Velodyne SMS-1 Subwoofer Management System 
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Written by Brian Kahn   
Sunday, 01 October 2006

It is not often that a product comes along that can either make a complex process one button simple or provide the tweaker with nearly unlimited adjustments in the pursuit of perfect sound but the Velodyne SMS-1 does just that. A couple of years ago Velodyne launched their Digital Drive series of subwoofers which included a digital signal processor, microphone, parametric equalizer and digital servo controlled subwoofer. The Digital Drive subwoofers received rave reviews including from’s own Christopher Zell.

The Velodyne SMS-1 at $749 incorporates many of the features of the Digital Drive series, except of course the servo controlled subwoofer. The Subwoofer Management System features a full suite of controls housed in a svelte 1 rack unit high black box. The unit itself measures 2 inches high by 16.5 inches wide by 6.5 inches deep and weighs 17 pounds and is rack mountable. The front panel features an LCD in the center and three horizontal accent lines across the length of the panel. The front panel LCD shares its space with a power button, IR sensor, XLR microphone input and volume controls. The rear panel is packed with balanced XLR LFE input and output, XLR microphone input, IR repeater input, RS-232 input and output, S-video and composite video outputs, three single ended LFE outputs, stereo analog EQ signal outputs, thru outputs for additional daisy chained SMS-1 units, single ended LFE inputs, single ended outputs with a 80Hz 6dB slope high pass crossover, 12 volt DC power supply input and lastly a barrier strip with 12 volt trigger and speaker level inputs. In addition to the main unit itself the SMS-1 also comes with a remote control and calibrated precision microphone, microphone stand and 20 foot XLR cable.

The front panel display indicates volume, preset selection and operating mode. In order to utilize the full power of the SMS-1 it is necessary to connect the unit to a video display which allows the user to run the auto EQ function with a simple keystroke sequence or access the following slew of adjustments, an eight band graphic or parametric equalizer with +6/-12 dB of adjustment; a defeatable low-pass crossover that is adjustable from 15Hz – 199Hz with slopes adjustable from 6 – 36dB per octave; variable relative subwoofer volume control; phase control adjustable in 15 degree increments; 6 presets, dimmer, and night mode.

The beauty of the SMS-1 is that the multitude of controls listed above can be ignored by the user when in auto mode or each one can be adjusted individually to your heart’s content. All incoming signals are digitized then manipulated in the digital domain. The operable frequency range is 15Hz -200Hz the equalizer functions between 15Hz and 110Hz which allows the computing power of the SMS-1 to exercise all of the features described above. Full frequency range digital signal processors / equalizers such as those by Tact or Rives require significantly more computing power than the limited frequency range SMS-1. By limiting the operable frequency range to those in and adjacent to the range of the subwoofer Velodyne can provide all of the features necessary to maximize a subwoofer’s performance at a lower price.

I first inserted the SMS-1 into my stereo system between my Krell 300iL (being utilized as a preamplifier) and a Halcro MC50 amplifier. The MC50 was driving a pair of Snell LCR 7s and the SMS-1 was controlling a Sunfire True Subwoofer. I placed the SMS-1 in my equipment rack, plugging its wall wart power supply in and then began with the audio and video connections. I plugged the line level outputs of the Krell into the SMS-1’s inputs, the SMS-1’s outputs into the Halcro so that the SMS-1 would act as a cross0ver effectively bi-amping my system. Next the Sunfire was plugged into the SMS-1’s LFE output and lastly I connected the EQ audio outputs to an open input on the Krell and the video to my monitor. Once all the connections were made I plugged the included microphone into the SMS-1’s front panel and placed it in my listening position. As the SMS-1’s firmware is upgradeable I went to the website to confirm I had the latest software (I did) then moved forward.

The SMS-1 was then ready to earn a place in my system before it even began to process any signals. I initiated the frequency sweep which caused a 15Hz-200Hz sweep to play every few seconds. The video monitor that I hooked up to the SMS-1 displayed a real time frequency response graph above a graphical representation of the equalizer settings currently in place. Watching the monitor I could see my system’s response below 200Hz as I began to move things around, obtaining significant changes with relatively minor movement. I found that I was able to quickly find the best available placement in my room using the sweep tone and real time response graph making this feature alone extremely valuable. Finding the best position and smoothing out the response curve as much as possible before beginning adjustments means you have more room to work with and less processing that needs to be done.

