ALTI-EXPO 2020 CONTENT

Continuing a long tradition of presenting world class content for every faction of the Audio and Loudspeaker Technologies industry! From engineers to CEO’s, ALTI-EXPO is the place to be. Look for presentation abstracts and special announcements about the premier event for our industry. Our schedule will be posted soon! We will update weekly or as needed.

Our Content for ALTI-EXPO is FULL! At this time, we are accepting only Advertorials for Exhibitors and Sustaining Members. Register with our Call for Content link below.

Get it here!

The schedule below is not final until 31 March 2020. Updates will be posted as needed. More content to come! Updated 12 March 2020

A detailed breakdown of the 4 Modules in the System Builders Workhop will be released soon!

Content Abstracts

COMSOL Multiphysics Workshop (9AM to Noon June 15)

By Jinlan Huang, PhD

Workshop: June 15, 2020 2PM to 5PM in NAPA C

This workshop will be divided into two sessions. In the first session, we will give an overview on the capabilities of COMSOL Multiphysics in loudspeaker simulation to different level of complexities. A specific model example will be presented to showcase how COMSOL may be used not only to simulate the behavior of a loudspeaker but also to optimize its design to the desired specifications. 

In the second session, the attendees will have a chance to use the trial software to create a simplified loudspeaker model right in the classroom by following the leader. You are able to learn the basic work flow in creating a multiphysics model inside COMSOL that includes defining global parameters, importing CAD models, setting up acoustic-structure interaction physics, meshing, solving, and postprocessing.

Prior sign up to the 2nd half hands-on session it is required to get a trial license so that the COMSOL Multiphysics software can be downloaded beforehand. (NOTE: Details of preregistration will be posted in March, 2020. Bring your laptop or media device to participate in the hands-on segment. There is no fee to attend this workshop)



Multidomain Modeling of Speaker  Nonlinearities with Simulink and Simscape June 14, 5PM to 6PM, NAPA C

By Stephen Thompson, PhD- Penn State University

Multidomain modeling of acoustic transducers can be implemented in many ways, from older analog circuit tools such as SPICE to modern multidomain FEA tools. Each level of model complexity has its place. An intermediate level of complexity is available with tools such as those that use Modelica or Simscape. These are not full partial differential solvers. They use a combination of ordinary differential equations and algebraic equations to calculate the performance in each physical domain (e.g. mechanical, electrical, magnetic, etc.) and provide the necessary physical coupling between the domains. They provide reasonable fidelity with less computational intensity, so they can be used as components in a larger modeling system that includes programmable controls to reduce distortion or energy losses. 
This seminar will demonstrate the use of Simscape to model a moving coil speaker including multiple nonlinearities. It will demonstrate the ability to model a control system around the speaker for improved far field performance.

Speaker Builders Workshop (SBW)  June 14, 9AM to 6PM. NAPA A/B 

By Jerry McNutt- Eminence Loudspeaker, Jinlan Huang- COMSOL, Brian Myers-Parts Express/Dayton Audio

This hands-on workshop covers the development of a loudspeaker product from concept to design, to modeling, to materials choices, to building a working loudspeaker and testing to confirm it fulfills the desired application specs. Then we will design, model, and add an appropriate enclosure and tune a port for best response.

Every level of the design and fulfillment supply chain will benefit from taking part in this session, and learning the difference between a customer’s desire and the actual product possibilities. A thorough understanding of the tools available to reduce design time and minimize redesigns and “tweaks” will also be extremely useful.

Attendees will keep the driver and enclosure.


Amplifier Builders Workshop (ABW)   June 15, 8AM to Noon, NAPA A/B

By Dan Foley- Audio Precision and Brian Myers- Parts Express/Dayton Audio

This hands-on workshop focuses on the design, assembly and testing of a two-way bookshelf loudspeaker system incorporating a Class D amplifier with integral Bluetooth capabilities.  A maximum of eight teams with no more than six people per team will compete to create a finished product that meets or exceeds key design specifications related to frequency response and sensitivity among others.  Each team’s finished product will be tested for acoustic and electrical (impedance) performance.  Members of the team with the best performing product will win a Dayton Audio DATS V3 Computer Based Speaker & Audio Component Test System.

