Model 55 Central Controller, Model 56 Control Console, and

Model 55 Central Controller, Model 56 Control Console, and

Model 55 Central Controller,

Model 56 Control Console, and Related Components

User Guide

Issue 5, August 2005

This User Guide is applicable for serial numbers:

Model 55 M55-00280 and later

Model 56 M56-00280 and later

© 2005 by Studio Technologies, Inc., all rights reserved

www.studio-tech.com

50063-0805, Issue 5

Model 55/56 User Guide

Studio Technologies, Inc.

Table of Contents

Foreword

Introduction ................................................................... 7

What This User Guide Covers .................................. 7

System Overview ..................................................... 7

System Features ...................................................... 7

Installation ....................................................................11

Confi guration ................................................................15

Model 56 Confi guration Chart—Main Functions ......18

Model 56 Confi guration Chart—

Alternate Functions .............................................19

Operation ......................................................................20

Troubleshooting ............................................................22

Technical Notes ............................................................24

Specifi cations ...............................................................28

Appendix A ...................................................................30

MIDI Messages ........................................................31

Block Diagrams

Model 55 Central Controller

Model 56 Control Console

Model 35 Talent Amplifi er

Model 70 Interface

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Model 55/56 User Guide

Studio Technologies, Inc.

Foreword

I am pleased to present the StudioComm series of products. As both president and owner of Studio Technologies, I take a very personal approach when designing products. Getting older has increased my appreciation of the more subtle things in life—be they a part of nature or the nuances contained in a well-designed piece of electronic equipment. Do the technical and operational aspects of a product work together to “feel” right? A Studio Technologies’ design is ready to go only when I am completely satisfi ed. My entire focus for the

StudioComm series was to make a system that you’d really enjoy using, and one that would perform reliably for years. I hope you share my enthusiasm.

Many fi ne people worked toward making the StudioComm “happen.” Mitch Budniak (ace consulting engineer) designed many of the circuits. Jim Cunningham contributed to the analog design. Larry Leviton wrote the excellent micro-controller software. Al Lux designed the printed circuit boards. Carrie Loving designed the graphics. Fred Roeck performed the mechanical design. Joe Urbanczyk coordinated the safety testing and agency approvals.

Many thanks to Bob Tjarks, professional audio sales manager at Gand Music & Sound,

Northfi eld, Illinois. Bob brought to my attention the need for a product to serve digital audio workstations. His product idea evolved into the StudioComm series. Additional thanks to

Timothy Powell of Metro Mobile Recording, Glenview, Illinois, who provided his excellent ears when issues of sonic quality arose. His extensive fi eld and studio experience was extremely helpful in keeping me on the audio “straight and narrow.”

Please contact me with your questions, comments, and suggestions. I can be reached by voice at (847) 676-9177, fax at (847) 982-0747, or via the Internet @ www.studio-tech.com.

Sincerely,

Gordon K. Kapes

President

Model 55/56 User Guide

Studio Technologies, Inc.

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Model 55/56 User Guide

Studio Technologies, Inc.

Introduction

What This User Guide Covers

This User Guide is designed to assist you when installing, confi guring, and using the Model 55 Central Controller, Model 56

Control Console, Model 35 Talent Amplifi er, and related components.

System Overview

The Model 55 Central Controller, along with the companion Model 56 Control Console, are members of the StudioComm family of products. The Models 55 and 56 are specifi cally designed to work in conjunction with digital audio workstations to provide a full set of monitoring and communications functions. Features include control room monitoring, meter output, an integrated headphone system, dubbing, and communications functions that include talk to phones and slate. All StudioComm functions perform to a level that rivals even the largest recording consoles. Many of the functions are user confi gurable, allowing unmatched fl exibility.

A complete StudioComm system consists of a rack-mounted central controller, a desktop control console, and one or more portable talent amplifi er units. The Model 55

Central Controller and the Model 56 Control

Console work together, interconnecting using a standard 5-pin MIDI-style cable.

Circuitry in the Model 55 routes any of four stereo inputs to the control room, meter, headphone, and dub outputs, with commands provided by the Model 56 Control

Console. The Model 56 Control Console’s built-in microphone lets you talk to the headphone output. It also allows you to talk to the dub output, or to the dub and headphone outputs using the slate function.

Model 55/56 User Guide

Studio Technologies, Inc.

The Model 35 Talent Amplifi er is a portable amplifi er unit capable of driving one or two pairs of high-impedance stereo headphones. A single microphone-type cable links the Model 35 with the Model 55

Central Controller. The Central Controller provides power and left and right audio over just three wires.

System Features

Stereo Line Inputs

The Model 55 contains four stereo linelevel inputs which are compatible with both balanced and unbalanced signals. Each input is independently software confi gurable for a nominal input level of –10 dBV or +4 dBu. This allows direct connection with virtually any audio source. Each input can also be confi gured to operate as a mono input. In this manner, a signal con- nected to the left input is routed to both the left and right outputs.

Control Room Monitoring

The control room section provides a stereo line-level output for driving a power amplifi er associated with monitor loudspeakers.

Four buttons are used to select the input source to be monitored. Normally, only one of the four input sources is selected for monitoring. For special applications, the system can be confi gured to allow two input sources to be simultaneously monitored. The control room level is adjusted using a smooth-feeling rotary potentiometer. The Dim button allows the control room level to be temporarily reduced. The

Mono button allows the sum (L+R) of the selected source to be sent as the control room output.

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Meter Output

The meter output provides a stereo output that “follows” the source(s) selected for the control room. The signal is not affected by the control room level circuitry, but is

“post-mono.” The meter output is intended to be connected to VU- or PPM-type meter panels that contain series current-limiting resistors or input buffer amplifi ers.

Dub Output

A stereo line-level output is provided as a dub (copy) output. Any of the four inputs can be assigned to the dub output.

The slate function allows communications

(voice) audio to be sent out the dub output.

Communications Functions

The Model 56 Control Console contains an internal microphone that is used in conjunction with the two communications functions. The talk to phones function either interrupts the phones source or adds

(sums or mixes) to the phones source. The slate function interrupts the dub source and, if confi gured, the headphone source and connects communications audio. The audio level of each communications function is individually adjustable.

MIDI Control

All Model 55 Central Controller functions are controlled using system-exclusive

MIDI messages. The Model 56 Control

Console “speaks” this language, and in most applications a Model 56 will be utilized. In special applications the Model

55 Central Controller can be connected directly to a MIDI bus, allowing the creation of a fully automated recording or audio routing system. For more information on MIDI support, refer to Appendix A.

Model 55 Front Panel

Power present LED

Input data present LED

Model 56 Control Console and

Talent Amplifi er over current LED

Model 55 Back Panel

AC mains connection

Mains voltage confi guration chart

To/from Model 56

Control Console

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Output to talent amplifi ers

Meter output

Dub output

Control room output

Stereo line inputs 1-4

Model 55/56 User Guide

Studio Technologies, Inc.

Model 56 Front Panel

Confi gure button switches between normal operation and confi gure mode

Source selection for control room (CR), headphones, and dub; three columns of LEDs show the currently selected sources

Model 56 Back Panel

Built-in microphone for communications functions

(talk to phones, slate)

Change the control room level; listen in mono (L+R); or reduce the level by a preset amount

Talk to the headphones; slate; set communications levels

Connection to the Model 55

Central Controller

Confi guration

The Model 56 Control Console can be confi gured to make the system meet a user’s exact operating environment. All confi guration parameters, along with

“power down” operation conditions, are stored in nonvolatile memory.

Each of the four stereo line inputs can be independently set for –10 dBV or

+4 dBu operating levels.

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Studio Technologies, Inc.

Each input can be set for either mono or stereo operation. In the mono mode a signal connected to the left input is sent to the left and right outputs.

