CrossoverShop. Advanced Crossover Simulation & Analysis

Transcription

1 Computer Aided Engineering & Measurement Systems Loudspeaker Enclosure Analysis Program CrossoverShop TM Advanced Crossover Simulation & Analysis Features CrossoverShop provides a powerful arsenal of system modeling, design, and analysis tools for the process of developing crossovers from actual measured data. Both analog and digital or even mixed crossover architectures are supported. Analog Passive Crossover Design & Analysis Analog Active Crossover Design & Analysis Digital Filter FIR Crossover Design & Analysis Digital Filter IIR Crossover Design & Analysis Extensive Analog & Digital Filter Synthesis Mixed Domain Analog & Digital Designs Advanced Global Optimization Engines Optimization of SPL, Group Delay, Impedance Graphical Schematic Entry & Editing Fully Automated Crossover Design Wizard 22 Advanced Specialized Circuit Components Advanced Electrical/Acoustical Circuit Simulator Thermal, MonteCarlo, Sensitivity Circuit Analysis Reference Manual Pages Application Manual Pages A unique acoustic/electric circuit simulator with graphical schematic editing is provided, which supports passive/active analog and digital FIR/IIR crossover development. You may synthesize your circuits from one of the many included topologies, or create and analyze any arbitrary circuit desired. The crossover design Wizard supports a wide variety of different structures, parameters, and options - automatically producing a fully optimized complete crossover design in minutes! CrossoverShop includes powerful optimizers and synthesis tools for passive, active, and digital crossovers. Optimization may be performed on SPL, impedance, voltage, or group delay data, using single-curve or constraint-based target types and frequency weighting capability. Robust features enable large amounts of curve data to be handled with ease including extensive post processing and numerous utility functions. LinearX Systems Inc 9500 SW Tualatin-Sherwood Rd. Tualatin, OR USA TEL: (503) FAX: (503) sales@linearx.com

2 Introduction The process of loudspeaker crossover design is complex, involving both measured data along with mathematical components, all combined within a circuit simulator. Moreover, both electrical as well as acoustical computations and references must be maintained throughout the process in order to obtain accurate acoustical and electrical results. Traditional circuit simulators merely handle electrical components and lack the needed features to properly handle the unique requirements of this mixed environment. CrossoverShop features a proprietary electroacoustic simulator with highly specialized components, offering all of the capabilities necessary for advanced crossover design and analysis. It allows a procedural design flow methodology, rather than trial & error analysis, or the more time consuming, iterative, and expensive method of build and test. A multitude of different crossover designs can be simulated, examined, and refined in a fraction of the time required to construct and measure a single physical design. CrossoverShop computes all of the electroacoustic response curves automatically and plots them on an assortment of different graphs, each controlled by a full featured scale system. A graphical schematic editor is also provided for circuit construction and editing. Over two dozen extensive synthesis tools turn nearly any filter idea into instant reality. A detailed treatment of the many subjects within the software would be far beyond the scope and space limitations of this brochure. Rather it will define and explain some of the more significant capabilities and features offered by CrossoverShop to design systems of many different types, structures, and complexity. With CrossoverShop, designing great crossovers has never been easier! Application Software The main program screen is shown below. CrossoverShop is a large Win32 program and contains over 100 dialogs, extensive 2D graphics, a wide assortment of post processing utilities, and intensive numerical mathematics. Over 80 specialized Windows custom controls were created for the program. All simulations are performed utilizing both frequency and time domain analysis. Many of the numerical floating point routines are written in 80x87 assembly language and were highly optimized using the Intel VTune Performance Analyzer to maximize FPU performance and minimize analysis time. All computations are performed with either Double (64bit) or Extended (80bit) floating point precision.

