall
Relay Contact
Pin 1 common
Pins 2 & 3 relay contact (isolated from
common)
P16 DC OUT 1: Auxiliary DC Output 1
Pin 1 common
Pin 2 +12
Pin 3 –12 Vdc
P17 DC OUT 2: Auxiliary DC Output 2
Pin 1 common
Pin 2 +12
Pin 3 –12 Vdc
P18 SW INS: Remote Switch Inputs
Pin 1 common
Pin 2 main output control
Pin 3 talkbac
Vdc
Y OUTS MAIN: Form-A (normally
y contact (isolated from
y open, not-shorted) Solid-State
Vdc
Vdc
k output control
Issue 1, December 2015 Model 211 User Guide
Page 31 Studio Technologies, Inc.
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