Friday, March 28, 2014
Crown DRIVECORE Install (DCi) Series Network Amplifiers Installed In Sweden Arena
The new system was designed based around eight Crown DCi 4|600N and eight DCi 4|300N networkable power amplifiers.
Himmelstalundshallen is an indoor arena in Norrköping, Sweden that is home to the HC Vita Hasten ice hockey team. The 4,480-seat facility also hosts concerts and other sporting events.
The oval-shaped arena opened in 1977 and even then its audio system would hardly be mistaken for state of the art—making it overdue for an upgrade by Sound contractor Micab under the direction of installation specialist Mikael Bergvall. The arena is the largest in Sweden to install Harman’s Crown DCi Series Network amplifiers.
“In addition to providing clear, intelligible audio we needed to achieve a system that provided equal coverage at every seating area,” said Bergvall.
Working with Christer Lidberg and Jan Hedlund at Swedish Harman distributor Septon Electronics a system was designed based around eight Crown DCi 4|600N and eight DCi 4|300N networkable power amplifiers. The amplifiers are linked together using BSS Audio Soundweb London BLU-101 and BLU-160 devices with BLU-Link. Twenty JBL AM5215 loudspeakers complete the installation.
Bergvall pointed out that the Crown DCi Network amplifiers offer a number of advantages not available from conventional amps. Having both Ethernet and BLU link connectivity enables them to be easily networked over long distances and “using BLU-link to network the audio system is extremely cost effective.”
Thanks to their use of energy-efficient DriveCore Technology, the Crown DCi Network amplifiers also use less power and take up less space.
“All of these factors are major assets in performance, ease of installation and savings on long-term operating cost,” Bergvall adds.
The DCi Network amplifiers offer networked monitoring and control via Harman HiQnet Audio Architect system software, and digital audio connectivity using the Harman’s proprietary BLU link as well as analog inputs. In addition to the main system, a Crown ComTech DriveCore CT8150 amplifier is used to power the speakers in the spectator’s entrance.
The JBL AM5215 loudspeakers are hung equally spaced around the perimeter of the arena and aimed into the seats, a configuration that directs the output of the loudspeakers to the seating areas while minimizing reflected sound from the walls and ceiling along with any gaps or overlaps in coverage. The 2-way AM5215 employs a 15-inch woofer and a waveguide that can be rotated horizontally or vertically to facilitate installation in a wider variety of applications.
“The system really came together well and more than met the arena manager’s expectations,” said Bergvall. He noted that the support from HARMAN and Septon was “critical” in ensuring that the system’s components all worked together seamlessly and delivered optimum performance. “The quality of the sound in the Himmelstadlundshallen has been completely transformed. Everyone in every seat now enjoys clear, full range reproduction for game announcements, music and audio.”
The memory of the previous sound system is now just a fading echo.
Bose RoomMatch System Chosen For Legacy United Methodist Church
New worship space for longtime area congregation features state-of-the-art sound thanks to Bose RoomMatch arrays
Legacy United Methodist Church in Bismarck, North Dakota, opened the doors on its new worship space in late fall 2013, just in time for the holiday season. Featuring contemporary worship and music styles, the church hosts several services each weekend to a large and vibrant congregation.
The challenges selecting a sound system were familiar: vocal intelligibility from the pastor and the musicians, a well-balanced sound mix for music, a versatile system for a number of applications, even coverage for the space, and so on. Bismarck-based A/V firm Dakota Sound Systems, Inc., installed a system consisting of RoomMatch loudspeakers from Bose Professional Systems.
It has already proven to be the perfect fit for the church, with rave reviews from the congregation and the church’s pastoral staff alike.
“This project was several years in the making,” notes Jay Griffin, Vice President and Co-Owner of Dakota Sound Systems. “Originally, the plan was different, and we had an entirely separate system specified. The project was shelved for a time and reworked, and when we revisited things, the church made it clear that they wanted the best and latest system.
“This was the perfect opportunity to install our first RoomMatch system. We put together a model of the system for the decision-makers at the church, and it was clear that this would be the right fit for the space and the church’s worship needs.”
The final system consists of the following Bose products: a middle array of RoomMatch RM12040 and RM9020 modules (one unit each), with two RM9060 modules, one on either side of the center array. Processing is handled by a Bose ControlSpace ESP-00 Series II engineered sound processor, and a Bose PowerMatch PM8500 power amplifier handles amplification for the system (an additional PM4250 amplifier powers a separate system in the church’s fellowship area).
The church’s Worship Pastor Dan Weigel, who leads music ministry, stated, “We are thrilled with this system. I cannot say enough good things about the coverage of the space, the speech intelligibility, and the smooth, balanced sound. We had a complication with some rafters potentially getting in the way of the dispersion, but Dakota Sound personnel were able to quickly compensate using Bose Modeler software.
“Everything is now dialed in perfectly, and it offers us exactly what we need for our style of music and worship. And moving forward, it is versatile enough to handle just about anything we could throw at it, application-wise.”
Griffin continues, “I had not personally been present at the RoomMatch training sessions, so it was unclear to me exactly what this system would be like in comparison to the system we originally specified. Now that I have experienced the system, I can confidently state that it offers great speech intelligibility, but it can be a smack-you-in-the-face music system too.
“It covers the whole gamut. And it fills the space really well. We’re happy with the way it turned out, and comments from the church have all been positive. It’s an amazing group of products.”
Bose Professional Systems
Thursday, March 27, 2014
VUE Audiotechnik al-4 Line Array Selected For Spring Hill Baptist Church In Florida
Church leadership identified sound quality, dependability and value as the leading factors in their decision
Spring Hill Baptist Church (Spring Hill, FL) recently selected a VUE Audiotechnik al-4 compact line array as the centerpiece of a system upgrade within its worship sanctuary.
Working with Atlantic Pro Audio, church leadership identified sound quality, dependability and value as the leading factors in their decision to move ahead with the VUE al-4 after a thorough search and audition process.
“This church took their install very seriously, and was absolutely determined to explore multiple options before making a final call,” explains Atlantic Pro Audio’s Bobbie Bennett. “They sent a total of six people to a demo at our Altamonte Springs location—a two hour drive. After listening to multiple systems from several well known brands, their selection of the VUE al-4 was ultimately unanimous.”
This was one of the very first VUE installations for the team at Atlantic Pro Audio after first hearing the al-4 line array at the 2013 InfoComm show in Orlando, just a few short months after the product’s introduction. Subsequently, the company arranged for a demo system of its own.
“We spent a few days with the al-4 at our facility before showing it to any customers,” says Craig Beyrooti, founder and CEO at Atlantic Pro Audio. “We were impressed by the fullness and warmth of the VUE line array.”
