Tuesday, November 05, 2013
Self-Powered Meyer Sound Loudspeakers Raise Fidelity & Flexibility At Houston Airport Terminal B
Despite large reflective surfaces and tall ceilings, announcements and music are projected with crisp clarit
At the new Terminal B at Houston’s George Bush Intercontinental Airport (IAH), self-powered 48-volt Meyer Sound loudspeakers in the south concourse have raised the bar for audio fidelity and flexibility. Despite large reflective surfaces and tall ceilings, announcements and music are projected with crisp clarity.
“The audio quality, intelligibility, and uniformity of coverage are distinctly better than most terminals across the country,” says Ulf Lueders, Terminal Services group manager of the Houston Airport System (HAS). “With this upgrade, travelers can enjoy the various concessions without having to worry about missing a flight announcement. Higher quality also allows the concourse operator to choose from a wider variety of background music, without being restricted to the ‘elevator music’ compatible with lower fidelity systems.”
Both airport management and the concourse operator, United Airlines, worked to offer across-the-board improvements in traveler experience. Improving audio quality in the concourse proved a challenge, as the 27-foot high ceiling, the room’s large size, and the expansive glass area presented acoustical difficulties. To control unwanted reverberations, Houston-based HFP Acoustical Consultants designed both the room’s acoustical treatments and the Meyer Sound self-powered loudspeaker installation as a balanced, integral system.
“Self-powered loudspeakers, with amplification and signal processing inside the cabinet, provide inherently better audio reproduction,” explains HFP’s Bill Schuermann. “Without the transformers and long cable runs typical of airport systems, they provide flatter frequency and phase response, lower distortion, and extended bass. The result is remarkable intelligibility with a natural voice quality, and far superior musicality.”
The principal Meyer Sound components comprise 60 UPM-1XP 48 V loudspeakers, 44 MM-4XP self-powered loudspeakers, and two Stella-4C installation loudspeakers, with a Galileo loudspeaker management system with seven Galileo 408 processors providing system optimization. LD Systems of Houston installed the system.
“If conventional systems have to be rezoned to accommodate a new floor plan, you usually have to change wiring in the ceiling,” Schuermann notes. “But with self-powered systems, all the changes can be quickly accomplished inside the equipment room.”
“We’ve raised the bar with Terminal B south,” says Lueders. “It is certainly the airport’s prime location as far as audio quality and coverage is concerned.”
IAH Terminal B south concourse was designed by Cheryl Gajeske and Ivan Pire of Houston-based PGAL. The $97 million project opened in 2013 with 15 active gates for United Express regional flights, with expansion to 30 gates planned by the end of the year.
New Websites Launched For Grundorf And Grund Audio Design
Faster navigation, more details, enhanced search capabilities and more
Grundorf Corporation has launched two new websites—one for the division that sells cases and accessories (Grundorf) and the other for the division that sells loudspeakers, audio processors, and related equipment (Grund Audio Design). The two websites are located at www.grundorf.com and www.GrundAudio.com.
The two sites are visually distinct in their color selections—green for Grundorf.com and blue for GrundAudio.com—in order to help visitors identify each website. Beyond that, the navigation attributes of the two sites are the same, enabling visitors to quickly become familiar with either destination.
For each product offering, available options have been incorporated for each product offering, including add-ons, along with color options for products such as cases.
Similarly, recommended accessory items are displayed for applicable products. As an example, a customer making a case purchase that includes a microphone locker might want/need a lock.
As many products from Grundorf Corporation are highly customizable, the company has added an online catalog on each home page available for either online viewing or downloading. By downloading the catalog, customers are able to review all the available options at their leisure.
Also included on the new sites are enhanced search capabilities that make the process of locating specific models or types of products quick and easy.
Frank Grund, president of Grundorf Corporation, states, “The ability of delivering information quickly is a critical element for today’s online shopper. By helping our customers locate what they’re looking for faster and by augmenting that search with all relevant options and accessories, I believe we remove much of the guesswork that many people experience when shopping for pro audio equipment and accessories.”
Grund Audio Designs
Monday, November 04, 2013
Martin Audio Presents Exclusive MLA Compact Demos In New York City & Washington, D.C.
Attendees include leading theatrical sound designers, acoustic consultants, audio engineers and event production management
Martin Audio recently hosted exclusive demonstrations of its MLA Compact loudspeaker platform for leading theatrical sound designers, acoustic consultants, audio engineers and event production management in New York City and Washington D.C.
The New York demo was held in the Grand Ballroom, Manhattan Center Studios, while the Washington D.C. demo took place in the Lisner Auditorium at The George Washington University.
Both events provided a unique opportunity for attendees to learn more about MLA Compact’s cellular drive technology while experiencing the coverage, dynamic audio quality and clarity of speech the system is known for in person.
Hosted by Martin Audio U.S. director of operations Rob Hofkamp, the demonstrations featured a detailed technical presentation by research and development director Jason Baird and a live demonstration of the system including unique optimization techniques around hard avoid and non-audience areas.
More than 100 people attended the demos and the response was uniformly positive. Enthusiastic attendees came from as far away as Paraguay and Austria.
Hofkamp states, “It was a pleasure to do these demos and receive such positive feedback on our presentation and the MLA Compact . The attendees also enjoyed the exceptional live acoustic performances from singer Layla Davias & guitarist Frank Portalatin, alongside full-bore metal recordings from Rammstein in excess of 110 dB. Special thanks also to Jim Risgin of OSA and Mike Scarfe of MHA for their support of the NYC and Washington DC demos respectively.”
