For this issue of Voice Coil, Vance Dickason expands his series of explorations in the world of outboard DSP, this time with the Flex HTx, one of the most interesting rack units from Hong Kong-based miniDSP. The 8 in 8 out miniDSP Sharc chip-based HTx processor is primarily intended to support home theater applications and has both balanced XLR and unbalanced RCA inputs and outputs. It is a more cost-effective model than the previously featured DSP processors mentioned in this series, with a retail price of $570 for the TRS balanced IO model. The feature set, however, is similar to some of the other processors in this series and is quite extensive, revealing why miniDSP is revered for the extreme value of its products. For this issue’s Voice Coil Focus, Mike Klasco writes a series of interesting considerations about what is driving the category of microspeakers. In "Microspeakers — Getting Respectable," the Menlo Scientific founder and principal takes us into an interesting exploration of this world that achieved unimaginable volumes with the invention of the modern mobile phone, and subsequently the introduction of the smartphone, where microspeakers gained even more predominance by expanding from voice communications to full stereo sound. Obviously, mobile devices have very challenging space restrictions, and manufacturers have since then embarked on a bold journey to provide higher performance audio from the smallest transducers, also leading to the development of new topologies. In this article, Mike Klasco explores the wild frontiers of taking microspeaker topologies to extremes of deeper bass and higher dynamic range, where the category is now evolving.
This exploration is greatly enhanced by the complementary inclusion of the 2025 Microspeaker Vendors, in this case limited to vendors supplying microspeakers for smartphone and laptop applications. The category includes major manufacturers and ODMs such as AAC Technologies to leading acoustic technology companies such as Glass Acoustic Innovations and Sound Solutions Austria.
An additional subdirectory follows for microelectromechanical systems (MEMS) microspeakers, a technology presently focusing on in-ear applications but which will eventually address smartphone receivers. MEMS speakers have unique amplifier requirements, and there are different approaches to manufacturing, which makes the whole category still ripe for innovation. Reflecting on the pioneering efforts, this directory lists some completely new companies exploring this field.
And moving on to this month’s Test Bench, Vance Dickason characterizes the new TW 104.28 N/Ag 1.1" Soft Dome Tweeter from RS Speakers, a new Italian brand recently introduced by SICA Altoparlanti. Based in Trecastelli, Ancona, Italy, SICA was founded in 1979 manufacturing primarily musical instrument speakers for organs and keyboards. Recently, SICA decided to enter the high-end home transducer market with its RS line of speakers, named from the initials of Raimondo Sbarbati, SICA’s founder and head designer. The driver on this Test Bench is a 28mm soft dome tweeter that features a treated silk dome directly bonded to the voice coil, with a wide roll surround and an unusual wire screen to keep the damping in place beneath the dome. Remaining features include a copper-clad aluminum wire (CCAW) voice coil winding on an aluminum former, driven by a neodymium ring magnet motor structure that has a vented top plate that opens into a damped rear cavity. Last, the TW 104.28 N/Ag has a flared 104mm diameter 4.6mm thick aluminum faceplate and gold-plated terminals.
The second driver on this month's Test Bench is also a tweeter, but this time from the SEAS Prestige Titan Line. This is a new 1" (25mm) tweeter featuring a one-piece centenary profile dome and wide surround fabricated from SEAS pre-coated lightweight Sonolex material, both integrated into a 1/4" thick injection molded faceplate. The voice coil consists of a non-magnetically conducting titanium former wound with round copper wire. Driving the removable dome assembly is a ferrite magnet with a damped vented pole piece that is coupled to an injection-molded acoustically damped rear cavity. The SEAS 27TFC/T (H1889-06) motor structure also includes a copper pole cap shorting ring for reduced distortion and reduced voice coil parasitic inductance as a result. Recommended frequency range for the 27TFC/T is 1.8kHz to 20kHz with a characteristic sensitivity of 89dB 2.83V/1m, and 150W long term power handling (IEC 268-5 via a second-order high-pass filter at 2.5 kHz).
As usual, this issue of Voice Coil wraps up with a selection of Industry News, from the upcoming perspectives for the 2025 High End Show in Munich to the news of an interesting new Class-D plate amplifier from Tang Band (TB) Speaker. Always so many reasons to explore every monthly issue of Voice Coil.
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 to renew your subscription, go to: Voice Coil Subscriber Services.
Subscribers can go to - www.gotomyvcoil.com - to download this issue.
To access the digital subscription platform, just log in using your subscriber number and post/zip code as displayed on your mailing label.
