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Merlin Integrated Signal Processor ISP-100 User Manual

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Summary of Contents for Merlin Integrated Signal Processor ISP-100

  • Page 3 The Merlin product information and design disclosed herein were originated by and are the property of Telex Communications, Inc. Telex reserves all patent, proprietary design, manufacturing, reproduction, use and sales rights thereto, and to any article disclosed therein, except to the extent rights are expressly granted to others.

  • Page 4: Shipping To Manufacturer For Repair Or Adjustment

    ANY AND ALL IMPLIED WARRANTIES, INCLUDING THE IMPLIED WARRANTY OF MERCHANTABILITY ARE LIMITED TO THE DURATION OF THIS EXPRESS LIMITED WARRANTY. NEITHER TELEX NOR THE DEALER WHO SELLS MERLIN PRODUCTS IS LIABLE FOR INCIDENTAL OR CONSEQUENTIAL DAMAGES OF ANY KIND.
  • Page 5 IMPORTANT – Please read this document carefully before using this product. THIS DOCUMENT STATES THE TERMS AND CONDITIONS UPON WHICH TELEX COMMUNICATIONS, INC. (the “COMPANY”) OFFERS TO LICENSE THE INSTALLED SOFTWARE OR PROGRAM (the “SOFTWARE”) FOR USE WITH THE PRODUCT IN WHICH IT WAS INSTALLED. YOU ARE AGREEING TO BECOME BOUND BY THE TERMS OF THIS AGREEMENT.

  • Page 6: Table Of Contents

    Table of Contents An Overview of the ISP-100 ... 1-1 About this Manual ... 1-2 Customer Support ... 1-2 Conventions Used in this Manual ... 1-2 Introduction... 2-1 Unpacking ... 2-1 Front Panel Features ... 2-1 Rear Panel Features ... 2-2 Power Requirements ...
  • Page 7 Table of Contents LowPass Filter ... 4-2 HighPass Filter ... 4-2 AllPass Filter... 4-2 LowShelf Filter ... 4-2 HighShelf Filter ... 4-2 Notch Filter ... 4-2 PEQ ... 4-3 Combine ... 4-3 Input ... 4-3 Output ... 4-3 ISP-100 Component Plots ... 4-3 Compressor ...
  • Page 8 Table of Contents Minimum System Requirements ... 5-1 Identifying a Serial Port ... 5-1 Loading the Software ... 5-1 Updating the ISP-100’s Operating System ... 5-2 Configuring the Software ... 5-4 Starting VUE-IT ... 6-1 Starting a New Project ... 6-2 VUE-IT File System ...
  • Page 9 Table of Contents OpenDevice Status Panel on Error ... 7-4 Display QuickMAP Pop-Up names ... 7-4 Display Filter Bandwidth in “Q” ... 7-4 System Configurations ... 7-4 New Projects ... 7-4 Component Library ... 7-4 QuickMAP Library ... 7-5 Company Name ... 7-5 Designer’s Name ...
  • Page 10 Table of Contents Polarity Control (+/-) ... 8-3 Mute Control (M) ... 8-3 Bypass Control (master) ... 8-3 Compressor ... 8-4 Familliar Controls ... 8-4 Unfamiliar Controls ... 8-6 Metering ... 8-8 Notes on Operation of the Compressor ... 8-8 Meter ...
  • Page 11 Table of Contents Bypass Control (master) ... 8-28 Filter ... 8-29 Filter Bands ... 8-29 LowPass Filters ... 8-30 HighPass Filters ... 8-30 LowShelf Filters ... 8-31 HighShelf Filters ... 8-31 Notch Filters ... 8-32 Parametric EQ Filters ... 8-32 Peaked HighPass Filters ...
  • Page 12 Table of Contents Familiar Controls ... 8-46 Unfamiliar Controls ... 8-48 Notes on Operation of the Limiter ... 8-49 Meter ... 8-50 Threshold ... 8-50 Attack, Window, Release, and Crest Factor Controls ... 8-51 Fine (F) or Coarse (C) Control ... 8-51 Knee Control ...

  • Page 13: An Overview Of The Isp-100

    Thank you for choosing the ISP-100™ for your signal processing needs. The ISP-100 is the first in a line of high quality signal processing products from TELEX Communications, Inc.’s Merlin division. The ISP-100 represents a continued commitment to understanding and meeting our customers needs through the development of innovative and intuitive solutions.

  • Page 14: About This Manual

    closures. This interface allows users to change system settings directly and/or scroll through various settings. About this Manual This manual is covers the installation and operation of the ISP-100’s hardware and software. The ISP-100 has been designed to be as user-friendly as possible. However, this manual should be read before attempting to install or operate the ISP-100.

  • Page 15: Introduction

    Therefore, carefully inspect the outside carton for signs of abuse. If for any reason the ISP-100 should need to be returned, use the shipping carton that it came in. TELEX Communications, Inc. cannot warranty against damage that occurs as a result of improper packaging.

  • Page 16: Rear Panel Features

    Rear Panel Features (see Figure 2-2) Figure 2-2 ISP-100 rear panel features. 1. AC Power—Connects to mains via an IEC type AC power cord. 2. RS-232 Port—Links the PC to the unit via a RJ-45 connector. 3. External Sync—Precision frequency reference input to the unit. 4.