Workshop attendees will learn:

– Utilizing a passive radiator versus a tuned port for extended bass response

– Passive crossover networks; benefits as well as limitations 

– Switching amplifier (Class D) operational theory and practice

– Basics of Bluetooth audio codecs 

– Best practices for assembly and test of a finished powered multi-way loudspeaker system

Business Builders Workshop (BBW) Part 1 (2PM to 7PM NAPA A/B on June 15. Dinner included)

Brand as Publisher

by Adrian Weidmann- StoreStream Metrics

The three sessions of the Business Builder’s Workshop have been designed to provide pragmatic marketing and sales principles and tools that will allow you to successfully communicate and sell your innovative, technological designs and products to a global community. You’ll be shown how to use freely available tools and methods that will allow you to compete globally- regardless of your company’s size.

Based upon the popularity of ‘The Power of Brand’ workshop along with the need to communicate, differentiate, and amplify your brand voice in a noisy, competitive landscape, this first of three sessions, will introduce the concept and power of ‘Brand as Publisher’.

Learn about content and multi-channel marketing- how and why you can use your voice and narrative to not only share, but amplify, your unique brand story to a global audience, but to create a meaningful dialog.  Never thought about Pinterest as a valued marketing tool for your business- think again. We’ll identify and define specific free online tools and methods that will allow you to proactively engage your audience, whether you a small entrepreneur or large corporation.

The practical insights and recommendations shared during the scheduled five hours of the Business Builder’s Workshop will culminate in helping each participant develop a winning presentation for ‘Piranha Pond’ at InfoComm!

All participants in the Business Builder’s Workshop are cordially invited to a working dinner where the workshop presenters will be helping all the teams develop their winning presentations for the ALTI version of Shark Tank: ‘Piranha Pond’ to be held at the Technology Innovation Stage at InfoComm.  Booth #C4854 on Thursday, June 18 at 11AM.

Activating on The Consumer- First Positioning (Part of BBW)

By Spencer Knisely- Textile Creative Studios

The workshop seeks to expand on the concepts put forward in the ‘Power of Brand’ session, adding the positioning and marketing of product benefits to specific customer sets.

This session introduces concepts which will help to define distinct customers by needs and attitudes, then how to position a product by addressing those defined needs directly in the planning of marketing programs and sales enablement content.

Finally, the session will present support for the rich understanding and utilization of CRM software to enable selling and marketing activity. Definition and discussion of the strategies used to create a portfolio of knowledge about each customer which involves tracking, logging and responding through planned workflows proven to streamline operations and increase sales.

Business Builders Workshop Part 2: Piranha Pond

Prianha Pond hosted by Adrian Weidmann  (June 18 11am – Noon on the Technology Innovation Stage, booth C4854 at InfoComm. )

Part 1 of the Business Builders Workshop concentrated upon branding, marketing development and methods to differentiate your product from other similar ones. Piranha Pond is our version of the Shark Tank concept. 3 teams from part one will present their product to a panel of audio professionals that actually make buying decisions like these. It’s putting the classroom into practice in an entertaining and educational format.

The Piranha Pond will be on the Technology Innovation Stage, booth C4854. Here is a handy map!

DSP Builders Workshop (DBW)  June 17, 1PM to 4PM at InfoComm. ( place TBA)

By Dan Foley- Audio Precision, Brian Myers- Parts Express/Dayton Audio, Jason Merriman- Parts Express/Dayton Audio, and Chris Perez-Parts Express/Dayton Audio

Digital Signal Processing (DSP) is one the biggest advances with improving listener audio quality. However, DSP is often used as a panacea to “solve” audio issues when the root-cause lies elsewhere.  This hands-on workshop will focus on what DSP can and cannot do regarding how to get the best audio quality from a multi-way loudspeaker system.

The two-way powered loudspeaker that was assembled in the ABW will be used in conjunction with a DSP board that incorporates an Analog Devices audio DSP chip.  A maximum of eight teams with no more than six people per team will compete to substitute DSP-based crossovers and parametric EQ techniques for the passive crossover used for the ABW product.  Each member of the team whose finished product best meets or exceeds stringent frequency response and time alignment targets will win a C-Note MT Bookshelf Speaker Kit Pair with the Class-D/Bluetooth and DSP used in the ABW and DPW.