The dub output level can be set for a nominal –10 dBV or +4 dBu output level.

Unique to the system is the ability to confi gure the dim level to one of three values, allowing a 15, 20, or 25 dB reduction when dim is active.

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Three functions can be set for push-tolatch operation if desired: talk to phones, slate, and control room mono.

The auto dim off function, when confi gured, allows any change in the control room level potentiometer to automatically turn off an active dim state.

The slate function can be confi gured to talk to the dub output, or talk to both the dub and headphone outputs.

The talk to phones function can be set to interrupt the normal phones source or add (sums) to the phones source.

The system can be confi gured to allow only one input source, or one or two input sources to be selected as the control room source(s).

Headphone Monitoring

The StudioComm system contains an integrated, full-featured headphone (cue) system. Up to four Model 35 Talent Amplifi ers can be connected to the Model 55’s talent amplifi er output. A single 3-conductor microphone-type cable carries power and stereo audio.

Using the Model 56 Control Console, any of the four stereo inputs can be assigned to the talent amplifi er output. The talk to phones and slate functions allow communications (voice) audio to be sent to the talent amps. The talent amplifi er output is short circuit protected. Error conditions are displayed by the Over Current LED on the

Model 55’s front panel.

Each Model 35 Talent Amplifi er can drive two sets of high-impedance headphones

(>150

Ω). The audio output is loud, and very “clean.” The units feature a built-in level control, a stereo/mono switch, and a power present LED.

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Model 35 Front Panel

Power present

LED

Headphone output level control

Switch between stereo and mono

(L+R) output

Two headphone outputs

Model 35 Back Panel

Connects to additional talent amplifi ers

Connects to the Model 55 or another talent amplifi er’s loop thru connector

Model 55/56 User Guide

Studio Technologies, Inc.

Installation

In this section you will be installing the

Model 55 Central Controller in an equipment rack. Audio input and output connections will be made using the Model 55’s multitude of jacks. One or more Model 35

Talent Amplifi ers may be connected. A location will be selected for the Model 56

Control Console, and it will be connected to the Model 55. AC mains power will be connected to the Model 55.

System Components

The main StudioComm shipping carton contains a Model 55 Central Controller,

Model 56 Control Console, 5-conductor

MIDI-style cable, User Guide, and warranty card. Units destined for North America are shipped with an AC mains cord. Your dealer or distributor will provide an AC mains cord for non-North American destinations. Model

35 Talent Amplifi ers, along with accessories, will be contained in separate cartons.

Please check to ensure you have everything you need.

Mounting the Model 55

The Model 55 requires one space in a standard 19-inch (48.3 cm) equipment rack. Select a location near where the

Model 56 Control Console will be located.

A cable is provided to connect the Model 55 to the Model 56. You can supply a longer cable, however 50 feet (15.3 m) is the recommended maximum length. It is desirable to locate the Model 55 to allow easy access to both the front and the back panels. The back panel contains all of the input and output connectors, while the front panel contains several LED indicators. The Model

55 is secured to the equipment rack using two mounting screws per side.

Audio Inputs and Outputs

The Model 55’s line-level audio input and output connections are made using

¼ -inch 3-conductor phone jacks. For reliable audio interconnection, the plugs you use must comply with industry standard

RS-453. Switchcraft No. 297, Neutrik

NP3C, or equivalent will work correctly.

Stereo Line Inputs

The Model 55 provides four stereo linelevel inputs. Each input is electronically balanced, and can be confi gured for compatibility with –10 dBV or +4 dBu signal levels. The Model 56 Control Console gives you pushbutton control, so you can easily change input sensitivities at any time (refer to the Confi guration section under Input Sensitivity). Monaural sources should be connected to the left (L) input and confi gured for mono operation (refer to the Confi guration section under Stereo/

Mono Input).

Prepare the mating connectors (plugs) so that tip is signal high (+ or hot), ring is low (– or cold), and sleeve is shield. With an unbalanced source connect the tip to high (+ or hot), and both the ring and sleeve to shield. If connecting to an unbalanced source in this manner results in hum or noise, connect tip to high (+ or hot) and ring to shield; leave the sleeve unterminated.

Balanced Input and Output Connections

Ring: –

Tip: +

Sleeve: Shield

(Switchcraft No. 297, Neutrik NP3C, or equivalent)

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Control Room Output

The Model 55 contains a stereo line-level output for connection to an audio power amplifi er. This audio amplifi er serves a pair of loudspeakers that are located in the control room. (Of course the control room output can be connected to loudspeakers that contain integral power amplifi ers, such as the products from Genelec.)

The output is electronically balanced and capable of driving loads of 600 ohms or greater. In most situations best performance will be obtained if the audio amplifi er’s input sensitivity is set to near maximum. Refer to the Technical Notes section for details on setting amplifi er sensitivity.

The control room output utilizes two ¼-inch

3-conductor phone jacks for interconnection.

Prepare the mating connectors (plugs) so that tip is signal high (+ or hot), ring is low

(– or cold), and sleeve is shield. To connect to an unbalanced load connect the tip to high (+ or hot), and both the ring and sleeve to shield.

Meter Output

The meter output is intended to be connected to a VU- or PPM-type meter panel that contains input buffer circuitry or series current-limiting resistors. Each output is unbalanced, has a nominal level of +4 dBu, and is capable of driving loads of 2 k ohms and greater.

The meter output utilizes two ¼-inch

3-conductor phone jacks for interconnection.

Prepare the mating connectors (plugs) so that tip is signal high (+ or hot), sleeve is low

(– or cold); ring is not connected.

Dub Output

The Model 55 contains a stereo line-level output which is intended for connection to

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a variety of analog audio devices. The dub output is electronically balanced and capable of driving 600 ohm loads or greater.

With the input impedance of most audio devices at 10 k ohms or greater, the dub output can easily drive ten or more devices simultaneously.

The dub output can be confi gured for a nominal level of –10 dBV or +4 dBu, so you can connect to all line-level inputs with no hassle (refer to the Confi guration section under Dub Output Level).

The dub output utilizes two ¼-inch

3-conductor phone jacks for interconnection. Prepare the mating connectors

(plugs) so that tip is signal high (+ or hot), ring is low (– or cold), and sleeve is shield.

To connect to an unbalanced load connect the tip to high (+ or hot), and both the ring and sleeve to shield.

Talent Amplifi er Output

Up to four Model 35 Talent Amplifi ers can be connected in any combination to the Model 55’s talent amplifi er output.

The output connector is a 3-pin male

XLR-type. For best performance, use lowcapacitance shielded microphone-type cable to distribute the talent amplifi er signal. If you have a choice, select cables with the heaviest wire gauge commonly available. This will reduce voltage drop when using long cable runs. Refer to the

Technical Notes section for additional information.

The simplest installation would use a microphone cable to connect the Model 55 to the fi rst talent amplifi er; the loop through connector on that talent amp sending the signal on to the next talent amp.

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Studio Technologies, Inc.

For convenience, you may want to wire your facility to allow easy access to the talent amplifi er signal at all locations where talent amplifi ers might be used.

The talent amplifi ers connect to the Model

55 in parallel, so the connectors on the distribution panels or mult boxes must be wired in parallel.

Warning: Do not connect the Model

55’s talent amplifi er output to anything but Studio Technologies’ talent amplifi ers. Some audio equipment may be damaged by the +23 Vdc contained on pin 2 of the talent amplifi er output connector.

Several mounting options are available for the Model 35 Talent Amplifi er. For details refer to Mounting Options in this section.

In special cases you may need to obtain a stereo, balanced line level output signal from the Model 55 talent amplifi er output.

The Model 70 Interface is available for this purpose. For details refer to the end of this section.

