Studio Technologies 220 User Manual
User Guide
Issue 5, February 2013
This User Guide is applicable for serial numbers:
M220-01151 and later
Copyright © 2013 by Studio Technologies, Inc., all rights reserved
www.studio-tech.com
50306-0213, Issue 5
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Table of Contents
Introduction ................................................................... 5
System Features ...........................................................
Installation and Setup ................................................... 11
Configuration ................................................................
Operation ...................................................................... 24
Advanced Operation ..................................................... 29
Technical Notes .............................................................
Specifications ................................................................
Appendix A .................................................................... 42
Block Diagram
6
15
30
41
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Issue 5, February 2013 Model 220 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 220 Announcer’s Consoles with
serial numbers 01151 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 220 Announcer’s Console is
designed to serve as the audio control
“hub” for announcers, commentators,
and production talent. The tabletop unit is
suited for numerous applications including
on-air sports broadcasting. The Model 220
is compatible with essentially all broadcast
and audio system environments. Standard
connectors are used to interface microphone, headphone, on-air, talkback, and
IFB signals.
Whether it’s microphone switching, talkback outputs, or headphone cue feed,
superior audio quality is maintained
throughout. A microprocessor provides
the Model 220’s logic power, allowing exacting control of the unit’s operation. With
extensive flexibility built in, creating the
desired operating configuration is a simple
matter. While the operating features of the
unit can be extensively configured, the
user is presented with an easy-to-use set
of controls and indicators. Power on the
inside, simplicity during use—that’s the
hallmark of the Model 220.
A truly next-generation product, extensive
research into the needs and desires of
field production personnel was integral to
the Model 220’s creation. While primarily
targeted for on-air television applications,
specialized features are included to allow
the Model 220 to be used in a variety of
other audio applications. These include
on-air radio broadcasting, stadium announcement, and voice-over/narration
booths.
Figure 1. Model 220 front panel
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Figure 2. Model 220 back panel
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
and condenser microphones. The microphone power source is 48 volts nominal
and meets the worldwide P48 phantom
power standard. 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
functions.
Main Output
The Model 220 provides a main output that
is designed to serve as the on-air, stadium
announcement, or other primary audio
feed. Nominally –2 dBu, it is designed as a
fully professional interface with high output
capability, low distortion, and low noise. It
features a high-performance output transformer expressly designed for professional
audio applications.
Talkback Outputs
The two talkback outputs are intended to
provide production trucks, control rooms,
or support personnel with talent-originated
cue signals. These outputs are transformercoupled with +4 dBu nominal signal levels.
They contain resistors in series with their
output connector, allowing the talkback
outputs from multiple units to be directly
“summed.”
For non-on-air applications, a special
Model 220 feature can be enabled, placing
the unit in a “production” mode. This allows
the main output to be used as a third talkback output. In this configuration the unit
can be even more powerful when used in
corporate or theatrical events, for example
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 laser-trimmed
voltage-controlled-amplifier (VCA) integrated circuit for quiet, low-distortion level
control. The signal from the compressor
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is always used by the talkback outputs.
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 not appropriate for major on-air situations, having dynamic range control of the
main output can offer increased performance for many applications. These could
include stadium announcement positions,
sports events using nonprofessional on-air
talent, and situations where cable crosstalk is of concern.
User Controls and Status
Indicators
Three pushbutton switches, four 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. Two
additional pushbutton switches control the
status of the two talkback outputs. These
are the audio outputs used to communicate with producers, directors, “spotters,”
or other behind-the-scenes production
personnel. A status LED is associated with
each talkback button. Two rotary controls
allow the user to adjust the level of the
headphone output.
Flexibility
A large part of the Model 220’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-todisable operation. This operation is similar
to that found in many broadcast intercom
system user stations.
The two buttons associated with the talkback functions 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 220 is used in a production-support
application.
In addition to the two modes provided for
talkback 1, the button associated with talkback 2 supports three additional operating
modes. One mode allows talkback 2 to be
disabled. This is useful when only talkback
1 is to be utilized. The other two modes
provide special momentary and hybrid
functions. With these modes the operation
of the main and talkback outputs are not
impacted. This allows the talkback 2 button to control the state of the Model 220’s
auxiliary relay, making specialized implementations possible.
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The main button mode configures how the
main output, when it is in the “latched” on
state, responds to talkback activity. One
choice momentarily turns off the main
output when talkback is active, returning
the main output to the on state when the
talkback function has ended. The other
choice “unlatches” the main output in
response to a talkback function.
IFB Input
A broadcast-standard “wet” (DC with audio) IFB circuit can be directly connected
to the Model 220’s IFB input. Originated
by sources such as the RTS™ 4000-series
IFB system or IFB interface devices from
Studio Technologies, the connected IFB
circuit can provide DC power to operate
the Model 220 as well as two channels of
cue audio.