  • Page 17: Card Installation Procedure

    Card Installation Procedure Figure 2-3 Battery/module tool. 1. Ground yourself using a wrist strap and anti-static mat. 2. Turn off the ISP-100. 3. Remove the screws securing the module slot cover. 4. If you are not replacing an existing card please proceed to step 6. 5.

  • Page 18: Cable Diagrams

    Cable Diagrams Analog Audio (MIM-1, MIM-2, MOM-1) Figure 2-6 Analog inputs. Balanced Input from Balanced Output Connect the positive (+) side of the line to pin 2 of the male 3-pin XLR connector and the negative (-) side of the line to pin 3 of the connector.

  • Page 19: Digital Audio

    Balanced Output to Unbalanced Input Connect the “hot” wire to pin 2 of the 3-pin female XLR connector and the shield wire to pin 1 of the connector. To avoid a 6 dB drop in level, connect pin 3 to pin 1 of the connector. See Figure 2-7 for more information.

  • Page 20: Serial Communications

    AES/EBU Output Figure 2-10 AES/EBU output. Connect the positive (+) side of the line to pin 2 of the 3-pin female XLR connector and the negative (-) side of the line to pin 3 of the connector. In keeping with standard wiring practices, the shield should be connected at this end;...
  • Page 21 The converter on the PC end of the connection can be PC powered, but the converter at the ISP-100 end of the connection must have its own power supply. Before buying converters please contact TELEX Communications, Inc. for an application note on this topic.
  • Page 22 Table 2-1 RS-232 signal pinouts for RJ-45, DB-9, and DB-25 connectors. Figure 2-16 Connector pinouts.

  • Page 23: General Purpose Inputs (Gpi)

    General Purpose Inputs (GPI) Figure 2-17 GPI connector pinout. Dry (i.e. switch) or electronic (i.e. open collector) contact closure should be sufficient. The closure can be either momentary (10 ms minimum duration) or continuous. Connect the desired input (1-8) through the contact closure to common (9). See Figure 2-17 for more information.

  • Page 25: User Modifications

    > > > CAUTION < < < NO USER SERVICEABLE PARTS INSIDE. HAZARDOUS VOLTAGES AND CURRENTS MAY BE ENCOUNTERED WITHIN THE CHASSIS. TO AVOID ELECTRICAL SHOCK DO NOT PERFORM ANY SERVICING OTHER THAN THAT CONTAINED IN THESE OPERATING INSTRUCTIONS. User Modifications Modifications to Merlin products are not recommended.

  • Page 26: Diagnostics

    Diagnostics Table 3-1 LED diagnostic messages. The ISP-100 was designed with built-in diagnostics that activate when power is applied to the unit. During the power-up cycle, the ISP-100 performs several self-checks. The ISP-100 also will report problems, as they happen, while the unit is running. The diagnostic messages are communicated through the front panel LEDs.

  • Page 27: Retrieving Version Numbers

    Retrieving Version Numbers Figure 3-1 About VUE-IT dialog Application, OS, and DSP version numbers can be obtained by clicking on the Help menu and then selecting the About entry. See Figure 3-1. If an ISP-100 is not online, only the application version number will be reported.

  • Page 28: Changing The Fuse

    All countries using 220/240 VAC, except Australia, use a ½ A slow-blow fuse. Schurter P/N: 0001.2501 Telex P/N: 51-04-052488 All countries using 100/120 VAC and Australia use a 1 A slow-blow fuse. Schurter P/N: 0001.2504 Telex P/N: 51-04-051487 Changing the Battery Figure 3-3 Battery/module removal tool.
  • Page 29 Doing so could cause damage. See Figure 3-3. Replace the battery with a Renata CR2450N battery. Replacement battery/module removal tools as well as replacement batteries are available from Telex. Their part numbers are: Battery/Module Removal Tool Replacement Battery Dispose of used battery promptly.

  • Page 30: Technical Support

    Technical Support Technical questions should be directed to: Customer Service Department - Merlin Telex Communications, Inc. 9600 Aldrich Avenue South Minneapolis, MN 55420 U.S.A. Telephone: (612) 884-4051 Fax: (612) 884-0043 Helpful Information Be prepared to provide the following information (if possible): 1.

  • Page 31: Shipping To Manufacturer For Repair Or Adjustment

    All shipments must be sent to the following address and must include the Return Authorization. Factory Service department Telex Communications, Inc. West 1 st Street Blue Earth, MN 56013 U.S.A. Upon completion of any repair the equipment will be returned via United...

  • Page 33: Components

    Components Compressor Property Bypass Threshold Compression Ratio Attack Time Release Time Detection Window Crest Factor Knee Sidechain Channel Crossover Property Slope Class Cutoff Frequency Gain Absolute Polarity Delay* Property Delay Dither Property Bypass Level Gain** Property Input Gain Mute Absolute Polarity Gate Property Bypass...

  • Page 34: Limiter

    Limiter Property Bypass Threshold -60 dB to 0 dB Attack Time 20 msec to 50 ms Release Time 20 msec to 5 sec Detection Window 20 msec to 5 sec Crest Factor Knee Sidechain Channel self, max of both, or Filters Property Bypass...

