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Velodyne
Digital Drive SMS-1
Subwoofer Management System
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DescriptionModel:
Digital Drive SMS-1
Price: $749 USD
Dimensions: 16.5"W x 2"H x 6.5"D
Weight: 10 pounds
Warranty: Two years parts and labor |
Features
- Eight bands of graphic or parametric equalization
- Adjustable low-pass and subsonic crossover slopes
- Auto or manual setup
- Calibrated microphone
- Six presets
- XLR and RCA LFE inputs and outputs
- Three stereo RCA outputs
- S-video and composite-video output
- XLR, stereo RCA, composite video cables included
- Remote control
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Take, for example, their innovative line of Digital Drive
subwoofers. These high-quality subs feature powerful digital amplifiers; massive,
high-excursion, servo-controlled drivers; and a unique DSP-based management system. This
system, which Velodyne calls Digital Drive, uses a calibrated microphone and eight bands
of equalization to control every conceivable subwoofer setting. With Digital Drive,
Velodyne claims that the output of their subwoofers can be modified to compensate for many
of the frequency-response anomalies caused by room interactions.
Until recently, the only way to obtain the benefits of the
extremely useful Digital Drive system was by purchasing one of Velodyne’s DD
subwoofers. Velodyne has now made the DD technology available in a standalone unit called
the Digital Drive SMS-1. The SMS-1 can be inserted between the subwoofer and the receiver,
processor, or preamplifier, thus imparting all of the benefits of Velodyne Digital Drive
to any manufacturer’s sub. The SMS-1’s suggested retail price is $749.
Why would I need bass equalization?
One of the major problems with any subwoofer is that, no
matter how well it’s designed and manufactured, its performance will be greatly
affected by the room in which it’s placed. To put it simply, the wavelengths of
low-bass frequencies are so long (on the order of several meters) that when they reflect
off room boundaries and objects, their interactions with each other result in peaks or
nulls. In listening terms, this means that certain low frequencies, at certain points in
the room, are unnaturally amplified or diminished. Virtually every room produces an uneven
frequency response. Moving the subwoofer to a different location in the room can usually
solve some of these problems, but achieving a perfectly flat and even frequency response
from a subwoofer is nearly impossible in most rooms.
The Digital Drive SMS-1 is designed to overcome many of
these problems by using digital signal processing (DSP) to compensate for
frequency-response problems. With the SMS-1’s calibrated microphone, graphic video
display, and well-designed user interface, it is now possible for the average A/V
enthusiast to correct a subwoofer’s uneven frequency response in his or her room with
relative ease.
What’s in the box
The Digital Drive SMS-1 comes with everything you need to
quickly get it up and running. Most important is the SMS-1 itself, which is housed in a
standard rack-mountable black metal case measuring 16.5"W x 2"H x 6.5"D. On
the rear is a multitude of connections, on the front an LCD display. Also included are a
calibrated microphone with a tabletop stand, a 20’ XLR cable, and a stereo RCA cable.
Even a composite video cable is provided to allow connection to a video monitor to display
the graphic user interface. A small DC power supply similar to those used by laptop
computers powers the SMS-1, and a large, full-featured remote control is provided.
The SMS-1 has a full suite of inputs and outputs. Up to
three subwoofers can be connected to its RCA outputs; there is also an XLR subwoofer
output. An LFE signal from a surround processor or receiver can be connected via RCA or
XLR inputs. RCA connections are provided for stereo inputs and outputs to provide an
unaltered throughput signal, or one with a fixed 80Hz, 6dB/octave high-pass crossover. An
additional stereo output can be connected to the input of a receiver or processor so that
the calibration frequency sweeps are also output through the main speakers. The microphone
connects via an XLR input. There are high-level speaker inputs, a 12V trigger, RS-232
ports for software upgrades, and S-video and composite-video outputs.
Bass-management options
Setting up the Digital Drive SMS-1 can be as simple or as
involved as the user desires. The Self-EQ function requires only that the SMS-1 be
connected to a subwoofer and the LFE output of a receiver or processor. The microphone is
then connected to the SMS-1 and placed at the listening position. Pressing
"3-2-1" on the remote begins a series of 25 test-tone sweeps, after which the
subwoofer is equalized. The user then adjusts the volume of the sub to match the levels of
the other channels in the system, and the job is done. Using Self-EQ resulted in a fairly
smooth frequency response that the SMS-1’s graphic video display measured at
plus/minus only a few dB for the subwoofer’s entire frequency range. Considering that
it took only a few minutes to install the SMS-1 and run Self-EQ, this is actually quite
remarkable.
The above method of equalization affects only the
subwoofer. If the SMS-1’s EQ stereo outputs are connected to a receiver’s or
processor’s inputs, the resulting equalization will take into account the output of
the main speakers. This should result in better integration of the subwoofer with the main
speakers in the crossover region.
Self-EQ allows quick and easy setup of the SMS-1, but the
advanced user will want to take advantage of its extremely flexible parametric
equalization to further smooth a system’s bass response. Parametric EQ allows the
user to choose the frequency and level of adjustment of each band of EQ, as well as the Q,
which can be thought of as the range of adjustment. By changing the Q, the amount of
correction to frequencies on either side of the center point of each EQ band can be
controlled. Each of the eight bands of EQ can apply up to 6dB of boost or 13dB of
attenuation in 0.5dB increments and can be set from 15 to 120Hz in 1Hz steps.
