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Harman Audio Test System (HATS)

Harman Real-World Audio Test Results in Precision Not Thought Possible

Being located in the “entertainment capital of the world,” JBL Professional has a unique opportunity to participate in the sound design and installation of our tour sound products in many highprofile, showcase Los Angeles venues such as the Staples Center, Nokia Theater, Club Nokia, Walt Disney Concert Hall, Valley Performing Arts Center, Regal Cinema Stadium 14, Disney Fantasyland Theater and the Wiltern, to name a few. All of these venues feature JBL VERTEC® or VTX sound systems, and over the past five years we have been field testing the HARMAN Audio Test System (HATS) in these spaces as a tool for system tuning and optimization with a high degree of success.

Developed by Allan Devantier, formerly with HARMAN International’s Corporate Technology Group, HATS was primarily intended as a lab measurement and sound system optimization tool for automotive and high-end home theater applications (aside: for those of you familiar with ARCOS, it is a customized version of HATS). Following the success of HATS in Lifestyle division applications, JBL Professional began using HATS for loudspeaker development for the Record & Broadcast market segment. As I became aware of this technology, it became of interest to see if HATS could be adapted from small-space acoustic environments to large-room acoustics and used for tour sound

applications. After having used HATS on numerous projects while refining our measurement and tuning methodology, in my opinion, it has allowed us to obtain truly excellent results with a level of precision that was previously not possible.

Recently, the historic Wiltern Theater went through a power amplifier/digital signal processing upgrade from Crown Audio MacroTech to latest-generation I-TechHD amplifiers, allowing their existing VERTEC VT4889 system to be upgraded to a significantly higher level of performance through the implementation of VERTEC V5 presets. As part of the upgrade, JBL HiQnet Performance Manager™ software was introduced for system control and monitoring.

Defining Our WorkflowTo understand how we optimize

the sound system for a venue like the Wiltern, let’s start by taking a look at the four basic steps involved in optimizing line array performance: optimize the individual loudspeaker, optimize the size and shape of the array to suit the venue, calibrate the array and equalize the array to compensate for the effect of room acoustics. Let’s use the Wiltern Theater as a case study to see how these four steps were implemented and the various roles that HATS played in the process.

Optimizing the individual loudspeaker starts with rigorous acoustic design to ensure that vertical coupling criteria are satisfied, allowing

Harman Audio Test SystemHarman Real-World Audio Test Results in Precision Not Thought PossibleBy Paul Bauman, Associate Director – Tour Sound JBL Professional,

HARMAN International

innovation paper

JBL’s Line Array Calculator software and HiQnet Performance Manager™ software are critical elements in HATS.

multiple enclosures to couple properly when arrayed in a vertical column as a line array. This is followed by preset development to optimize the performance of the individual loudspeaker through crossover filtering for low, mid and high sections (for an active three-way design such as VTX V25 or VERTEC VT4889), corrective equalization and time alignment for each section, plus additional phase linearization via FIR processing for the case of V5 presets. To develop loudspeaker presets, detailed measurements are performed on individual reference enclosures using HATS to optimize frequency response over the weighted -3 dB coverage region, simultaneously optimizing horizontal coverage while conforming to a target frequency response that will scale properly for larger line arrays consisting of multiple enclosures.

Once the individual line array element is optimized, when coupled together in a vertical column, multiple enclosures behave collectively as one single loudspeaker. By adjusting angles between enclosures, the shape of the array can be optimized to provide even coverage throughout the venue in terms of sound pressure level (SPL) distribution and frequency response over the audience. Essentially, the line array is “customized” to suit the coverage requirements for a given venue by referring to a section view representation of the audience profile and the loudspeaker array to determine installation parameters such as array trim height, array orientation and inter-enclosure angles. To optimize the size and shape of the array, JBL Line Array Calculator (LAC) software provides a practical modeling tool while EASE offers more detailed 3D SPL mapping capability.

