Velodyne DD15-Plus Subwoofer Review

Titanium fist in a velvet glove.

by AVForums
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4

Reference Status
Velodyne DD15-Plus Subwoofer Review
SRP: £4,500.00

Having been founded in 1983 by David Hall, who remains the CEO and Chief Engineer, Velodyne is one of the grand daddies of subwoofer design. They didn't exactly start slow either, patenting the the first high-gain servo controlled subwoofer utilizing sealed accelerometer technology in 1984. A what? I'll save that for later in the tecnobabble, but suffice it to say the technology isn't marketing bull, fundamentally remains the cornerstone of all of Velodyne's top line subwoofers and quite literally sets them apart from every other manufacturer on the market.

What also sets Velodyne - and in particular the DD (Digital Drive) - subwoofers apart from the crowd, is the lack of prejudice their products suffer from. There are favourites of the hi-fi fraternity and favourites of the AV/Movie crowd, but somehow the DDs have always managed to sit comfortably in both camps and be appreciated by both. That's not to say other products aren't worthy of use in both rolls, indeed it's my firm belief that the the qualities required for optimal reproduction of both movies and music are are exactly the same and there's more than one way to skin that particular cat. No, its just that the Velodyne DDs have never been marketed as anything other than a high quality, low distortion, accurate subwoofer. Period. Overt boasts about massive SPLs or belief stretching claims about academic frequencies plumbed are absent, even if they are actually delivered.

The subwoofer we have for our delectation here is the the 15" model from the brand new range topping DD+ line. This replaces the DD Series (which continues) at the top of the Velodyne range, with the sole exception of the wonderfully over the top, DD1812 Signature - a one off statement product, if ever there was one. Compare the specs of the DD+15 to its DD15 predecessor on Velodyne's website and you could be forgiven for thinking the new model to be little more than a cosmetic makeover. Dear reader this is far from the truth; Read on....

Velodyne DD15+

The Velodyne DD15 subwoofer is one of my favourite ever subwoofers and remains so. This is remarkable, considering it was introduced in 2003. Think about it; how much of your system is eight years old and, if it is, how close to state of the art do you think it's performance remains? Probably not very, with the possible exception of power amps. The truth is, if you like the Velodyne style of bass, then right up until the release of the DD+ Series this year, you probably still had the best product you'd be likely to buy and, even now, it hasn't been consigned to the level of an also ran.

This longevity is in part due to the Servo technology Velodyne use and also, in part, to the upgradable nature of the Digital Drive firmware. In 2003 this was an unusual feature on any product - even the Sugarbabes were only on Version 2 - and certainly extremely unusual in a subwoofer. HDMI had yet to be invented (some say they still haven't finished it) and multi-region DVD was still a £50 'option'. That, or a worrying fifteen minutes of combination button presses, plus a prayer that your interweb downloaded firmware wasn't somehow corrupted when you burned the file to a CD, thus bricking your £800 player. The digital heart that governs the DD Series remains and has been updated and expanded for the DD+, but that's far from all that has changed, so for the uninitiated, lets start from the beginning.

Technology

Velodyne DD15+

As touched upon, the cornerstone of the DD15+ is the Servo feedback technology employed. Feedback, in this case, is a method whereby the motion of the subwoofer's driver is monitored by a sensor, the signal of which is sent back to the amplifier. This signal is compared to the input signal and then that same input signal is modified, in real time, to ensure the output of the driver is true - read low distortion - to the original input. There are two ways to engineer a sensor. One is to provide a separate winding on the voice coil to monitor its motion and the other is to place an accelerometer on the cone, thus including its motion and breakup modes into the equation. Velodyne, having patented the technology, favour the latter. This makes sense to me, as you actually hear the cones output, rather than just that of the voice coil and so it should be taken into account.

Where Velodyne really force home the advantage of their Servo Feedback technology is in the application of the DSP (Digital Signal Processing) applied to the feedback signal. Unlike a normal amplifier, most of which use feedback to control distortion in - dare I say it - a dumb, fixed level analogue kind of way; Velodyne apply the feedback according to output signal level, frequency and, indeed, include a user definable level of application. The DSP is pre-programmed to limit distortion to a given level (quoted as 0.5%THD) and thus results in a progressive limiting of output as frequencies drop, but the manual control allows slightly more bottom end output at the expense of a little more distortion.

Velodyne DD15+

I should be careful to emphasize that distortion, in this context, is very low regardless of what setting the user chooses and this is, in no small part, due to the entirely new driver the DD+ subs use. The new Rochacell-fibregalss laminate cone is derived from that used in the DD1812 Signature, rather than the Kevlar weave of the older subs. This is suspended from a visually far more massive roll surround, promising far greater travel. Testing the limits of the suspension is an entirely new motor structure. Gone is the old long coil, short gap and in is the new short coil, long gap underhung motor structure. In the former a long coil moves through a short magnetic gap, the idea being that a portion, but not all, of the voice coil is always subjected to the maximum motor force. In the new motor, the force of a larger magnet (13kg v 10kg) is focused into a longer gap, so that the shorter voice coil stays within, throughout it's entire travel. Although the images don't convey it, this is a more exacting way of controlling the voice coil, but is also more expensive due to the precision and scale of the engineering involved.