Workshop attendees will learn:

– Where DSP can and cannot overcome audio-quality issues

– How DSP easily enables complex crossover networks compared to RLC networks 

– Proper time-alignment of multi-way systems

– Basics of designing audio DSP systems using Analog Devices SigmaStudio

NOTE: This workshop will be held at InfoComm on June 17 in the afternoon. Exact time/place TBA


The Art and Science of the Pitch  (Part of the Business Builders Workshop on June 15, 2pm – 7pm, NAPA A/B)

By: Ed King, Chief Experience Officer, HighStreet + Living Retail Lab

Pitching for anything is a learned discipline. Whether it’s pitching to win a business deal, pitching for investment dollars, or convincing your youngest to eat their broccoli, The Art and Science of Pitching must-attend session that will become a valuable tool you will lean on again and again.

By understanding how the audience receives stories (hint – it’s not the chronological way we intuitively tell stories), attendees will learn how to use the power of persuasion to create the most advantageous buying opportunity from the audience.

Plan to get hands-on and build your 5-slide story: agitate the problem, explain the idea, outline why their solution is perfectly positioned in the market, tell the audience just enough about how it works to give them a reason to believe, and break down barriers to buy-in


Advanced ANC Headphone Measurements Part 2  June 14. 4PM tp 5PM,  NAPA D 

By Jacob Soendergaard- Head acoustics 

This is the sequel to the ANC headphone presentation from ALTI-EXPO 2018 that presented a whole new way to evaluate ANC based on hearing models and perceptual metrics.

This presentation will again draw on the same principles, methods and metrics, but take a much closer look at the latest evolution of ANC: Talk-Through mode.

Talk-Through mode is intended for the headphone user to be able to communicate effortlessly with others in the same space, regardless of noise – and, crucially, without having to remove the ANC device.

This presentation will share data taken from commercially available devices and highlight some of the different approaches taken to implement Talk-through mode and ultimately evaluate how successfully those products are in improving the listening and conversational experience in noisy environments.

The Perception and Measurement of Headphone Sound Quality June 15, 11AM to Noon, NAPA C

By Dr. Sean Olive- Harman International

We recently completed a 7-year research project aimed at understanding the perception and measurement of headphone sound quality. A virtual headphone listening test method was developed to provide controlled, double-blind comparisons of different models of headphones and target response curves using a large number of trained and untrained listeners in USA, Canada, Germany, and China. From these data, we identified a new headphone target curve that is preferred by the majority of listeners. Statistical models were developed that predict listeners’ headphone sound quality ratings based on objective headphone measurements. More recently, cluster analysis of headphone listening test data has shown there are three segments or classes of listeners based on similarities in their headphone sound preferences. Both demographic (i.e., age, gender, listening experience) and acoustic factors are associated with membership in each headphone segment. This information can help guide future headphone design that is aimed at a specific class or segment of listener.


Resonado Introduces Flat Core Speaker Technology  June 14, 10AM to 10:30AM, NAPA D

 By Darrell Adams – Resonado, Inc.

Technology across industries has always followed the trend of getting thinner, lighter, more efficient, and more sustainable. The speaker industry has had numerous breakthroughs that have catered to that trend with flat driver technologies; yet if you take apart virtually any mass-produced audio-emitting device today, you’ll still find a conventional cone-type electrodynamic loudspeaker as the source of sound.

Why? None of these flat driver technologies have been able to hit that level of ubiquity because they all lack in at least one crucial aspect: cost, scalability, sound quality, or ease of full frequency spectrum reproduction. Resonado’s proprietary Flat Core Speaker (FCS) technology, a new take on the electrodynamic loudspeaker structure that implements bar magnets with a planar voice coil mounted perpendicularly to its flat “racetrack” diaphragm, is primed to be the first.

All attendees are invited to learn how Resonado, a startup from the University of Notre Dame, became a rapidly growing company with transducer technology that has garnered attention from multinational industry leading corporations, Silicon Valley venture capitalists, and mainstream media. The majority of the session however will be devoted to providing insights into the significant benefits FCS technology can provide, due to its aspect ratio and novel motor structure, in varying applications across industries.

 

Magnetics Landscape for 2020 and beyond  June 14, 9AM to 10:30AM, NAPA C

Panel Discussion Moderated by:  Mike Klasco, Menlo Scientific

Panelists (preliminary)

Dr. Malcolm Gander, Geologist

Michael Rosenthal, Chirman and CEO MP Materials

Dr. Miha Zakotnik, Urban Mining Co

A panel discussion on neodymium magnetics impact on audio products; early development, mining ore, processing and fabrication of magnets, the geopolitical forces on the supply chain and past events, the present and its future impact on the loudspeaker industry. The future of alternative magnet materials, recycling neo, higher performance magnetic structure materials and related topics. 

