Von Schweikert VRS-1 Owners manual

Von Schweikert Audio

World Class Reference Speaker Systems for Music and Film

VR-S/1

HIGH-SPEED

Subwoofer

Instruction Manual

Please read this manual thoroughly before using your new subwoofer. There are
several different ways to connect the VR-S/1 and proper adjustment of your system can
be found in this Manual.

Thank you for purchasing the VR-S/1 engineered by Von Schweikert Audio, a leader in
scientific loudspeaker technology. This active subwoofer system has been designed to
combine an extremely high level of clarity with very deep bass (20 Hz @ -3 dB) at high
output levels. Transient response speed and accuracy have been optimized by our use of
space age technology and unique engineering not available at this price point from any
other manufacturer.

• The transient response of many subwoofers often suffers because large woofer cones are

typically too heavy to respond quickly to the input signal, blurring the sound. In addition, large
diameter woofers are susceptible to cone flex, which further muddies the sound quality. Most
subwoofers, when played without the main speaker, sound like a “roar,” without any pitch
definition or timbre. It is often quite difficult to determine whether the bass sound was caused by
a train going by or a kettle drum.

EXTREME-DUTY DRIVER
To eliminate transient speed problems and cone flex distortion (approaching 30% at low
frequencies at high power output!), the VR-S/1 Extreme-Duty woofer utilizes a space
age diaphragm made from carbon fiber reinforced ABS, an incredibly rigid and
lightweight material specifically designed for low frequency clarity combined with
massive "punch." The 10" cone has enough surface area to energize very large rooms,
allowing high SPLs to be generated with extreme clarity, a combination of sonic factors
not found in competing models. To handle high volume levels without distortion, we
have employed a Low Distortion Motor System with an extremely long voice coil (2"
peak-to-peak excursion), high temperature rated 2.5" diameter voice coil (can handle
1,000 watt peaks without burning), and double-spider suspension with Bias Control.
One of our two major advances in technology relating to the extremely accurate speed
and lack of transient blur is the Bias Control spider design. Since most subwoofer drive
units employ only one spider to hold the voice coil in position in the magnetic gap, the
cone tends to continue to vibrate long after the signal has stopped, since the cone mass
cannot be easily damped with a loose suspension system. Our solution was to use two
spiders, with one biased towards the outward cone travel motion, while the second
spider is biased in the opposite direction. Since the two extra-heavy duty spiders are
opposing each other, they mechanically "brake" the cone motion very quickly after the
input signal has stopped. In fact, our subwoofer has 4 times less ringing than

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Von Schweikert Audio

World Class Reference Speaker Systems for Music and Film

conventional designs! When combined with our very thick and stiff edge surround and
15 lb magnet with a very high degree of magnetic damping, our Double Spider system
with Bias Control is a major advancement in transient response clarity. If you are
wondering whether these improvements actually contribute to an audible difference, we
offer the fact that the VR-S/1 is the only subwoofer we have tested that is as fast and
clean as a midrange driver! Imagine being able to hear each mallet strike in a kettle­drum roll or the sound of fingerprints brushing the catgut strings of an upright bass. If
you are an action movie fan, be prepared to experience window-rattling power!

CABINET DESIGN
Since the enormous pressures generated by our Extreme-Duty driver would distort an
ordinary cabinet, causing serious resonances that would interfere with its clarity and
output, we over-engineered the cabinet's rigidity. The maximum density resin­fiberboard is twenty-five millimeters thick with heavy internal bracing, eliminating wall
flex. Since the VR-S/1 had to be as small as possible without compromising the extreme
engineering and sonic standards we envisioned, it was not possible to use any type of
porting to augment the deep bass range since the cabinet is too small to use a port.
Consequently, this is a sealed design, with no resonant signature. As small cabinets
normally truncate the deepest bass frequencies, we have preprogrammed the amplifier
with a correction circuit combined with electronic servo control that ensures powerful
response down to 20 Hz (-3dB).