3 Analog Passive Crossovers Passive crossovers have enjoyed widespread use for over one hundred years. They range from very simple and low cost, to extremely complex and expensive. Design requirements for passive crossovers are complicated by the non-ideal nature of the components themselves, and the fact that the passive networks are loaded by the transducer impedances, which are highly complex. CrossoverShop provides extensive tools and features to tackle these passive crossovers utilizing both automatic synthesis and powerful optimization. Actual transducer data for both acoustic SPL and electrical impedance can be imported for each transducer. Moreover, parasitic component models are featured representing real world components. A variety of powerful synthesis tools are available, including fully automatic and optimized design of conjugate networks to flatten any transducer impedance. Analog Active Crossovers Active crossovers are also historically known as bi-amped or tri-amped systems with respect to 2-way or 3-way designs. All active crossovers utilize independent multiple power amps for each section, with the transducers directly attached to the power amps. Active crossovers are the favorite of high power high performance systems with far lower losses and distortion. CrossoverShop provides two levels of analog filter modeling: high level transfer function blocks, and low level actual circuitry. The filter synthesis tools produce designs as transfer function blocks which can then be realized into actual circuitry. Optimization is also invaluable here. Multiple libraries are included for over 1,500 opamps containing accurate gain bandwidth, input/output impedance, and voltage/current noise models. Extremely fast circuit analysis even with dozens of opamps. Digital FIR Crossovers With the modern advancements in digital signal processing, digital crossovers are becoming increasingly common. Many things are possible with digital filters that were traditionally difficult in the analog domain. Time correction is trivially easy, and constant group delay using FIR filters also becomes possible. FIR filters offer the ability to apply equalization of driver/enclosure defects as never before resulting in razor flat response. Due to the extremely high order of FIR filters, nearly any response curve can be produced. The extremely sharp transitions at the crossover knees virtually eliminate multiple driver lobing and off-axis effects. CrossoverShop provides FIR synthesis with coefficient export in a wide variety of formats. Finite precision simulation is also included. Digital IIR Crossovers The second class of digital filters are the IIR type. These filters essentially emulate the well known classic response behavior of analog filters. IIR filters are created by transforms of prototype analog filters. A set of analog crossover filters are first designed, and then various transforms used producing IIR equivalents. CrossoverShop provides many different types of transforms since each has its own particular characteristic. Finite precision effects can also be explored which are critically important for IIR filters. Advanced optimal approximation and frequency sampling methods are also available for detailed equalization.

4 Advanced Specialized Circuit Components There are many different types of circuit components supported in the program. Many of these components have unique capabilities and were specifically created to support advanced filter design and crossover analysis. Both analog and digital circuit analysis is provided including any combination of mixed designs. Resistor This component also includes parasitic models for parallel capacitance and series inductance. It also includes a exponential frequency dependent model to simulate losses in ferrite/iron core inductors. Capacitor This component also includes parasitic models for series resistance and inductance. It also includes a exponential frequency dependent model to simulate various types of dielectric behavior. Inductor This component also includes parasitic models for parallel capacitance and series resistance. It also includes a exponential frequency dependent model to simulate losses in ferrite/iron core inductors. FDNR (Frequency Dependent Negative Resistor) This component could be described as a capacitor squared. It is commonly used in the design of gyrators. Potentiometer A powerful component to simulate pots, with automatic rotation and curve production. Libraries of tapers provided. Transformer Primary, secondary, mutual, leakage inductance and turns ratio. Imported Impedance Real components can be measured and their impedance curves imported for use in the circuit simulations. Switch Various pole arrangements. Model includes resistance and shunting capacitance. TFB (Transfer Function Block) Very powerful component which can generate a wide variety of transfer functions, including imported curves. Generator Basic source of signals in all circuits. Also includes noise generator and custom response modification. Summer This component enables signals to be added or subtracted. It has two or three inputs, each with selectable polarity. The inputs and output have finite impedance and are ground referenced. This component is useful for taking differential measurements and/or producing single ended outputs from balanced circuits. SCN (Switched Capacitor Network) The SCN models the frequency domain sampling behavior of switched capacitor resistor structures. IIR Filter This component models the frequency domain behavior of a digital IIR filter. FIR Filter This component models the frequency domain behavior of a digital FIR filter. Buffer Provides three precision functions: invert the polarity of a signal, change the gain of a signal, or delay a signal. Transducer Undoubtedly the most important component of the electroacoustic circuit simulator. This component defines both the electrical and acoustical properties of the transducer, and also specifies the 3-D location of the transducer on the enclosure. Full support for dual-voice coil transducers is also provided.