  • Page 35: Peq

    Property Center Frequency Boost/Cut Bandwidth Combine Property Channel “1” Entry Gain Channel “1” Entry Polarity Channel “2” Entry Gain Channel “2” Entry Polarity Input Property Left Gain (A) Right Gain (B) Left Pad (A) Right Pad (B) Output Property Left Gain (A) Right Gain (B) Left Mute (A) Right Mute (B)

  • Page 36: Gate

    Gate Linkwitz-Riley 3-way Crossover Notch Filter Parametric Equalizer Filter Peaked HighPass Filter Shelving Filter AP is a trademark of Audio Precision, Inc.

  • Page 37: System Measurements

    System Measurements System Frequency Response System Noise Floor System THD+N AP is a trademark of Audio Precision, Inc.

  • Page 38: Mim-1 & Mim-2* Analog Input Modules

    MIM-1 & MIM-2* Analog Input Modules Power Performance Miscellaneous Notes (Unless otherwise specified measurements are at unity gain with +16 dBu signal. * MIM-2 differences parenthetically noted.

  • Page 39: Mom-1 Analog Output Module

    MOM-1 Analog Output Module Power Performance Miscellaneous Notes...

  • Page 40: Mdm-1 Aes/Ebu Digital I/O Module

    MDM-1 AES/EBU Digital I/O Module Power Performance (Sample Rate Converter Engaged)

  • Page 41: Performance (Sample Rate Converter Bypassed)

    Performance (Sample Rate Converter bypassed) Miscellaneous...

  • Page 42: Notes

    Notes Physical Height 1.75 inches (44.5 mm) Width 19.0 inches (483 mm) Depth 14.5 inches+0.5” (368 mm + 12.7 mm) for protrusions Weight Approx.12.9 lbs. (5.9 kg) Included Accessories IEC power cord, user’s manual, software, spare fuse Power Universal AC input voltage 90-264 VAC;...

  • Page 43: Minimum System Requirements

    Minimum System Requirements CPU: Pentium® processor. OS: Microsoft® Windows 3.1x, Windows 95, or Windows 98 Memory: 8MB RAM Hard Drive: 5MB of available space (beyond swap file needs) Disk Drive: 3.5 inch high-density Monitor: 640X480, 256 color Pointing Device: mouse or other Windows compatible pointing device Communications: free COM port (1-4) with 16550 UART Identifying a Serial Port The ISP-100 requires a serial port to communicate with the PC.

  • Page 44: Updating The Isp-100'S Operating System

    Updating the ISP-100’s Operating System Figure 5-1 OS mismatch dialog. Figure 5-2 OS download request dialog. The updating of the operating system contained in the ISP-100’s flash memory is usually required after loading a new version of VUE-IT on the computer.
  • Page 45 Figure 5-3 Open OS file dialog. 5. Download the OS software file you need via the application when prompted. See Figure 5-3 for more information. The default location for OS files is “c:\program files\vue-it\isp-100”. Figure 5-4 Download progress dialog. 6. The lights will continue to rotate with only brief pauses. You will also see a progress indicator on the PC’s screen similar to the one in Figure 5-4.

  • Page 46: Configuring The Software

    Configuring the Software Turn on the ISP-100. The power switch is located at the far right under the front access panel. This is accomplished by placing the switch in the down position. See Figure 2-1 for the location of the power switch. Check to make sure that the LEDs light in a percentage complete fashion.
  • Page 47 Figure 5-8 ISP-100 not detected dialog. If a dialog box like the one in Figure 5-8 appears in place of the one in Figure 5-7, the cable connecting the computer to the ISP-100 should be checked. If no problem is found there, try selecting a different serial port. Figure 5-9 Communications error dialog.

  • Page 49: Starting Vue-It

    Starting VUE-IT Figure 6-1 VUE-IT workspace. When VUE-IT is started, you will see a screen similar to the one in Figure 6-1. The window displayed in Figure 6-1 is the basic environment in which all interactions with VUE-IT take place. There are six key features of this window that users should be aware of: 1.

  • Page 50: Starting A New Project

    Starting a New Project Figure 6-2 Create new project dialog. To start a new project select New Project from the File menu. A panel similar to the one in Figure 6-2 will appear. You are allowed to select a name of up to eight characters for the project, assign a path for the project to be stored, and create a new subdirectory if needed.

  • Page 51: Vue-It File System

    used to create the QuickMAP. The QuickMAPs can be sorted by Name, I/O Configuration, Creation Time, and Modification Time. To sort the QuickMAPs, click on the heading button of the property you wish to sort by (i.e. Name, I/O Configuration, etc.). The first click of the mouse will sort the QuickMAPs in ascending order and the second click will sort them in descending order.

  • Page 52: Archiving Projects

    Archiving Projects To save a project for archival purposes do the following: 1. Exit VUE-IT. 2. Save the project directory and the four files mentioned previously to the archival media (i.e. floppy disk, zip™ disk, tape, CD, etc...). The directory name will usually be the name you assigned the project. Mounting Projects To install a project from an archive do the following: 1.