He adds, “It’s clear the VUE designers have experience working the real world. The al-4’s coverage is so well defined and it’s incredibly easy to scale up or down as needed.”
Predictable pattern control was critical for the Spring Hill’s traditionally vocal heavy services. The church’s narrow space, rear balcony, and abundant reflective surfaces demanded tightly defined coverage. What’s more, the room’s architectural elements called for minimal visual impact.
“The al-4’s coverage is so well defined that we were able to do a very discreet center hang consisting of eight boxes,” explained Beyrooti. “The installation and setup went very smoothly. We used nothing more than splay angles to achieve ideal coverage from left to right, front to back, as well as the balcony. And the sound quality of the al-4 is simply amazing.”
A VUE V4 Systems Engine provides power and processing for the al-4 line array, while a pair of VUE-18a powered subwoofers deliver additional low frequency extension. An external delay processor ensures optimized time alignment between the subs and array.
“We are very pleased with the system,” concludes Spring Hill’s Doug Boog. “We love how compact the system is and how great it sounds. It’s exactly the combination we were hoping for.”
ARC-Productions First Belgian Company To Back Martin Audio MLA Platform
Purchases 16-enclosure Martin Audio MLA Compact and Mini PA rigs
Belgian pro audio and lighting specialists ARC-Productions has confirmed the purchase of 16-enclosure Martin Audio MLA Compact and Mini PA rigs, the first company in that country to do so.
Based near Ghent in Flanders, Marc De Baets’ sales and rental company has a long history with Martin Audio dating back to the purchase of a W8 Compact in 2001. He has subsequently invested in WT2, LE1200 and 1500s, WS 218X subs and W8LC.
“His complete speaker inventory has been made up of Martin Audio for many years,” notes Steven Kemland of FACE, the manufacturer’s Belgian distributor, who serviced the recent order.
De Baets had been operating under his own name before setting up ARC-Productions at the end of 2008 and had been in conversation with Kemland about the MLA from its inception. “The first time I heard the MLA was on the Summerfestival in Antwerp three ago,” he remembers. “I was particularly impressed with the MLX subs, not only the output but also the weight.
“The biggest advance of the MLA system is the even coverage, making it a great tool to counter undesired noise pollution, a very hot topic in Belgium. The compact size and weight, requiring less truck space, were other advantages.” Marc was also present at the MLA Compact European launch in London last year.
Kemland adds, “Marc first heard the MLA Mini in our demo room. The full MLA system is too big for a mid-range company but with MLA Compact and MLA Mini—supplemented by some DD6 and XD12 or DD12 cabinets—it is possible to manage any job between 100 and 10,000 capacity.”
De Baets had initially planned to buy only the MLA Mini version to run alongside his existing W8LC, but after considering the importance of the sound pollution problem in Belgium, he opted for a complete change and purchased 16 x MLA Mini and 16 x MLA Compact, with four MSX subs planned for next year. Meanwhile the system will be run with ARC-Productions’ WS218X subs.
Delivery is planned for the beginning of April, with system training in Belgium and the system will make its major debut at Leiepop Festival in early May before going on to do other festival work (as well as servicing ARC-Productions’ other busy work program).
Kemland states, “Having conducted a lot of MLA demos, which have really got the market talking, it is important to have followed this up with our first system sale in Belgium. This investment is a big step up for ARC-Productions and gives them the opportunity for growth.”
In summary Marc De Baets promises this is just the start of his adventure into the world of MLA. “I really believe in this new technology,” he concludes.
Wednesday, March 26, 2014
Meyer Sound Launches New Website Design
Improvements make finding critical information easier for customers
Meyer Sound has launched a new website, redesigned to streamline the navigation of essential product information and enhance the overall user experience. Check it out here.
In addition to its more pleasing appearance, the new website highlights a number of improvements that make finding critical information easier for customers. They include more intuitive product selection parameters that enable quicker access to product descriptions, datasheets, operating instructions, and AutoCAD files. The improved support page gives more direct access to tools like the Amperage/BTU Calculator and rigging guides.
The Meyer Sound website provides access to product information, technical support resources, webinar archives, videos, and project stories, all of which combine to give an overview of the company’s solutions. Website users can continue to download software updates, subscribe to company product and education news, register to attend seminars and webinars, and find Meyer Sound dealers, distributors, and rental providers.
Tuesday, March 25, 2014
Community Completes New Loudspeaker Test Facility
Community has opened a new, state-of-the-art indoor test facility at its factory in Chester, Pennsylvania USA.
In keeping with its commitment to accurate and complete loudspeaker technical data, Community has opened a new, state-of-the-art indoor test facility at its factory in Chester, Pennsylvania USA. Designed by Charlie Hughes of Excelsior Audio and operated by Senior Measurement Technician, Hadi Sumoro, the new test facility enables loudspeaker measurements with unprecedented accuracy and precision.
With its indoor location, the new facility makes it possible to control temperature and humidity. It eliminates wind problems and minimizes interference from outside noise sources. This allows Community engineers to accurately measure complex loudspeaker data and to gather polar data in precise 1-degree resolution. Measurements are automated with an ELF robotic rotator system controlled by EASERA software.
The new test facility follows in the footsteps of a long tradition of loudspeaker measurements at Community. Community’s first test facility was a 32-foot-high tower built in 1975 on a southeast Pennsylvania hilltop which provided measurements that closely corresponded to anechoic chamber standards and established Community as an early leader in providing accurate loudspeaker specifications.
In 1981, Community built a semi-anechoic room in its factory to manually collect spherical propagation data of loudspeakers using Time Delay Spectrometry (TDS) technology developed by Richard Heyser and Gerald Stanley. In 1994, Community built a new outdoor test facility extending from the third floor of its factory building in Chester.
At 40 feet above the ground and with a microphone to loudspeaker distance of 39 feet, this system is still utilized today and uses TDS software to collect far-field and free-space data and to minimize outdoor noise and reflections. The outdoor test system provides the ability to measure low-frequency loudspeakers in near-free-space conditions.
Regarding the new test facility, Community’s Director of Technical Services, Dave Howden said, “Community’s outdoor measurement systems were an important resource for our TAG (Technical Applications Group) Group as we worked with systems designers and end users. Now, this new indoor facility provides phase data and other new information for systems designers and will help Community’s engineering team design the next generation of great loudspeakers.”
Chinese Manufacturer Donlim Celebrates 25th Anniversary With Adamson Systems
An Adamson Energía system was called in to reinforce a concert for 10,000 celebrating Chinese small household appliance manufacturer Donlim’s 25th anniversary.
The outdoor concert, featuring popular Chinese artists Sun Nan, Mao Ning and Sun Yue, drew a tremendous crowd at the campus of Shunde Polytechnic vocational college.