Once I used the SMS-1 to determine the best room position I then engaged the self EQ function by simply pressing 3-2-1 on the remote. The sweep signal began to play again while the SMS-1 began its adjustments, a couple of minutes later the whole process was over. In this mode the Velodyne equalizes the subwoofer only, in the Auto EQ mode which can be easily accessed through the menu, both the subwoofer and speakers are affected by the equalizer. The SMS-1 also allows the user to manually adjust equalization, crossover settings, phase and more. Settings other than EQ are on a “System Settings” page which is essentially a page that shows all of the settings for each preset and allows them to be selected and changed. By then going back to the “System Response” page once can initiate the frequency sweep and visually see what effects resulted from those changes.

The plethora of adjustments available can be overwhelming at first but the manual is well written and walks the user through the steps to manually adjust all the available settings to obtain the best possible performance. It is important to be careful not to overdrive your subwoofer, unlike the Digital Drive subwoofers, the DSP can not monitor the subwoofer to see if it is nearing its limit. The manual provides well placed reminders to be cautious with certain adjustments to which I add a recommendation to keep the volume relatively low while making the adjustments and listen carefully for signs of stress. While the SMS-1 can make many improvements, every subwoofer has its limits. I give credit to both Sunfire and Monster for making subwoofers stout enough to handle the increased load that the SMS-1 placed on them.

For those of you who want to get even tweakier there is a computer program available for download online called Room EQ wizard that is designed to work with the SMS-1. To use these programs you play the test tones through your system, the playback of which is then analyzed by your computer which provides you with the recommended adjustments for the SMS-1. As this is not part of the SMS-1 package I did not use it for the review but want to point it out to those of you who have the inclination to spend more time tweaking your system.

Setting up the SMS-1 in my theater system was very similar. The main difference was that the SMS-1 was connected to the LFE channel output of my processor and the main channels bypassed the SMS-1. I connected two Monster THX Select 200 Subwoofers to the LFE outputs of the SMS-1. While the SMS-1 has three outputs and can drive up to three subwoofers they are all fed the same signal. So my two identical subwoofers received identically processed signals, which cannot compensate for the differences in their responses due to room placement. I moved the subwoofers around until I obtained the flattest response possible with both subwoofers running while each subwoofer running individually has a similar response curve. This way each subwoofer is affected similarly by the adjustments made by the SMS-1. For those of you who want to obtain the optimum response from each subwoofer, you can daisy chain the SMS-1’s so that each subwoofer gets its own individually optimized signal. While multiple Velodynes for multiple subwoofers would be ideal, using one Velodyne for two subwoofers yielded significant benefits.

Music and Movies
My first listening experience with the SMS-1 was in the two channel system and the Sunfire subwoofer. Crystal Method’s “Busy Child” from their Vegas album (Outpost Records). Regular readers know that I like the synthesizer bass line on this track for checking a system’s ability to play fast and powerful bass notes. As I mentioned above the Velodyne unit has 6 presets, one of which is EQ defeat which let me easily disengage the processing so I could easily check the results. The bass line was noticeably tighter and faster with the processing engaged. The synthesized drum beats were noticeably more powerful, seemed to reach deeper with more detail with the processing than without. The bass integrated better with the mids and highs with the SMS-1 engaged than without.

The infamous opening of Dire Straits’ “Money for Nothing” (Warner Brothers) off of their album of the same name was likewise improved by the use of the SMS-1. The drums were noticeably more detailed and coherent with the processing than without. The soundstage was better defined, with the instruments having more solidity and presence with the processing than without. The bass guitar seemed to really come alive with the SMS-1 engaged while the drums gained strength and detail that allowed them to more firmly occupy their space on the soundstage. While the biggest benefits were with the bass guitar and drums, the entire track benefited from the processing as there was a greater sense of coherence from top to bottom than without.

