Albert wrote this about the sub placement when he released the VR-100XS speaker. He tells me the same principle applies.
The external sub-woofers, the “XS” of the system, are also an all new VSA engineering solution. They are designed to be placed near the rear of the listening area and are aimed at the main towers. Von Schweikert’s new patent pending technology will “eliminate room response anomalies when integrated with the already outstanding bass performance of the VR-100XS towers”. The XS subwoofer amplifiers have Time Delay controls to adjust the response for the room dimensions and can be adjusted to compensate for standing wave modes in any room, no matter the size. “The elimination of standing bass waves in the room is not achieved by equalization in the subwoofer amplifier, but is achieved by acoustical cancellation of Eigentones throughout the room, without any digital implementation of any sort”.
Bass extends down to 10 Hz and has transient response speed and clarity that equals the response accuracy of the loudspeaker’s midrange drivers. The supplied subwoofer amplifier is designed and built in the USA; it supplies over 1,000-watts r.m.s. into each of the four voice coils of the Super Duty High-Speed Infrasonic Subwoofer driver. With a 60 pound motor and four 5” voice coils configured in Push-Pull operation, the 15” magnesium cone with a 3” total excursion potential has the” lowest distortion and quickest transient response speed of any subwoofer on the market”. A Signal Sensing Cable made by Delphi Aerospace is supplied to connect the Main Towers to the Sensing Inputs of the XS subwoofers – the subwoofer signal is not sent from the preamplifier. In order for the subwoofer to “follow” the main woofers, Von Schweikert have implemented a ‘servo-controlled’ feedback loop from the main woofer’s back-emf (electro motive force) output to “tell” the 15” woofer where to go, in terms of speed and tonal quality.