The Adamson system was provided by DMX, a prominent professional audio and distribution company headquartered in Guangzhou, China. The sound company provided left/right line arrays of six E15 and four E12 enclosures. A total of 12 T21 subwoofers provided for low end – six stacked on the left and right of the stage.
“The Adamson system sounded excellent,” adds Chen Luò, FOH engineer for Sun Nan. “I’ve worked with a lot of different PAs and was impressed with the sound – it was very stable and balanced throughout the entire show.”
Infill was also covered with Adamson enclosures. Two arrays of four SpekTrix and two SpekTrix subwoofers were tasked with the job and performed admirably.
“The system performed extremely well,” explains David Dohrmann, Senior Applications Engineer, Adamson Systems. “We were covering an area of 120 x 80 meters and it sounded great in every seat.”
The day before the event Realmusic, Adamson’s main distributor in Russia, and DMX hosted a professional audio training event featuring Adamson Systems loudspeaker technology at Tian Technology Park and Technology Exchange Center in the Pan yu District, Guangzhou City. The day-long event featured technical seminars, interactive quizzes and other educational aspects of audio as well as complete demonstrations of the full Adamson product line. The day culminated with a trip to the outdoor venue where the Adamson Energía system was set-up for the Donlim concert.
“More than 150 Chinese audio professionals came to hear the demonstration and left extremely impressed with the sheer volume obtained from a system with such a small footprint,” adds Dohrmann. “The outdoor venue provided the ideal environment to evaluate all of the features and benefits of the larger Adamson line array system.”
Many of the rental companies on site also commented on how easy the system was to set-up as well as the efficiency of the design – making it ideal for rental inventory. But most importantly, “The sound was in your face even 50 meters away,” one attendee concluded.
Monday, March 24, 2014
Harman Professional Names Prosound Distributor For Albania
Harman Professional has appointed Prosound of Tirana as distributor in Albania for its AKG, BSS, Crown, dbx, JBL Professional, Lexicon and Soundcraft product lines.
Harman Professional has appointed Prosound of Tirana as distributor in Albania for its AKG, BSS, Crown, dbx, JBL Professional, Lexicon and Soundcraft product lines.
As Prosound is also the existing Albanian distributor for Martin Professional lighting, the company is positioned to address all the key vertical markets where Harman Professional is active in the country.
Prosound began operations in 2006, beginning with a small rental system and growing its business every subsequent year. The company is involved in the most prestigious sound and lighting projects in Albania, serving customers, dealers and contractors as a one-stop solution.
Prosound offers unparalleled service in the region for concerts, corporate events and other staging applications, while also installing systems in Albania’s most prestigious clubs, bars, retail outlets and cultural venues.
“With Harman we are more solid than ever and we will elevate Harman’s presence in Albania to the top—where it belongs!” said Kliton Gjika, Managing Director, Prosound. “As Harman’s regional distributor, we will deliver our services with professionalism and after-sales care, backed up by clear and effective strategies.”
“At Harman, we are placing an increased focus on integration between product lines as we seek to address crucial vertical markets,” said Jamie Ward, Senior Sales Manager, EMEA Central, Harman Professional. “We see a wealth of opportunities in Albania and Prosound is poised to deliver on these opportunities thanks to its depth of experience in the markets we serve!”
Touring Musician Jamie Kent Relies on Bose L1 Systems On The Road
The L1 system helps Kent dial in his band’s sound for venues nationwide, and the support he receives from Bose staff are the perfect fit for the independent troubadour
Jamie Kent is a cut above the average singer-songwriter. Not merely an acclaimed musical act and creative voice with soulful and rootsy influences, Kent is fiercely independent and entrepreneurial, creating a unique business model (known as “The Collective”) that has helped him build his fanbase from the ground up. He has since expanded “The Collective” concept to “The Collective Music Group,” which sees Kent consulting other artists on how to build their fanbases after Kent’s example.
As he tours the country with his band, Kent travels with two L1 Model II systems from Bose Professional Systems.
Relying on the sound of the L1 systems and working with the artist community of fellow Bose L1 users, Kent has been able to advance his career by thrilling audiences with accomplished performances and building strong relationships with other like-minded independent artists.
A few years ago, Kent connected with Matt Szlachetka, the primary guitarist/vocalist for California-based act The Northstar Session. The two bonded over their shared roots (the same hometown in western Massachusetts), and Szlachetka got Kent in touch with Bose and exposed him to the L1 system, which he has used ever since. Immediately, the Bose team welcomed Kent into the fold, forging a close relationship that Kent values to this day. “My Bose people are my close friends, and they would do anything for me,” Kent notes. “The level of support that Bose provides is something that you don’t see from many companies.”
The L1 Model II systems have been a more-than-welcome addition to Kent-and-band’s stage setup. Running through the L1 systems are vocals, keyboards, acoustic guitar, banjo and accordion. For the full band lineup, Kent will use two L1 systems, and shows with a streamlined lineup will usually use a single L1 Compact system.
“The sound of the L1 system is just what we need – things sound right and pure, which makes us comfortable on stage,” Kent notes. “I am admittedly very picky about my vocals, and the L1 system helps me capture an authentic quality when I sing. And we couldn’t believe how light and easy to pack it was – with the amount of gear we have, that was key.
“Aside from that, what we really appreciate is the automated and customizable settings. Each venue is different, but once we get a sound dialed in, we can call it up and tweak accordingly. The on-board instrument presets on the T1 ToneMatch audio engine help bring out the natural qualities of each instrument, which we can also alter when we need to.
“Things started out amazing when we first used the L1 Model II system, and they’ve just gotten better and better as we have homed in on our sound. It’s like traveling with your own sound guy, because the settings are matched to you every night.”
“The Northstar Session and other artists that we work with are very close – we all support each other and help each other with booking and playing shows,” he states. “It’s a tightly knit community, and it has helped all of us grow in our careers while making good friends and inspiring one another. And Bose is there too, helping us grow in a big way. It’s a great thing to be a part of.”
Bose Professional Systems
CCTV Installs QSC Active Line Array
Chinese State Broadcaster Chooses KLA System for Conference Hall at Beijing HQ
Chinese State Broadcaster CCTV has installed a QSC Audio KLA Active Line Array system at its Beijing headquarters, in a 400-seater multi-purpose hall used for meetings, seminars, demonstrations, lectures, and live broadcasts.
The installation comprises eight QSC KLA12 elements (four per stereo channel) and two KLA181 subwoofers, all finished in white to match the CCTV building’s aesthetics.
Prime Connections Inc (PCI), the QSC distributor in China, undertook the installation of the KLA system at the CCTV’s architecturally distinctive ‘loop’-shaped skyscraper, familiar to anyone who saw coverage of the 2008 Beijing Olympics. The irregularly-shaped, predominantly glass-fronted building presented PCI with some acoustic challenges.