New ADAM Audio F Series Contest Stresses Creativity
Entrants get a chance to win a pair of F5 or F7 active studio monitors
ADAM Audio is giving away four pairs of autographed special edition F-series monitors to those with the most creative photo ideas.
Entrants who send in the most imaginative photographic submissions in November and December 2013 will get the chance to win a pair of F5 or F7 active studio monitors.
The one-of-a-kind models are custom-designed and signed by ADAM founder and CEO Klaus Heinz. Only two pairs each of these F5 and F7 monitors will exist worldwide.
Entrants need to download a picture of the F5 or F7 at www.adam-audio.com, print it out and blend it into their photographic arrangement. Drawings of the monitors and other creative concepts are also welcome.
ADAM Audio will select the two most inventive pictures from all of the entries in November and December, so entrants are encouraged to be creative and let it all hang out.
The contest begins on November 1 and ends December 31, 2013. Pictures submitted from November 1 through November 30 are eligible to win a pair of F5s or F7s, the same applies for entries from December 1 through December 31, 2013. Each participant can submit a maximum of one picture.
ADAM Audio USA
Slovak National Theatre Upgrades To Renkus-Heinz IC Live
EASE analysis led MediaTech to recommending the IC Live digitally steerable system by Renkus-Heinz.
Completed in 1886, the Slovak National Theatre was designed by Viennese architects Ferdinand Fellner and Hermann Helmer. Since 1920, the ornate, 1,000-seat building has been the seat of the Slovak National Theatre opera and ballet ensembles. The hall has also hosted performances by some of the world’s top opera and ballet talents.
Its acoustics, however, have come under more scrutiny. The room’s very short reverberation time, while acceptable for opera, doesn’t suit orchestral performances. Its narrow stage faces a long auditorium where the rear seats are 75 ft (22 m) away. Uneven sound coverage confronted its numerous balconies.
A subtle sound reinforcement system was needed, effectively invisible to the audience, and the theater approached MediaTech, Bratislava’s largest pro audio company.
EASE analysis led to them recommending the IC Live digitally steerable system by Renkus-Heinz. Its clear, uncolored musical sound, the ability to steer multiple sound beams into specific areas of the audience offered precisely the solution that was needed. And its slim, low profile design - complete with a custom paint finish - complemented the theatre’s décor perfectly.
The system includes extra reverb for orchestral shows via a TC Electronics with a Yamaha PM5D console linked directly to the IC Live system via CobraNet.
“The audience had to be unaware of sound reinforcement,” says manager Miroslav Paciga. “IC Live allowed us to achieve that subtle effect visually unnoticeable.”
TiMax At Core Of Handen Culture And Arts Centre
For the building’s expansive Grand Theatre space a d&b loudspeaker system was specified in conjunction with a 16x16 TiMax2 SoundHub audio delay matrix for overall system management
China’s Handen Culture and Arts Centre is a green architectural dream, strongly characterized by its stunning hybrid concrete and steel ellipsoid structure, which is also built to withstand substantial seismic pressures.
Even with such a focus on the structure itself, the aural niceties of grand theatre design were not left wanting. A multichannel distributed speaker system installation controlled by TiMax SoundHub was installed to meet world-class performance and event sound reinforcement standards.
Working together with system integrator, Beijing Rangl Audio Co., Ltd, TiMax distributor SWS Hong Kong were well placed to propose a solution best suited to the particular demands and challenges the venue presented.
For the building’s expansive Grand Theatre space a d&b loudspeaker system was specified in conjunction with a 16x16 TiMax2 SoundHub audio delay matrix for overall system management, zone level control and equalisation, in addition to the all-important TiMax speciality of delay-based localisation.
Over the stage a central d&b Qi1cluster was flanked left and right by further clusters of d&b Qi1 and Qi7 and supported by a combination of d&b B4-SUB and d&b B2-SUBs. Amplification was provided by d&b D12 and D6 amplifiers.
Meanwhile, 12 d&b E0’s provided fill, with eight d&b 8S as rear fill – amplified again by D6s. Fixed stage monitoring is supplied by 13 d&b 8S, while a further eight cabinets are available as mobile stage monitors.
16 d&b 8S are distributed around the auditorium, with a further 12 supplying the first floor balcony and a further 12 again for the second tier. Ceiling effect speakers are comprised of d&b MAX12 and d&b B2-SUBs. Again, amplification was provided by d&b D12 and D6 amplifiers.
Freddie To, of TiMax distributor, SWS Hong Kong, commented, “The installation has been very successful – the theatre is now able to present productions technologically equivalent or even superior to any show that can be seen in the West.”
Harman Pro Audio Brands Provide Versatile Audio Solution For Rhema Bible Church
Audio consultants SoundGP and Harman Professional South African distributor, Wild & Marr (Pty) Ltd., provided an integrated audio infrastructure and broadcast/production facility consisting Harman Professional products.
The popular Rhema Bible Church in Randburg, Northwest Johannesburg, is a house of worship dedicated to learning and growing.
With a seating capacity of 7,500, the Rhema Bible Church was in need of an upgrade to its sound reinforcement system for its large 180-degree bowl-shaped auditorium.