From a technical perspective, nothing can compare to the performance of neodymium, enabling higher sensitivity, lower weight and bulk and higher excursion. Neo has brought new performance levels from microspeakers, hearing aids, IEMs, to compression drivers and woofers. Time to revisit underhung voice coil and radial topologies.

Perhaps the most newsworthy aspect of neodymium is the politics and volatility of the supply chain. Commonly assumed is that neodymium rare earth ore is all from China, in reality about 20% comes from Mountain Pass mine about an hour from here and another 20% from Australia. What is missing from full U.S. neo supply independence are the magnet fabrication processing steps following the initial chemical separation of the mined ore.    


Change Is Here To Stay – China’s Perfect Storm and Where Do We Go from Here  June 15, 9AM to 10AM, NAPA C

By Mike Klasco, Menlo Scientific

Over the last few decades we have all grown complacent with sourcing our products, or at least most of our components, from China. Long established relationships, trustworthy suppliers that know what we want and need, are losing their position as viable vendors. The rising cost of goods from China, the tariff war, the Hong Kong struggle with Beijing, and now the corona Virus have reached the tipping point and staggered what was once the obvious country of choice for audio products. The tariff war was sold as re-shoring – bringing our production back home – yet it seems that we have just further burdened ourselves with adding the tariff to ourselves and sent most of us looking elsewhere in Asia for new suppliers.

Vietnam, Philippines, Indonesia, Malaysia, Thailand, India, not to mention Korea, Miramar and Cambodia – are all getting finding themselves bathed in the first waves of brands exploring their options. We will review the landscape of long established as well as new speaker factories.

 What about bringing the audio business back home? We have the stick of tariffs that we have beat ourselves with, how about the carrot of tax incentives, grants and matching funds for R&D –perhaps these perks contingent on the new technology built in the U.S. ideally in state-of-the art factories similarly incentivized.

Finally, a discussion of how should ALTI help its members navigate through the storm?

Linking Cost, Performance, End-User Satisfaction by Physical and Perceptual Assessment June 14, 2PM to 3:30PM, NAPA C

By Marian Liebig- Klippel GmbH

This tutorial discusses the maximization of the end-user value, which determines the success in the market. The end-user value can be described more practically by the performance/cost ratio which considers physical, perceptual and other non-technical features and the cost structure of the product.
The discussion starts with the target performance as seen by the end-user, which is the basis for the development. The tutorial focuses on the assessment of the sound quality and discusses listening tests, auralization techniques and perceptual modeling to define the audibility threshold and the impact on the end-user value to generate acceptable tolerances. Those are required to generate meaningful specifications and PASS/FAIL limits. The manufacturing process should provide the defined performance at minimum production cost and with practical risk management (prevent field rejects). The discussion ends with new opportunities provided by digital signal processing and electrical control for in-situ monitoring and improving the performance, endurance and reliability of the product in the final application.

Towards Digital-Electro-Mechano-Acoustical Transducer Modules June 15, 2:30PM to 4PM, NAPA D

By Marion Liebig- Klippel GmbH

This tutorial discusses the new opportunities for creating all-in-one active transducer modules that combine adaptive, nonlinear control and other DSP algorithms, amplification and electro-acoustical conversion. Those modules only have a digital input for audio streaming and communication and use a simple, cost-effective power supply. They can be used in any enclosure with additional acoustical components (e.g. passive radiator) to realize headphones, conventional loudspeakers and modern arrays for 3D audio applications. The main objectives are to maximize the overall efficiency and minimize the cost by matching the components to each other. Current sensing at the terminals is the basis for the adaptive nonlinear control which generates a desired linear transfer behavior of the system over product life. The tutorial addresses the consequences for the practical system design and the benefits for the end-user.

Making Membership Pay! June 15, 10AM to 10:30AM, NAPA D

By Barry Vogel- Executive Director ALTI

Joining ALTI will not build your business or career. Joining ALTI and taking advantage of the many FREE benefits designed to set our members apart can. ALTI is committed to our member’s success. You need to be just as committed. We’ll show you how.

