This year’s 145th Audio Engineering Society (AES) International Convention is being held at the Jacob Javits Center in New York City, NY. In Industry News & Developments, Vance Dickason highlights everything you need to know to get ready for this major industry event, including the comprehensive Technical Program content, the new Audio Builders Workshop and all the loudspeaker-related paper sessions and posters.KCK Media, the publishers of Voice Coil, audioXpress, and The Loudspeaker Industry Sourcebook will also be attending the AES convention in New York. Stop by Booth 452 to meet the staff and possibly one or two of our contributing authors and to sign up for a free subscription to Voice Coil.
In this month's Voice Coil Spotlight, Mike Klasco (Menlo Scientific, Ltd.) offers a unique perspective on Soundbar Audio Signal Processing. As an audio consumer product category, soundbars very much remain a top seller, having replaced receivers and their associated passive speaker systems, which have sadly been reduced to legacy product categories. More than 10 million soundbars are sold annually, and this market is just warming-up now that consumers realize soundbars can be much more than just convenient under-TV speakers. These days, soundbars have become a true smart home audio hub, with connectivity and voice interfaces. And with immersive and object-based audio formats reaching consumers, the soundbar is getting ready to become the hottest selling category in home-theater systems and are equipped for next-generation audio.
Following this important industry update, Klasco also prepared a complete directory of Integrated Electronics, Powered Speaker Vendors, and DSP Specialists for those looking to take their soundbar ideas to the next level. The 2018 update directory includes OEM/ODM contract manufacturers of finished goods, subcomponent assemblies and modules, as well as DSP software specialists for voice and music processing, some of which also have IC or module solutions.
In this month's Acoustic Patents column, James Croft (Croft Acoustical) has fun reviewing a Controlled Passive Radiator patent recently awarded to inventor Tony Doy, on behalf of Sonos (Santa Barbara, CA.) The patent details multiple techniques to control a passive radiator, including a device buffering successive samples of audio content and predictive techniques on active designs. Well versed in such designs, James Croft revisits the advantages of powered speakers and the many useful techniques that have been applied toward the same goal, such as that of “motional feedback” (MFB) - the sensing of the motional output of the transducer diaphragm to monitor the device’s behavior as compared to the reference input signal and realize a difference signal to be used to determine an appropriate compensation for any correctable errors - and for which there are dozens of patents and papers. In this extensive review, Voice Coil readers will not only better understand the merits of Sonos' new patent, but also get a valuable perspective on key possible innovation areas.
In Test Bench, Dickason characterized two very different drivers - a 10.75” high-end home audio subwoofer from China OEM manufacturer Wavecor and a new 12” NBR pro sound woofer from B&C Speakers.
The first driver, is the Wavecor SW275BD01, part of the brand's rather extensive line of subwoofers, 24 models in all, ranging in size from 2.75” to 12”. The SW275BD01 is the 4 Ω version and has a well-appointed feature set that includes a proprietary cast eight-spoke (four twin spokes) cast aluminum frame that has minimal reflection surfaces and has a completely open 1.5” deep space below the spider mounting shelf. Other features include the incorporation of a very stiff black mica/paper composite cone, further stiffened by a 4” convex black hard paper dust cap. Suspension is provided by a FEA optimized low-loss (high Qm) NBR surround plus dual 6” diameter black flat conex spiders (dampers). All this is driven by a 65 mm diameter (2.5”) voice coil wound with round wire on a black fiber glass nonconducting former. The motor system powering the cone assembly utilizes three 18 mm thick by 135 mm diameter ferrite magnet sandwiched between a black plated 7 mm thick front plate and a black plated 10 mm thick T-yoke that incorporates an 18 mm diameter dual-flared pole vent surrounded by eight 10 mm diameter peripheral vents.
The second driver is the B&C Speakers 12BG76-8 12” woofer with a continuous power handling rating of 1000 W (500 W nominal), ideal for two and three-way PA speakers and compact two-way designs for high SPL in limited spaces. Features for the 12BG76-8 are fairly substantial. Starting with the frame, the 12BG76-8 uses a proprietary six twin-spoke cast aluminum frame, incorporating six 40 mm × 3 mm rectangular vent holes in the area below the spider mounting shelf for enhanced voice coil cooling. This series of cooling vents enables air to move past the voice coil and across the front side of the neodymium motor assembly. The cone assembly consists of a curvilinear paper cone with a TWP waterproof coating on both sides of the cone along with a 5” diameter paper dust cap, likewise with a waterproof coating. Compliance is supplied by a NBR surround, which is unusual for a pro sound woofer, mostly because NBR surrounds are heavier than the pleated cloth-type surrounds found in most pro woofers. Remaining compliance comes from a double silicone 6” diameter flat spider (damper). The motor design on the 12BG76-8 utilizes an inside neodymium slug along with a T-shaped pole piece. The neodymium magnet motor was FEA-designed using a 76 mm (3”) diameter voice coil wound with round copper wire on a non-conducting glass fiber former. Motor parts, the return cup, and front plate are coated with a black heat-emissive coating for improved cooling, with the cooling additionally enhanced by a 36 mm flared pole vent.
In this edition, Dickason also honors the memory of loudspeaker industry icon Siegfried Linkwitz (1935-2018), who sadly passed away on September 11, 2018. Anyone who has been involved with loudspeaker design knows his name, ostensibly for his co-invention of the Linkwitz-Riley network transfer function with Russ Riley (developed in 1975 while they both worked at Hewlett Packard). Linkwitz will always be remembered for his tireless work in the pursuit of greater fidelity, musicality, and detail in reproduced music. He will be missed.
In Industry Watch, readers will find updates on AES and ALMA recent activities as well as a complete update on Klippel latest announcements, among other vital news for the loudspeaker industry.Voice Coil October 2018 is now available for download and on the mail for print subscribers. Subscribers can just go to - www.gotomyvcoil.com - to download this issue.
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