Cue Sources
The Model 220 allows up to four audio
sources to be selected for routing to the
headphone output. The sources are IFB
channel 1, IFB channel 2, line input 1, and
line input 2. Each source can be individually assigned to the left channel, right
channel, or both left and right. This allows
a wide variety of stereo and mono headphone mixes to be created.
systems, and audio consoles. 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.
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 level control mode, which provides independent
control of the left and right channel volume. For use with stereo cue signals, or to
support user preference, the 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.
The two audio signals associated with the
IFB input can be assigned to the headphone output. Originating in production
trailers, control rooms, or remote locations, these unbalanced sources normally
provide DC power and program-with-interrupt audio on one channel and programonly audio on the other.
For application flexibility, two line-level
audio sources can also be connected to
the Model 220. Possible signal sources
include off-air receivers, wireless IFB
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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 220’s circuitry is carefully tailored to provide excellent audio performance. Professional-quality components
are featured throughout. For reliability all
audio routing is performed using solid-state
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 Sources
The Model 220 can derive its operating power from either the IFB input or an
external nominal 24 volt DC source. For
redundancy, both power sources can be
connected simultaneously. An internal
switch-mode power supply ensures that
all Model 220 features, including phantom
power, are available when the unit is powered by either source.
The Model 220 is compatible with IFB
circuits provided by most standard broadcast systems. However, maximum performance can often be obtained by using the
IFB interface devices available from Studio
Technologies. The provide high-quality
audio along with an excellent source of
DC power. They’re directly compatible with
most matrix intercom systems, as well as
standard line-level audio signals. Refer to
the Studio Technologies website for details.
Auxiliary Relay
The Model 220’s circuitry includes a general-purpose relay, allowing specialized
configurations to be created. Under software control, the relay can be configured
to follow the state of the mic, talkback 1, or
talkback 2 buttons. Taking advantage of the
locations provided for additional XLR connectors, a technician may easily implement
a variety of functions such as mic active
indication, audio muting during talkback, or
audio insertion control. Several modes were
specifically included to allow direct control
of the relay using the talkback 2 button,
without impacting any of the audio signals.
The auxiliary relay is also used by the
optional direct microphone output card.
Configuration
Model 220 configurations are made using
a number of DIP switches and two trim
potentiometers. One 8-position switch assembly is used to set the gain of the microphone preamplifier and the on/off status of
phantom power. Another 8-position switch
assembly configures which of the cue audio
sources are routed to the headphone output. Two additional 8-position switch
assemblies communicate the desired
operating modes to the microprocessor.
Two rotary trim pots are used to adjust
the input sensitivity of the line inputs. All
switches and trim pots are accessible via
the bottom of the Model 220’s enclosure;
the unit does not have to be disassembled.
Changes made to any of the configuration
parameters become active immediately. To
prevent access to the configuration controls
a security plate, included with each unit, is
attached to the bottom of the enclosure.
Connectors
The Model 220 uses standard connectors
throughout. The microphone, IFB, and line
inputs use 3-pin female XLR connectors.
The main and talkback outputs use 3-pin
male XLRs. The headphone output utilizes
a ¼-inch 3-conductor jack. The external
source of 24 volt DC power is connected
by way of a 2.1 x 5.5 mm “locking” coaxial
power jack.
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Additional Connector Locations
In the world of broadcast and production
audio it’s fair to say that applications vary
widely. To this end, up to three additional
XLR connectors can be easily mounted
into the Model 220’s back panel. Multiple
3-position “headers” located on the Model
220’s circuit board provide technicianaccess to literally every input and output
connection. Using a factory-available interface cable kit, these allow a Model 220 to
be optimized to meet the exact needs of
specific applications. For example, some
applications may prefer to use a multipin XLR connector to interface with a
headset. This could be easily accomplished by adding the appropriate 5-, 6-,
or 7-pin XLR connector and making a few
simple connections. Other applications
may benefit from having “mult” or “loopthrough” connections, something easily
incorporated into a Model 220.
Multi-Pin Headset Connectors
As previously mentioned, some broadcast
applications use headsets that interface
using a multi-pin connector. In most cases
these connectors are 6- or 7-pin male
XLRs wired to an industry-standard pinout
scheme. Studio Technologies offers headset connector assemblies that allow fast
and painless installation into a spare connector location in the Model 220’s back
panel. Details about these optional assemblies are available on the Studio Technologies website.
Options
The Model 220’s standard resources are
more than sufficient to directly support a
large number of applications. But in the
“real world” of audio and intercommunications special needs always seem to arise.
To that end, Studio Technologies offers a
number of option cards. In addition to passive or active components, each card contains an integral connector, allowing simple
installation into a spare connector location
on the Model 220’s back panel. For interest,
the resources provided by some of these
option cards are worth describing.
