As Vance Dickason introduces in this July 2023 issue, over the years, the work of Peter Larsen has produced a group of programs and measurement hardware that accomplishes all the various tasks required for a complete system design, the transducers, the enclosures, and passive crossover designs. His company, Loudsoft, refers to this collection of hardware and software as the “FINE Circle” of design. This inspired Vance to invite Peter Larsen to develop a tutorial for the design of a complete loudspeaker from transducer to final product. A great way to gain a practical perspective of the whole family of Loudsoft software tools. The target design will be a two-way speaker with a 6.5" woofer and a 1" dome tweeter, and this issue contains part one of this valuable exercise.Next, Mike Klasco and Nora Wong (Menlo Scientific) have worked on a timely update for the annual directory of Adhesives, Coatings, Sealants, High-Tech Thin Films, Converters, and Dispensing Equipment vendors. This is a vital area in loudspeaker design and manufacturing, and any designer knows the value of these vendor profiles, which includes suppliers of performance enhancing treatments, from resisting UV, hydrophobic (water), oleophobic (sweat), corrosion, detergents, and fungus to anti-microbial treatments.
For this month's Acoustic Patents, James Croft looks at two patents from Resonado Labs, the young speaker company that has been pursuing a new speaker topology — originally called Flat Core Speaker (FCS) technology and now rebranded as Res-Core — using a reconfigured speaker with a planar voice coil mounted perpendicularly to its flat diaphragm. Headquartered in Chicago, IL, Resonado was founded in 2017 by Brian Cho, Christian Femrite, Erikc Perez-Perez, and Peter Moeckel. This review covers two of the company's patents granted in 2022, titled "Speaker Comprising Split Gap Plate Structure," and "Flat Speaker Driven by a Single Permanent Magnet and One or More Voice Coils."
James Croft originally reviewed the first Resonado patent (US 10743097), "Bidirectional Speaker Using Bar Magnets," in the July 2021 issue of Voice Coil. Now, with these two new patents, you have access to a better understanding of the novel aspects of the architecture of the device, essentially a full-range driver with one or two oblong or "racetrack" diaphragms and surround form, connected to at least one extended length, blade-like voice coil, immersed in a magnetic field provided by elongated bar magnets. This new review expands on the added innovations and benefits.
In Test Bench, Vance Dickason characterizes the SB29SDNC-C000-4 29mm cloth dome tweeter from SB Acoustics, a shielded neodymium motor driver with a compact 72mm diameter injection-molded face plate and large surround, featuring a copper cap shorting ring on the pole piece, internal pressure equalization, and a flow resistor for non-resonance cavity coupling. With this characterization, Test Bench now offers a large overview of the innovative tweeter designs launched over the more recent years by Sinar Baja, all designed and developed by former Danish Vifa/Scan-Speak engineers Ulrik Schmidt and Frank Nielsen at Danesian Audio.
The second Test Bench article focuses on the M25 mkII 1" silk dome surface-mountable tweeter from Stereo Integrity, a North Carolina-based company. Founded in 2001, Stereo Integrity is an OEM speaker driver manufacturer that also designs its own range of hi-fi amplifiers, sold directly to consumers online. Transducers include subwoofer models from 12" to 24" diameters, as well as an 11" shallow mount subwoofer, along with a line of components drivers. This includes a 1" dome tweeter (M25 mkII), a 3" carbon fiber midrange, plus 6.5" and 8" midbass woofers. Stereo Integrity sent its high-end tweeter design, the M25 mkII, which features a 25mm silk dome diaphragm and surround, a dual-magnet neodymium motor, a black anodized aluminum motor housing with a tuned rear chamber, two-layer CCAW wound voice coil, and a compact 50mm diameter face plate with a steel anodized grill. While the mounting ring is intended primarily for car audio mounting situations, it also facilitates mounting to custom aluminum plates for home audio.
And this month, Vance Dickason served a generous dose of characterizations, with a third Test Bench article, this time focusing on a ribbon tweeter from Fountek Electronics. This company from Shanghai, with manufacturing operations located in Hefei (Anhui Province), sent its NeoPro 5i high-end ribbon tweeter, which combines a large 145mm × 15mm reinforced sandwich ribbon diaphragm with a closed-back injection-molded rear cavity, two aluminum heatsinks and a built-in transformer. Other features for this design include the neodymium motor system, a cosmetically attractive black aluminum face plate, and a black mesh screen protecting the diaphragm. This fairly heavy high-frequency device features 100dB 2.83V/1m sensitivity, rated for 60W nominal power handling (120W maximum), and a recommended crossover frequency of 1.5kHz at 24dB/octave.
This July 2023 issue is complemented as always with the Industry Watch section, this month detailing new thin-profile woofers from Neotera Audio, a company with manufacturing in Italy and engineering in Sweden, plus new product announcements from Wavecor and Genelec, among other interesting news.
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