“The directivity of the loudspeaker system had to be carefully controlled in order to minimise unwanted reflections from the glass walls,” explains a PCI representative. “With its precise directionality and calculated vertical coverage, the QSC KLA system enabled us to keep the sound away from the glass walls, ensuring that the amplified sound in the hall remains clear with accurate imaging, and the spoken word is reinforced for live broadcasts without compromising intelligibility.”
Posted by Julie Clark on 03/24 at 01:10 PM
Turbosound Turns To Audio Precision For Loudspeaker Design And Test
MUSIC Group deploys APx instruments to become world’s largest pro audio user of Audio Precision analyzers
Audio Precision, the recognized standard in audio test, announces a significant investment in Audio Precision test instruments by MUSIC Group for use in the design and production of Turbosound products.
Following in the footsteps of Music Group’s other industry-leading pro audio brands Midas and Klark Teknik, British loudspeaker icon Turbosound has purchased Audio Precision (AP) test instruments for use in their new UK research, development and manufacturing facility in Kidderminster.
APx audio analyzers will now test every single Turbosound product, from the earliest concept stage, to final production – ensuring the highest standards of sonic performance and reliability.
Leveraging the powerful new electro-acoustic test software for APx, the Production Engineering Testing UK team has designed an extensive, automated software package for the state-of-the-art APx Series – a move that will raise Turbosound’s already impressive testing standards to an unprecedented level.
MUSIC Group founder and CEO Uli Behringer had the following to say, “We have invested in a $4 million dollar (USD) state-of-the art building in Manchester to house our high-tech research and development center, where the staff has grown from 8 to over 70 in less than three years, and we are continuing to recruit in an effort to create the very best products in the pro audio world.”
“We are very excited to continue working with the MUSIC Group,” says AP President David Schmoldt. “They have achieved remarkable success in pro audio, and we are proud to be a part of that story. AP is expanding the definition of audio test to cover all aspects of the signal chain using a single platform from analog through digital and electro-acoustics, and the work done at TURBOSOUND exemplifies this converged approach.”
Renkus-Heinz Iconyx Tames Timeless Chamber
Metro Sound Pros designed a solution utilizing a creative application of Renkus-Heinz Iconyx Series IC7-II manually steered column arrays.
Overlooking the Hudson River just minutes away from Manhattan, Mercy College was founded in 1950 by the Sisters of Mercy. The Rotunda is an important focus for all Mercy students and is a popular multi-purpose activity center.
The historic structure was a former house of worship, and carries with it both the decor and the sonic character of a majestic old cathedral. Its soaring brick walls, stained glass windows and high, rounded shape and domed ceiling create a natural reverberance that makes even normal conversation nearly impossible.
“Picture a circle, with 50 ft stone walls, eight pillars and a massive video wall,” Leo Garrison of Metro Sound Pros elaborates. “The space is a natural reverb chamber.”
Depending on the event, a podium can be set up in any part of the room, creating an even greater challenge - designing a system that could achieve audio clarity amid this ever changing footprint.
Metro Sound Pros designed a solution utilizing a creative application of Renkus-Heinz Iconyx Series IC7-II manually steered column arrays.
Four pairs of columns are mounted at 90 degrees from each other, providing selectable coverage from any direction. The Iconyx steered beam technology enables the sound to be focused on the audience, and away from the walls, windows, and other problematic surfaces.
As Garrison explains, while the assignment was to deliver coverage and intelligibility, the building’s landmark status meant that aesthetics trumped all else. “Protecting the room’s historic architecture was of utmost importance,” he states. “The profile of the IC7s are so small and slim, they just blend right in.”
Garrison concludes, “With a project like this one, we always face a balance between the need to preserve the natural beauty of the architecture, and the need to create a space that is functional. The integration of the Iconyx series into the Mercy College Rotunda gave us the performance and intelligibility we needed, while maintaining the building’s classic aesthetics. They were a great choice.”
Posted by Julie Clark on 03/24 at 11:30 AM
Sunday, March 23, 2014
RE/P Files: Electrotec’s System For Roxy Music, August 1983
New Lab-Q loudspeakers in operation at San Diego State University's amphitheater, three decades ago
This article, from the archives of the late, great Recording Engineer/Producer (RE/P) magazine, provides an in-depth look at a new concert sound loudspeaker system unveiled in 1983 by leading touring company Electrotec. The text is presented unaltered, along with the original graphics.
Roxy Music has not toured in the U.S. since the late Seventies. The band actually dissolved in 1979, and only came together again during early 1982 to produce Avalon; in April of this year, the group was on the road to promote that album, as well as the recently released, live four-song “mini LP,” The High Road.
Twenty-six shows were scheduled over a period of 30 days, in various venues around the country ranging in size from 6,000- to I6,000-seat capacity. According to Roxy Music’s production manager, Chris Adamson, those 26 shows were very important to the group as it attempted to re-acquaint concert-going audiences with its music.
Electrotec Productions, Inc. (formerly TFA) was selected to handle sound reinforcement for the tour, as well as supply stage lighting. Of particular interest was the fact that Electrotec’s sound system for Roxy Music included the recently completed Lab-Q series loudspeaker cabinets,
Regarding the group’s choice of sound companies, Adamson says, “It was basically a mutual decision made at management level. Robin Fox, our house engineer, felt that the new Electrotec system would be a good vehicle with which to present the group’s new material, and we were particularly interested in finding a company which could offer a package deal on sound and lighting.”
House engineer Robin Fox (left) and monitor engineer Bill Chrysler.
As Robin Fox recalls, “At rehearsals, I used four pairs of the new speakers in the main room at Studio Instrument Rentals [Hollywood], and I was favorably impressed with them indoors. This tour has a lot of indoor dates, but the outdoor shows are where we will really tell whether or not a system has what it takes. So far, I think we made a good choice.”
Lab-Q Loudspeaker System
The Electrotec Lab-Q is a three-way active/fourth-way passive, two-cabinet speaker system, capable of being stacked on the ground, or flown in the air with no additional special hardware. According to Pierre D’Astugues, Electrotec’s senior vice president, the new system is the result of more than three years of research and development.
“The low-end of the system was computer-designed and manually tuned so as to offer a response to below 40 Hz,” he says. “Our mid-cabinet is also computer-designed, and can achieve a true 60-degree coverage angle. Right now, the system is at a certain point in its evolution; this is not necessarily where we plan to stop with it. The basic cabinet structuring will be a constant, but as new transducer and electronics technologies hit the market we plan to adapt this system to fit the new developments.”
D’Astugues feels that the Lab-Q system is fully taking advantage of today’s available technology, but that a 10% to 15% improvement in the system will be evident by next year, due to engineering advances. “Feedback from engineers—[both] our own, and those employed by the accounts we service—is bringing about positive changes, and this system is exciting in that respect,” he remarks. “It is an ongoing thing. Crossover circuitry, transducer manufacturing technologies, and component alignment are all three areas where advances will occur.”