Locating the Model 56 Control Console

The Model 56 was designed for desktop use, however provision has also been made for microphone-stand mounting.

For details refer to Mounting Options in this section.

Connecting the Model 55 to the

Model 56

A standard 5-conductor MIDI-style cable is used to connect the Model 55 to the

Model 56; a cable is included with your system. Just connect the cable between the female 5-pin DIN-type connectors on the back of the Model 55 and 56, and you’re done.

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Studio Technologies, Inc.

Note: If you require a longer cable, be

certain to buy a MIDI cable that has all fi ve pins wired. If they aren’t all connected, the

Model 56 will not operate. This is because the Model 55 powers the Model 56 with the pins that aren’t used for MIDI data.

For best performance, the cable that connects the Model 55 with the Model

56 should be limited to 50 feet (15.3 m).

Should you need to exceed this length, refer to the Technical Notes section of this guide for details on the cable requirements.

For more information on MIDI, and using controllers other than the Model 56, please refer to Appendix A.

AC Mains Power

The Model 55 is internally confi gured to operate from either 100, 120, or

220/240 V, 50/60 Hz. In most cases, units shipped to North America are factory selected for 120 V operation. Units bound for Japan are selected for 100 V, while our friends “down under” and in Europe receive units set for 220/240 V. Before connecting the Model 55 to mains power, check that it is confi gured to match the local mains voltage. Look on the back panel, adjacent to the power entry connector, for the confi gured voltage(s). Note than an incorrect confi guration could seriously damage the unit. Should it be necessary to change the unit’s operating voltage it must be performed only at the factory or by an authorized service technician.

The Model 55 uses an IEC standard connector to mate with the AC mains cord. The wire colors in the AC mains cord should conform to the internationally recognized CEE color code and must be wired accordingly:

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Neutral (N)

Line (L)

Light Blue

Brown

Protective Earth (E) Green/Yellow

Safety Warning: The Model 55 does not

contain an AC mains disconnect switch.

As such the mains cord plug serves as the disconnection device. Safety consideration requires that the plug and associated outlet be easily accessible to allow rapid disconnection of mains power should it prove necessary.

As soon as mains power is applied, the

Model 55’s power present LED will light.

The Model 56 will go through its powerup sequence lighting each LED in a rapid sequence. The power present LEDs on the talent amplifi ers will also light.

The Over Current LED located on the front panel of the Model 55 should not be lit.

If it is fl ashing, immediately refer to the

Troubleshooting section of this guide.

If everything appears to be functioning properly you are now ready to confi gure the system.

Model 35 Stand Mounting

Included with each Model 35 Talent Amplifi er is a nifty mounting adapter that allows the unit to be conveniently attached to a microphone stand. Please refer to the

Installation Guide provided in the Model

35’s shipping carton for details.

Model 56 Mounting Options

The Model 56 Control Console includes provisions for mounting to microphone stands, equipment consoles, etc. To avoid

“reinventing the wheel,” our products are compatible with the 25 Series components

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from OmniMount Systems, a supplier of fi nely engineered mounting systems.

This fi rm makes many versions of the

25 Series; one of which should fi t your needs. If you desire microphone stand mounting the following components would be appropriate: 25RST-25H Straight Tube

Reverse Mount with Quick Release, along with a 25MA Microphone Stand Adapter.

(If quick adjustment is not required the

25RST Straight Tube Reverse Mount can be used in place of the fi rst item.) When connecting to metric-thread stands please contact OmniMount for the correct part numbers.

The design of the Model 56 did not allow the inclusion of threaded inserts, so holes of adequate size to allow ¼ -20 round head machine screws are provided.

It is intended that screws of

5 /

8

-inch length, along with lock washers and machine nuts, will securely attach a 25 Series mounting clamp assembly. The cover of the Model

56 will have to be removed to gain access to mounting holes. Be careful when selecting the mounting screws—exceeding the recommended

5 /

8

-inch length will cause the mounting screws to damage the Model

56’s internal components.

Model 70 Interface

In most cases Model 35 Talent Amplifi ers will be used to drive headphones associated with a StudioComm installation. In special cases a line level signal may be required to interface the Model 55 Central

Controller’s talent amplifi er output with other audio equipment. An example would be to use the Model 55 with an existing headphone system. The Model 70 Interface is used to convert the talent amplifi er signal to a stereo, balanced line level signal.

Model 55/56 User Guide

Studio Technologies, Inc.

Installation is very simple. Connect the Model 70 to the Model 55 Central

Controller’s talent amplifi er output using a standard 3-conductor microphone-type cable. For best performance, use lowcapacitance shielded cable.

The Model 70 provides independent left and right balanced outputs. Pin 1 is shield, pin 2 is signal positive (+ or hot), and pin

3 is signal negative (– or cold). The electronically balanced outputs have a nominal signal level of +4 dBu and are capable of driving loads of 600 ohms or greater.

The Model 70 can be used by itself, or in conjunction with up to four Model 35

Talent Amplifi ers. The loop through connector on the Model 70 can be used to connect to a Model 35 Talent Amplifi er.

Model 70 Front Panel

Model 70 Back Panel

Confi guration

Many StudioComm functions can be confi gured to meet the exact needs of your installation. Here’s an overview of what you can confi gure:

–10 dBV or +4 dBu sensitivity for each input

Stereo or mono for each input

–10 dBV or +4 dBu level for the dub output

Dim level

Momentary or latching operation for mono, talk to phones, and slate buttons

Auto dim off function

Slate feed to phones

Talk to phones interrupts or adds to phones source

Allow simultaneous selection of two control room sources

The Confi gure button allows the Model 56 to go into the confi gure mode. While in the confi gure mode, all the Model 56’s buttons and LEDs are associated with confi gure functions. Refer to the Model 56 Confi guration Chart later in this section.

To enter the confi gure mode, press and hold the Confi gure button for two seconds.

While in the confi gure mode, all audio outputs switch off and the orange LED beside the Confi gure button will fl ash. As you make changes, the Model 56 keeps track of the new settings and updates the system when you exit the confi gure mode.

You must exit the confi gure mode before any changes take effect.

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Input Sensitivity

The CR column of four red LEDs shows you whether an input is set to be compatible with –10 dBV or +4 dBu signal levels.

When a red LED in the CR column is off, it means the input is set to –10 dBV. When lit, the corresponding input is set to +4 dBu.

Just press the CR buttons to toggle inputs 1 through 4 between –10 dBV and +4 dBu.

Stereo/Mono Input

The Phones column of green LEDs indicates whether an input is confi gured for mono or stereo operation. When a green

LED in this column is off, the input is set for stereo; the LED on means the corresponding input is set for mono. In mono mode, the left input is sent out both the left and right outputs. To toggle a channel between stereo and mono, press and hold the Phones button and press the CR buttons that correspond to inputs 1 through 4.

After you leave the confi gure mode, inputs confi gured for a mono source will fl ash during normal operation.

Dub Output Level

The Dub column of orange LEDs will help you confi gure two options: dub output level and dim level. The orange LED in the fi rst row (number 1 at the top) tells you whether the dub output is set to –10 dBV or +4 dBu.

When the LED is off, the dub output is set to –10 dBV; when it’s on, the dub output is confi gured for +4 dBu.

Dim Level

The dim function is used to reduce the control room output level a preset amount whenever you press the Dim button. You can take a quick phone call without using the level control to change the control room level. Also, any time you press the talk to

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phones or slate buttons the dim function is activated.

In the confi gure mode, LEDs 2 through 4 in the Dub column indicate the selected dim level. Dim can only have a single setting, so only one of the orange LEDs is on at a time.

