Test Bench: Purifi Audio’s PTT4.0X04-NFA-01 Home Audio 4" Midbass.

This Test Bench addresses Purifi Audio’s PTT4.0X04-NFA-01 4” midbass, which is very similar to the PTT6.5X reviewed in Voice Coil July 2021, and includes the same constant Sd surround and low magnetic hysteresis motor design. The distinct cone assembly for this driver consists of a flat profile paper cone made with a proprietary fiber mix, a concave dust cap that covers about 90% of the cone surface, plus the addition of a V-shaped edge reinforcing ring glued around the outside rim of the back side of the cone. Compliance is provided by a unique NBR surround, which as in the PTT6.5X surround, deserves to be explored, motivating Vance to discuss it with Purifi’s co-founder Lars Risbo.

While Voice Coil Test Bench reviews only make use of the Large Signal Identification (LSI) data from the Klippel analyzer, the reality is that there is an amazing list of 30 modules available for the KA3 that are seriously valuable for transducer and system development. As space permits, I will be covering a number of these modules in future issue of Voice Coil. The first module in this series is the Time Frequency Analysis (TFA) module. This article was originally published in Voice Coil, October 2021

This Test Bench focuses on Eighteen Sound’s latest ND2T, a 1.4” neodymium compression driver, combined for characterization with the XT1464 elliptical-shaped horn, also from Eighteen Sound. This ultra-compact compression driver features a 2.4” diameter edge-wound voice coil wound with aluminum wire on a non-conducting Nomex former with a proprietary treatment. This assembly drives a field-replaceable pure titanium diaphragm and proprietary tangerine radial phase plug design. This article was originally published in Voice Coil, October 2021.

This Test Bench explication characterizes the 15DS100 15” professional subwoofer from B&C Speakers. This new transducer from the Italian company is a very high power handling design, able to deliver 3kW continuous (1.6W nominal), thanks to B&C's latest generation of very long voice coils - a great asset in applications from discreet PA subwoofers to three-way PA speakers. The B&C 15DS100-4 uses a proprietary 12-spoke cast aluminum frame with cooling vents for the neodymium FEA motor, which uses a 4” four-layer voice coil wound with round aluminum wire on a non-conducting glass fiber former. This article was originally published in Voice Coil, October 2021.

This Test Bench combines three new 25mm high-frequency transducers from German brand BlieSMa into a single characterization: the BlieSMa T25S-6 Silk Dome, the BlieSMa T25B-6 Beryllium Dome, and the BlieSMa T25D-6 Diamond Dome. All three tweeters appear to be built on the same platform, but optimized for each diaphragm material, and all three share pretty much the same feature set. BlieSMa was founded in January 16, 2018 by former Morel and Accuton engineer, Stanislav Malikov. This article was originally published in Voice Coil, September 2021.

This article characterizes a coaxial driver from B&C Speakers, a 5.25” woofer and 1.4" compression driver combo specifically built primarily for sound reinforcement applications. This driver's cooling is exclusively provided by the motor mass, a substantial neodymium ring magnet that powers both HF and LF units. No other vents are required for the 300W power rating given by B&C Speakers to the 5CXN44, which is impressive. This article was originally published in Voice Coil, August 2021.

This Test Bench characterizes the Beyma 12LEX1300Nd 12" driver from Beyma's new LEX Series. This latest design features a FEA-optimized neodymium magnet structure and 4" voice coil, and is targeted at two- and three-way PA speakers, or band-pass subwoofer designs. The entire woofer is optimized with a substantial set of features for very high-performance, including the company's unique Maltcross forced convention cooling system. This article was originally published in Voice Coil, July 2021.

The Purifi Audio PTT6.5X04-NFA-01 midbass transducer is an over-achiever, and to help understand why, Dickason talks with Lars Risbo about the research and thought process that lead to many of the features found in this woofer. Including the unique cone assembly that consists of a mildly curvilinear paper cone made with a proprietary fiber mix, a 3.13” concave dust cap, and a V-shaped edge reinforcing ring, the NBR surround, and what Dickason calls "probably the most unique surround in the history of Voice Coil’s Test Bench. This article was published in Voice Coil July 2021.

This article characterizes a cutting-edge product from BDNC, a patented “race track” shaped driver, and the first of its kind to use a glass diaphragm composite made up of two layers of “Schott AS87 Glass” with an internal layer of viscoelastomic damping material and aluminum alloy foil. The motor structure uses two neodymium bar magnets driving a two-layer race track-shaped voice coil wound with round copper wire on an aluminum former. This article was originally published in Voice Coil, June 2021.

This Test Bench article characterizes the SB Acoustics Satori MW16TX-8 TeXtreme Cone 6.5” Woofer, the third diaphragm transducer in Test Bench using this material, following the Eminence N314X-8 compression driver, and the SB Acoustics TW29TXN-B-4 dome tweeter. TeXtreme diaphragms are definitely finding acceptance among loudspeaker manufacturers. The MW16TX-8 is part of the SB Satori line of high-end transducers and has a substantial feature set. This article was originally published in Voice Coil, June 2021.