DOWNWARD FIRING DRIVER

To reduce the dips and peaks caused by standing waves, our design target specified a
360-degree radiation pattern. This was accomplished by firing the woofer at the floor,
and the result is a more uniform bass-wave propagation. All enclosed rooms generate
standing waves due to boundary reflections, and this causes severe dips and peaks of up
to 18 dB in the frequency response! By using a 360-degree dispersion pattern, the
standing wave situation is broken up into smaller dips and peaks spread out over a wider
range, greatly reducing the audible "room boom." Another advantage of firing the
woofer downwards is the physical slot loading of the bass pressure. In theory, the
woofer's diameter is not large enough to efficiently couple with the air in the room;
however, using the slot loading technique (where the woofer's bass wave pressure is
modified by the floor boundary 2" from the cone), the radiation resistance is more
closely matched to the room. The result is louder, tighter bass response. To accomplish
slot loading, we supply 2" spikes that elevate the cabinet.

AMPLIFIER
Most competing subwoofers use Class D switching amplifiers due to their low cost, light
weight, and high efficiency. However, in side-by-side listening tests against Class A/AB
High Current amplifiers, the Class D switching amps do not have the depth or heavy
impact of the traditional High Current Class A/AB amps. For this reason, we have
engineered a 300- watt Class A/AB High Current amplifier with 600 watts of peak
power available. The huge transformer and large filter capacitors enable the bank of

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Von Schweikert Audio

World Class Reference Speaker Systems for Music and Film

high current transistors to put out enormous peaks without distortion (0.08% THD).
Since the small sealed cabinet would not normally allow the woofer to respond at 20 Hz
due to the high internal air pressure and subsequent high resonance frequency, we have
engineered a feed-forward pre-programmed correction circuit into the input stage.
However, since the overall output has to be monitored to ensure correct moment-to­moment transient response accuracy, we have designed an electronic monitoring circuit,
which samples the back electromotive force generated by the woofers voice coil. With
feedback correction, we have simplified the principle of servo control, ensuring an
extremely high quality response to the most challenging input signal. The VR-S/1 will
probably be the best sounding subwoofer you have ever heard! Naturally, all necessary
controls and inputs/outputs are provided, as well as a removable IEC power cord,
117V/230V switch and 2" spikes to elevate

AMPLIFIER CONTROLS

• Volume Level control potentiometer;

• Crossover Frequency control, calibrated from 50 Hz to 100 Hz.

• Phase Reversal switch, two position, 0- degree and 180- degree selection.

• Crossover Bypass switch.

•

For adjustment information, see the SETUP section below.

SUBWOOFER PLACEMENT

The VR-S/1 Subwoofer has been designed to be placed almost anywhere in the room.
When used in a two channel stereo system with small speakers, it is desirable to place
the sub between the speakers, on the same plane, if possible. This will integrate the
sound stage in a very coherent manner. However, since the bass waves will reflect from
all of the room boundaries, there will be a series of peaks and dips in the bass response if
the sub is placed in the wrong place. The smoothest bass response occurs when the
subwoofer is placed against the wall or better yet, in the corner of the room. However,
this does not automatically guarantee that the bass will be totally integrated with the
main speakers unless they are also placed for the smoothest bass response. For this
reason, placement experimentation is mandatory with both the sub and the mains. If you
are happy with the linearity of the bass response you are obtaining with your main
speaker system and do not hear problems with dips and peaks, then placing the sub in
the room corner will most likely result in a good blend. If the main speakers are more
than ten feet away from the sub and you hear a “hole” between the mains and the sub,
try reversing the phase of the sub using the Phase Reversal Switch. Keep in mind that
deep bass is largely non-directional at frequencies below 80 Hz, and that system
integration will be facilitated with the BASS LEVEL, CROSSOVER FREQUENCY,
and PHASE controls. For adjustment of these controls, please see the SETUP section
below. It is recommended to keep the VR-S/1 at least 3 feet from conventional video
monitors, as the magnet is not shielded.

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