Business Networking For Fun and Profit (panel discussion-  June 14, 11AM to Noon, NAPA D)

By ALTI Executive Committee

Shifting from academia to the business world is not always easy. Getting back into the workforce after a long term employment is a challenge. This panel discussion will focus on quality networking and how to build connections that will benefit career growth throughout your career path. There is more to it than “making friends”. It will not happen solely through social media and emails. Networking is a (multi) contact sport.

 

Testing Quality of Microphones  June 14, 10:30AM to Noon, NAPA C

By Gregor Schmidle- NTi Audio

Due to the increasing use of microphones in many applications such as automotive or artificial intelligence, the demand for fast and reliable processes for testing the quality of the microphones is growing. In this seminar we will describe a typical microphone test system, and explain the function of each component. Besides explaining the theory, we will also perform practical measurements with different types of microphones. We will identify common pitfalls and show strategies to implement reliable and reproducible procedures.

Challenges in Rental System Testing  June 15, 10AM to 10:30AM, NAPA C

By Brian MacMillan- NTi Audio

Live performance is a major revenue generator in the music industry. The equipment needed to take the music to the fans: speaker, amplifiers and microphones, can lead a hard life. Often the equipment is rented and returned at the end of the tour.

Rental companies need to document what they send out initially is in good working order and assess each device on its return from tour. Testing is similar (frequency response, rub & buzz, etc.) to what manufacturers test in their outgoing final inspection. Additional challenges for rental companies include a large number of unique models, each model with its own pass/fail limits, and health tracking of each unique asset.

Modeling a Planar Carbon Nanotube (CNT) Speaker June 15, 2PM to 2:30PM, NAPA D

By Siraj Prabhu- Michigan Tech University 

CNT speaker technology was first demonstrated at ALTI by Mahsa Asgarisabet, Troy Bouman, and Dr. Andrew Barnard in 2016. Currently, research is ongoing for using CNT speakers for active noise cancellation devices in pipes and ducts. Focus areas of application are noise cancellation in automotive exhaust, and automotive and industrial HVAC systems. Different designs of the CNT speakers are being tested for their suitability to specific applications as well as to obtain better performance. Advantages of CNT speakers include order of magnitude reduction in speaker size and weight, ability to operate in high temperature environments, and when designed in a coaxial manner, do not invoke any back pressure on pipe and duct systems.

The main focus of this research is to develop a method to model an enclosed, coaxial CNT speaker for automotive exhaust applications. The modeling method will be developed using COMSOL Multiphysics. However, the complex physics of the problem required validation of modeling techniques. A modeling method will be validated using the testing results and will include the effect of flow and temperature of the ambient medium on the speaker performance. This paper shows a comparison between a finite element model in MATLAB, multiphysics model in COMSOL and the analytical equations for the SPL generated by an open planar CNT speaker. This comparison will assist in validating the coupling method used in the COMSOL model as well as understanding the process used by COMSOL for simulating the planar CNT speaker. Validating the simple planar CNT speaker model is crucial as similar coupling between the physics will be used for a more complicated model of an enclosed, coaxial CNT speaker in COMSOL.

Thin-ply Carbon Diaphragm (TPCD) Technology – Speaker Diaphragms Engineered to Sound like You Want Them to Sound June 14, 3PM to4PM, NAPA D

By Martin Turesson- Oxeon TeXtreme

Thin-ply Carbon Diaphragms (TPCD) is a new category of speaker diaphragms. Our vision is to engineer loudspeaker diaphragms that sound like you want them to sound. Our approach to do so is radically different compared to how speaker diaphragms are traditionally engineered.

The ideal speaker diaphragm should be stiff, light and well damped – properties that are largely incompatible, leading to compromises. Only relying on material properties to reduce unwanted characteristics of a speaker diaphragm – for instance adding damping to reduce the effects of undesired break up modes or increasing the stiffness to push the break up modes higher up in frequency is like treating a sore back with pain killers – you might reduce the effects of the problem but you don’t fix them and you may end up with other problems.

The approach with TPCD is radically different and aims to eliminate the cause of the unwanted characteristics, for instance in the form of undesired break up modes, rather than just reduce their symptoms. Much like the tone of a guitar string can be tuned by adjusting the tension, the behavior and sound of a TPCD can be tuned by adjusting its material structure and construction.

This presentation will show how TPCD enables the combination of pistonic motion with controlled and smooth break up through engineered break up modes for a clear and natural sound.