Row Number

2

3

4

Dim Value (dB)

25

20

15

When the orange LED is on in row two, dim is down 25 dB. Dim is down 20 dB in row three, and 15 dB in row four. To change the dim level, hold down the Dub button while pressing the CR button of your choice.

Mono Function

The Mono function allows the control room output to be placed in the mono (L+R) mode. When you’re in confi gure mode, the red LED labeled Mono tells you whether the Mono button works as a momentary or latching button. When the button is set to momentary, the LED will be off and mono mode will only be active while you press and hold the Mono button. When the LED is on, the button is set to latch. With this setting, you can press the Mono button once and it will remain in mono mode until you press it again.

Auto Dim Off

The auto dim off function is unique to

StudioComm products, making the dim function respond to real world operating conditions. When enabled the function automatically turns the dim function off if a change is made to the control room level potentiometer while the unit is already in dim mode. This prevents a heart-stopping

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blast of audio when an engineer presses the dim button to turn dim on, but actually turns it off because the unit was already in the dim mode. While it’s hard to explain unless you’ve used a console and experienced this in person, trust us, this situation does happen! Auto dim off is a wonderful

“real-world” function and in most cases should be confi gured.

In the confi gure mode the Dim LED tells you if auto dim off is enabled. When the dim LED is off, the auto dim off function is off; when the Dim LED is lit, the auto dim off function is on.

Communications Functions

There are two Communications buttons at the bottom center of the Model 56.

Moving from left to right, the buttons are talk to headphones and slate. During confi guration, LEDs above the Communications buttons tell you whether the buttons will latch when you press them. When an

LED is off, the button below it won’t latch.

You would have to press and hold the button to activate the function. When an LED is on, it indicates that the button will latch.

Pressing the button will activate the function until it’s pressed again.

Alternate Confi gure Functions

To allow additional functions to be confi gured, an alternate confi gure mode is utilized. By pressing and holding the

Level Up button the alternate functions are accessed. This is like the ALT key on your personal-computer keyboard.

Slate to Phones

When you press the slate button, the

Model 56’s microphone is fed to the dub output. This is how you can record your own voice for marking takes. But there

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Studio Technologies, Inc.

are times when it’s convenient to have the slate provided in the headphone output as well.

While holding Level Up, the Phones LED is used to display whether the slate will go to the phones. When the LED is off, slate goes to the dub output only; when the LED is on, slate goes to both the dub and headphone outputs. While holding Level Up, press the button below the LED to toggle the setting.

Talk to Phones Interrupt or Add

The talk to phones function can be confi gured to either interrupt the source selected for phones audio and connect communications audio, or to have the communications audio added (summed or mixed) with the phones audio.

While holding Level Up, the slate LED is used to display whether talk to phones will interrupt the phones source, or add to the phones source. When the LED is off, the selected phones source will be interrupted and the communications audio source will be connected; when the LED is on the communications audio source will be added (mixed) to the phones audio source.

While holding Level Up, press the button below the LED to toggle the setting.

Allow Two Simultaneous Control Room

Sources

A feature has been added that allows any two of the four input channels to be simultaneously selected for monitoring over the control room output. This was added for applications where multiple “rough” or

“scratch” audio signals need to be monitored at the same time. This feature can be enabled or disabled using the confi guration procedure on the Model 56 Control

Console.

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Reset Factory Defaults

Provision has been made to allow you to return all confi gurable parameters to the factory default values. With the Model 56 in the confi gure mode, press and hold both the Dub and Phones buttons. After two seconds the factory defaults will be stored in memory, the confi gure mode will automatically end, and the Model 56 will return to normal operation.

Model 56 Confi guration Chart—Main Functions

Press and hold

Confi gure for two seconds to enter or exit the confi gure mode; while in confi gure, LED will fl ash

Press and hold

Dub and Phones for 2 seconds to reset all parameters to factory defaults

Press CR 1 through 4 to toggle each channel’s input sensitivity between –10 dBV and +4 dBu; LED on means input is set to +4 dBu

Press and hold Phones, then press CR 1 through 4 to toggle the inputs between stereo and mono operation; LED on means input is set to mono

Press and hold Dub, then press CR 1 to toggle the dub output between –10 dBV and +4 dBu; LED on means dub is set to +4 dBu

Press a Communications button to toggle between latching or momentary operation; LED on means the button is set to latch

Press and hold Dub, then press CR 2 through 4 to select a dim level:

LED 2 is 25 dB

LED 3 is 20 dB

LED 4 is 15 dB

Press Mono to toggle between latching or momentary operation;

LED on means the

Mono button is set to latch

Press Dim to toggle the automatic dim off function; LED on means auto dim off function is active

Press and hold Level

Up to activate alternate confi gure functions

(refer to next page)

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Page 18

Model 55/56 User Guide

Studio Technologies, Inc.

Model 56 Confi guration Chart—Alternate Functions

Press and hold Level

Up to activate alternate confi gure functions

Press CR 1 to toggle between allowing only one control room source or allowing one or two control room sources; LED on means two sources are allowed

Press Talk to Phones to toggle slate feed to phones; LED on means slate to phones is on

Press Slate to toggle between phones interrupt and phones add; LED on means talk to phones is add

Model 55/56 User Guide

Studio Technologies, Inc.

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Operation

Now that you’ve installed and confi gured the system, you’re ready to go. You should fi nd operation very easy.

Model 55 Central Controller

The Model 55 front panel contains three

LEDs. The power present LED should be lit whenever AC mains power is connected. During normal operation the Over

Current LED will not be lit. It will fl ash only if there is a problem interfacing with the

Model 56 Control Console or the talent amplifi ers that you have connected. Refer to the Troubleshooting section if the Over

Current LED lights.

The Input Data LED will light whenever a message is received. Refer to the

Troubleshooting section if the LED does not fl ash in response to a message from the Model 56 Control Console.

Model 56 Control Console

All StudioComm functions are controlled using the Model 56 Control Console.

To make things easy, we’ve divided the

StudioComm functions into three main groups: input-output selection, control room output, and communications functions.

Control Room/Meter Source Selection

To select an input for monitoring in the control room, press one of the four CR buttons. The corresponding LED in the

CR column will light to let you know which input is selected. If the input is set for mono the LED will continually fl ash on and off as a warning. The same source will be connected to the meter output.

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The system may have been confi gured to allow two control room sources to be selected simultaneously. If so, select the fi rst source by pressing and holding one of the four CR buttons. Then, while keeping the fi rst button pressed, select the second source by pressing one of the three other CR buttons. The two sources will be added (summed or mixed) together: L+L, R+R.

Headphone Source Selection

To select an input source for the headphone output, press and hold the Phones button and press one of the four CR buttons. In the Phones column, the LED for the input you select will light. If the input is set for mono the LED will continually fl ash on and off as a warning.

A special function allows you to select no input to be sent to the headphones. This ensures a quiet feed to the phones, but still allows the talk to phones function to be used. To select no input, simply press and hold the Phones button, then press both Communications Level buttons at the same time. The Level buttons are located to the right of the two Communications buttons. All LEDs in the Phones column will be off when no input is selected. To again select one of the four inputs, press and hold the Phones button, then press one of the four CR buttons.

Dub Source Selection

To select an input source for the dub out-put, press and hold the Dub button and press one of the four CR buttons. The appropriate LED in the Dub column will light. If the input is set for mono the LED will continually fl ash on and off as a warning. You can select no input just as you did for the headphones. Press and hold

Model 55/56 User Guide

Studio Technologies, Inc.

the Dub button, then press both Level buttons at the same time.

Control Room Output

Associated with the control room output are two buttons and one level control.

In addition, the Communications Level buttons are used. Use the Control Room

Level knob to set the control room output level. There is no on/off switch. Just select an input and turn the knob to the level you want.