Figure 1 (click to enlarge)
The Lab-Q low-end cabinet, of which 26 were used on the Roxy Music tour, houses a single 18-inch cone driver capable of handling 600 watts RMS. “The speaker is not currently available to the public,” explains D’Astugues. “It has been developed especially for us by JBL, and is a bit different from the similar, commercially available speaker.” When pressed for details, all he would offer by way of elaborating was that, “it’s more
expensive, I’ll tell you that much!”
The cabinet, which covers the sound spectrum up to 250 Hz, is a folded-horn design with center bracing, and currently is equipped with two round porthole vents (Figure 1).
System Mids and Highs
The second half of the loudspeaker system is a cabinet of identical dimensions designed to stack directly via locking corner mechanisms on top of the low-end cabinet, and thus create columns that tower approximately 8 feet above ground level. The mid/high cabinet contains two 12-inch JBL E120s loaded in a deep horn chamber; a new constant-directivity, bi-radial horn mounted on a JBL 2445 driver; and two specially modified JBL ultra-high frequency units that are passively crossed over (Figure 2). The system crossover point between the 12-inch speakers and the compression driver is 1.5 kHz.
Figure 2 (click to enlarge)
The combined mid/high cabinet is rated at 400 watts RMS in the mid-range section, and 200 watts RMS on the top end. Coverage pattern of the horn-loaded 12-inch speaker section is matched to that of the bi-radial fiberglass horn, giving the cabinet an even 60 degrees of horizontal dispersion, Electrotec claims.
The cabinets arc constructed of a very dense plywood, manufactured with a patented process. “The wood is of considerable importance when putting together a speaker cabinet,” says D’Astugues. “Many people tend to ignore that part of the design process, but we have gone to great lengths to find the best material. The sound damping of the Lab-Q boxes is so good that nearly all of the energy goes into projecting the audio to the front of the cabinet, where it should be; walk around behind the box, out of the coverage pattern, and you will find very little SPL back there.”
According to D’Astugues, there has been no “magic” involved in the development of the Lab-Q system, just correct application of currently available speaker system technologies, a lot of trial and error, and much hard work.
At time of writing, Electrotec has been using Soundcraft consoles several years now, and its custom-designed version for slightly more than a year. The consoles have a distinctive custom metalwork outer housing finished in chrome (Figure 3). The module configurations are unique to the Electrotec boards; Soundcraft is building this console series especially for the PA company.
Figure 3 (click to enlarge)
According to Soundcraft’s technical manager, Shane Morris, “These desks are similar to our Series Three in some ways, but they do not have any dual-concentric knobs ... every function is laid out with a separate control. The desks are equipped with a front-access patch panel which utilizes Switchcraft mini-patch cables, and which is protected by a clear plastic cover on hinges.”
House and monitor consoles are nearly identical in appearance. The monitor console is equipped with 32 inputs, 16 outputs, and two additional effects sends; it offers four-way parametric EQ on all input channels and 16 outputs. The front-of-house console is equipped with 40 input channels, eight subgroups, and six effects sends.
The Electrotec Soundcraft consoles have been designed to operate on 120 volts AC. Since most regions of this country have a slight variance in their available AC voltage, a Variac is put in the line which feeds the 12-volt DC power supply, to step up the voltage to ensure a consistent 120-volt source.
At the Roxy Music concert in San Diego attended by this writer, the available AC supply measured a slightly unsteady 118V—just low enough to possibly cause the consoles to lose headroom, and become unstable. To prevent problems, the Variac boosted the AC voltage to 123 volts; the unit also includes an AC power line monitoring meter, which is always handy to have around.
House Signal Processing
As supplied for Roxy Music’s house mix engineer Robin Fox, the Electrotec system was equipped with the company’s standard Brooke-Siren Systems Model 340 electronic crossover (Figure 4).
This device has a built-in limiting circuit on each pass band that is individually tuned for the affected frequency range. Input subsonic and high-frequency filters are offered with 24 dB per octave filter slopes. Crossover cards are of modular design.
Figure 4 (click to enlarge)
House equalization was accomplished through the use of White Model 4000 third-octave filter sets, which feature rotary-pot controls as opposed to a graphic layout. A White real-time analyzer provided Fox with an accurate display of the system’s frequency response and sound pressure level. An AKG C451E microphone supplied signal input to the analyzer, while an internal pink-noise source is available for system testing.
Other signal processing equipment in the house system included dbx Model 160 limiters for the main left and right outputs, and another pair of the same device for patching into the kick drum and bass guitar channels. Four Audio + Design Scamp Model 100 noise-gates were patched into drum input channels, and four Scamp SOl compressors were available for processing vocals.
Figure 5 (click to enlarge)
Special effects devices included a Lexicon Model 224 digital reverb, Marshall Time Modulator, Audio + Design Compex F760XRS stereo limiter, Eventide H949 Harmonizer, and an AMS Model DMX 1580S stereo digital delay. House processing gear was contained in three identically sized 19-inch rack-mount cases (Figure 5), and was tied into the house mix console via dedicated multipair cabling.
In the house system, playback of prerecorded music was accomplished with two ReVox two-track reel-to-reel decks and an Akai stereo cassette player.
Electrotec has chosen the JBL Model 6233 as its exclusive power amplifier for both house and monitor systems. The Model 6233, because of its high-frequency switching power supply, weighs only 34 pounds per unit, yet develops 400 watts RMS per channel into a 4-ohm load.
Figure 6 (click to enlarge)
A total of 63 of these amplifiers were on the road with Roxy Music, packed three to a case: 18 for the monitor system, and 45 in the house.
Each amplifier rack has front-panel access to inputs and outputs, and AC connectors for each rack located at the base of the front panel (Figure 6). The 6233 amplifier contains one possibly unique design feature: a front-panel foam-lined vent provides flow-through ventilation to cover cooling requirements, so that units may be stacked directly one on top of another to conserve rack space with no ill effects.
The concert that this writer observed was staged at San Diego State University’s outdoor amphitheater, an open-air stage below ground level with high-rise concrete seating that describes an area of nearly 140 degrees.
To adequately cover such a venue, the main speaker stacks must be laid out to provide unusually wide coverage.
Electrotec sound system engineer Mike Gibney chose to set up the system in two stacks of 21 boxes each. The stacks were given a slight hemispherical curve out to the sides, and in towards the center of house (Figure 7). Low-end cabinets were arranged in columns of three, and mid/high cabinets put up in similar fashion.