5 Electrical & Acoustical Simulation Crossover modeling requires simultaneous dual domain analysis utilizing both measured electrical and acoustical data. In order to provide accurate acoustic summations due to the response from each section, the 3D spatial coordinates of each driver must also be known. The key component of any crossover simulation is the Transducer. This component carries all the required measured SPL and Impedance data within its own data structure. In reality each of these components is a virtual curve library itself storing up to 50 curves representing both on-axis as well as off-axis acoustic data. This enables CrossoverShop to compute both on-axis as well as off-axis and polar response plots. The simulation of system polar response requires the availability of measured Off-axis SPL data for each transducer in the system. The angular resolution of this data is solely up to the user. If no polar simulations are of interest, then Off-axis data for the transducer may be omitted. +y +y +z +x M M Tweeter Voice Coil Coord: 0.00, 0.00, 0.00 Meter Woofer Voice Coil Coord: 0.00, -0.25, Meter The Impedance and SPL curves for each driver are measured individually on an actual prototype enclosure. The first decision which must be made when starting any design is the location of the enclosure origin. A point must be chosen as the X,Y,Z reference on which all coordinates will be based. Generally this is somewhere on the surface of the baffle board of the enclosure. Two common origins are either the center of the tweeter or the center of the baffle board. The choice for the origin location is entirely up to the user. The on-axis and polar plot computations will be calculated relative to this position. Acoustic phase data is critically important. There are two possible choices for the phase data contained in the SPL curves. These choices denote the relative reference location represented in the phase data.

6 Crossover Wizard If you ever wanted a method of designing a crossover simply by clicking a button, the crossover Wizard was created for you. This utility is a sophisticated collection of highly automated routines which can automatically design complex crossovers of many different types. The user is still responsible for collecting and providing the necessary information and measurements. The Wizard is a series of dialogs which provide an easy and quick means of designing a crossover. Prior to starting the crossover Wizard you must import all of the Impedance and SPL curves necessary for your design. The Wizard will ask you a short series of simple questions and then will automatically layout the complete crossover circuit for you. It will also optimize the crossover design. Using the Wizard is one of the easiest ways to get an initial crossover setup. However once the Wizard has completed its tasks, you can certainly edit, change, or modify the design as you would any other design. The Wizard is simply another means of starting a crossover design. In some cases the results from the Wizard may be very close to what you desire. The Wizard was constructed to perform common crossover designs. It is not meant to provide every possible design permutation and special exception. For those situations you will need to modify the final Wizard design, or construct your own design manually as normal. Step-1 The first step is to choose what type of crossover you desire, and define how many sections there will be. These choices will control what parameters and options will be needed in the following steps. Step-2 In this step the order and frequency points of the crossover objectives are defined. These are the alignments to which the response will be optimized. There may also be some optional crossover items available, depending on the type of crossover design. Only one of the four tabs will be available, and this selection will be made for you based on the type of design. Step-3 Here you will define the location of the data curves for each of the crossover sections, the actual filter orders, and also the coordinates of each transducer. If a particular section is not used, it will be grayed out. Choose the proper SPL and Impedance curve entries where you placed the transducer data. The Order selection defines the actual filter order to use for each crossover section in the design. This is often not the same as the optimization objective order for the alignment. The filter order is often less than the objective order, due to the non-flat response of the transducer itself. Step-4 When optimizing the crossover sections, the frequency region where the optimization will be performed must be specified. This is shown as the Red line across a portion of the transducer's response. You can change the limits of the crossover optimization frequency range by simply clicking the mouse near the ends of the Red line. Some regions of the transducer's response may not be controllable by the crossover and should therefore not be included.

7 Finished - Processing After Step-4 is completed, the processing begins. A summary dialog will be shown which lists the tasks completed along with the current task underway. Other dialogs will also appear and disappear depending on the type of crossover, the number of sections, and the options selected. The processing may take anywhere from 30 seconds to 15 minutes or more depending on the crossover design and the speed of your computer. There can be many tasks required to complete the design. When all the dialogs are gone the Wizard has finished. You can then inspect the circuit and response graphs. Since so much of the processing is dependent on user data and parameters, any number of things could go wrong with the automated design process due to improper or incorrect data. This is an example of the ease with which crossovers can be designed using the Wizard. If you were not satisfied with this design you could quickly repeat the Wizard design process but this time with different parameters. All of the driver information is now in the design file and does not need to be re-entered. During each run the Wizard clears the existing schematic and creates a new one. The user could also choose to edit and optimize the design manually after having used the Wizard to create the basic crossover design. Using the Wizard to create a basic crossover design often provides a quick means of creating the overall schematic. The user can then make further modifications and refinements.