The Dim button lets you lower the control room level by a fi xed amount. The amount of attenuation depends on the dim level set in the confi gure mode (refer to the

Confi guration section for help). The Dim button is always set to latch the function on or off.

If the auto dim off function is enabled, whenever dim is on and the control room level is changed, dim will automatically return to the off state. Note that the auto dim off function is not active whenever dim is on due to one of the communications functions being active.

The Mono button lets you send L+R to both the left and right control room outputs.

The Mono button can be confi gured for momentary or latching operation.

For diagnostic purposes, the control room left-only or right-only mode can be activated. To enter the mode you use the

Communications Level buttons. Press and hold both Level buttons for two seconds.

The control room will switch from stereo operation to the left-channel-only mode.

Press and hold the Level buttons again, and the control room switches to right channel only. Press and hold the Level buttons a third time and the control room switches back to stereo operation. The

Model 55/56 User Guide

Studio Technologies, Inc.

Level buttons continue to cycle through left, right, and stereo monitoring as you press them.

The Mono LED indicates when you are in left-only or right-only modes. During left-only operation the LED will fl ash once; in right-only operation the LED will fl ash twice.

Note that the mono function is disabled during single-channel operation. If mono is active when entering the single-channel mode, the system will terminate the mono mode.

Communications Functions

Four buttons are associated with the communications functions. The two main buttons are called talk to phones and slate.

They have symbols that represent (from left to right) a pair of headphones and a slate board (or “clapper”). Pressing each button activates the Model 56’s built-in microphone and sends its audio to the appropriate output(s). Press the button under the headphone symbol to talk to the headphones; press the button under the clapper to slate. Remember that during a slate, microphone audio goes to the dub output or, depending on the confi guration, to the dub and phones output. When you press one of the communications buttons, the LED above it will come on to tell you the function is active. Note that only one communications function can be active at a time.

When you press the communication buttons, various things happen depending on the Model 56’s confi guration. Either of these buttons may be confi gured to stay on (latch) when you press them. Also, if the headphones are confi gured to receive slate audio, both the phones and slate

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LEDs will light when you press slate. The communications level to the headphones will be determined by the slate level setting

(not the talk to phones level).

The talk to phones function is confi gured to interrupt or to add to the selected headphone source. If interrupt is selected, activating talk to phones disconnects the selected headphone source and connects communications audio. If add is selected, activating talk to phones leaves the headphone source connected and adds (sums or mixes) the communications audio.

You can independently set the output level for the two communications functions. To set the communications levels, press and hold either the talk to phones or slate button and press the Communications Level buttons. (If the talk to phones or slate buttons are set to latch, you won’t have to hold them.) The LEDs above the buttons will fl ash each time the level is increased or decreased until you reach the top or bottom of the range. At this point, if you continue to press the same Level button, the LED won’t fl ash, indicating you’re at the top or bottom of the eight-step level range.

Headphone Level

The headphone output level is controlled only at the Model 35 Talent Amplifi er.

There is no headphone level adjustment using the Model 56.

Confi gure Mode

Refer to the Confi guration section for an understanding of how to use the Confi gure button.

Model 35 Talent Amplifi er

Warning: protect your ears! The Model

35 talent amplifi er is capable of driving headphones to extremely high sound pressure levels. Hearing experts advise against continuous extended play, especially at high levels.

The power present LED should be lit whenever the Model 35 is connected to an operating Model 55. The Model 35 has a Level control and a Stereo/Mono button.

You can plug in one or two pairs of headphones with a total impedance of 75 ohms or greater. Turn the knob to the output level you want and select stereo or mono by pressing the button. Both headphone outputs are controlled by the one level control. The Mono button sends L+R to both the left and right output.

Troubleshooting

If you’re having problems getting the

StudioComm system up and running, this section can help. If you haven’t read the other sections of this guide, you should do so before proceeding.

If the Model 56 Doesn’t Work At All

Your StudioComm system was supplied with a 5-conductor DIN-type cable that is used to connect the Model 56 Control

Console to the Model 55 Central Controller. This cable has an important characteristic; it implements all fi ve conductors.

This means that all fi ve pins on each plug connect to each other using a length of

5-conductor cable. If you choose to use your own cable it’s easy to get in trouble;

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Studio Technologies, Inc.

many MIDI cables only have three conductors! You must use a 5-conductor MIDIstyle cable or the Model 56 will not power up and function. Five conductor MIDI cables are not hard to fi nd, but you must ask for them and ensure that you get what you asked for. Be warned!

Over Current LED

During normal operation the Over Current LED, located on the front panel of the Model 55, should not light. It will light, fl ashing on and off, in response to problems with the Model 56 Control Console and/or the Talent Amplifi er output.

The Over Current LED will light if the power source that supplies the Model 56

Control Console is loaded to exceed its maximum output current. The most common reason for an over current condition would be a shorted 5-conductor MIDI-style interconnecting cable. A major fault in the

Model 56 would also cause the LED to light.

The Over Current LED will also light if the talent amplifi er output is loaded to exceed its maximum output current. The most common reason for an over current condition would be a shorted interconnecting cable. Also, connecting more than the specifi ed maximum of four Model 35 Talent Amplifi ers can also cause the LED to light. Possible, but not likely, would be a fault condition in a Model 35.

If the Over Current LED does light, troubleshooting should prove quite simple. Begin by disconnecting the cables that are plugged into the Control Console/MIDI In and the talent amplifi er output connectors.

Perform the disconnection directly on the

Model 55’s back panel. The LED should stop lighting. Now reconnect to Control

Model 55/56 User Guide

Studio Technologies, Inc.

Console/MIDI In. If the LED again lights, follow this paragraph. If the LED does not light, skip to the next paragraph. Check the interconnecting cable that links the Model

55 with the Model 56 Control Console.

You need to determine where the short circuit condition is located. The Model 55 will not be damaged if the Over Current

LED is lighting so you should use it to help you locate the fault. In just a few minutes you should be able to isolate exactly if the cable or the Model 56 is causing the problem. Replace the cable if it proves to be bad—remember you’ll need a MIDI-style cable with all fi ve conductors connected.

If the Model 56 appears to be at fault, it will need to be returned to the factory for repair.

If the LED did not light when you reconnected to Control Console/MIDI In, reconnect to the talent amplifi er output. The LED should now light, identifying that the problem is with the talent amplifi ers or associated cabling. In most cases you will fi nd that a cable is at fault. If a talent amplifi er is found to be at fault, it will need to be returned to the factory for repair.

Input Data LED

The Input Data LED lights only when data is received that is valid for the Model 55.

The Model 55 uses MIDI system-exclusive messages to perform all operations. When the Model 56 Control Console is connected to the Model 55, the LED will light any time the Model 56 generates data. This is because the Model 56 will only generate data that is compatible with the Model 55.

If you are not using the Model 56, and instead are supplying MIDI data using another device, the LED should prove extremely useful when troubleshooting.

Only when the MIDI data conforms to the

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Model 55’s MIDI system-exclusive format will the LED light. Refer to Appendix A, located at the end of this guide, for details on how data must be sent to the Model 55.

Clicks in the Audio

As covered in the Confi guration section of the manual, the four stereo line inputs can be confi gured for –10 dBV or +4 dBu operation. Setting an input for –10 dBV, while connecting an audio source with a

+4 dBu nominal level will lead to distortion

(“clipping”) of the signal. In this fault condition the user would hear a harsh “clicking” sounds in the audio, especially when peak levels occur in the program material. To remedy this problem simply use the Model

56 Control Console to confi gure the input for

+4 dBu operation. The distortion will go away and the gain structure of the StudioComm system will be correctly established.