The center of each stack comprised two columns of three low·end boxes apiece—quite a concentration of low-frequency energy in one spot. Since the distance between stacks was in excess of 60 feet, the monitor sidefill stacks were called upon to do double duty as center-house fill. Sidefills were placed slightly upstage of the front mike line, and angled across the downstage performing area, with their coverage pattern
hitting the center house seating sections.
Figure 7 (click to enlarge)
The San Diego concert was only the second show of the Roxy Music tour. Since the system was fresh out on the road from rehearsals, much time was spent during the afternoon before sound check carrying out basic road preparation: cables were labeled, case packing charts prepared, and loose hardware tightened.
According to Gibney, basic system maintenance never ends when a system is on tour. “Every day there are things to watch for, gear to check on,” he says. “For instance, right now I am tracking down a hum in the house system, which is not normally present with this gear. There seems to be a ground loop occurring at the interface between the house and monitor consoles (splitter box), and it is a trial-and-error process to isolate and correct the problem.”
As Gibney got the main stacks in the air and hunted down the few inevitable bugs, Electrotec engineer Chris Amison tuned the system for the band’s engineer, and then proceeded to start the stage input hookup.
Roxy Music features vocalist Bryan Ferry and saxophonist Andy Mackay, both of whom worked the downstage area. Ferry’s vocal mike was a Shure SM-78, while the sax was picked up with two inputs: an AKG D224E was fed into a small Yamaha self-contained 6-channel mixer, sweetened with a Roland Space Echo, and fed through Yamaha speaker cabinets, one of which was miked. Additionally, a wireless unit was taken as a direct input for a clean, unprocessed signal.
Electric guitar amps were miked with Shure SM-57s, while the bass guitar was taken as a direct input, as were the keyboards. A Yamaha 12-channel mixer received signal input from Guy Fletcher’s two Roland Jupiter synthesizers, Solina string synthesizer, Korg organ, Yamaha CP-80 electric piano, and Wurlitzer electric piano.
The resultant mix was processed through a Roland SDE-2000 delay unit, and then sent to the house and monitor consoles. Additionally, a direct input was taken on each individual keyboard instrument to ensure clean signals at the desks.
Figure 8 (click to enlarge)
Roxy Music’s stage set this time out contained a generous amount of percussion, as can be seen in Figure 8. Andy Newmark’s large drum set, complete with gong, was picked up with two overhead AKG C414EB condenser mikes. Toms were miked individually with Sennheiser MD421s. and the kick received an Electro-Voice RE-20. The snare was miked from the top with a Shure SM-57, and hi-hat cymbals given an AKG C451 E. The auxiliary percussionists’ congas, roto-tom, chimes, and bells were picked up with a pair of Beyer M160 mikes.
A three-way splitter with individual ground-lift switching on each input line passed the signal to the house and monitor consoles, leaving one split available for broadcast pick up or recording. Model 8226 AMP brand connectors on 11-pair multicable carried the microphone signals to the splitter box from satellite plug·in boxes distributed around the performing area. These boxes were designed with an extra female connector on the end, so that boxes could be “daisy-chained” for additional length when needed.
Stage monitors were handled by Electrotec engineer Bill Chrysler. The Electrotec Soundcraft 32-channel board was driving 13 separate stage monitor speakers, arranged on 10 mixes.
“I’m using the 10 mixes for Roxy Music, so that still leaves me with six discrete outputs for opening acts,” Chrysler offers. “After Roxy’s sound check, I go around to the back of the board and change my output patching; that way the levels I’ve set for Roxy don’t get touched until they come on stage again. Six more mixes is usually more than adequate for most opening acts.”
Chrysler’s 10 monitor mixes for the headline band were set up as follows: sidefills; keyboardist; bass guitarist; lead guitarist; Ferry’s downstage vocal mix; drummer; background vocal; sax; stage-left guitarist; and percussionist. During sound check he was able to speak directly to each stage monitor mix area via the console’s built-in talkback facility.
Monitor speakers were of three types. Sidefills comprised a Lab-Q stack on each side. The keyboard mix was heard through a three-way composite box measuring approximately 3 by 4 feet.
All remaining mixes were driven through an Electrotec single-I5 floor slant, which contains a single 15-inch JBL E130 speaker and a 2441 driver on a 2390 horn/lens attachment (Figure 9). The wooden box has a cutout around the lens that serves as protection for the fragile metal lens plates, while offering unobstructed lateral dispersion at the same time; it also serves as a carrying handle.
Figure 9 (click to enlarge)
Electrotcc’s monitor system features Klark-Teknik DN27 third-octave graphic equalizers, into which have been built the crossover units. Using the DN27’s power supply, each custom-designed card offers bi-amp mix capability with a crossover point of 1.5 kHz. High and low output adjustments are located on the equalizer’s front panel. The system Chrysler was tending for Roxy Music offered these third-octave EQ/crossover units on 12 of the board’s available 16 mixes.
Graphics and other monitor processing gear were contained in three electronics racks, which he stacked on top of his monitor amp racks for quick access (Figure 10). The racks included eight sides of Omnicraft GT-4 noise gates for drum use; according to Chrysler, however, they had not been necessary yet with this show.
Figure 10 (click to enlarge)
One of the system’s more sensible features was a spare power supply for the monitor console located in the same road case as the primary supply, pre-wired and switchable on-line should the need arise. Referring to the monitor system at his disposal. Chrysler says that usually he will adjust the graphic equalizers during Roxy Music’s sound check, and then leave them set.
“I don’t get into changing things just for an opening act—that can jeopardize Roxy’s set,” he continues. “If a mix does not sound right for the opening act with that EQ in-line. I can easily switch it out. Our wedges (monitors) are really quite flat, so that works fine. I can make both acts happy with very little dial-twisting.”
The Electrotec slant monitor is claimed to have a frequency response of 70 Hz to 18 kHz, ±3 dB. A sound pressure level of 125 dB at the listener’s ears is said to be possible with this system. Chrysler’s Electrotec/Soundcraft monitor console offered great flexibility in the EQ department, he says, with its four-band parametric capabilities on each output mix, also switchable in and out of the line.
Output mix levels are displayed on an LED ladder-type visual readout. “I will rarely, if ever, go into the red zone,” he relates. “With the (JBL) 6233 amplifiers, and the crossover line-drivers in the EQ units, I have tons of headroom. The system sort of idles through the show, which is really good; no distortion.”
With the Lab-Q stacks on stage for sidefill speakers, onstage monitor levels were quite high during sound check, yet the console’s LRD displays were consistently percolating 4 to 6 dB below clipping.
Showtime—The Acid Test
Roxy Music presents a musical show that covers a great dynamic range, with the included program material ranging from soft instrumental ballads with alto sax lines, to double-guitar-riffing, sledgehammer rockers. The Electrotec sound system was called upon to respond instantly to level changes of 25 dB or so, and appeared to be remarkably quiet—no “hiss” was present during the softer numbers.