8 Curve Libraries Crossover design often involves massive amounts of data. To handle this requirement CrossoverShop provides two curve libraries: System Curves and Guide Curves. The System Curve library contains all of the simulation results produced by the system itself after analysis. The Guide Curve library contains arbitrary data that is transferred (copied) from the System Curves, generated by processing functions, or externally imported into the program by the user. There are a maximum of 200 curves in each library. A single curve entry actually contains two data arrays, (Left/Right) which generally hold both magnitude and phase. Curves are automatically displayed on the various graphs according to the type of data they contain. Each curve can be enabled/disabled for display, and assigned line color/style/width. System Curves Curves generated by the system analysis are named automatically, and do not allow for any user modification. Many curve names are derived from the labels given by the user to the Data Node or Transducer components in the circuit. The following are System Curves: Impedance load on all generators individually Impedance of all networks in parallel Voltages at any circuit Data Nodes SPL of each transducer SPL of all transducers summed Group Delay of SPL of each transducer Group Delay of SPL of all transducers summed Horz Polar SPL of each transducer Horz SPL of all transducers summed Vert Polar SPL of each transducer Vert SPL of all transducers summed Guide Curve Processing The Guide Curve library contains many processing capabilities to realign and modify a curve s data points. Various interpolation and extrapolation methods are provided both in log and linear formats. Curve Import/Export & Direct Transfer Import and Export of curve data is supported via simple text spreadsheet style column formatting. Curves can also be transferred easily between other applications such as LMS and EnclosureShop through the Windows clipboard using Cut & Paste without any need of file transfer.

9 Optimization The circuit optimizer is a powerful tool for optimizing the values of many circuit components, which would otherwise be impossible to compute. By using this tool the required component values of a circuit can easily be found that best approximates any arbitrary response objective. Optimization of both the individual sections as well as the total system response summation is supported. Any number of components or parameters can be selected/deselected for optimization. Optimizations can be performed based on SPL, voltage, impedance, or group delay. Optimizations based on magnitude squared or complex data are also supported. The optimization can minimize either peak or average error. Individual enables are provided for each of the available component values, as well as manual editing of component values. Multiple memory storage is also provided to save and recall previous component set results. The optimizer also supports both curve based as well as constraint based optimization, through use of a pair of Max/Min curves. Additional features are provided to control the exact frequency range for optimization, and the weight applied to any portion of the frequency range. Moreover, optimizations can be conducted for acoustic response while simultaneously maintaining a minimum impedance constraint. Optimizer Dialog The optimizer dialog contains several buttons, and a large data grid listing all of the available component parameters which can be optimized. Two fields at the bottom of the panel display the total number of parameters and the number of parameters currently selected (active) for optimization. Another field at the top displays the current Error between the system data curve and the objective. The data grid displays each parameter's value, name of the component, the parameter's units, an index, and whether or not it is selected for optimization. You can manually change or enter values for the parameters in the grid, and recalculate the circuit response manually using the Update button. The Optimize button starts the process. A dialog will appear displaying the current error, evaluation count, and iteration. Weighting Function The importance of the error at each frequency can be increased using the features on this tab. Increasing the weight at a given frequency forces the optimizer to reduce the error relative to other areas where the weight is unity. The grid shows a plot for a multisegment line which represents the weighting function. The horizontal frequency axis is based on the current system frequency range. Objective Generator This tab panel provides a very quick and easy means of generating an objective curve for optimization. Both sectional and system objective response curves can be generated with these features on this panel. The capabilities offered here are designed to cover the general needs of most crossover design requirements. If you require more specialized objectives, they can be created through other analytic means using transfer function blocks, or maually defined using the Curve Editor utility. You may also import objective curves by numerical data or capture them graphically from external sources using the Curve Capture utility.

10 Synthesis Tools CrossoverShop contains an extensive catalog of explicit equation formulations and numerical solutions for filter design. The synthesis dialogs receive your parameter values, designs a circuit fragment that performs the filter function, and then pastes it into the schematic for you. You may then integrate the circuit fragment into the rest of your circuit as needed, or edit, or optimize it.

