Based in Bulgaria, European audio company Thrax has been active since 2009. Their ingenious and varied design approaches seen over several product lines have continued to intrigue me with their conceptual originality, innate musicality, and imaginative use of a broad spectrum of technologies. Their products range from valve (tube) amplification to digital audio and, more recently, loudspeakers. There are 16 products in the Thrax range.
Thrax founder and chief engineer Rumen Artarski packs a capacious scientific kitbag. His love of music and fine sound reproduction is self-evident. In the disputes that sometimes occur between measuring and listening, Rumen says, decisions made by the ear are final.
Writing for HiFiCritic in 2012, I supported Chris Bryant’s evaluation of the all-tube Thrax Spartacus, a 40Wpc triode-based power amp. In 2014, Bryant examined the all-triode Orpheus phono preamp.1 You could say that we—Bryant and I—were both pretty much solid state diehards, even though we’d both enjoyed good experiences with tube designs over the years. In both the 2012 and 2014 reviews, we described how we were shaken up by these two thermionic designs, whose purist tube technology had been finessed using advanced electronic design principles to deliver a winning combination of tonal accuracy and transparency with the dynamics and musicality of low-feedback triode circuitry. We knew then that Artarski’s Thrax was a force to be reckoned with. The range of distinctive high-end electronics has continued to expand to include a loudspeaker, the standmount Lyra, now joined by the smaller Siren ($13,600/pair), also a standmount and the subject of this Stereophile review.
Technology and engineering
Weighing a substantial 44lb (20kg), this standmount two-way marries an exotic, costly 6.5" (170mm) midwoofer to an unusual, semi-elliptical (biradial) horn of significant size. The horn “compression loads” a small, application-specific high-frequency driver, a 1" (25mm) ring-diaphragm design from pro audio specialist BMS.
Under the leather-covered central section, the construction is birch plywood reinforced by a cross brace. The walls of the 16 liter enclosure are not perfectly damped, but a knuckle rap is rapidly dissipated. Those substantial front and rear sections are milled from solid billet aluminum alloy. Fourteen stainless steel socket head bolts attach the rear panel. A filling of natural sheep’s wool damps internal reflections. Artarski notes that the box/port system is tuned at 40Hz, with typical in-room extension to 33Hz at normal listening levels. The port’s