Advanced ANC Headphone Measurements Part 2  June 14, 4PM to 5PM, NAPA D

By Jacob Soendergaard- Head acoustics 

This is the sequel to the ANC headphone presentation from ALTI-EXPO 2018 that presented a whole new way to evaluate ANC based on hearing models and perceptual metrics.

This presentation will again draw on the same principles, methods and metrics, but take a much closer look at the latest evolution of ANC: Talk-Through mode.

Talk-Through mode is intended for the headphone user to be able to communicate effortlessly with others in the same space, regardless of noise – and, crucially, without having to remove the ANC device.

This presentation will share data taken from commercially available devices and highlight some of the different approaches taken to implement Talk-through mode and ultimately evaluate how successfully those products are in improving the listening and conversational experience in noisy environments.

The Roadmap Towards Digital Twins For Automotive Audio Systems  June 14, 9AM to 9:30AM, NAPA D

By Dr. Alfred J. Svobodnik- Mvoid

Digital twins are one of the most important technology trends, currently reaching a maturity level that allows entering mainstream use. In product development, production and service, the use of this technology promises vast benefits through the possibility of monitoring the behavior of products and production processes with the help of a digital twin, developing new customer oriented services or drawing conclusions for product improvements from product data. Digital twins can change and accelerate the entire engineering process.

Audio systems in production vehicles are known to exhibit vehicle to vehicle performance variance. Hence, such systems are an ideal candidate to utilize the digital twin method where e.g. particular attributes can be modified between comparisons. Adopting loudspeaker drive units from within manufacturing tolerance, system comparisons and thus performance changes can be assessed and improved.

The digital product twin of sound systems in vehicles additionally helps to explore the impact of different design alternatives and allows simulations and tests to ensure that product designs meet the requirements and fulfill customer expectations.

Multidimensional Optimization of professional Audio Systems Using Advanced Multiphysical Models  June 15, 4PM to 4:30PM, NAPA D

By Thomas Gmeiner- Mvoid

The fundamental principle of virtual product development is to optimize the performance of products and systems in the early phase of the development process. Engineering is the art of realising desired functions by technical solutions embedded in a system of interacting elements. Multi-dimensional target requirements come with trade-offs to be made and the quest for the best product boils down to finding the sweet spot between all the interacting influences. The optimal product is the treasure of companies, nurtured by the business processes linking market research, customer relations, product management and engineering, traditionally grown by experience and empirical know-how.
Virtual product development adds and changes the process landscape by new approaches: Product designs can be varied over a wider range to explore what is theoretically achievable. The planned product can be consciously positioned within the explored space, therefore better understood and explained to the customer. User tests can be performed with the virtual prototypes to confirm decisions or explore new properties.
Audio systems act in various physical regimes. For a full digital model, a combination of simulation methods, mesh sizes, mathematical models and physical theories must be applied. The application of the methodology is presented with a use-case of optimizing a subwoofer.

 

Engineering Student’s Guide to Loudspeaker Design  June 15, 9AM to 10AM, NAPA D

By Mark Glazer- ALTI Board of Directors and Harman International

There is an increasing demand for loudspeaker engineers due to the growing market of “smart” loudspeakers. This presentation will enlighten the student with knowledge on loudspeaker engineering, as well as how to design your own bookshelf speaker. Topics discussed will be, loudspeaker directivity and the Listening room, loudspeaker linearity, design goals, transducer design and selection, Thiele-Small definition and measurements, transducer measurements, enclosure design and construction, crossover design, and system measurements

Design of Active Loudspeaker Systems with Typical Program Material  June 15, 11AM to Noon, NAPA D

By Marian Liebig- Klippel GmbH

Lumped parameter modeling of the transducer and passive acoustical component is an effective starting point for building passive loudspeakers. However, digital signal processing (DSP) available in modern active loudspeaker systems creates new possibilities for the design of the passive components by actively equalizing the system to a desired target response. Thus, efficiency is one of the most important key design criteria for creating small speakers where power is saved in the pass band and used for an extensive bass boost at lower frequencies. This presentation, which is part of the Speaker Builder workshop, uses a new linear simulation tool (LSIM) to optimize the maximum output SPLmax for a given spectrum and crest factor of the audio signal (e.g. music) considering the maximum peak voltage and current capabilities of the amplifier.