11 Simulation Accuracy While CrossoverShop contains all of the features and parameters necessary to compute the response of a system with very high accuracy, there are limiting factors which will always produce some differences between the simulation and the actual results. The calculation of a crossover system involves many elements and data. Some of the data is measured and other elements such as component values may be assumed ideal or unknown at the time of simulation. Some of these factors include: Measurements of final results are generally taken at a time much later than the original transducer measurements. Environmental conditions (temp, boundaries, references, etc.) often change between those periods of time and can affect the transducer response. Components may not be modeled accurately enough to represent their real behavior. This is entirely under the control of the user and the effort, time, and care they take to represent the components. Often a problem for passive crossovers where component characteristics are very complex. Modeling an inductor as a fixed resistance & inductance is only a crude approximation. Measurements of drivers operating alone, and then together as a system, will likely produce changes. Mutual coupling is present when they are operated together in the crossover regions, which was not the case when they were measured alone. Measurement These two graphs show a comparison of the system acoustic and impedance responses of a 3-way passive crossover system. The woofer section consists of a ported enclosure with 10 Inch woofer, a 4.5 Inch mid, and a 1.2 Inch rubber dome tweeter. Simulation Simulation Measurement Simulation Measurement Simulation Measurement The two graphs here demonstrate a comparison between the system acoustic and impedance responses of a 3-way passive crossover system. The woofer section consists of a ported enclosure with 2-8 Inch woofers, a 6.5 Inch mid, and a 1 Inch Alum dome tweeter.

12 CrossoverShop Highlights Mixed Electroacoustic Circuit Simulator Analog Passive Network Crossover Design Analog Active Filter Crossover Design Digital IIR Filter Crossover Design Digital FIR Filter Crossover Design Mixed Analog & Digital Crossover Design Synthesis of Passive Allpole/Elliptic/Conjugates Synthesis of Active Allpole/Elliptic/EQ/Circuits Synthesis of IIR Matched-Z/Bilinear/Conv/Inv Synthesis of FIR Window/FreqSamp/Optimal Advanced Global Optimization Engines Curve based Peak/Average Optimization Constraint based Max/Min Optimization Frequency Range Restricted Optimization Weighting Function Modified Optimization Memory Store/Recall of Optimization Results Optimization of SPL, Impedance, GroupDelay Automatic Optimizer Objective Generators Graphical Schematic Entry/Editing Automated Crossover Design Wizard Polar Simulation with Measured Off-Axis Data 22 Advanced/Specialized Circuit Components Opamp Model Library, 1000 predefined Potentiometer Taper Library, 250 predefined Thermal, MonteCarlo, Sensitivity Analysis Powerful System & Guide Curve Libraries Post Processing Utilities & Math Functions Accurate Dual Voice Coil Simulations Import, Export, Cut & Paste Curve Data Graphics Export Raster & Vector Formats Curve Capture/Converter from Raster Image Curve Editor, Node Smoothing, Add, Delete Air Core Inductor Designer Comprehensive 2-Volume Manual Set System Requirements CrossoverShop is a highly intensive numerical application. The program contains literally hundreds of numerical mathematics algorithms, some of which are extremely large and place very high demands on the CPU's floating point performance. CrossoverShop will use all of the speed your processor has to offer, and can probably want more. Depending on the speed and type of CPU in your system, and the complexity of your design, some of the circuit analysis can require many minutes to run. CrossoverShop also uses extensive graphics. For best results a 1024 x 768 video resolution is suggested with at least 64K (16-bit) color depth. Minimum System Requirements: Mouse and Keyboard USB port for License Key Windows 95, 98, SE, ME, NT4, 2000, XP 250MB free Hard Drive space 64MB RAM Memory Pentium II / 350 or equivalent Video 800 x 600 Resolution / 256 Colors TrueType or Adobe Fonts Recommended System Requirements: Windows 2000 or Windows XP 300MB free Hard Drive space 256MB RAM Memory or more Pentium III / 800 or equivalent Video 1024 x 768 Res / 64K or 16M Colors Adobe Fonts with Adobe Type Manager Note: Due to the limitations of Win9X, not all of the program's features and/or capabilities will be available in those operating systems. LINEARX SYSTEMS INC 9500 SW Tualatin-Sherwood Rd Tualatin, OR USA Tel: Fax: sales@linearx.com Contact factory or visit our web site for a list of International Dealers. All specifications subject to change without notice All Rights Reserved. Printed in the U.S.A. MAR