Senior Pastor Ray McCauley turned to audio consultants SoundGP and Harman Professional South African distributor, Wild & Marr (Pty) Ltd., who provided an integrated audio infrastructure and broadcast/production facility consisting of Harman’s JBL Professional, Crown, and Soundcraft components.
The audio system had to support the multi-functional needs of Sunday morning services, with spoken word being the top priority. In addition, it needed to deliver high-end concert performance over the substantial audience noise levels generated in the large auditorium, while providing the necessary capability for international touring artists, without the need for additional equipment.
“The previous system was unable to cope with the new high-energy content being generated in many forms — from live music to AV,” stated Pastor Alan Plant, who heads logistics for Sunday services. “Due to its age, the speech coverage was uneven and not up to the level of consistency required to ensure a pleasant listening environment.”
Wild and Marr chose JBL’s VTX line array system powered by Crown’s flagship I-Tech 12000 HD power amplifiers. The system is controlled by the latest version of JBL HiQnet Performance Manager software. The system needed to be transformed into one that communicated to a fast-growing, youth-focused audience.
“This market consumes media in a different way with expectations of seamless integration of varying media streams from acoustic rock to low-end electronica bass tracks to multimedia streaming,” explained Gustav Teitge, Wild & Marr Systems Engineer.
To fulfill the church’s requirements, Wild and Marr outfitted the auditorium with four arrays of six JBL VTX V25 loudspeakers and two JBL VERTEC VT4886 subcompact enclosures per array acting as down fills. The system also includes three JBL VTX S28 subwoofers per side in a cardioid array. Eight JBL STX815M loudspeakers were also used to provide delays to the rear seating area.
By using a specially designed MADI routing solution, the church now has expanded routing flexibility and is capable of future expansion. This is a first-of-its-kind solution in such an environment, enabling the sound operators to mix 96 channels from the Soundcraft Vi6 stage box mic pre-amplifiers.
Sixty-four of these channels are made available to the monitor Soundcraft Vi1 or the Soundcraft Vi1 in the broadcast/production facility as well as the permanent recording PC, which also doubles as a virtual sound check playback device.
The Soundcraft Aviom expansion card provides flexibility of routing to any console bus feed. This digital signal backbone also provides adequate tie lines for signal interconnection between the various consoles while passing AES/EBU signal to the main PA via the MADI router. An analogue signal routing system provides redundancy from the main PA ensuring reliable signal transport to the Crown I-Tech HD amplifiers.
Gustav Teitge adds that the system performance objectives had been clearly met by installing JBL VTX. “The new technology incorporated into the D2 driver, as well as other innovations, like decreased component gaps and structural changes, make seamless audio interconnectivity when moving around the auditorium a priority — thus lending itself to extremely smooth and accurate audio distribution.”
SoundGP owner, Cristo Hattingh, was responsible for the voicing of the system. In addition, challenges faced and overcome along the way included restricted height due to the funnel shape of the space’s profile (incline floor, decline roof towards the rear) creating unique standing waves in the low-mids and making it very challenging to achieve an even low-end distribution.
The implementation of a collaborative Harman product line was the first of its kind in Africa using this type of technology.
“Utilizing the new VTX loudspeaker system all the way down to a MADI integrated Soundcraft fiber signal distribution and control backbone provided an innovative and successful solution to the many challenges the Rhema Bible Church presented,” concluded the design team.
Meyer Sound Assumes Canadian Sales Distribution & Hires Franck-Olivier Fabry As Sales Manager
Company taking direct rolw in supporting Canadian customer network
Meyer Sound has assumed distribution responsibilities for Canada and appointed Franck-Olivier Fabry as the new sales manager.
Working closely with the Berkeley, CA headquarters, Fabry is tasked with supporting the Canadian customer network by facilitating sales, technical assistance, and design services.
Fluent in both English and French, Fabry comes to his new post with over 14 years of experience in pro audio sales, much of it in the Canadian market. For 12 years, he held top-level sales positions at Bosch Security Systems (previously Telex Communications), where he handled sales for lines such as Electro-Voice, Dynacord, Midas, Klark Technik, and Bosch in Canada, the U.S., Latin America, Africa, and the Middle East. Fabry also directed global sales efforts at Williams Sound.
GerrAudio was formerly the Canadian distributor for Meyer Sound. “We are grateful for the dedication and hard work of GerrAudio in the past 25 years,” says Antonio Zacarias, Meyer Sound vice president of worldwide sales. “As Meyer Sound takes over Canadian distribution and with Franck’s wealth of industry experience, we are in a great position to build upon our momentum in Canada and provide customers with more direct access to our full range of services.”
“Meyer Sound’s product quality is respected worldwide, and no other company provides customers with such a high level of comprehensive support,” says Fabry. “I believe that success comes naturally when we’re enthusiastic about what we do, and I look forward to bringing new energy and passion to serving the company’s Canadian customers and consultants.”
Born in Paris to French and Swiss parents, Fabry lived in both countries before moving to the U.S. He holds bachelor’s and master’s degrees in business from France’s Ecole Supérieure de Commerce de Toulon and the University of Aix-en-Provence, respectively.
World’s Biggest Studio Monitors? Thoughts On Modern Loudspeakers
Philosophical changes in the way we put such technology to work?
In many ways, loudspeaker technology is the primary limiting factor in sound reinforcement system design and performance.
Transducers are always problematic, having to comply with the laws of thermodynamics and all. Not only are they inefficient at turning electric energy into acoustic energy, they also add a significant amount of distortion to the signal during the process.
