The UniField Series uses curved side walls to minimize internal standing waves. In addition, much effort has gone into making the cabinets acoustically inert, which is all about minimizing cabinet-wall vibration. And that means reducing wall flexure by using thicker and stiffer materials. VSA’s elegant solution is based on the concept of constrained-layer damping but also strives to eliminate energy transfer from the drivers to the baffle by decoupling them with a 6mm-thick viscoelastic clay-polymer gasket. VSA’s triple-wall laminate combines three materials of different resonant signatures. The outer layer is MDF which is bonded to a layer of synthetic stone, fabricated from crushed gravel, minerals, and resin binder. The inner layer is hard felt, which is absorptive of sound energy. The total wall thickness is an impressive 2.5 inches and is the type of construction currently deployed in every Von Schweikert Mk2 speaker system. This approach is the antithesis of the British, so called BBC-style, thin-wall speaker-cabinet designs. The notion of “tuning the cabinet to the orchestra” comes to mind, and while it could be argued that some cabinet resonances are less objectionable to the ear and might in fact be consonant with the music, the end result is inevitably a sonic coloration. After auditioning the UniField Mk2, it seems to me that VSA’s approach of minimizing all cabinet resonances is the correct one in that it clearly raises the bar in terms of achievable bass precision.
The cabinet is vented which suggests a bass-reflex loading, and that is in fact the case, the box tuning being 38Hz. But this turns out to be no ordinary bass-reflex design. Four internal chambers filled with Acousta-Stuf define a mini-labyrinth, which significantly dampens the twin impedance peaks produced by a typical bass-reflex design. The measured minimum impedance was 3.8 ohms at 100Hz and the impedance magnitude was nearly single-peaked and fairly flat, varying by only a factor of two in the deep bass. VSA refers to this bass tuning as a hybrid reflex/transmission line. I like the idea of contouring the overall Q of the speaker system using acoustic damping. Although conceptually it is still a long ways from a classic transmission-line bass loading, this tuning works in practice by nudging bass performance toward that of an aperiodic sealed box.
In-room bass extension measured flat to about 38Hz. It was a case of bass reach coupled with a surprising degree of punch. Most stand-mounted speakers are not well suited for reproduction of symphonic music. The UniField Two proved to be a welcome exception. It possessed sufficient bass heft and dynamic prowess for realistic reproduction of an orchestra’s power range. The bass balance, usually an issue for stand-mounted speakers, was shifted toward the midbass. There was considerably more midbass energy relative to the upper bass which manifested as a slight emphasis of an upright bass’ body tone. Choice of partnering amplifier became an important issue. The UniField boogied superbly when matched with high-damping-factor solid-state amplifiers. It also scored highly in bass precision, a performance benchmark undoubtedly attributable to the combination of an acoustically inert cabinet and an aluminum-coned woofer. However, bass resolution suffered substantially when the UniField was driven by a low damping factor tube amplifier. Lacking amplifier control, the bass range took on a distinctly tubby character. The good news is that there is no shortage of high-damping-factor solid-state amplifiers in the 100 to 200Wpc range.
In the bass range, the UniField Two Mk2 offers impressive performance for a small box speaker. As such, it competes effectively with British stand-mounts from Spendor and Harbeth. Think greater rhythmic precision and bass heft. Its coaxial technology bestows upon it exceptional image focus. In fact, if you like mini-monitor soundstaging, you’ll love the UniField Two. Optimally set up, it will reward you with a steady stream of musical delight. And that’s what it’s all about.
SPECS & PRICING
Frequency response: 32Hz–25kHz (-6dB), 40Hz–20kHz (+/-2dB)
Nominal impedance: 4 ohms
Sensitivity: 88dB 1W/1 meter, anechoic
Power rating: Up to 200 wpc
Weight: 51 lbs.
Dimensions: 10" x 17" x 14"
Price: $7995 (stands included)
Von Schweikert Audio
1040-A Northgate St.
Riverside, CA 92507
GAS Ampzilla II amplifier modified by Mike Bettinger of GAS Audio, Lamm Audio M1.2 Reference and Bob Carver Cherry 180 monoblock amplifiers; Apple Mac BookPro running Sonic Studio’s Amarra Version 2.6 software, EAR DACute DAC, April Music Eximus DP1 DAC/ Pre and Stello U3 digital data converter; Kuzma Reference turntable; Kuzma Stogi Reference 313 VTA tonearm; Clearaudio da Vinci V2 phono cartridge; Pass Labs XP-25 phono stage and XP-30 line stage; FMS Nexus-2, Wire World, and Kimber KCAG interconnects; Acoustic Zen Hologram II speaker cable; Sound Application power line conditioners