  • Page 53: Open Project

    VUE-IT has a variety of commands available to the user. These commands are accessible via the menu items along the top of the VUE-IT workspace window. File (see Figure 7-1) Figure 7-1 File menu. New Project - Creates a new project file. Open Project - Loads an existing project.

  • Page 54: Refresh Directories

    Edit (see Figure 7-2) Figure 7-2 Edit menu. Cut - Removes the selected item(s) and places them on the clipboard. Copy - Places a copy of the selected item(s) on the clipboard. Paste - Inserts item(s) from the clipboard. Tools (see Figure 7-3) Figure 7-3 Tools menu.

  • Page 55: Arrange Icons

    Window (see Figure 7-5) Figure 7-5 Windows menu. Cascade - Arranges panels in overlapping layers. Tile - Arranges panels side-by-side. Arrange Icons - Arranges minimized panels side-by-side. Help (see Figure 7-6) Figure 7-6 Help menu. About - Lists the current application software version, OS version, and DSP version if an ISP-100 is connected and online.

  • Page 56: Display Recently Opened Files In The File Menu

    there is when changing between QuickSETs or using a GPI mute. The total time for ramp-up and ramp-down is twice the time specified. (i.e. If 50 ms of time is specified, the ramp-down will be 50 ms and the ramp-up will be 50 ms. Thus, the total time between the start of the ramp-down to the end of the ramp-up is 100 ms.) Display recently opened files in the File Menu The check box turns on and off the Most Recently Used files (MRU)

  • Page 57: Quickmap Library

    QuickMAP Library This is the directory under which QuickMAP templates are stored. To modify the path, click on the Modify... button located to the right of the directory path entry. Company Name This entry is reserved for possible future use in documenting projects. You can enter the company name, but it currently will not be saved in a project.

  • Page 58: Properties For The Isp-100

    able to access ISP-100 statistics such as free memory, number of QuickSETs, etc. Properties for the ISP-100 Figure 7-10 ISP-100 properties dialog. Properties for the ISP-100 (see Figure 7-10) reports statistics on the ISP-100. It is accessed by double clicking on the entry next to the star icon (see Figure 7-9), or by clicking on the entry next to the star icon (see Figure 7-9) and then clicking on the Properties button in the Project Manager.

  • Page 59: Project Properties

    Project Properties Figure 7-11 Project properties dialog. Project properties (see Figure 7-11) provides the user with information on the name of the project, project location, and notes related to the project. It is accessed by double clicking on the project name entry, or by clicking on the project name entry and then clicking on the Properties button in the Project Manager.

  • Page 60: Quickmap Properties

    Configuration, etc.). The first click of the mouse will sort the QuickMAPs in ascending order and the second click will sort them in descending order. See section 6 for the location of the QuickMAP directory. QuickMAP Properties Figure 7-12 QuickMAP properties dialog. QuickMAP Properties (see Figure 7-13) appear by clicking on the QuickMAP entry in the Project Manager and then clicking on the Properties button.

  • Page 61: Component Export

    Clicking on a component (i.e. Cut, Compressor, Limiter, etc.) in the Project Manager (see Figure 7-9) and then clicking on the Properties button displays the properties for the selected component. Component Properties allow the user to name the component and enter notes related to that component.

  • Page 62: Component Import

    Component Import Figure 7-16 Component import dialog. To import component settings from the Project Manager, click on the desired component entry in the project manager (see Figure 7-9) and then click on the Import button. You will then see a dialog box like the one in Figure 7-16.

  • Page 63: Creating New Quicksets

    The QuickSET Manager (see Figure 7-17) allows the user to develop and manage multiple groups of component settings. The QuickSET Manager is opened when a component is opened. Creating New QuickSETs The user can name a group of settings by clicking on the New button and then entering the name in the pop-up window and clicking on the OK button.

  • Page 64: Testing The Gpi Assignments

    will appear, and the proper command can be selected from the list by clicking on it. The list displays the following options: Empty - No command assigned to input pin. Mute Combo - The initial contact closure causes the outputs to mute.

  • Page 65: Quickmap

    QuickMAP Figure 7-20 QuickMAP panel. Double clicking on the QuickMAP (name) entry or by clicking on the entry and then clicking on the Design button can access a graphical representation of the selected QuickMAP (see Figure 7-20). Clicking on the green input triangles in the QuickMAP will open the I/O Properties dialog (see Figure 7-21).

  • Page 66: I/O Properties

    I/O Properties (see Figure 7-21) Figure 7-21 I/O properties dialog. Input The Input Function controls the levels entering the unit. This function can be accessed in any of the following three ways: 1. Clicking on the green input triangles. 2. Right clicking on either the green input or green output triangles and selecting Properties from the pop-up list.

  • Page 67: Output

    Output The Output function controls the output levels from the unit. Using the Stereo Control This button controls the tracking of the Gain/Attenuator levels. If the LED is gray, then the two channels do not track each other. If the LED is blue, then the channels will track each other. Clicking on the button will toggle the setting.

  • Page 68: Status Information

    Status Information Figure 7-22 Digital I/O status panel. Status information can be obtained for card slots 1 and 2 by clicking on the Status button in the desired slot. See Figure 7-22. Sample Rate Converter On indicates that the sample rate conversion option is selected on the card.