Some years ago I was in Washington, D.C., doing research for a potential patent for a vibration reducing device, and I came across some of the early patents for dynamic loudspeaker drivers from about 100 years ago. Guess what? They looked basically the same as what we have now, and were certainly based on the same principles.
It made me realize that, like the internal combustion engine, loudspeakers as we know them have been around for a long time, and are in a constant state of refinement because we simply haven’t developed anything better yet.
But what about all of that refinement? Indeed, as stable as the technology is in many ways, loudspeakers have been radically transformed, particularly over the past two decades.
Inside the Box
In my mind, the first big evolution came several decades ago in the form of cabinet design. Once designers had a handle on the acoustic properties of the transducers themselves, we began to see very good loudspeaker designs that took advantage of the strengths and minimized the weaknesses of the various drivers. Crossovers followed suit, becoming ever more sophisticated.
Next came the move to active designs, led by Meyer Sound and others during the late 1970s and early ‘80s. This was the first real step towards developing a complete system between amplifiers, crossovers, cabinets and drivers. I was fortunate enough to tour in the 1990s with Meyer Sound MSL3s, UPA1s, USWs and USMs—great loudspeakers (particularly for the day) that made my job much easier.
Next was the line array revolution, led by L-Acoustics, further changing the game. Certainly, line arrays aren’t the ideal solution for all applications, but they’ve lightened the load of countless tours while delivering quality sound to millions around the world since their introduction.
By the late 1990s, I noticed two things that were primed to have an effect on stage microphones. First, the introduction of in-ear monitoring systems dramatically lowered stage volume levels, improving signal-to-noise ratio while also accommodating the deployment of better microphones—even condensers—on live stages. Second, improved loudspeaker designs meant that those better microphones, no longer confined to the studio, could now be clearly heard by a live audience.
As a result, I worked with the team at Neumann (my employer at the time) to come up with the KMS105 vocal microphone. There were similar models developed by Shure, Audix, and others, and we were all responding to the newfound fidelity of the loudspeaker systems. Artists like Norah Jones, Diana Krall, Tori Amos, Sarah McLachlan and many others were able to deliver a “studio-quality” experience to their audiences. I know—I was there! At the time, it really seemed like a breakthrough, probably because, well, it was.
Now we’re seeing a new generation of loudspeaker technology that more than ever takes advantage of the wonders of digital signal processing. However, this work has been ongoing for some time now.
Ever heard of the KF900 designed by Dave Gunness for EAW in the mid-1990s? It was arguably the first attempt at controlling every aspect of large-scale loudspeaker system performance via DSP.
Fast forward to 2011 when the Martin Audio MLA (Multi-cellular Line Array) system hit the market. It was the first time I’d heard such an elaborate system (each driver matched with its own signal processing line).
My thought? Wow! Not only does it sound great, but it provides an amazing degree of control of coverage. Also from what I’m told, the new Anya system from EAW in its implementation of DSP also produces impressive results, and these aren’t the only examples.
We’ve now arrived at a place where most modern loudspeaker systems for sound reinforcement, in the words of many, “sound like big studio monitors.”
I agree—they’re more neutral, with less distortion and better pattern control, than ever. And this brings about some interesting philosophical changes in the way we might put such technology to work.
For decades, there’s been a relationship between certain mixers, the sound companies they choose, and the loudspeaker systems they run.
There are many reasons for this, not the least of which is familiarity with a certain approach to the way the loudspeakers sound. Audiences not only receive the sound of the band on stage, but the signature sound of the mixer, with the loudspeakers an integral part of that sound.
Like it or not, there have always been anomalies specific to those loudspeakers, reflecting the preferences of the designer. Some emphasized “even coverage in the midrange” while others pushed “linear phase” and still others went for efficiency. And on and on… Each of these strengths and tradeoffs were part of why we chose those products.
Now, however, due to these newer design philosophies, the sonic signature of a box may no longer be such a key part of the selection criteria that also includes rigging, truck pack, weight issues, powering considerations and the like.
The sound of today’s latest models might be neutral enough that it is no longer a major tradeoff. We can expect most of these loudspeakers to sound A) amazing, and B) neutral, so we can put our own personal stamp on the mix without having to fight an anomaly or take some kind of inherent sonic signature as given.
To me, this is an amazing development and stands to make it possible for all of us to develop the best mixes of our careers. Even better, I think we can expect it to continue to get better, with even lower distortion, more coverage control, and probably smaller, lighter, and more efficient boxes. In short: what a great time to be in this business.
Karl Winkler is director of business development at Lectrosonics and has worked in professional audio for more than 20 years.
Friday, November 01, 2013
Tech Talk: Building Directional Subwoofer Arrays
Working toward consistency throughout the listening area
Directional subwoofers are one more tool that can be used by sound system designers in their quest to achieve consistent sound throughout the intended listening area.
When using traditional, more or less omni-directional bass reflex (a.k.a., “vented,” “ported,” or “front-loaded”) subs arranged left and right of a stage, there is a build-up or “power alley” created in the center, where the energy from each source location shows up at the same time, with no phase difference, and sums quite nicely.
Moving left and right off of the center line, this area of addition is followed by alleys of cancellation.
Wavelengths of 40 to 100 Hz are roughly 11 to 23 feet long. At any frequency in this range, as you move away from the center line and change the path length difference between the two sources by half a wavelength (about 5.5 to 11.5 feet) there will be a cancellation, with higher frequency “nulls” encountered first.