There are six presets, each with independent settings for
low-pass crossover frequency and slope, subsonic filter frequency and slope, contour
frequency and level, phase, polarity, volume, and the eight bands of EQ. The subsonic
filter can be set to roll off below a certain frequency to prevent a subwoofer from trying
to reproduce extremely low frequencies that could cause it to distort. The contour setting
is like an additional band of EQ that can be used to boost or attenuate a certain
frequency. This could be used to add "excitement" to a movie soundtrack at 40Hz,
for example. The settings for low-pass crossover frequency (adjustable from 15 to 199Hz),
polarity, and phase are similar to those found on most subwoofers. However, the SMS-1 has
one additional, critical setting that lets the user adjust the slope of the low-pass
crossover. This can be set from 6 to 48dB/octave in 6dB steps that allow the user to
better match the rolloff of the subwoofer to that of the main speakers.
I found the SMS-1 relatively easy to use while providing
remarkably flexible and comprehensive bass management. The Auto-EQ setting provided
surprisingly good results, but with the manual parametric equalization I was able to
achieve an even flatter response. I was even able to tweak the response to provide fuller
bass for more excitement with movies, or flatten it out for a tighter, more accurate sound
with music. There are lots of things one can adjust with the SMS-1, but the graphic
display and test-tone sweeps always made it easy to see how changing any of these settings
would affect the response.
Do I need bass equalization?
My reference subwoofer is the Paradigm Reference Servo-15
v.2, which not only produces prodigious output but provides a tight, musical sound. The
Paradigm’s servo mechanism continuously analyzes the subwoofer’s output and
immediately corrects it to ensure that it closely matches the incoming signal. Although
this ensures that the Servo-15 v.2’s driver accurately reproduces the audio signal,
it does nothing to compensate for any room problems that occur once the soundwaves leave
the sub. Using a simple RadioShack SPL meter and the test tones generated by my Anthem
Statement D1 processor, I was already aware that my room had some bass problems, though I
still thought the Servo-15 v.2 sounded quite accurate.
It wasn’t until I used the SMS-1 that I realized how
much better my system’s bass could be in my room. The Servo-15 v.2 didn’t seem
to play any louder or go any deeper, but the bass was now more defined and seemed to image
better. Instead of bouncing haphazardly around the room, the bass was now totally locked
to the room and tightly focused. The perfectly controlled subterranean bass in chapter 1
of Blade II inaudibly and ominously filled the room. Most subwoofers have
difficulty reproducing this scene, tending to sound somewhat distorted at high playback
levels. Without the SMS-1, the Servo-15 v.2 sounded good but was slightly boomy, which
tended to exaggerate the bass and draw attention to the sub. With the SMS-1 in the system,
except for the threateningly low bass that permeated the room, the background was dead
quiet, which created a tremendously creepy sensation. The lack of boom in the dance-floor
scene, in chapter 10, helped to highlight the crowd noise and Foley effects, making this
excellent-sounding scene even more enveloping and involving. The low frequencies were
still all there, but more low-level detail was now noticeable amid all that roaring bass.
It wasn’t just movie soundtracks that benefited from
the SMS-1. The bass in Jennifer Warnes’ The Hunter [CD, Attic 5736-21344-2] is
difficult to reproduce and can sometimes overload a room when played back at high levels.
My reference Bel Canto eVo amps, Paradigm Signature S8 speakers, and Paradigm Reference
Servo-15 v.2 subwoofer do an admirable job of playing back this bass-laden album, but the
SMS-1 further refined the sound. There was now more discernible attack and decay in the
thunderous drums of "Way Down Deep," which imaged clearly between the speakers
rather than sounding diffuse and indistinct. As with movie soundtracks, the cleaned-up
bass had the effect of making music sound cleaner and more transparent. The
lightning-fast, articulate double bass on "Somewhere, Somebody" danced deftly
between Warnes’ and Max Carl’s delightfully refined vocals.
Eight bands are better than one
My Anthem Statement D1 processor has one band of parametric
equalization that I use to flatten out peaks in the 60Hz range, but the best I could
achieve with the D1’s bass-resonance filter was a frequency response of +/-5dB, with
a dip of about 10dB just below 30Hz. There was no comparison in the quality of the bass
with the SMS-1 providing EQ and bass management for my system. The Velodyne’s graphic
display showed a much flatter response: a deviation of less than 3dB from 20 to 100Hz. But
the proof was in the listening.
Dadawa’s "Seven Drums," from Voices from
the Sky [CD, Warner Bros. 06301 87682], has massive amounts of bass, but it was the
low-level rumbling at the beginning of the song that most impressed me. This subsonic bass
was incredibly controlled and forceful, which enhanced the intense mood of the song. There
was also a single drum stroke that previously had sounded a little weak and distant. With
the SMS-1, it was more solid, with far greater presence. And when the big drums kicked in
midway through the song, they had tons of impact but sounded considerably
"faster," with almost no overhang. Even so, the sound was always rich and
musically satisfying.
DSP -- a brave new world
Velodyne’s Digital Drive SMS-1 is an amazing product
that lets you maximize the performance of any subwoofer. Its use of DSP to provide
automatic or manual equalization and complete control of subwoofer integration, all in a
convenient package, is groundbreaking. A standalone subwoofer management and bass-EQ
system might seem overkill to some, but the Velodyne SMS-1 has made a believer of me. It
improved on my system’s already excellent bass in ways I had not thought possible.
For anyone who owns a high-quality audio/video system with a high-performance subwoofer,
$749 is a small price to pay for absolute bass control.
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System |
| Speakers - Paradigm
Reference Signature S8 (mains), Signature C3 (center), Servo-15 v.2 (subwoofer) |
| Preamplifier-Processor
- Anthem Statement D1 |
| Amplifiers - Bel Canto eVo4
Gen.II, Bel Canto eVo6 |
| Sources
- Arcam FMJ DV29 DVD-Audio/Video player, Pioneer Elite DV-45A universal A/V player |
| Cables - Analysis Plus,
Audio Magic, ESP |
| Monitor
- JVC 34" direct-view CRT |
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