  • Page 69: Device Status Panel

    Device Status Panel Figure 7-23 Device status panel. Clicking on the entry next to the star icon (see Figure 7-9) and then clicking on the Design button in the Project Manager opens the Device Status Panel. See Figure 7-23. The device status panel has five simulated LEDs: Clock Sync (red) The main board cannot lock to specified location or frequency.

  • Page 70: Output Meters

    Output Meters Figure 7-24 Output meter panel. The Output Meters (see Figure 7-24) provide monitoring of the outputs of the DSPs before digital-to-analog conversion. To activate the Meters, click on the green output triangles in the QuickMAP, or click on the Meter Bank entry in the Project Manager and then click on the Design button.
  • Page 71 The components used in the VUE-IT interface have a wide variety of controls for adjusting settings. Each component description begins with a full explanation of the component including all of the parameters that can be adjusted. In some areas the explanations may go into more depth than the average user would need.

  • Page 72: Combine

    Combine Figure 8-1 2-to-1 combine component. The Combine component (see Figure 8-1) adds multiple input signals together and sends the sum to a single output. In QuickMAPs, 2-to-1, 3-to-1, and 4-to-1 combines may exist. The combine’s default attenuation is set so that the combine’s output level is unity. In every case the attenuation applied to each input channel may be independently adjusted between -96 dB and 0 dB, or muted, and the polarity applied to each input channel may be independently set to + or - (in-phase or out-of-...

  • Page 73: Fine (F) Or Coarse (C) Control

    Fine (F) or Coarse (C) Control This button determines the increment/decrement associated with the UP/DOWN arrows. Fine produces small steps in value, while Coarse provides large steps in value. Clicking on the button will toggle the setting. Polarity Control (+/-) This button determines the polarity of the signal.

  • Page 74: Compressor

    Compressor Figure 8-2 Compressor component. A compressor (see Figure 8-2) is used in situations where the input signal has a greater dynamic range, or ratio of loudest to softest, than is desired in the output signal. Compression is accomplished by preventing the output signal from changing in level as much as the input signal, and can be thought of as a form of automatic gain riding.
  • Page 75 threshold value, no compression takes place and the change in level of the output signal exactly matches the change in level of the input signal. When the input signal level is above the threshold value, compression is used and the change in level of the output signal is less than the change in level of the input signal by the amount dictated by the selected compression ratio.

  • Page 76: Unfamiliar Controls

    2.5 dB below the input level at the threshold. The divergence continues to increase gradually until approximately 6 dB above the threshold, beyond which the output level rise is dictated solely by the selected compression ratio. There is a smooth, gradual transition from no compression below the threshold to compression above.
  • Page 77 Crest Factor Sensitivity A signal’s crest factor is the ratio of a its peak level to its average level. The signal having the lowest possible crest factor is the square wave, whose peak and average levels are equal and whose crest factor is therefore 1.0. The peak level of a pure sinewave tone is 1.414 times its average level;...

  • Page 78: Metering

    input signal was going to be, then the Crest Factor Sensitivity control would ideally be set to: Crest Factor Input Since this quantity is not generally known, it is best to experiment until satisfactory results are obtained. Metering The compressor meter shows the attenuation applied to the signal passing through the compressor at any given moment in time.

  • Page 79: Meter

    not its compressor control settings. If multiple compressors utilize the same channel as their sidechain sources, then all controls on all compressors must still be configured. Meter The meter located at the left of the component indicates the amount of attenuation taking place in dB. Threshold The Threshold can be adjusted three ways: Using the Slider...

  • Page 80: Fine (F) Or Coarse (C) Control

    Using the UP/DOWN Arrows To increase the level, click on the up arrow. To decrease the level attenuation, click on the down arrow. The amount of increase or decrease is controlled by the fine/coarse control. Fine (F) or Coarse (C) Control This button determines the increment/decrement associated with the UP/DOWN arrows.

  • Page 81: Crossover

    Crossover Figure 8-3 Two-way crossover component. Crossovers (see Figure 8-3) are used to divide the audio signal into multiple bands appropriate for different types of loudspeakers or loudspeaker elements. In QuickMAPs, 2-way, 3-way, and 4-way crossovers may exist. Each of these crossovers may be implemented using Bessel or Butterworth filters with 1 st - through 4 th -order slopes, or Linkwitz-Riley filters with 2 nd - or 4 th -order slopes, or combinations thereof.
  • Page 82 The lowpass filter LP and the highpass filter HP independently configured as: Bessel 6 dB/octave (1 -order) Bessel 12 dB/octave (2 -order) Bessel 18 dB/octave (3 -order) Bessel 24 dB/octave (4 -order) Butterworth 6 dB/octave (1 -order) Butterworth 12 dB/octave (2 Butterworth 18 dB/octave (3 Butterworth 24 dB/octave (4 Linkwitz-Riley (Butterworth-Squared) 12 dB/octave (2...