To alleviate this there are three methods that have been employed: line arrays of subs, end-fired sub arrays, and cardioid subs, which are sometimes combined.
Lines of subwoofers are one application of what Harry Olson discussed in the 1957 text Harry F. Olson, Acoustical Engineering, when he described a straight line source; using omni-directional elements, in a line, all reproducing the same signal, with relative close spacing compared to the wavelength, pattern control can be achieved.
Imagine a row of subs is assembled across the front of a stage. If it’s longer than the wavelength of the lowest frequency for which pattern control is desired (25 Hz is about 45 feet) and if the elements are close enough to one another, within two-thirds of a wavelength of the highest frequency produced (100 Hz is about 11 feet, so 2/3 is about 7 feet), cancellation at the ends of the line and addition in front of the array (and behind the array!) will be achieved.
Observed from the audience area, from one end of the line to the other, enough of the energy from each of the elements of the array arrives within +/- 120 degrees, at about the same level and sums.
Observed from the end of the array, enough energy from each of the elements arrives enough out of time but at similar enough level, causing destructive interference and level loss.
The use of a line array (yep, that’s what it is) of subwoofers can avoid horizontal differences in frequency response and deliver more energy to the audience area, while avoiding those nasty side wall reflections at lower frequencies.
Further, maximizing spacing can reduce the level differences from the front to back. In the interest of making sound where the audience is and not making noise where they are not, this is one option.
Remember, though, that the energy is the same in front and behind the array.
These arrays can also be assembled vertically, though space between the elements is not easily achieved with most rigging systems, so they are generally closely spaced arrays.
In amphitheater and arena situations where coverage to the sides is desirable, incrementally delay-tapering the horizontal array - so that moving away from center, each sub is slightly later than the one before it - can spread the coverage out towards the sides.
The end-fired array can be made up of two or more subs, spaced closely together, one facing the rear of the next, in a row along the “z-axis,” facing the audience and the direction of coverage.
Yes folks; it looks like it won’t sound “right.” Each cabinet needs its own drive line because we are going to incrementally delay all but the rear-most.
The rear, upstage, sub is delay time zero.
Moving towards the audience, each sub needs delay added corresponding to its distance from “sub zero.”
Let’s say the spacing is 3.5 feet: the delay time would be 3.1 ms (speed of sound = 0.9 ms/ft) for the next element.
The end-fired array produces gain in front of the array because the energy from each of the elements arrives in time at all frequencies being reproduced.
Cancellation behind the array is the summation of the energy produced by each source that is out of time and arrives at almost the same level.
There are a number of dips in frequency response based on the number of signals that have 180 degrees of phase difference. The level difference between front and rear is about 18 dB with a four-element array.
A few manufactures make multi-driver, single-cabinet cardioid enclosures, but they can be created with simple arrays of two or more cabinets.
The physical arrangement can be one of two options, both speakers facing the audience, one upstage of the other, lined up on the ‘z-axis,’ or one sub oriented facing backwards next to one or more facing forward. Again, people will question the appearance.
When both subs are facing the audience, one upstage of the other, delay and a polarity flip are applied to the signal going to the rear speaker.
In the rear, the energy from both loudspeakers arrives in time, at almost the same level, but with reversed polarity, resulting in broadband destructive interference and reduced level. In front of the array, the two signals arrive with polarity different and out of time.
This is a little tricky, but the first dip in the comb filter in this example is going to be at 160 Hz, out of band of the sub. If the spacing between the subs is 3.5 feet and the delay time is 3.1 ms, the two signals arrive 7 feet apart in front.
The wavelength of 160 Hz is 7 feet. With the polarity flip, the first dip of the comb filter will be at 160 Hz, not 80 Hz. The two signals in front are also at about the same level, so the dip will be significant.
The cardioid arrangement using forward and rearward facing subs can be assembled vertically or horizontally, subs stacked one on top of another or laid side by side, in a line, some facing the audience and one or more facing backwards.
Talk about looking like it won’t sound good. Behind the array, the output of the front and rear facing elements of the array need to match in time and be very close in level, but polarity backward to create cancellation behind the array.
A polarity flip and delay of the rear facing loudspeakers achieves this.
Determining the number of forward and rearward facing elements depends on model and how much energy needs to be created behind the array to cancel the energy from the forward facing subs.
The delay time will vary too, depending on model, and dimensions of the array, both vertically and horizontally.
Measurement is needed to determine level and time relationships between the front and rear subs.
An FFT transfer function can quantify this accurately. In front of the array, the summation of the rear facing loudspeakers is out of time and polarity different from the energy being produced by the forward facing subs.
The problem in frequency response, that first dip in the comb filter, must be kept out-of-band, higher in frequency than the operational range of the subs.
A hybrid approach, combining cardioid pairs, arranged in a line across the front of the stage, results in cancellation left, right, and to the rear. Alternatively, combining end-fired arrays and line-arrays also achieves additional directional control.
Using a directional array left and right affords the opportunity to join -6 dB down points in the middle of the audience and minimize the interaction between the arrays by minimizing the area where they are level similar, moving quickly into isolation of one or the other arrays. This would lend itself to very wide audience areas, such as amphitheaters and festival sites.
Directional arrays are often misconceived, mis-assembled, or are faulty in their operation. They require a knowledgeable operator, good equipment, and proper implementation.