As the show progressed, the louder numbers became almost welcome. The Lab-Q low-end section was capable of punching a lot of air in the 40 to 100 Hz region, which had positive effects on the crowd’s response. One young woman 200 feet or so from the speaker stacks asked me why she could feel.the music’s low notes “in her chest” ... I found it best not to try to answer that one.
(click to enlarge)
The San Diego State University outdoor amphitheater is a venue that usually dispels the show’s low-frequency program material by the time sound reaches the upper regions of the seating area, but the Lab-Q system changed that. The upper half of the amphitheater seating area actually seemed to have a greater bass response than the closer-in front seating rows; a reflection, perhaps, on the three-high stacking of the low-end cabinets, which created strong bass line arrays.
And the high frequencies carried well too—vocal sibilance and intelligibility was excellent, even in the highest seating rows. As stacked in that venue, the Lab-Q speaker system arrays did indeed have a high “Q” (directivity factor). As I walked the upper perimeter from left to right, it was possible to tell when I was directly on-axis with the center of each stack of three cabinets.
However, the transitions were smooth, and an untrained ear would not have noticed the hot spots. All told, an excellent outdoor speaker system that would almost certainly perform just as well in arena situations.
The Electrotec Lab-Q system also was servicing Bob Seger, Alabama, Rick Springfield, John Cougar, and Tom Petty as this article is being written. Concert sound engineers would find a visit to one of these shows well worth a listen, since, to this writer at least, the new Lab-Q speaker system represents a qualitative improvement over the company’s older component sound system.
Editor’s Note: This is a series of articles from Recording Engineer/Producer (RE/P) magazine, which began publishing in 1970 under the direction of publisher/editor Martin Gallay. After a great run, RE/P ceased publishing in the early 1990s, yet its content is still much revered in the professional audio community. RE/P also published the first issues of Live Sound International magazine as a quarterly supplement, beginning in the late 1980s, and LSI grew to a monthly publication that continues to thrive to this day. Our sincere thanks to Mark Gander of JBL Professional for his considerable support on this archive project.
Read more RE/P Files here.
Friday, March 21, 2014
Adamson Systems Adds Atmosphere To The Chapel’s Green Campus
The Chapel's Green Campus adds Adamson line arrays to sanctuary to provide more even, musical coverage.
The Chapel, located in Akron, Ohio, added another campus to their rapidly expanding church in 2003. Since then the Green Campus, located in Green, Ohio, has become a staple of the community.
The original sanctuary sound reinforcement system was based around a center cluster of loudspeakers. However, that soon proved to be problematic, providing uneven coverage throughout the room. Recently the Green Campus renovated the sanctuary and installed an Adamson sound reinforcement system to resolve those issues.
Because the worship services vary including live praise bands, piano, or choir, it was important that the system be musical while also providing the intelligibility important during services. On occasion the sanctuary is also used for concerts, which have a different set of requirements as well.
The church leaders called in Pro Audio Innovations, located in nearby Canton, Ohio, to assist with the design and installation of a new system that would handle their needs today and in the future.
“The sanctuary is a clamshell shaped room with a balcony and ramped seating on the sides,” explains Dan Giarrana, owner of Pro Audio Innovations. “The room seats around 1,700 and the services are very well attended. They wanted a new system that would cover the room evenly and also be aesthetically attractive.”
Giarrana explored a number of system concepts before deciding upon a line array system. After that it was a matter of deciding which one.
“There are a number of great systems on the market, but when we checked out the Adamson SpekTrix line arrays we knew we had found our solution,” adds Giarrana. “Online Marketing, the local rep firm was extremely helpful with fine-tuning the design and providing installation advice.”
The main PA consists of eight SpekTrix enclosures flown left and right, run in stereo. A center cluster of two SpekTrix subwoofers are flown in a cardioid pattern – making a complete in line 4-way system. Two T21 subwoofers located on the ground crossed below the SpekTrix subs receive an analog signal sent on an aux, creating essentially a 5-way system.
The Adamson SpekTrix Series offers the benefits of a true line-source array via patented wave shaping sound chamber technology. The SpekTrix is a three-way enclosure exhibiting extremely high output for its compact size. The sound chamber has a defined coverage pattern of 5-degrees vertical by 120-degrees horizontal and produces a slightly curved, iso-phase wave front.
The SpekTrix Sub is equipped with two powerful 18” AW18 Kevlar Neodymium bass drivers mounted in a tuned, vented and fully braced cabinet. The single-sided enclosures may be arrayed conventionally or in back-to-front pairs for true cardioid performance.
The side, ramped seating and balcony fill is provided by 9 Adamson Point Concentric PC12 loudspeakers run passive and inline with the main AES L/R feed.
Once the system was designed, it was time for installation, which presented more of a challenge than originally anticipated.
“In order to hang the arrays to optimally cover the room, they needed to be at a certain height,” explains Giarrana. “Once we explored the ceiling we realized that a) we were going to have to build a structure that could handle the weight of the arrays and b) it would have to hang down 11 feet in between heat ducts already in the ceiling – so there was little room to work with.”
Needless to say, Giarrana and his team were up to the task. They built a structure that could hold the 2,000 pounds and also included motors that could raise and lower the arrays for maintenance if needed. All of the chain, wires and cable lines were neatly hidden in 4-inch conduit painted to match the line arrays.
Pro Audio Innovations provided Lab.gruppen PLM amplifiers to power the system. Two Yamaha M7CL consoles are located at front-of-house to handle both FOH and monitor duties. An Apogee Big Ben and ProCo Momentum digital snakes tie the system together.
“The church leaders are absolutely ecstatic with the results,” concludes Giarrana. “They could not be happier. The have heard nothing but compliments from their members and everyone is in agreement that this was a tremendous upgrade to services.”
Cable Anatomy 101: Key Factors To Keep In Mind
Identifying the basics, combined with knowing what to look for and critical evaluation...
Cable selection presents two primary challenges: myriad choices and overall quality. I’ve explored these challenges and have defined six factors that can help point you in the right direction.
These factors include appearance, durability, flexibility, sonics, conductivity and shielding. Let’s have a look.
Understand the difference between the look of quality—like shiny gold-plated connector housings—and actual quality construction and materials.
A primary problem arises when assumptions are made that the materials inside a cable housing are as fancy as those that can be easily seen in the connector. For example, molded cable housings can hide poor construction, such as inadequate shielding.
Copper is the most widely used material cable component, offering high conductivity. (Silver is also highly conductive, but cost can make it impractical.) It only makes sense that signal should travel through copper, tip to tip.
If possible, when evaluating cable, open the connector and check the soldering. Make sure there are no blobs (too much solder) and no contaminates from wire insulation or foreign particles.