  • Page 83: Three-Way Crossovers

    Two-way Linkwitz-Riley Crossovers Linkwitz-Riley designs constitute a special, even-order in-phase class of two-way sum-to-allpass response crossovers, and they must be configured in accordance with very strict phase and polarity requirements. A properly implemented 2-way, 12 dB/octave Linkwitz-Riley crossover is characterized by: •...
  • Page 84 implementation of Linkwitz-Riley crossovers, for which the ISP-100 has been optimized. The filters marked optional in Figure 8-5 will be explained in the Linkwitz-Riley Crossover section, below. The lowpass filters LP (except for the optional LP highpass filters HP may each be independently configured as: Bessel 6 dB/octave (1 -order) Bessel 12 dB/octave (2...
  • Page 85 In the ISP-100, 3-way Bessel and Butterworth crossovers are implemented as shown in Figure 8-6. Bessel crossovers utilize Bessel filters. Bessel filters are designed for maximally-flat group delay, meaning that they have nearly linear phase and excellent transient response. Their amplitude response is not as flat and their cutoff is not as sharp as those of Butterworth filters.
  • Page 86 band and LP lowpass filter in the low band. The inclusion of these filters is mandatory for proper implementation of the 3-way Linkwitz-Riley crossover; they ensure that the phase shift and magnitude response in each band match those of the other bands to maintain the fundamental Linkwitz-Riley sum-to-allpass quality.

  • Page 87: Four-Way Crossovers

    Four-Way Crossovers Figure 8-8 Four-way crossover implementation. In the ISP-100, 4-way crossovers are implemented as shown in Figure 8-8. This parallel structure was selected over the more common binary- tree structure for its suitability to the distribution of filters among multiple DSPs.
  • Page 88 The attenuation in each band is continuously variable from -96 dB and 0 dB, plus mute. The polarity in each band is selectable as + or - (in-phase or out-of- phase). Each band may be bypassed, in which case all of the crossover filters in that band will be bypassed while the crossover filters in the other bands will not be affected.
  • Page 89 Four-way Linkwitz-Riley Crossovers Figure 8-10 Four-way Linkwitz-Riley crossover implementation. In the ISP-100, 4-way Linkwitz-Riley crossovers are implemented as shown in Figure 8-10. Linkwitz-Riley designs constitute a special, even-order in-phase class of 2-way sum-to-allpass response crossovers, and they must be configured in accordance with very strict phase and polarity requirements.

  • Page 90: Sum-To-Allpass Characteristics Of Linkwitz-Riley Crossovers

    A properly implemented 2-way, 12 dB/octave Linkwitz-Riley crossover is characterized by: • 2 -order Linkwitz-Riley (Butterworth-Squared) lowpass filter, -6 dB magnitude response at crossover frequency • 2 -order Linkwitz-Riley (Butterworth-Squared) highpass filter, -6 dB magnitude response at crossover frequency • polarity of highpass band opposite that of lowpass band In a 4-way crossover the bands associate in non-obvious ways (see Sum-to-Allpass Characteristics of Linkwitz-Riley Crossovers).

  • Page 91: Low, Low-Mid, Mid, Mid-High And High Controls

    depending upon whether 12 dB/octave or 24 dB/octave filters are used, respectively. The following sections will show this sum-to-allpass trait to hold true for the ISP-100 Linkwitz-Riley 3-way and 4-way crossover implementations. Three-way From Figure 8-6 Summed Response = LP = (LP ±...

  • Page 92: Class

    Class To change settings, click on the arrow next to the number in the text box. A selection list will appear. The list may or may not be scrollable. To make a selection click on the desired entry. Cutoff Frequency The Cutoff Frequency can be adjusted three ways: Using the Knob Click on the indicator on the knob and while continuing to hold...

  • Page 93: Fine (F) Or Coarse (C) Control

    Fine (F) or Coarse (C) Control This button determines the increment/decrement associated with the UP/DOWN arrows. Fine produces small steps in value, while Coarse provides large steps in value. Clicking on the button will toggle the setting. Polarity Control (+/-) This button determines the polarity of the signal.

  • Page 94: Cut

    Figure 8-11 Cut component. The Cut (see Figure 8-11) can apply as much as 96 dB attenuation, or mute completely, and invert polarity. Attenuation and Polarity Application of attenuation is accomplished by multiplying each data sample by a number whose absolute value lies between 1.0 (0 dB) and 0.000015625 (-96 dB).

  • Page 95: Fine (F) Or Coarse (C) Control

    Fine (F) or Coarse (C) Control This button determines the increment/decrement associated with the UP/DOWN arrows. Fine produces small steps in value, while Coarse provides large steps in value. Clicking on the button will toggle the setting. Polarity Control (+/-) This button determines the polarity of the signal.

  • Page 96: Delay

    Delay Figure 8-12 Delay component. Delay (see Figure 8-12) is used to compensate for differences in the physical alignment of loudspeakers or loudspeaker drivers. In the ISP-100, the delay in each output channel is adjustable in the range 0 – 2,500 milliseconds (depending on QuickMAP used) in 20.833 microsecond (single sample) increments.

  • Page 97: Dither

    Dither Figure 8-13 Dither component. Dithering (see Figure 8-13) is used when shortening high resolution digital audio data words to a lower resolution; for example, when sending 24-bit ISP-100 audio data to 20-bit D/A converters, or directly to a 16-bit Digital Audio Tape recorder through a digital interface.

