As previously announced, this December 2024 issue of Voice Coil continues a series of product reviews of outboard DSP hardware, this month focusing on the MIR260A DSP processor from Marani Pro Audio. Supported with expert measurements performed by Charlene Chow on a flagship APx555B analyzer (courtesy of Audio Precision), this month Vance Dickason looks at this professional DSP processor with two inputs and six outputs. The MIR260A offers the company's proprietary Marani linear (zero) phase Linkwitz-Riley IIR filter, as well as its 40dB octave horn-type NXF crossover filters, and FIR filters available with up to 512-taps per channels and up to 120dB/octave slopes. The Marani MIR260A DSP processor is a more cost-effective model than the MIR480I, previously featured in the September 2024 issue of Voice Coil.And this month, Voice Coil offers a reference article written by Lars Risbo (Purifi Audio), which basically expands on Claus Futtrup's "Loudspeaker Bass Reflex Alignments" article series published in audioXpress (available here) and expanded with dedicated articles in Voice Coil. The "alignments" concept - so called because the response was "aligned" to match a classical filter response - was expanded with new classes of generalized alignments such as QB3 and SC4, already explored in Futtrup's article series, with tuning parameters commonly found in tables in cookbooks and embedded in box simulators. After seeing many speaker designers returning to trial-and-error approaches that seem to forget the historical work and analytical approach, Lars Risbo decided to explore numerical optimization to synthesize attractive alignments both for reflex and passive radiator box types.
As scheduled for this December issue, Nora Wong and John Lam (Menlo Scientific) compiled an updated directory of Test & Measurement solution suppliers of interest to the audio industry and more specifically to loudspeaker applications. Apart from listing the more relevant companies that should be top of mind in this essential domain, the directory is complemented with updated insights into trends, new developments in hardware, and test techniques.
This useful resource is expanded with a dedicated directory of Simulation and CAD Software vendors compiled by Mike Klasco. With computer modeling and simulation being an essential part of the design, validation, and optimization process for the loudspeaker industry, it's essential to understand the specific tools that are available. From sophisticated computer simulation programs for advanced work to specific tools for acoustics simulation and auralization.
And moving on to the essential Test Bench articles that are the core of this publication's mission, Vance Dickason has characterized two cutting-edge drivers in two extremes of application segments.
The first to be characterized is the HF110 Neodymium Motor Compression Driver from Faital Pro. This is a 1" conical exit compact compression driver that was measured along with the Faital Pro STH100 elliptical Tractrix flare horn (80° × 70°) and targets applications such as stage monitors and PA speakers. The Faital Pro HF100 incorporates a 37mm (1.4") diameter high temperature Keytone Polymer diaphragm with an annular phase plug design, driven by a voice coil wound with aluminum wire on a high Qm non-conducting Kapton former, and powered by a neodymium ring magnet. Specifications detail a 2kHz recommended crossover frequency (second-order or higher high-pass filter), a 110dB 1W/1m sensitivity (8Ω version) and a 40W AES power handling rating (80W maximum power handling).
The second driver on Test Bench is the 6.5" MR16TX-8 TPCD Midrange from SB Acoustics' prestige Satori line. Targeting hifi and high-end audio applications, the new Satori MR16TX-8 midrange expands the company's already significant investment in TPCD Textreme diaphragms. While SB Acoustics was one of the first OEMs to start using TPCD cones, SEAS and Scan-Speak have both recently announced a new line of transducers based on TPCD, and Scan-Speak is even replacing all its beryllium transducers with Composite Sound's metamodal TPCD solutions for its top-of-the-line tweeter diaphragms. In terms of features, the 6.5" MR16TX-8 is built on a proprietary two-piece six-spoke cast-aluminum frame, completely open below the spider (damper) mounting shelf for cooling. Additional cooling for this driver is provided by six 4mm diameter vents in the voice coil former, as well as a 12mm diameter flared pole vent. The cone assembly consists of a curvilinear inverted single piece, "bowl" shaped TPCD cone, glued to an inverted NBR surround, with the remaining compliance coming from a flat BIMAX spider. The motor is an FEA-optimized neodymium magnet and the 35.5mm (1.4") diameter voice coil is wound with round copper-clad aluminum wire (CCAW) on a nonconducting fiberglass former.
This month's traditional Industry Watch section closes the December 2024 issue with more details about Scan-Speak's Metamodal TPCD strategy.
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