The SMS-1 provided similar benefits when I moved to my theater system. I played Missy Elliott’s “Get ur Freak On” from the album Miss E…So Addictive” (Elektra). The repetitive bass line on this track shifted in position and increased in both detail and depth with the processing in place. I listened to the next few tracks and found the improvements to be very similar from track to track.

The SMS-1 provided similar benefits when I moved to my theater system. I played Missy Elliott’s “Get ur Freak On” from the album Miss E…So Addictive” (Elektra). The repetitive bass line on this track shifted in position and increased in both detail and depth with the processing in place. I listened to the next few tracks and found the improvements to be very similar from track to track.

The Eagles’ “Hell Freezes Over” (DTS) remains a favorite 5.1 music album. The drum beat on “Hotel California” is one place where I noticed a difference between the Monster THX Select Subwoofer 200 and my more expensive reference Cantons. With the SMS-1 processing engaged this difference, while not completely eliminated, was significantly reduced. As before, the subwoofers acted quicker and lighter with the processing than without. The kick drum had more depth and detail both in the impact and decay with the processing than without. While I was careful to make sure the bass level was the same with and without the processing, there seemed to be more impact with the processing engaged than without.

Movies also benefit from the processing. I watched “Robots” (20th Century Fox) and in the scene where the two robots are riding through a pinball machine type maze across the city in a ferris wheel type of ball the LFE channel is used to provide visceral impact to the ride. The effects are more subdued than the Crystal method bass line or a series of explosions from the latest James Bond flick but just as important and involving to this scene. The increased detail afforded by the SMS-1 really maximized the impact of the effects.

The scene from “Robots” reminded me of the Blue Room scene from “Hero” (Miramax) before the bamboo came crashing down. I went through my collection and found “Hero” and confirmed my suspicions, the SMS-1’s processing brought increased detail and depth adding impact to the low frequency effects both to the subdued effects and the later impact of the collapsing bamboo.

Knowing that the SMS-1 worked well with subdued bass lines I wanted to see what it would do with an aural assault such as that of a battle scene. The battle scenes from “Master and Commander – the Far Side of The World” (20th Century Fox) seemed appropriate. The canons and explosions did not disappoint. Even without the SMS-1 in place the visceral impact of bass in this scene could not be ignored. However, with the SMS-1’s processing in place the explosions were not as overwhelming, as they had more finesse to accompany their strength.

The Downside
The SMS-1’s manual set up options can be a bit overwhelming at first. The unit is capable of doing so much that if you want to do something other than the Auto EQ at first it could seem to be insurmountable to those new to room tuning. I think Velodyne has done a pretty good job with the manual that walks you through the set up process, providing tips and warnings as appropriate. I would also recommend downloading Outlaw Audio’s free guide to the SMS-1 as it provides good information and is (relatively) easy to follow.

One change that I would like to see is an option for stereo subwoofers, each with their own individual controls. Currently one can hook up multiple subwoofers, each receiving the same signal or you can daisy chain multiple SMS-1’s. I for one would be happy to pay a small premium to have a stereo option available which would make it quite easy to Auto EQ a pair of subwoofers.

I heartily recommend the SMS-1 to anyone who has a decent subwoofer yet is unhappy with the bass response in your room. Those of you with a downright awful subwoofer would be better served by upgrading your subwoofer first as the SMS-1 can only do so much and may actually be too much for a lesser subwoofer. No matter what signal you feed to a subwoofer, you can’t make it play louder or lower than the unit is physically capable of. That said there are a lot of subwoofers out there that can benefit from the processing of the SMS-1.

The SMS-1 provides high quality room correction at a relatively low price by limiting itself to the 15Hz to 110HZ frequency range. This is a smart idea as this is the range that is often so problematic to solve without unacceptable compromises. If you are completely happy with your bass response or are buying a full frequency DSP for your entire system, move on to the next review, if not, find a local Velodyne dealer and see what the SMS-1 can do for your system.
Manufacturer Velodyne
Model SMS-1 Subwoofer Management System

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