Once the shape of the array is correct, LAC software also allows for the determination of array calibration parameters to provide a useful starting point for optimization of the system after it has actually been installed

in the field. When used in larger arrays, active three-way enclosures are typically circuited in groups of two or three cabinets, allowing for calibration of overall array performance by performing circuit-level adjustments such as gain shading or frequency tapering in order to obtain even sound pressure level and frequency response over the audience area. In the case of powered line arrays, such as the VT4889ADP-DA enclosures installed at the Staples Center, we have individual enclosure resolution (single cabinet circuits) that allows for more detailed gain shading and tapering. For the case of the Wiltern Theater, eight VERTEC VT4889 loudspeakers are arrayed per side and powered in three circuits. Numbered from top to bottom, the top circuit has enclosures 1-3 in parallel, the middle circuit has enclosures 4-6 in parallel and the bottom circuit has enclosures 7 and 8 in parallel. Figure 1 above shows the JBL LAC simulation for the installation.

innovation paper / Harman Audio Test System Real-World Test Results

Figure 1: Line Array Calculator simulation

When individual frequency response curves for all 12 HATS microphone locations are superimposed, even response throughout the venue is observed, and the above measurement averages show an extremely well-behaved response, with +/- 2 dB variations above 500 Hz and a healthy 15 dB low frequency contour (without subwoofers). Such a low frequency contour is suitable for demanding rock applications but can easily be shelved down to provide a more modest contour for spoken word events, and Performance Manager provides a convenient user interface for making such adjustments.

Last But Not LeastSubwoofer time alignment is key to a great-sounding venue, and the

SoundField Management (SFM) feature in HATS is highly useful for this purpose. Time aligning flown line arrays with ground stacked subwoofers always implies compromise, and when selecting a single reference location, it is normally an attempt at reaching an “optimum” compromise. By using multiple microphone locations and HATS SFM, an improved optimum compromise is reached with better overall sub/low summation, coherency and impact for a larger majority of the audience with reduced power alley and lobing effects.

This sequence of steps corresponds to the workflow that has been specifically designed into Performance Manager software, guiding end users toward good working practice and helping them to obtain optimum results in the field. This is also the methodology that is taught during VERTEC/VTX Training Sessions that are regularly held at JBL Professional’s Northridge location. HATS has allowed us to do more detailed system tuning than was previously possible, and the methodology is constantly evolving as we gain experience with HATS in real-world situations. Supporting our local dealers and installation contractors on these showcase venues allows us to gain valuable, real-world, handson experience with JBL Professional tour sound products, and new ideas for better products, better installation practices and system tuning procedures are a direct result. It is also important to validate modeling

software, such as JBL Line Array Calculator, and further refine system Performance Manager control software as well as the HATS measurement system itself. After every field trial, there are always new ideas as to how can we do this faster, better, more efficiently.

Ultimately, detailed optimization of these showcase installations allows HARMAN to put our best foot forward and make a good impression on visiting artists and artist production management. It’s a win-win for everyone—we gain valuable field experience, allowing us to develop better products (loudspeakers, modeling/control software) and procedures (measurement and system tuning techniques); the venue has a truly optimized sound system that provides their audience with a great concert experience; and visiting artists, management and production have an easy day in a great-sounding room, allowing JBL to make a good impression on these influential and important “system specifiers.”

innovation paper / Harman Audio Test System Real-World Test Results

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Paul Bauman has driven the development and widespread growth of adoption of VTX line arrays across the globe since the product’s introduction in January 2012, while also growing JBL’s VERTEC customer base. Bauman has been a key member of the JBL Professional team since 2007, having spent the past two as Senior Manager, Tour Sound. Bauman has also held the positions of Director, Tour Sound Product and Application Engineering, and Senior Manager, Product Development, Tour Sound. Bauman has more than 29 years of professional audio and global touring industry experience, including key positions at L-ACOUSTICS, Maryland Sound International and Adamson Systems Engineering. Bauman’s background comprises loudspeaker and sound reinforcement system design, live sound system engineering and mixing, as well as studio mixing, engineering and producing (including radio broadcast).

HARMAN (NYSE:HAR) (www.harman.com) designs, manufactures and markets premier audio, visual, infotainment and integrated control solutions for the automotive, consumer and professional markets. With 15 leading brands, including AKG®, Harman Kardon®, Infinity®, JBL®, Lexicon®, Mark Levinson® and Revel®, the Company is admired by audiophiles, musicians and the entertainment venues where they perform. More than 25 million automobiles on the road today are equipped with HARMAN audio and infotainment systems.

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