The benefits can be substantial and are sometimes worth the risks. Avoiding some reflections in rooms, decreasing the amount of low-frequency energy on the stage (turn the floor monitors down, folks), and making the coverage smoother in amplitude and frequency response in the audience area are the substantial benefits when considering the use of directional low-frequency arrays.
There are several critical factors of performance that must be considered when assembling these types of arrays. Control of low frequency directivity is only possible when using exceptionally linear systems, precision-manufactured to perform identically.
The relationship between individual components must be consistent. What is sent electrically to the array elements needs to be turned into acoustic energy, without distortion or changes in frequency response as signal level changes.
Historically, directional low-frequency loudspeakers have been in existence for some time.
Meyer Sound developed the first commercially available design, the PSW-6, a dozen years ago.
The PSW-6 uses a four-channel amplifier and signal processing built-into an enclosure that houses dual 18- and 15-inch drivers facing the audience, plus two more 15-inch drivers mounted in its rear.
This self-powered subwoofer provided cardioid vertical and horizontal polar response, serving as a new tool in the challenge of designing sound systems.
It eliminated 15 to 20 dB of the energy from the rear that would have bounced around and arrived in the audience area late.
Another advantage was the ability to place these loudspeakers in front of large walls without having to consider boundary reflections.
These and others continue to be advantages over omni-directional designs.
The PSW-6 design was a result of field experiments using the SIM (Source Independent Measurement) FFT measurement platform, along with prediction results from Meyer Sound’s then new MAPP Online (Multipurpose Acoustical Prediction Program).
MAPP, among its many uses, has become a tool that many practitioners use to design low-frequency directional arrays. Users are able to apply signal processing, arrange elements, and observe the results graphically as a narrow-band pressure plots or as broad-band Virtual SIM transfer functions, all predicted from the interaction of measured data sets of real loudspeakers.
“Measure twice and pile it up once.” Let’s face it, moving subs around in a parking lot is a lot of work and requires a substantial investment of time and effort, plus there’s tinkering with signal processing and measurement, as well as additional DSP and multiple drive lines.
On the other hand, moving subwoofers around on a computer screen is a two-finger event, and without the need for real subs, signal processing, and measurement platforms, a real time and money saver.
Not having to build and measure subwoofer arrays in the physical world as a first step has allowed users to design arrays that they might not have spent the time to experiment with in real life.
Steve Bush is a technical support representative for Meyer Sound.
A Matter Of Frequency: The Nyquist Plot Explained
The most informative frequency domain plot, by far
Harry Nyquist is famed for his work on feedback circuit analysis.
His Nyquist plot makes visual simultaneously the following viewpoints of the signal:
1. The real part
2. The imaginary part
3. The magnitude
4. The phase angle between the real and
5. The polarity of the system
6. The causality or non-causality of the
7. The presence of resonant systems
8. Non-signal synchronization by
The Nyquist plot can be used in sound system work, where in acoustics the real part is particle pressure and the imaginary part is particle velocity (near a boundary or in a standing wave) and in impedance measurements where the real part is the resistance and the imaginary part is the reactance.
Let’s label some key observations to be made about the Nyquist plot of a pair of loudspeakers.
Figure 1: The analytic signal displayed as a Heyser Spiral.
Dennis Gabor proposed the “analytic signal” which Richard Heyser developed into what has since been named the Heyser Spiral.
The Nyquist plot is the “end view” shadow of the complex analytic signal
An Interesting Anomaly
Apparent non-causal’ signals are being encountered more frequently these days. A non-causal signal is one that arrives before it is sent. Impossible you say?
Yes, in the real world, to the best of our knowledge that is true. But in the world of measurements, thanks to digital technology, we find our measurements telling us a signal is not causal Let’s look at an example:
Figure 2: The “end view” of the Heyser Spiral (Nyquist).
We have a two-way loudspeaker with a crossover frequency of 2 kHz. The energy-time curve (ETC) shows the tweeter arriving before the woofer (Fig. 3-Pg. 2).
We now choose to call the woofer arrival the time point of reference, while attempting to measure the full-range response.
When we do this our measurement instruments will see the tweeter energy as arriving before we sent the signal and the Nyquist will rotate counter clockwise above crossover, indicating non-causality on the instrument, which is not aware that the woofer arrival was chosen as the time reference.
Note that in the diagram the cursor is set at the point where the reverse rotation begins, the cursor coordinates being indicated to the lower left of the plot.
This situation can also occur with a digital crossover net work where one frequency range has one delay associated with it and the other frequency range still another delay.
In measuring phase response, choice of a correct origin and time is paramount if you want a meaningful measurement of the phase response of a device rather than a delayed measurement of the signal path.
For a quick overview of the acoustic signature from a loudspeaker array I know of no tool that is the peer of the Nyquist plot.
When large complex acoustic arrays require a rapid overview that will allow analysis of what problems, if any, are present, the Nyquist instantly tells which component relationships are incorrect, be it signal synchronization, digital crossover or other delays not obvious.
Figure 4: ETC of a two-way loudspeaker. Using the woofer arrival to set the reference time and measuring the full-range response causes the Nyquist to rotate counterclockwise above crossover.
Also obvious are inverted polaritys, unexpected resonances or even measurement mistakes in choosing the correct signal origin.
The Nyquist plot, as embodied in contemporary acoustic analyzers, usually computes at the bottom of the screen the values for frequency, real part, imaginary part, phase, and magnitude for a given cursor position on the screen.
Moving the cursor allows clockwise or counter clockwise frequency changes to be observed.