The good (top), the bad, and the ugly when it comes to solder. (click to enlarge)
The solder should have a smooth slightly shiny surface. A dull solder joint indicates poor workmanship and a poor or non-existent connection (termination).
Other termination methods avoid foreign materials (like solder), which can increase the risk of interfering with signal flow. One process is IDC (insulation displacement connection), done by creating a cradle for the wire in the shape of a “V.” When the wire is inserted into the cradle, it’s pushed to the smallest point of the V, stripping away the cable insulation at the contact points. (This technique does require sturdy strain relief; more on this later.)
A more recent termination method relies upon ultra-sonic welding, a process by which the center conductor and the connector are vibrated together at a high rate of speed while being compressed. This causes them to intermingle and fuse together as one.
Durability & Flexibility
Exposure to temperature, humidity, chemicals, floor traffic and the like can wreak havoc on cables and connectors. Dirt is an extreme abrasive, while foot (and wheel) traffic frequently shred many types of shielding, internal insulation and even the center conductor—sometimes without showing noticeable outer jacket damage.
Durability and flexibility may be opposing demands. One can come at the expense of the other.
Durability may come in the form of strain relief, termination, the outer jacket and the materials used inside the cable. The outer jacket surrounds the individual conductors and is intended to protect the shielding and conductors from the elements.
While outer jackets are commonly made of polyvinyl chloride, differing chemical compositions and blends can yield a similar look with vastly differing strengths and ranges of flexibility.
A cable that is thicker might look and feel more durable, and if that size is due to a double-thick outer jacket, flexibility can actually be increased. Simply, the cable can be more impervious to damage, meaning it can be used in more applications.
The size of conductors, as well as the types of shielding, also impact durability and flexibility. Understand that everything comes at a price. A more durable cable will (and should) cost more. You get what you pay for.
The term strain relief refers to the relief of strain at the point where a connector attaches to a cable—the termination point. Strain can come from several different sources, such as pulling on the cable rather than grasping the connector to disconnect; stepping and pulling on the cable; repeated tight coiling, flexing and other common abuses.
The sonics of a cable (or its “sound quality”) can be assessed in several ways. Like loudspeakers and amplifiers, cable can “color” sound based on shielding and/or conductivity.
Capacitance and inductance affect frequency response the most. Look at the capacitance per foot figure to evaluate how the high-frequency response may be affected over long runs. It’s usually measured in per foot (pF), so short lengths aren’t affected much.
The materials used as the inner conductor insulators also affect the capacitance and the signal propagation.
Beyond this, it’s vital to listen for noise and hum, both with and without signal present. Any extraneous noise can be prime indicator of poor construction techniques or substandard materials.
It’s important to listen to a length of cable with it terminated properly at the source end. An open-ended cable will have an extremely high impedance, making it act like an antenna—as soon as a mic is plugged in, the noise disappears.
While copper has a certain amount of resistance to signal flow, steel and aluminum have significantly more. This resistance dissipates in the form of heat. (It’s why steel and aluminum alloys are great for constructing toasters and space heaters but not so great for cables.)
Some cable conductors are made with a combination of aluminum (slightly better than steel) clad in copper. This is a more cost-effective approach and can be effective in meeting conductivity needs, but the more copper (preferably high purity or oxygen-free), the better the conductivity.
The more electrons to move, the larger the conductors must be. This is the overriding reason that an instrument or patch cable shouldn’t be used in place of a loudspeaker cable.
According to the AWG (American Wire Gauge) system, conductor area doubles with each reduction of three in AWG. For example, a 13 AWG conductor has twice the copper of a 16 AWG conductor, while a 10 AWG has twice the copper of a 13 AWG, and so on.
Unlike instrument and microphone cables, which typically carry currents of only a few milliamps (thousandths of an amp) or less, the current to drive a loudspeaker is much higher.
Other connector termination methods include IDC (left) and ultra-sonic welding. (click to enlarge)
An 8-ohm speaker driven with a 100-watt amplifier will pull about 3.5 amps of current. By comparison, a 600-ohm input driven by a line-level output only pulls less than two milliamps. (0 dB = .775 volts / 600 Ohms = 1.29 mA) (For more about cable gauge, lengths, Ohm’s Law and more, see “Science or Snake Oil?”.)
Cable conductors need to be shielded from noise, of which there are two common types. The first is handling noise, in the form of cracking, swishing, scratching, popping, buzzing or humming sounds.
Top to bottom: Braided shield, spiral shield, foil shield with drain and a snake cable with foil shield. (click to enlarge)
Handling noise can be heard with the cable plugged in but no source audio present. This can be due to substandard electrical termination at the connectors, worn or partially broken center conductor, or inferior wiring in general.
The actual cable construction and the relationship between inner conductors, shielding and outer jacket also affect handling noise.
The second type of noise is interference, of which there are two common types: RFI (radio frequency interference) and EMI (electromagnetic interference).
RFI can be caused by very high radio band frequencies. (You might actually hear a radio station through your system, or high-pitched squeals or hiss.)
EMI can be caused by electromagnetic fields that can emit low frequencies. These fields can surround transformers, power lines and other devices that use or transport large amounts of electrical current. (It’s also often heard as hum or buzz.)
Three primary types of shielding are employed to combat these problems: braid, spiral and foil. In terms of cost, braid shielding is the most expensive, involving copper strands woven into a braided pattern around the center conductor’s inner jacket.
The braided approach works best with microphone cables because of their low inductance. (Inductance is the storage of magnetic energy. Magnetic energy is stored as long as current keeps flowing).
Spiral shielding is more flexible than braiding, and is commonly used in guitar cables. A drawback to spiral wrap is that, like a slinky in motion, one side compresses while the other separates. It’s through these separated strands that RFI can enter.
To compensate for the rejection loss of RFI, sometimes a secondary shield is added, using carbon as a semi-conductor. This is generally effective over very short distances.
The carbon is not a solid sheet, rather, microscopic bits of carbon mixed into another, more flexible material (usually a plastic composite). The bits of carbon conduct current from bit to bit.
Foil wrap shielding is the least expensive shielding method, and some provide full 100 percent coverage. It can be very effective against RFI.
A drain wire runs next to the foil, providing a way to terminate the foil at the connectors, and is a technique is most often used in the construction of snakes. (Note: The drain wire runs along the foil shield to provide a means to connect the foil shield to the connector. The drain wire itself doesn’t actually do much shielding at all.)
It’s often true that the last thing on the system professionals mind is cable. After all, like roads and highways, they can be utilitarian by nature.
But as with roads and highways, making the right choices is the optimum way to get to your destination, which is good, clean optimized audio. All it takes is some attention to the basics combined with critical evaluation.
E. Victor Brown is a veteran pro audio writer. And special thanks to Cable Factory and Gotham Audio contributing to this article.