Adaptive Nonlinear Control of the Transducer  Part of the Amplifier Builders Workshop. June 15, 8AM to Noon, NAPA A/B

By Peter Vanselow- Klippel GmbH

The transducer is not a linear component but limits the sound pressure output by nonlinearities and voice coil heating. A digital control algorithm based on loudspeaker modeling can compensate for undesired distortion and increases the maximum output without generating a mechanical or thermal overload of the system. This presentation, which is part of the DSP Builder Workshop, shows the practical application of the KLIPPEL CONTROLLED SOUND -technology (KCS) on a two-channel loudspeaker system developed in the Speaker Workshop. KCS is the first adaptive nonlinear control system integrated as an AUDIO WEAVER component in a cost effective DSP combined with a power amplifier driving the transducers. Adaptive control is realized by sensing the input current at the speaker terminals and compensating for production tolerances, climate, fatigue and load changes. KCS complements other DSP algorithms used for sound enhancement, echo cancelation, beam steering and further 3D sound effects.

Horizontally Omnidirectional Loudspeakers – Physics of Operation  June 14, 4:30PM to 5PM NAPA C

By Alexander Voishvillo, PhD, Fellow, Acoustics Engineering, Harman Professional

Horizontally omnidirectional loudspeakers have a uniform directivity response in the horizontal plane and a coordinate-dependent frequency response in the vertical plane. These types of loudspeakers have applications in omnidirectional hi-fi and hi-end audio systems, “party loudspeakers”, landscape installations, and small portable Bluetooth loudspeakers. Usually the uniformity of radiation in the horizontal plane is provided by a vertically directed dome or cone transducer that radiates against a reflector.

Two different types of horizontally omnidirectional transducers are considered in this work. One of them is a high-frequency compression driver based on an annular flexural diaphragm where the diaphragm’s axial vibration is transformed into radial radiation through a special phasing plug and a horizontally omnidirectional horn. The other one, a low-mid frequency cone loudspeaker, has a vertically vibrating diaphragm that radiates against a reflector, which is acoustically connected to a horizontally omnidirectional horn.

Acoustical models of both types of transducers are analyzed numerically and analytically, including the study of such effects as interference and diffraction. A practical implementation is demonstrated. 

This work compares acoustical models of two omnidirectional transducers. One transducer, based on a compression driver with an annular diaphragm is presented as a radially pulsating ring at the entrance of the horizontally omnidirectional horn. The other is based on an axially radiating cone speaker modeled as a piston oscillating vertically against a reflector and loaded by a horizontally omnidirectional horn. In general, two factors affect frequency response and directivity in the vertical plane – interference and diffraction. It is shown through numerical acoustical simulations that diffraction provides a strong influence on the response. A practical implementation is demonstrated.

Analytical and Numerical Analysis of Horns’ Acoustical Parameters  June 14, 4PM to 4:30PM, NAPA C

By Alexander Voishvillo, Balazs Kakonyi, and Brian McLaughlin. Harman Professional

A horn’s input acoustical impedance is obtained from the combination of matrix analysis and special electro-acoustical measurements. First, the square matrix of the transfer A-parameters of the compression driver are obtained through the measurement of the driver’s input electrical impedance and SPL frequency response on a plane wave tube and at the acoustically blocked exit. The obtained matrix parameters are used in the derivation of the horn’s input acoustical impedance. Two different approaches are used – one based on the expression for compression driver output at the horn’s throat and another based on the electrical impedance of the horn driver.

The frequency dependent loading of real plane wave tubes with different diameters are modeled in COMSOL and the results are embedded in the calculation of A-parameters, leading to high accuracy.

Several horns and compression drivers are used in the experiments and COMSOL simulations are utilized to prove the approach. The results are evaluated against analysis made through both the two-microphone and transmission line methods of horn impedance derivation.

The work also includes a derivation of the horn’s complex transfer function based on the condition of constant sound pressure at the horn’s throat. This makes it possible to differentiate the irregularity in the SPL frequency response produced by the horn only from the resulting acoustical response of the horn with the compression driver connected to it. This information is important in the evaluation of the driver’s performance and identifies SPL response irregularities coming from the horn and the driver.

The output acoustical impedance of several different compression drivers are compared with the input impedance of their corresponding horns to evaluate conditions for maximum efficiency. The output acoustical impedance of the drivers are obtained through matrix analysis and through COMSOL simulations.