Figure 5: The figure shows the Nyquist response of a bandpass filter (loudspeaker or other). It consists of a number of discrete data points determined by the FFT size.
Ron Bennett, many years ago, provided me with a program that allows acquisition of the real and imaginary part separately, i.e., acoustically as pressure and velocity: electrically as voltage and current; impedance as real and reactive.
After acquisition it then forms a complex analytic signal from those two parts for display. One innovative use is to see the complex signal formed by the left ear/right ear signals using ITE microphones.
What in 1928 was a truly laborious process, is today a major convenience and an important tool.
Don and Carolyn Davis are the founders of SynAudCon, the leading independent educational organization in professional audio.
VUE Continues Global Expansion With Distributor Appointment In China
Tom Lee Engineering to also distribute VUE in Hong Kong and Macau
VUE Audiotechnik has named Tom Lee Engineering as the company’s new distributor for China, Hong Kong and Macau.
“This is a truly exciting addition as we seek to further expand into Asia’s professional audio market,” states Jim Sides, VUE excecutive vice president. “As one of the largest and most respected pro audio distributors in China, Tom Lee’s sizable network and highly-skilled staff will dramatically bolster VUE’s overall presence in the region, while ensuring a high degree of professional support for our customers.”
“I have personally known Jim Sides and Ken Berger for over two decades and they have always delivered notable results,” adds John K. C. Lee, principal at Tom Lee Engineering. “The VUE systems are innovative in design with excellent sound quality. We are very happy for the opportunity to work with Jim and Ken again, and extremely proud to be appointed as VUE Audiotechnik’s exclusive distributor for China, Hong Kong and Macau. We are committed to establishing the VUE brand and building a professional supply chain in our market.”
Initial shipments of VUE Audiotechnik products are expected to arrive on the Chinese mainland in November. Product lines will include VUE’s entire range of sound reinforcement loudspeakers including the h-, a- and i-Class families, as well as the al-Class line arrays with Truextent beryllium compression driver technology.
Tom Lee Engineering
Thursday, October 31, 2013
QSC Audio Q-Sys Core 500i Keys Multifaceted System At Dark Hour Haunted House In Texas
System includes Q-Sys integrated platform as well as a variety of QSC loudspeakers and PowerLight 3 amplifiers
The latest addition to the billion-dollar haunted house industry, the new Dark Hour Haunted House in Plano, TX is outfitted with an all-QSC Audio multi-zone sound system controlled by dual redundant Q-Sys Core 500i processors.
The high-tech haunt comprises three terrifying realms—Dominion of the Dead, Coven Manor and Voodoo Vengeance—outfitted with a variety of QSC Audio active K Series, KW Series and KLA Series loudspeakers, as well as AcousticPerformance and AcousticDesign loudspeakers driven by CX Series and PowerLight 3 Series amplifiers.
The entire audio system is controlled and optimized by redundant Q-Sys Core 500i processors supporting multichannel audio file playlists and managing approximately 60 zones and the system also supports five paging stations and is tied into the building’s fire alarm system.
The QSC Audio solution is part of a large package of audio, projection, lighting, show production and building control equipment sourced and supplied by GC Pro, Guitar Center’s outside sales division, and installed in the 30,000 square-foot Halloween haunt. GC Pro Affiliate Program member DJ Sound & Lighting, Dallas-based audio, visual and lighting sales, service, rental and installation company, integrated and programmed the system.
The Dark Hour loudspeaker systems include AcousticDesign AD-S8T surface-mount 8-inch, 2-way loudspeakers driven by CX404 amplifiers plus AcousticPerformance AP-5102 10-inch, 2-way and AP-5122 12-inch, 2-way loudspeakers driven by PowerLight 3 PL340 amplifiers, as well as active K8 eight-inch, 2-way, K10 10-inch, 2-way loudspeakers and KW181 18-inch subwoofers.
A performance stage located next to the admission line is also outfitted with two flown hangs of three KLA12 active line array loudspeakers and two KLA181 subs each, and also includes KW122 12-inch, 2-way floor monitors.
A typical area in the haunt might have as many as eight loudspeakers, each with individual sound sources such as heartbeats, piano, ambiences and ghosts whispering and moving about, which was simple to set up, explains Troy Gallaher, project manager with DJ Sound & Lighting.
“But we have a vortex room, a big spinning tunnel that, when you’re walking through it with your eyes open, makes you feel like you’re going to fall over,” he adds. “So we added four speakers in different places along the length of the tunnel, and we’ve got them firing off at different times. So the sound makes you feel like it’s spinning, too. Close your eyes and you’re still disoriented. That was one of the fun ones that the QSC guys and I worked on. I’m happy with how it turned out.”
Kevin Deal, account manager, GC Pro, admits that he originally knew relatively little about haunted houses, but after immersing himself in the design and technology—including obtaining his Q-Sys certification online at qsctraining.com—and visiting other Halloween-themed venues, he says, “We have ended up with what’s probably going to become the top-rated haunted house in the country.”
Deal recommended QSC to the Dark Hour owners as a single-source solution for the audio system. “This is a gigantic solution, very complex, so I recommended that we go with one brand like QSC to do this,” he says. “So we built a robust network in there, all controlled by Q-Sys. And they’re very happy.”