Technical Notes

Talent Amplifi er Cable Length

There are no hard and fast rules defi ning the maximum cable length when connecting Model 35 Talent Amplifi ers to the Model

55 Central Controller. The maximum cable length is directly related to the amount of resistance in the connecting cable; the lower the resistance per foot (or meter), the longer the cable can be. (Although cable capacitance affects high frequency performance, resistance is the limiting factor is this case.)

To lay out the facts in grammar-school story-problem format: for correct operation, a Model 35 needs to see at least +20 Vdc between pins 1 and 2 of their input connector. The Model 55’s talent amplifi er output voltage across pins 1 and 2 is +23 Vdc, with a maximum current draw of 0.2 A

(200 mA). This difference between the voltage supplied and the voltage required results in a maximum voltage drop of 3 V over the interconnecting cables. Since cable is rated in ohms per 1000 feet (or ohms per

1000 meters), you need to know what the maximum cable resistance is. This can be easily calculated by dividing the maximum voltage drop by the maximum current fl ow:

3 V divided by 0.2 A = 15 ohms. For example, a standard 20 AWG microphone cable is Belden 8412, which has 10.9 ohms resistance per conductor per 1000 feet. Since we’re using two conductors to carry the signal (pins 1 and 2) you’d get 21.8 ohms per 1000 feet of microphone cable. With our

15 ohm maximum resistance you’d be able to use 688 feet (210 m) of this cable.

By using the numbers provided you can select a cable, and its maximum length, for your application.

Model 55 to Model 56 Cable Length

The Model 56 Control Console generates system-exclusive MIDI messages which are sent to the Model 55 Central Controller using a 5-conductor MIDI-style interconnecting cable. The MIDI signal is carried on two of the fi ve conductors. The three remaining conductors are for common/ shield, DC power, and communications audio. The limiting factor in the interconnecting cable’s length is the transmission of the MIDI data, which has a rate of 31,250 bits-per-second. The inter-conductor capacitance of the cable attenuates the data, and as the cable length increases the data becomes unusable; the cable serves as a low-pass fi lter. The MIDI specifi cation calls for a maximum cable length of 50 feet

(15.3 m), which will work fi ne connecting the

Model 56 to the Model 55. There is

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Model 55/56 User Guide

Studio Technologies, Inc.

really no reason why this length can’t be increased, as long as good lowcapacitance, shielded cable is utilized.

Runs of 100 to 250 feet (30.5 to 76.2 m) are possible using the latest sophisticated cable. Test to ensure that the StudioComm system works correctly with the desired cable length. There are too many variables to give a simple formula—good luck!

Defi nition of Level—dBu and dBV

Whenever possible, Studio Technologies has opted to use the dBu designation as it seems to be quite rational. Using dBm was fi ne when all audio line outputs were terminated with 600 ohm loads. In this way it was easy to say that 0 dBm is

1 milliwatt dissipated in the known load

(i.e., 0 dBm across 600 ohms will measure

0.775 V). In contemporary situations an output is rarely terminated with 600 ohms; generally 10 k ohms or higher. The dBu designation is better because it refers to dB referenced to 0.775 V, with no reference to load impedance. This takes into account today’s audio scene where signals have a low source impedance, and a high input impedance. The dBu designation is becoming the standard for the professional audio industry.

StudioComm equipment is designed to interface with audio signals that have nominal signal levels of –10 dBV and

+4 dBu. You might wonder why dBV came into the picture. Most people don’t realize that equipment that utilizes

“–10” levels usually mean –10 dBV— substantially different from –10 dBu

(–10 dB V = –7.78 dBu). The dBV designation is simply a different way of measuring signal level and is often used when dealing with portable or consumer audio equip-

Model 55/56 User Guide

Studio Technologies, Inc.

ment. The dBV designation refers to dB referenced to 1.0 V, rather than dBu which refers to 0.775 V.

“Hot” Disconnection of the Model 56

Control Console

Should you need to relocate the Model 56 while your StudioComm system is operating, there is no reason why you can’t disconnect the 5-conductor cable, move the unit, and then connect it again. If the

Model 56 is disconnected while it is operating, the current operating parameters are saved in nonvolatile memory and the

Model 55 Central Controller will continue to operate as it did when the link was broken.

No clicks, pops, or other noises will occur when the Model 56 is again connected.

The Model 56 will go through its standard power-up sequence, send a message to reset power-up defaults, then send the operating parameters as stored in its memory. You may notice a brief interval of silence while the Model 55 responds to the reset defaults message.

Control Room Mono Function

Many arguments where had while designing the control room monaural function.

Was the function supposed to be a true mono function, sending the sum of left and right to a separate mono control room output? Was mono to be the sum of left and right sent to both left and right channels? What about level build up with phase coherent signals that are in both the left and right channels? After much head scratching it was realized that the mono function that most people are accustomed to is really a means of observing the character of a stereo mix, and not a “true” mono function. To observe the stereo image of a mix you need to sum the left

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and right signals, drop the level, and send the result out the left and right outputs.

In our application we drop the level by

6 dB. This is what many recording consoles implement, and is what the Studio-

Comm does too!

Talent Amplifi er Mono Function

The Model 35 Talent Amplifi ers contains a monaural switch. The mono function sums the left and right input signals, drops the level of the sum by 6 dB, and sends the sum to both the left and right outputs.

Input Level and the Talent Amplifi ers

Optimal performance of the Model 35

Talent Amplifi er depends on the headphone source signal levels being at approximately the nominal input level, either –10 dBV or +4 dBu, depending on the confi guration. The headphone volume is adjusted only by the level controls on the talent amplifi ers. If the selected headphone source signal level is signifi cantly less than nominal, the talent amplifi er will simply not be able to create the maximum volume in the headphones. While there is some gain in the talent amplifi ers, optimal performance still requires an input close to nominal.

Communication Switch Noise

During fi eld trials of the StudioComm components one item came up for discussion concerning “thumps” in the communications functions. A brief discussion may be useful. Electrically the Model 55 and Model

56 electronics that support the communications functions are quite quiet, not adding appreciable “clicks, pops, or thumps.”

Software time delays are even added to minimize noise when a button is pressed.

Mechanical noise being picked up by the

Model 56’s microphone can be an issue.

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If the talk to phones or slate buttons are pushed using a relatively light touch no objectionable noise will be generated; pressing the switches with “gusto” will cause mechanical noise to be transferred into the microphone. While the Model

56’s microphone is of good quality, shock mounting it was not possible using a cost-effective method. The fact that the Model 56 is physically small and the buttons must be relatively close to the microphone adds to the diffi culty. (Note that most all recording consoles, both small and large, share this condition.) So in conclusion, use a light touch on the buttons and everyone should stay reasonably happy!

Power Amplifi er Input Sensitivity

Optimum StudioComm performance is obtained when the input sensitivity of the control room power amplifi er is adjusted to match the Model 55’s output level.

With normal, but loud, listening levels you should fi nd the level potentiometer on the Model 56 to be set to about 11 or

12 o’clock. If you fi nd that you don’t have to turn up the Model 56’s control that high, reduce the input sensitivity of the power amplifi er. Most power amplifi ers have controls on their inputs to allow easy adjustment of the input sensitivity.

Control Room Output Transient

Protection

Unique to the Model 55 Central Controller is a power up/power down transient protection feature. It limits the chance of damage to the control room loudspeakers during the time when AC mains voltage is connected, disconnected, or has signifi cantly changed from nominal. A combination of hardware and software is used to monitor one of the power supply “rails.”

Model 55/56 User Guide

Studio Technologies, Inc.

Until the rail voltage exceeds 81% of its nominal value, an electromechanical relay maintains a short circuit condition on the control room output. After a one-second delay the relay is released to function normally. Whenever the rail voltage drops below 79% of its nominal value, the relay immediately goes to its mute state. During testing it was found that upon power up the control room output remained very quiet; during power down a moderate “tick” was the worst that was heard.

