Von Schweikert Audio Ultra 9 Loudspeaker


Equipment report
Von Schweikert Audio Ultra 9 Loudspeaker

Immediately above the midrange, on the final one-third of the front baffle, which is perpendicular to the floor rather than being swept back as are the lower two-thirds, is a modified ScanSpeak 1" beryllium dome diaphragm tweeter. This 99% pure beryllium tweeter uses ScanSpeak’s unique AirCirc magnet system, reordering the traditional magnet structure from a large single magnet to an open magnetic circuit composed of six separate neodymium slugs that, in combination with other chamber modifications, optimize air flow within the chamber to eliminate reflections and resonances that compromise the performance of more traditional motors. With a large roll surround and outstanding off-axis dispersion, it operates in the 2.2kHz to 20kHz bandwidth, offering superlatively linear response. It is also fed by a fourth-order acoustical G.A.I.N. circuit.

The last driver, at the very top of the front baffle, is a 5" hybrid aluminum ribbon super-tweeter. A bespoke driver that is the product of the collaboration between two different manufacturers, its bandwidth begins at 20kHz and extends up past 60kHz, and it too receives its signal from the G.A.I.N. fourth-order network.

Moving to the top center of the rear baffle, we find the ambience-retrieval array—a feature unique to Von Schweikert loudspeakers. At the very top is the second 5" hybrid aluminum ribbon super-tweeter, identical to the one on the front baffle, but driven from a different portion of the dividing network.

Immediately below it is a 1" SEAS aluminum/magnesium-alloy dome tweeter. Featuring an optimally shaped dome, wide SONOMEX surround, and an immensely powerful magnet system, it leverages a stiff, stable rear chamber, optimal acoustic damping, and its proprietary DXT lens system to improve directivity, off-axis response, integration, and baffle diffraction. Chosen in part for its moderately low crossover frequency, it is an ideal driver to deliver the benefits derived from VSA’s proprietary A.I.R. and G.A.I.N. circuitry.

Moving to the very bottom of the much wider back-baffle, we find another remarkable driver, the 15" subwoofer. Formed from thick, one-piece Nomex honeycomb cones covered with woven, heavy-duty glass fibers, these “ultra-still” drivers are remarkably resistant to deformation, while “Tall-boy” rubber surrounds with integrated gaskets maintain driver surface area during extreme excursions. To allow for their 1000-watt power handling capability, increase thermal dissipation, and reduce power compression, large anodized formers and vented pole pieces with under-spider ventilation, and two-layer copper voice coils are employed. The substantial, dual-stacked, high-energy magnets have a large copper sleeve and copper pole cap to help reduce energy storage from induction, and offer the added benefit of lowering overall distortion for “faster” response and lower Qts (total Q). Dual spiders are used to maintain linearity over their full one-and-a-half-inch range of travel, which also helps limit distortion and rocking modes.

Between the SEAS tweeter and the exotic 15" subwoofer, occupying roughly the middle third of the rear baffle, we find the large silver aluminum plate that houses the dedicated subwoofer amplifier, a highly versatile and granular Room Integration suite, and all wiring connectivity. 

The plate amplifier driving the 15" subwoofer is a world-class, 1000-watt, Class D design, hand-built specifically for the VSA Ultra products by Channel Islands Audio in Port Hueneme, California. Using only the finest parts and exhibiting a build-quality befitting the exacting standards the Ultra 9 requires, its audio circuit is an advanced full-bridge UcD model, offering exceptional performance, reliability, and high efficiency.

The amplifier IEC socket is located on the lower left of this panel and two sets of speaker binding posts on the lower right. The lower set of posts feeds both the input board on the CI Audio amplifier and the passive crossover board for the woofers. The upper set of binding posts feeds the crossover boards for the midrange, front tweeter, ribbon super-tweeter, and the rear ambient array.

The Room Integration suite occupies a little more than the upper one-third of the panel, organized in two rows. The uppermost row includes three large Fostex 100-watt transformer-type attenuators, while the lower row includes a toggle switch on the left and three smaller variable-Q potentiometers. By using a transformer rather than a resistor network to attenuate voltage, output can be adjusted with no distinguishable degradation of the signal.

From left to right, the top row includes attenuation for the tweeter, the super-tweeter, and the ambient array, all three of which are variable in either 1dB or ½dB increments, selectable with the flick of the integrated switch. The lower row adds a two-position toggle switch to manage bass output below 25Hz (either 0 or +6 dB), followed by three potentiometers to manage subwoofer phase (variable from 0 to 180 degrees), low-pass frequency selection (variable from 50 to 100Hz), and subwoofer gain, variable from off (no output), through unity gain, to +9dB.

The top row of autoformers manages room interactions of the tweeter, the super-tweeter, and the rear ambiance array. The tweeter and super-tweeter adjustments allow users to compensate for boundary proximity, surface hardness, room size, shape, or spatial configurations, or even to accommodate personal tastes or recording-specific issues. The variable adjustment of the ambiance array affects staging and imaging, as well as altering the overall space of recordings, soundstage depth, illumination, and focus, and the reproduction of other details.

The bottom row of potentiometers manages the subwoofer’s room integration. The granular regulation allows users to select between pure monopole or pure dipole configuration, and any variable degree in between. In rooms where speaker placement near side or front walls reinforces bass, the resultant lift will cause excessive boom, overloading the space. Often, by running the subwoofers in their dipole configuration (variable up to 180 degrees out-of-phase with the front woofers), as was the case in my room, excessive bass energy (boom) is greatly reduced or eliminated, without affecting dynamic bass pressure and integrity. Conversely, if you have a room that absorbs bass frequencies, you can configure the sub to work closer to or in absolute monopole mode, which will reinforce the performance of the 8" woofers on the front baffle. The result is considerably higher resolution throughout the entire frequency range than can be attained with other reference-caliber loudspeakers. 

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