Gallaher programmed the system for iPad control, including a page that switches the entire system on or off: “It’s got a giant red button that says ‘Start.’ Hit it, and it turns green,” he notes. “And I gave them one UCI that has an individual start/stop and a volume for all of the rooms, and also a control to turn on what I call the Doppler Effect for the three different rooms that have that. They can go into one of those rooms, turn on the Doppler, and then turn on that sound and hear it bounce around just by itself, and adjust the volume.”
Five Q-Sys Networked Page Stations are tied into the Dark Hour system. Gallaher: “When they’re ready to go black, before they start the haunt, they’ll make a page to let the actors know that they need to be in the scene before it goes dark, or warn any of the techs that are working.” The stations can also key into the system: “We’ve got one master code so they can start the entire haunt with one code, and stop it the same way.
“Probably the best part of the whole process was QSC’s 24/7 support,” he adds, who reports that he challenged the QSC support team with some complex sound design questions. “Those guys are amazing and will work with you on anything, day or night. I got to know a lot of them on a first name basis, and it was a really great experience.”
Wednesday, October 30, 2013
Hey Marseilles Takes Mackie On The Road
402VLZ4 compact mixer and DLM12 loudspeaker meet versatile needs
Indie band Hey Marseilles, offering an unconventional mix of folk and classical (or, as they describe it, “folkestral”) has been maintaining a busy touring schedule in support of their sophomore release, Lines We Trace.
With a different venue in a different city almost every night, the band’s touring setup needs to be lean, flexible, and dependable. A Mackie 402VLZ4 4-channel compact mixer is an intrinsic part of the eclectic rig for accordion/keyboardist Philip Kobernik.
“I go back and forth between a Roland SR7 digital accordian, a Nord Electro, and a Moog Sub Fatty,” says Kobernik. “I send a mono feed from the Mackie mixer directly to the FOH engineer. Having the Mackie onstage with me allows me to control my own mix, and gives me a whole lot more control over my sound.”
Onstage, a second mono output from the mixer feeds a Mackie DLM12 12-inch, 2-way powered loudspeaker.
“It really packs a wallop for such a small, lightweight package,” says Kobernik. “I use it mainly as my onstage monitor, but it’s come in really handy in some other situations too. We’ve done a number of semi-acoustic gigs at record stores and radio stations, and I’ll just plug my Nord Electro into the DLM12.”
The DLM12’s onboard EQ and DSP adds to its versatility, Kobernik notes. “Onstage, I keep the signal pretty dry, and use mainly the effects in my keyboards. But when we do those smaller shows, it’s great to be able to add a little EQ to boost the bottom end a bit, and maybe a touch of chorus or some reverb. It’s really handy to have those effects, right on the back of the unit.”
Find out more about Hey Marseilles here.
The Church At Liberty Square Gets A Custom Fit With Renkus-Heinz VARIA
VARIA enables tapering of coverage pattern and provides consistent tonality
Founded in 1936, the Cartersville (Georgia) Church of God has grown slowly but steadily, and in January, 2003 moved to a new campus at Liberty Square, rechristening the church to reflect the new facility.
The 1,700-seat sanctuary is a modern fan-shaped auditorium with high ceilings and an open seating arrangement. But despite its pleasing aesthetics, the room’s acoustics have been an ongoing challenge, and the original audio system had long struggled with inconsistent coverage and poor intelligibility.
“There was a tremendous change in tonality from the main floor to the balcony area,” explains Kent Morris, principal of Canton, GA-based Cornerstone Media Group. “The main floor was very bright - almost excessively so in some areas - while the balcony seats were getting almost no high frequency content. The mix position is located in the balcony area, which made it very difficult for the tech team to mix.” Morris adds that the old system also created a visual impediment for some of the balcony seats.
The new sound system centers on left and right arrays of new VARIA modular point source line arrays from Renkus-Heinz. Each array is comprised of eight VARIA VA101-series boxes, with coverage patterns ranging from seven to 22 degrees.
“We looked at a number of different options, and they were won over by the VARIA system,” says Morris. “Their technical director Nathan Roach and audio head Ben Tomlinson are very astute, and the fact that VARIA enables you to taper the coverage pattern was a key factor for us. It really provided the most consistent tonality, with no harsh spots and no dead zones.”
Lead programmer Jeremy Alison was able to map out consistent coverage to the room’s most challenging areas. “With the VARIA, we were able to get articulation to the back rows of the balcony, and great coverage under the balcony as well, without having to add near fields or under balcony speakers,” says Morris. VA15S and PN212 subwoofers add low frequency power and punch, and three CF61 compact two-way boxes provide front fill.
“Being able to select among several boxes with different coverage patterns, and particularly being able to choose transitional boxes in between the fixed ones, makes a tremendous difference in designing a system,” he adds. “It’s almost as if every box is custom, but you don’t have to wait six weeks or pay top dollar.”
The entire system is networked via Audinate Dante over Ethernet, with several manufacturers’ technologies “playing nicely” together.
“We installed a Yamaha CL5 console at FOH, connected via Dante to two Rio stage boxes,” says Morris. “That enabled us to add a monitor console down on the floor and tie it all together with RHAON so they can monitor from FOH. We also added some devices to their existing Media Matrix NION system. Once we worked through the usual clocking issues, the system functioned flawlessly. You expect a lot of hair pulling, but it was so easy. It all worked out beautifully.”
“The VARIA system has really been an ideal solution for the church,” he concludes. “It’s a great looking system, and the cost factor and configurability made it a great fit. I just love working with Renkus-Heinz.”