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Specifi cations

Model 55 Central Controller

Audio Inputs: 4, stereo

Type: electronically balanced, direct coupled, compatible with balanced or unbalanced signals

Impedance: 24 k ohms

Nominal Input Level: –10 dBV or +4 dBu, each input individually software confi gurable

Common Mode Rejection: 100 dB @ DC and

60 Hz, 70 dB @ 20 kHz, 62 dB @ 40 kHz (typical)

Control Room Output: 1, stereo

Type: electronically balanced, intended to drive loads of 600 ohms or greater, balanced or unbalanced

Nominal Level: unity gain, audio inputs to control room outputs

Maximum Output Level: +27 dBu into 10 k ohms,

+26 dBu into 600 ohms

Frequency Response: 10 Hz-40 kHz +0/–0.5 dB

(down 1 dB @ 80 kHz)

Distortion (THD+N): 0.03% (measured at +4 dBu input, +4 dBu output)

S/N Ratio: 87 dB (20 Hz-20 kHz)

Dub Output: 1, stereo

Type: electronically balanced, intended to drive loads of 600 ohms or greater, balanced or unbalanced

Nominal Output Level: –10 dBV or +4 dBu, software confi gurable

Maximum Output Level: +27 dBu into 10 k ohms,

+26 dBu into 600 ohms

Frequency Response: 10 Hz-40 kHz +0/–0.5 dB

(down 1 dB @ 70 kHz)

Distortion (THD+N): 0.004% (measured at +4 dBu input, +4 dBu output)

S/N Ratio: 92 dB (20 Hz-20 kHz)

Meter Output: 1, stereo

Type: unbalanced, intended to drive loads of

2 k ohms or greater

Nominal Output Level: +4 dBu

Maximum Output Level: +21 dBu into 10 k ohms

Frequency Response: 10 Hz-40 kHz +0/–0.5 dB

(down 1 dB @ 70 kHz)

Distortion (THD+N): 0.004% (measured at +4 dBu input, +4 dBu output)

S/N Ratio: 92 dB (20 Hz-20 kHz)

Talent Amplifi er Output:

Application: provides power and audio signals for up to four Model 35 Talent Amplifi ers. The output connector (3-pin XLR-type, male) has common on pin 1, +23 Vdc modulated with left channel audio at –10 dBu on pin 2, and right channel audio at

–10 dBu on pin 3. Maximum output current 200 mA

(nominal).

LED Indicators: 3, power present, over current, and input data present

Connectors:

Audio Inputs and Outputs: ¼ phone jacks.

-inch, 3-conductor

Talent Amplifi er Output: 3-pin XLR-type, male

Control Console/MIDI In: 5-pin DIN-type, female

AC Mains: 3-blade IEC-type

AC Mains Requirement: 100, 120, or 220/240 V,

±10%, factory confi gured, 50/60 Hz, 100-120 V

0.4 A maximum, 220/240 V 0.2 A maximum

Dimensions (Overall):

19.00 inches wide (48.3 cm)

1.72 inches high (4.4 cm)

8.75 inches deep (22.2 cm)

Mounting: one space in a standard 19-inch rack

Weight: 8.5 pounds (3.9 kg)

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Model 55/56 User Guide

Studio Technologies, Inc.

Model 56 Control Console

Power Requirements: 15 Vdc fi ltered and regulated, 75 mA maximum, provided by Model 55

Central Controller

Connectors:

To Model 55 Central Controller: 5-pin DIN-type, female

Internal Microphone:

Type: electret condenser

Frequency Response: 3 dB roll off at 105 Hz

Dimensions (Overall):

7.2 inches wide (18.3 cm)

2.2 inches high (5.6 cm)

5.4 inches deep (13.7 cm)

Mounting: desktop; provision for stand mounting provided

Weight: 1.7 pounds (0.8 kg)

Model 35 Talent Amplifi er

Power Requirements: +20-32 Vdc (modulated with left channel audio), provided by Model 55

Central Controller

Power Present LED: red, indicates presence of operating power

Connectors:

Input (from Model 55): 3-pin XLR-type, female

Loop Thru: 3-pin XLR-type, male, connected in parallel with input connector

Headphone Outputs: 2, ¼

(stereo) phone jacks

-inch, 3-conductor

Headphone Output: 1, feeds two headphone jacks

Load: intended for connection to one or two pairs of headphones with total impedance of 75 ohms or greater

Output Level: user adjustable

Maximum Output Voltage: 16 V peak-to-peak into

150 ohms @ 1% THD+Noise, 400 Hz

Distortion (THD+N): 0.03%

Frequency Response: 20 Hz-20 kHz ±0.5 dB

Dimensions (Overall):

4.2 inches wide (10.7 cm)

2.0 inches high (5.1 cm)

5.3 inches deep (13.5 cm)

Mounting: desktop; provision for stand mounting available as option

Weight: 0.8 pounds (0.4 kg)

Model 70 Interface

Power Requirements: +20-32 Vdc (modulated with left channel audio), provided by Model 55

Central Controller

Power Present LED: red, indicates presence of operating power

Connectors:

Input (from Model 55): 3-pin XLR-type, female

Loop Thru: 3-pin XLR-type, male, connected in parallel with input connector

Left and Right Line Outputs: 3-pin XLR-type, male

Line Output: 1, stereo

Type: electronically balanced, intended to drive loads of 600 ohms or greater, balanced or unbalanced

Nominal Output Level: +4 dBu

Maximum Output Level: +20 dBu into 10 k ohms,

+19 dBu into 600 ohms

Frequency Response: 20 Hz-20 kHz +0/–0.5 dB

Distortion (THD+N): 0.02%

Dimensions (Overall):

4.2 inches wide (10.7 cm)

2.0 inches high (5.1 cm)

5.3 inches deep (13.5 cm)

Weight: 0.8 pounds (0.4 kg)

Specifi cations and information contained in this

User Guide subject to change without notice.

Model 55/56 User Guide

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Appendix A

Controlling the Model 55

The Model 55 Central Controller uses MIDI system-exclusive messages to control all functions. The Model 56 Control Console is programmed to generate a subset of what the Model 55 is capable of doing.

By using standard MIDI messages, the

Model 55 can be used for a wide range of special applications. Any device that can be programmed to send system-exclusive

MIDI messages can be used to control the

Model 55.

All MIDI messages to be acted upon are system-exclusive type (F0H). No channel mode, system common, or system real time messages are utilized. Studio Technologies, Inc. manufacturer’s ID number is 00H 00H 56H. The Model 55’s product device ID number is 02H.

Note that the 5-pin connector on the

Model 55’s back panel is wired somewhat differently from a standard MIDI input. While pins 4 and 5 meet the MIDI standard, the three remaining pins are implemented for use by the Model 56. Pin

1 supplies +15 Vdc power, pin 2 is shield

(ground), and pin 3 is communications audio input.

If you’re connecting your own controller, such as a computer’s MIDI interface, you might be concerned about the DC power on pin 1. Because the MIDI standard doesn’t use this pin, it is highly unlikely that it will be connected inside your controller, so there’s little chance of the DC causing damage. To be safe, you can use a MIDI cable with only two or three wires implemented.

The following pages provide a detailed list of all Model 55 system-exclusive MIDI messages.