• The direct microphone output card
provides access to the dynamic or condenser microphone that is connected to
the Model 220’s mic input. Passive components, along with the auxiliary relay
contact, create a “click-free” microphonelevel audio signal.
• The remote switch input card uses a 4-pin
XLR connector to provide access to the
Model 220’s remote switch inputs.
• The tally/remote switch input card pro
vides a current-limited DC voltage that
serves as a main output status signal.
It also provides a remote switch input
connection.
Other general purpose option cards provide
3-pin XLR, 4-pin XLR, and 8-pin EtherCon®
connectors. With the range of option cards
available it’s hard to imagine an application
that can’t be served. But you’re welcome
to try to “stump the chumps” in the Studio
Technologies technical support department!
But first please check the complete list of
the available option cards listed on the
Studio Technologies website.
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200-Series Announcer Console
Products
The Model 220 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.
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Installation and Setup
In this section interconnections will be
made using the input and output connectors located on the Model 220’s back
panel. Microphone input, IFB input, line
input, 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 220 Announcer’s Console,
user guide, button label sheet, and 24 volt
DC power supply.
Microphone Input
The Model 220 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 220’s 48 volt
nominal power source will support essentially all phantom-powered microphones.
The quality of the Model 220’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, Beyer, Neumann,
Sennheiser, and Shure will perform very
well in Model 220 applications.
The microphone input is also compatible
with line-level audio sources. This allows
the output of an external microphone preamplifier, microphone processor, or audio
console to be directly connected. When
the configuration DIP switches are set for
0 dB (no gain) the nominal level of the
source audio signal should be approximately –2 dBu.
Microphone interconnection is made
by way of a 3-pin female XLR connector which is located on the Model 220’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.
The Model 220 is not compatible with
unbalanced “electret”-type microphones
that require a source of low-voltage DC
for operation. These microphones, sometimes found in low-cost headsets, are not
generally suitable for on-air or other demanding applications.
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 220. 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 220.
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
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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 220’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 prove to be an issue as essentially all contemporary devices already meet
this condition.
Devices are connected to the headphone
output by way of a ¼-inch 3-conductor
phone jack located on the Model 220’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 “mono”
plugs can also be used with the Model
220’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. (100 ohm protection
resistors are electrically in series with the
headphone output circuits.) However,
energy will be wasted if an audio signal
coming out of the right channel goes into
a “dead” short. There is a simple solution
to this issue. No audio source should be
assigned to the right-channel headphone
output. Refer to the Configuration section
of this user guide for details.
Main Output
The main output is intended to be the
“on-air” 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 source 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 220’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 220 and connected
equipment, pin 1 on the main output’s
connector is isolated from any point in the
Model 220. 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.
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Talkback Outputs
The talkback outputs are intended for
connection to control rooms, production
trailers, or other locations where talentoriginated voice cues are required The
talkback outputs are transformer balanced with a nominal level of +4 dBu. To
enhance talkback audio quality, the com
pressor circuit controls the dynamic range
of the signal coming from the microphone
preamplifier.
For protection against accidental connec
tion to cables that have DC power present, the talkback outputs are capacitor
coupled. In series with the talkback output
leads 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 220 units to be
connected together.
The talkback outputs are connected by
way of 3-pin male XLR connectors which
are located on the Model 220’s back
panel. Mating connectors (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 cables’
shields can be connected to pin 1. But,
like the main output, in order to minimize
the chance that ground-interaction problems will arise, pin 1 on each talkback
output connector is isolated from the
Model 220’s chassis and circuitry. By
making pin 1 “float,” an often-feared
“ground loop” problem shouldn’t arise.
The talkback outputs are intended to drive
lengthy cable runs that are frequently part
of a remote broadcast application. While
the output circuitry is not intended to be
“on-air” quality, overall audio performance
should be very good. Devices connected
to the talkback outputs can range from
-
-
amplified loudspeakers to analog inputs
on intercom systems, and input channels
associated with audio consoles. Connecting the talkback outputs to devices that allow easy control of the signal level can be
helpful. For example, connecting to an input channel on an audio console will provide the flexibility to add gain or attenuate
as required. Then a talkback-associated
output connection on the audio console
can connect to the final destination(s).
As previously mentioned, the talkback
outputs on multiple Model 220 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. One side effect from
using this passive summing technique
is that signal attenuation will occur. The
audio quality won’t suffer, 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 an adjustable input sensitivity.
IFB Input
The Model 220’s IFB input is designed to
directly connect with “wet” (DC-biased)
IFB circuits. These circuits provide DC
power and one or two channels of audio
over a standard 3-conductor microphonestyle cable. Typically, the IFB circuit’s
interface connector is a 3-pin male XLR
wired so that common is on pin 1, DC with
channel 1 audio is on pin 2, and channel
2 audio is on pin 3. Some IFB circuits may
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