Large Speakers, Microspeakers, and Many Speakers in Voice Coil April 2019!

Voice Coil April 2019 is now available with the usual combination of great loudspeaker industry insights!

This edition features another great Focus article by Mike Klasco (Menlo Scientific, Ltd.) discussing trends in Microspeakers. With more than 1.6 billion mobile phones built annually, each with a microspeaker for the speakerphone and another for the receiver, this side of the speaker industry attracts the giants. Top players include AAC, Goertek, Gettop, ForGrand, Bujon, and Merry Electronics along with others that share the sizable crumbs from laptops and tablets. Fast ramp-up, intense pricing, and other tough challenges have kept many companies away from the segment, while many other vendors continuously search for a chance to get a piece of the action. Get the full scoop on one of the hottest market segments.

As usual, to complement this month's Focus topic, Nora Wong (Menlo Scientific) compiled the latest and most up-to-date Directory of key microspeaker vendors and solutions for mobile electronics.

In Acoustic Patents, James Croft (Croft Acoustical) reviews a recent patent awarded to Teppei Yamada, on behalf of Zorzo Co., Ltd. (Tokyo, Japan). The patent describes an original design of a loudspeaker apparatus that includes at least three drivers, and an enclosure with at least two sealed spaces. Each of the sealed spaces has at least two boundary diaphragms, and each one of those is disposed so that one of the surfaces faces inside the sealed space and a second one of the surfaces faces outside the sealed space. When at least one of the boundary diaphragms is driven outward from the sealed space, at least one of the other boundary diaphragms is driven inward to the sealed space.

To put it in other words, this is a low-frequency enclosure system incorporating multiple woofers inter-coupled in a manner similar to what is known as an isobaric or compound woofer enclosure. Croft reviews other approaches to the concept, starting in 1954 with a patent granted to Harry F. Olson on a dual, compound woofer system and later “reinvented” and popularized by Ivor Tiefenbrun of Linn Corp. in Scotland in 1975. Linn coined the label “Isobarik” as the name of the product, from the term “isobaric,” meaning constant pressure. In the new patent, the inventor uses an enclosure with as many as 12 woofers, all seriously couples through individual air chambers. Read the full review to find out more.

And for this month's Test Bench, Vance Dickason characterizes two new woofers, one from SEAS' new Extreme range, the L26ROY, and the 14NA100-8, a new 14” pro sound woofer from B&C Speakers.

The L26ROY is a 10” subwoofer from high-end Norwegian OEM manufacturer SEAS. As Vance Dickason reminds us, "The SEAS L26 series was popularized by several of Siegfried Linkwitz designs (sold by Madisound as kits), including his piece de resistance, the LX521.4, which utilized four L26RO4Y subwoofers (the four-layer version). These 10” woofers were built in Taiwan for SEAS, but that production has now been brought home to Norway and reintroduced as the Extreme subwoofer line. The Taiwan versions were the D1004 four layer and D1001 two layer, while the new Extreme series made in Norway updated versions are the XM004-04 L26RO4Y four-layer versions, and the XM001-04 L26ROY. The new driver features a well-appointed feature set that includes a proprietary cast-aluminum frame that has minimal reflection surfaces and is completely open 1.5” deep space below the spider mounting shelf. Other features include a very stiff and rigid aluminum cone, a 56 mm diameter (2.2”) two-layer voice coil wound with round copper wire on a glass fiber non-conducting former and two 22 mm thick and 175 mm diameter ferrite magnets sandwiched between a black plated 10 mm thick front plate and a black plated 10 mm thick T-yoke that incorporates a 14 mm diameter flared pole vent surrounded by eight 5 mm diameter peripheral vents. This format drives a substantial amount of air out the gap area and across the front plate below the spider mounting shelf for enhanced cooling of the motor system. 

The second driver, from B&C Speakers, is a high power handling 14” woofer, with a continuous power rating of 1.6 kW (800 W nominal), using a FEA-designed neodymium magnet motor. Applications range from two- and three-way PA speakers and compact two-way monitor designs for high SPL in limited spaces. Features for the 14NA100-8 are like most high-performance pro sound drivers, rather substantial. Starting with a proprietary 12-spoke (six twin spokes) cast-aluminum frame incorporating six rectangular vent holes in the area below the spider mounting shelf for enhanced voice coil cooling. The cone assembly consists of a curvilinear paper cone with a waterproof coating on the front side, along with a 4.5” diameter paper dust cap, likewise with a waterproof coating. Compliance is supplied by a three-roll pleated cloth surround, with the remaining compliance coming from a double silicone 6" diameter flat spider (damper). Tinsel leads are stitched into the spider for long-term stability.

Finally, in Industry Watch, Dickason pays tribute to Larry Hitch (January 10, 1941- February 15, 2019), Madisound founder and a great contributor to the loudspeaker industry.

All this and the usual compilation of important updates for the loudspeaker industry, now available for download and already in the mail for print subscribers. Subscribers can go to - www.gotomyvcoil.com - to download this issue.

Remember, Voice Coil is available in print and download for all registered subscribers, free for industry professionals. To qualify for a free subscription to Voice Coil, or renew your subscription, go to: audioxpress.com/page/Voice-Coil-Subscriber-Services.html.