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Function: Reset to Power Up Default Confi guration

Byte Value Description

2

3

4

5

6

7

00H 1st Byte of Studio Tech ID

00H 2nd Byte of Studio Tech ID

56H 3rd Byte of Studio Tech ID

02H Product ID (Model 55)

00H Function: Restore Power Up Default Confi guration

F7H EOX, End of System Exclusive

Action taken after Model 55 receives MIDI message:

1. Set control room level to minimum.

2. Set control room source 1 to no input.

3. Set control room source 2 to no input.

4. Set headphone source to no input.

5. Set dub source to no input.

6. Set control room output to off.

7. Set mono to off (stereo mode).

8. Set all input levels to +4.

9. Set dub output level to +4.

10. Set dim to normal, non-dim

11. Set dim level to 20 dB.

12. Set talk to headphones to off.

13. Set slate to off.

7

8

9

2

3

4

5

Function: Input Level

Byte Value Description

00H 1st Byte of Studio Tech ID

00H 2nd Byte of Studio Tech ID

56H 3rd Byte of Studio Tech ID

02H Product ID (Model 55)

Function: Level

0nH Input Channel, range 1-4, 1=input 1, 2=input 2, etc.

0nH Input Level, range 0-1, 0=–10, 1=+4

F7H EOX, End of System Exclusive

Function: Dub Output Level

Byte Value Description

6

7

8

9

2

3

4

5

00H 1st Byte of Studio Tech ID

00H 2nd Byte of Studio Tech ID

56H 3rd Byte of Studio Tech ID

02H Product ID (Model 55)

02H Function: Output Level

0nH Output Channel, range 1, 1=dub out

0nH Output Level, range 0-1, 0=–10, 1=+4

F7H EOX, End of System Exclusive

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Function: Control Room Source 1

Byte Value Description

6

7

8

2

3

4

5

00H 1st Byte of Studio Tech ID

00H 2nd Byte of Studio Tech ID

56H 3rd Byte of Studio Tech ID

02H Product ID (Model 55)

03H Function: Control Room Source 1 mnH Source Selected, m range 0-2: 0=stereo, 1=left only, 2=right only; n range 0-4: 0=no input, 1=input 1, 2=input 2, etc.

F7H EOX, End of System Exclusive

Function: Control Room Source 2

Byte Value Description

6

7

8

2

3

4

5

00H 1st Byte of Studio Tech ID

00H 2nd Byte of Studio Tech ID

56H 3rd Byte of Studio Tech ID

02H Product ID (Model 55)

04H Function: Control Room Source 2 mnH Source Selected, m range 0-2: 0=stereo, 1=left only, 2=right only; n range 0-4: 0=no input, 1=input 1, 2=input 2, etc.

F7H EOX, End of System Exclusive

Function: Headphone Source

Byte Value Description

6

7

8

2

3

4

5

00H 1st Byte of Studio Tech ID

00H 2nd Byte of Studio Tech ID

56H 3rd Byte of Studio Tech ID

02H Product ID (Model 55)

05H Function: Headphone Source mnH Source Selected, m range 0-2: 0=stereo, 1=left only, 2=right only; n range 0-4: 0=no input, 1=input 1, 2=input 2, etc.

F7H EOX, End of System Exclusive

Function: Dub Source

Byte Value Description

6

7

8

2

3

4

5

00H 1st Byte of Studio Tech ID

00H 2nd Byte of Studio Tech ID

56H 3rd Byte of Studio Tech ID

02H Product ID (Model 55)

06H Function: Dub Source mnH Source Selected, m range 0-2: 0=stereo, 1=left only, 2=right only; n range 0-4: 0=no input, 1=input 1, 2=input 2, etc.

F7H EOX, End of System Exclusive

Issue 5, August 2005

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Studio Technologies, Inc.

Function: Control Room Level

Byte Value Description

6

7

8

9

2

3

4

5

00H

00H

56H

02H

07H

0nH nnH

F7H

1st Byte of Studio Tech ID

2nd Byte of Studio Tech ID

3rd Byte of Studio Tech ID

Product ID (Model 55)

Function: Control Room Level

Level, MSB, range 0-3, see notes

Level, LSB, range 00-7F, see notes

EOX, End of System Exclusive

Notes:

MSB=0 allows LSB to control lower 128 level steps, MSB=1 allows LSB fi eld to control upper 128 level steps. During operation MSB=0/LSB=00 gives minimum output level (maximum attenuation),

MSB=1/LSB=7F gives maximum output level.

MSB=2 places function in reduced precision mode, where LSB=00 gives minimum output level (maximum attenuation), LSB=7F is maximum output.

MSB=3 places function in reduced precision, reverse range mode, where LSB=7F gives minimum output level (maximum attenuation), LSB=00 is maximum output.

Function: Control Room Output Select

Byte Value Description

2

3

4

5

6

7

8

00H 1st Byte of Studio Tech ID

00H 2nd Byte of Studio Tech ID

56H 3rd Byte of Studio Tech ID

02H Product ID (Model 55)

09H Function: Control Room Output Select nnH Output Selected, Range 00-11:

0

1

0

1

0

0

1

1

No Output

Left Only

Right Only

Left and Right

F7H EOX, End of System Exclusive

Function: Control Room Mono/Stereo Select

Byte Value Description

6

7

8

2

3

4

5

00H 1st Byte of Studio Tech ID

00H 2nd Byte of Studio Tech ID

56H 3rd Byte of Studio Tech ID

02H Product ID (Model 55)

0AH Function: Control Room Mono

0nH Output Selected, Range 0-1, 0=stereo, 1=mono

F7H EOX, End of System Exclusive

Model 55/56 User Guide

Studio Technologies, Inc.

Issue 5, August 2005

Page 33

Function: Control Room Dim

Byte Value Description

6

7

8

2

3

4

5

00H 1st Byte of Studio Tech ID

00H 2nd Byte of Studio Tech ID

56H 3rd Byte of Studio Tech ID

02H Product ID (Model 55)

0BH Function: Control Room Dim

0nH Status, Range 0-1, 0=No Dim, 1=Dim

F7H EOX, End of System Exclusive

Function: Talk to Headphones

Byte Value Description

2

3

4

5

6

7

8

9

00H 1st Byte of Studio Tech ID

00H 2nd Byte of Studio Tech ID

56H 3rd Byte of Studio Tech ID

02H Product ID (Model 55)

0EH Function: Talk to Headphones

0nH Status, Range 0-2, 0=no talk to headphones, 1=talk to headphones (interrupt),

0nH Level, range 1-8, 8 is loudest

F7H EOX, End of System Exclusive

Function: Slate

Byte Value Description

7

8

9

2

3

4

5

00H 1st Byte of Studio Tech ID

00H 2nd Byte of Studio Tech ID

56H 3rd Byte of Studio Tech ID

02H Product ID (Model 55)

0nH Status, Valid Values 0, 1, and 3, 0=no slate, 1=slate to dub output,

3=slate to dub and headphone output

0nH Level, range 1-8, 8 is loudest

F7H EOX, End of System Exclusive

Issue 5, August 2005

Page 34

Model 55/56 User Guide

Studio Technologies, Inc.

Function: Set Dim Level

Byte Value Description

6

7

2

3

4

5

00H 1st Byte of Studio Tech ID

00H 2nd Byte of Studio Tech ID

56H 3rd Byte of Studio Tech ID

02H Product ID (Model 55)

10H Function: Set Dim Level

0nH Status, Range 0-5:

0=full mute (approx. 70 dB)

8 F7H EOX, End of System Exclusive

Function: Control Room Mute

Byte Value Description

6

7

8

2

3

4

5

00H 1st Byte of Studio Tech ID

00H 2nd Byte of Studio Tech ID

56H 3rd Byte of Studio Tech ID

02H Product ID (Model 55)

11H Function: Control Room Mute

0nH Status, Range 0-1, 0=No Mute, 1=Mute

F7H EOX, End of System Exclusive

Model 55/56 User Guide

Studio Technologies, Inc.

Issue 5, August 2005

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Issue 5, August 2005

Page 36

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M35BD_C.sch-1 - Fri Aug 12 14:29:10 2005

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