  • Page 98: Dither Signal Characteristics

    numbers between 16 and 24 bits, inclusive. The bit level of the dither signal should be set to the bit resolution of the destination for the data. The resulting dither signal will have an amplitude equal to ±1.0 quantization level (peak-to-peak) at the selected Bit Level. Using the examples, the bit level for the dither signal should be set to 20 bits when the data are destined for the 20-bit D/A converters, and to 16 bits when the data are destined for the DAT recorder.

  • Page 99: Filter

    Filter Figure 8-14 Filter component. Filters (see Figure 8-14) are used to modify the spectral balance, frequency content, or phase response of the signals upon which they operate. Filter Bands The filters in the ISP-100 are arranged in bands, each of which represent a single 2nd-order filter in the DSP code.

  • Page 100: Lowpass Filters

    All filters in the ISP-100 are derived from analog prototypes. The analog filters are approximated by the Bilinear Transform method, prewarped to match response at the critical frequency appropriate for the type of filter (cutoff frequency for LowPass/HighPass and Peaked HighPass;...

  • Page 101: Lowshelf Filters

    In the ISP-100 highpass filters the passband slope is selectable from 6 dB/octave, 12 dB/octave, 18 dB/octave, and 24 dB/octave for the Bessel and Butterworth types, and from 12 dB/octave and 24 dB/ octave for the Linkwitz-Riley type. NOTE : Linkwitz-Riley filters are also known as Butterworth-Squared filters because they are the product of two Butterworth filters.

  • Page 102: Notch Filters

    The hinge frequency is defined as the frequency at which the magnitude of the filter response is changed by (approximately) 3 dB relative to the unfiltered signal. In the ISP-100 highshelf filters the hinge frequency is continuously variable from 20Hz to 20 kHz. In the ISP-100 highshelf filters the transition band slope is selectable from 6 dB/octave and 12 dB/octave.
  • Page 103 The EQ filters in the ISP-100 are full parametric. Each may be adjusted for center frequency, boost or cut, and bandwidth. Center Frequency The center frequency is the frequency at which the maximum boost or cut takes place. In the ISP-100 EQ filters the center frequency is continuously variable from 20 Hz to 20 kHz.

  • Page 104: Peaked Highpass Filters

    In the ISP-100 EQ filters the bandwidth is continuously variable from 1/12 octave to 3 octaves (which translates to Q between 17.3 and 0.404). Boost and Cut In the ISP-100 EQ filters the boost/cut is continuously variable from +12 dB to -12 dB. Peaked HighPass Filters The Peaked HighPass filter supplied with the ISP-100 is designed to provide bass boost appropriate for low frequency extension in...

  • Page 105: Allpass Filters

    Cutoff Frequency The cutoff frequency is the design frequency of the highpass filter, and is only approximately representative of the location of the magnitude peak. In the ISP-100 the cutoff frequency is continuously variable from 20 Hz to 20 kHz. AllPass Filters AllPass Filters shift phase without altering magnitude.

  • Page 106: Boost/Cut

    text box without pressing the Enter key will cause the setting to return to the number that it was before a change was attempted. Alternatively, click and drag across the number in the box to highlight the number in it. Type the new setting and press the Enter key when finished.

  • Page 107: Using The Magnitude (Mag.) Or Phase Control

    Alternatively, click and drag across the number in the box to highlight the number in it. Type the new setting and press the Enter key when finished. Using the UP/DOWN Arrows To increase the level, click on the up arrow. To decrease the level attenuation, click on the down arrow.

  • Page 108: Fine (F) Or Coarse (C) Control

    Fine (F) or Coarse (C) Control This button determines the increment/decrement associated with the UP/DOWN arrows. Fine produces small steps in value, while Coarse provides large steps in value. Clicking on the button will toggle the setting. Isolate (Iso) Control This button allows the user to toggle between viewing either the composite response of all active filters in the filter bank or the composite response of an individual filter.

  • Page 109: Gain

    Gain Figure 8-17 Gain component. Gain (see Figure 8-17) is the first function applied to all ISP-100 input data. The gain component performs many operations, including metering of raw input data (pre-fader), application of up to 18 dB gain, 96 dB attenuation, or full-muting, metering of data after the level has been changed (post-fader), and polarity inversion.

  • Page 110: Metering

    to 0 dB and its polarity to positive (in-phase). Bypassing in a muted channel un-mutes it. Metering The meter located at the left of the component measures level in dBFS. The meter’s level will turn red 3 dB before clipping. The red clip light is located at the top of the meter.
  • Page 111 (i.e. after the master attenuator). A green LED indicates that the meter information is pre-fader. Clicking on the button will toggle the setting.

  • Page 112: Gate

    Gate Figure 8-18 Gate component. A gate (see Figure 8-18) is used in situations where the input signal is characterized by long periods of silence and a noticeably high noise floor, such as a signal taken from magnetic tape or from an open microphone.

  • Page 113: Unfamiliar Controls

    Closing Time A gate monitors the level of the input signal and controls the level of the output signal accordingly. When the average input signal level decreases from above threshold to below, a gate closes (applies attenuation) so that the output signal level is less than the input signal level.

