Specifications

engaging the services of a professional audio calibrator using expensive instrumentation
to optimize the placement of the subwoofer(s) and/or employ some serious room
treatments. Unfortunately, these seldom proved totally acceptable or effective, due to
aesthetic or practical constraints, meaning that sub-optimal performance was all too
often the norm.
DIY attempts without proper instrumentation were always liable to be even more hit-or-
miss.
With the advent of digital equalization - while it is still important to find a good position
for a subwoofer - it is now possible to compensate to a large extent for less-than-ideal
subwoofer placements.
Some dedicated DIY enthusiasts have already discovered and used a number of discrete
tools to achieve an equalized in-room response, but the lack of integration makes the
process time-consuming and laborious. The newly released Velodyne SMS-1 now offers
this capability to the more mainstream subwoofer owner in a user-friendly, integrated
package.
The Design
The SMS-1 consists of a slim black box that can be placed on any spare shelf of your
equipment stand. It is also supplied with optional rack-mount ears, allowing installation in
a standard 19" rack. Front panel controls consist of the on/off switch and buttons for
volume. A small illuminated LCD display panel provides visual feedback for the main
operating functions, and there is an XLR socket that allows the supplied measurement
microphone to be conveniently connected.
On the rear panel, working from right to left, there is a 12V DC power socket to which
you connect the supplied wall wart power supply. A small terminal block provides high-
level connections from your speaker terminals if you choose this method of connection,
as well as a 12V trigger input.
Next is a pair of Input RCA jacks for connecting to the input signal. One of these can be
connected to the receiver or SSP's sub-output jack (mono), or the pair can alternatively
connect to the stereo L&R outputs from a preamp. The Output RCA jacks may optionally
be used to supply a stereo signal back to the power amplifier to drive the main L&R
speakers. This is subject to a fixed high-pass crossover filter within the SMS-1 at 80 Hz
with a 6 dB/octave slope using a conventional analog crossover circuit.
The Thru RCA sockets allow the unaltered input signal to be passed to another device
downstream. An example might be another daisy-chained SMS-1 controlling a second
sub. The EQ Output RCA sockets are where the sine-sweep test signal is generated and
should be connected to a spare analog input on the receiver or SSP.