  • Page 114: Metering

    Detection Window is adjustable in the range 20 µSec (one sample) to 5 Sec. Metering The gate meter shows the attenuation applied to the signal passing through the gate at any given moment in time. When the signal is below threshold and the gate is closed, the meter indicates negative values (gain less than 1.0).

  • Page 115: Open, Window, And Close Controls

    Alternatively, click and drag across the number in the box to highlight the number in it. Type the new setting and press the Enter key when finished. Using the UP/DOWN Arrows To increase the level, click on the up arrow. To decrease the level attenuation, click on the down arrow.

  • Page 116: Limiter

    Limiter Figure 8-19 Limiter component. A limiter (see Figure 8-18) is used in situations where the output signal must not exceed a given level, regardless of any increase in the level of the input signal. Limiting is often used for system protection purposes, such as the avoidance of amplifier clipping or the prevention of mechanical or thermal damage to loudspeaker components.
  • Page 117 Release Time A limiter monitors the level of the input signal and controls the level of the output signal accordingly. When the input signal level suddenly decreases, a limiter allows the output signal level to also decrease only as much as is appropriate, given the relationship between the new input signal level and the threshold setting.

  • Page 118: Unfamiliar Controls

    Unfamiliar Controls There are two controls on the ISP-100 limiter that are not available in traditional dynamic range limiters. These controls provide much greater flexibility and utility to this limiter than can be achieved with traditional limiters. Detection Window The detection window is the period of time over which the limiter computes the average signal level.

  • Page 119: Notes On Operation Of The Limiter

    one. The two quantities are then compared and the larger is returned as the signal level. When the Crest Factor Sensitivity is set to 0.00 the ISP-100 limiter operates as a traditional limiter responding to average signal levels; when the Crest Factor Sensitivity is set to 1.00 the ISP-100 limiter operates as a traditional limiter responding to peak signal levels.

  • Page 120: Meter

    Computation of Average Level There are two common methods of computing average signal level; one is based upon RMS (Root Mean Square) calculations, and the other is based upon Absolute Value calculations. Each of these methods produces a slightly different value for signal level, and the difference depends upon the characteristics of the signal itself.

  • Page 121: Attack, Window, Release, And Crest Factor Controls

    increase or decrease is controlled by the fine/coarse control. Attack, Window, Release, and Crest factor controls. All of these controls can be adjusted in three ways: Using the Knob Click on the indicator on the knob and while continuing to hold down the mouse button, move the mouse in an arc.

  • Page 122: Select

    Select Figure 8-20 Select component. The select function (see Figure 8-20) allows you to set the source that feeds portions of a QuickMAP. The user is allowed to select from as many inputs as the QuickMAP allows. An entire QuickMAP can be fed from a single source or multiple sources depending on the settings of the Selects within the QuickMAP.
  • Page 123 A to D Analog to Digital. Conversion of an analog signal to a digital representation. Amplitude factor See CREST FACTOR. Attack The rise of a musical note from zero to full volume. Attack time The time required for an applied signal that suddenly increases in amplitude to reach 1-(1/e), that is, 63.2% of its final, stable value.
  • Page 124 To reduce a signal’s overall amplitude. D to A Digital to Analog. Conversion of a digital representation to an analog equivalent signal. dBFS Decibels with respect to digital full scale. The full scale amplitude (zero dBFS value) is the peak value of a sinewave whose positive or negative peak just reaches full scale.
  • Page 125 Gate A device or circuit which has no output until it is triggered into operation by one or more enabling signals, or until an input signal exceeds a predetermined threshold amplitude. Limiter A device or circuit whose output-signal amplitude remains at some predetermined level in spite of wide variations of input-signal amplitude.
  • Page 127 VUE-IT ships with eighteen standard QuickMAPs. These mappings were designed to be flexible enough to be applied in a wide variety of signal processing applications. This appendix provides drawings of the QuickMAPs for reference purposes. The drawings begin on page B-2. Identification of Slots and Connectors The slots and connectors used are indicated by either the word IN in the case of an input or OUT in the case of an output.
  • Page 128 MONDOEQ.QMS...
  • Page 129 2X6CMBC.QMS...
  • Page 130 2X8COMB.QMS...
  • Page 131 3X6CMBC.QMS...
  • Page 132 2X8THRU.QMS...
  • Page 133 4CHAN.QMS...
  • Page 134 4X6CMBC.QMS...
  • Page 135 4X6THRU.QMS...
  • Page 136 3_2W.QMS...
  • Page 137 2WAYS.QMS...
  • Page 138 2_3WAY.QMS...
  • Page 139 2_2W_SUB.QMS...
  • Page 140 2_2W_FR.QMS...
  • Page 141 2_2W_2ST.QMS...
  • Page 142 4_2WAYS.QMS...
  • Page 143 4W_2FR.QMS...
  • Page 144 LCR.QMS...
  • Page 145 MONO3W.QMS...
  • Page 146 Copyright © 1997—98 9600 Aldrich Avenue South Minneapolis, MN 49107 TELEX Communications, Inc. All Rights Reserved. 7/98 Printed in USA P/N: 38109-744 Rev. A Ph. 612.884.4051 Fax 612.887.5588...

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