Motive force for the driver is provided by a 1250W continuous, 3000W peak, 'Class D' amplifier that, in raw specs, is unchanged from the earlier generation in quoted output. This leads one to suspect that maximum output is unchanged. As maximum output was always limited by the distortion limiting Servo - and the new driver offers the potential for much lower native distortion - the raw figures are actually somewhat misleading. In practice, the DD+ Servo's influence has actually been cranked up harder to quash distortion further, but the superior limits of the driver push this tighter defined envelope to higher levels before its influence starts to limit proceedings. It should also be noted that the Servo makes it, in all practical senses, impossible to overdrive the DD+. The imposed distortion limits happen long before the physical limits of the driver and/or amp, thus rendering the DD+ all but bomb proof.

The DSP offers further features, with respect to integrating the DD+ subs into their environment and these features are split into two sets, which can be either displayed via a composite video output on your TV or via USB on your computer desktop. The latter provides the number crunching brains for the full monty automated setup. The first is a screen that looks, on initial acquaintance, a bit baffling but reveals the unparalleled level of user tweakability. It allows you to set gain level, high and low pass filters with variable filter slopes and frequency cut-offs plus a contour curve at a selectable frequency and level and, finally, the level of the applied servo control. This set can be applied to a global setting and then each parameter can also be varied across one of six presets. These presets are (along with all of the above parameters) can be accessed from the comprehensive and, once you're used to it, intuative remote control. Each preset is nominally called 'Movie', Rock', 'Classical', etc, but it's ultimately up to you how you configure them.

Velodyne DD15+

The second screen shows the eight parametric EQ filters used to tune the subwoofer's in room response. These can be adjusted manually, using the on screen graph which is accompanied by a continuously sweeping test tone so you can see the effect of your adjustments on the fly. As with the first screen of parameters, you can adjust a global set and further tweak the tuning of the individual presets. If you like manual tuning, and I do, this is still the most fully featured set of user controls ever fitted to a subwoofer. The new suite of tuning options only comes available when you drop a test tone CD in your silver disk spinner and plug your computer into the mini USB socket hidden behind the front grill. Incidentally, this where you also plug the measurement microphone responsible for measuring the results of your ministrations. A small gripe here is that the standard XLR female socket of the DD Series has made way for a mini-XLR for no reason I can fathom. I prefer the bulk and strength of the full sized version which would be more resistant to knocks, but if you do kill a cable, the mini jacked version can still be bought from Pro Audio outlets for remarkably little.

Velodyne DD15+

Back to the USB connection; this brings into play the new PC suite of number crunching software that mirrors the functionality of the on-board controls, but adds a little extra. If there was one feature of the original DD Series that wasn't worth a pig in a poke, it was the 'Auto' EQ. This simply adjusted the eight PEQ filters up or down, with no attempt to vary filter frequency or Q (filter width) to match what was actually going on in your room. This made it little more than a glorified graphic equalizer and about as much use. The new software now does the job properly and takes into account the response of the speakers the DD+ is being asked to integrate with, going as far as applying a little extra low pass filter if required, adjust phase, filter frequencies and filter Q. It works very well and allows you some manual adjustment once the job is done, if you feel it's needed. I can't resist a fiddle and did manage to achieve a slightly flatter response, the audible results of which I found miniscule, if present at all. Once happy, you upload the results to the sub's DSP, unplug your cables and you're off.

It's a very effective system and one that, for stereo only listeners, can introduce a level of integration, and tuning, lesser featured subs would struggle to match. Multichannel AVR users may have some auto tuning built in, but with a few exceptions, this is almost never the case in the land of stereo music and that the system is so competently auto, is a real boon.

All of this considerable technology is wrapped up in a cabinet of absolutely top drawer finish. The extra bulk of the new DD+ is effectively disguised by a cabinet that tapers gently toward the rear and, in this case, was finished in an utterly non-ecological real wood ebony veneer. I did find it slightly ironic that, given the efforts that must have been made to beat off the tree huggers, the Ebony finish under it's deep piano lacquer tends to look exactly like Piano Black unless you park it in direct sunlight - not the natural habitat of any audio component, especially if you don't want your veneer to fade, but it is luscious.

The grill supplied isn't magnetic but given it's sheer mass, it's not surprising. Rock solid chrome pins locate in rubber cups on the grill, which also hides the mic and USB connections and also a blue LED display that displays the preset number upon start up, or the gain level should you adjust it. Mercifully, this turns itself off after a few seconds, thus saving me griping, yet again, about the entirely inappropriate fashion that is the blue LED in the home theatre environment.

Velodyne DD15+

Turning to the rear (a feat best accomplished by two persons of sturdy build) brings the plate amplifier into view and a very comprehensive set of connections, if not controls, as they are mostly reserved for the on-screen menus. There is an input level sensitivity control, used mainly to ensure the maximum output of your amplifier doesn't clip the input of the analogue to digital conversion that must be performed to allow all of the DSP to be applied in the digital domain, but that's it for knobs. The connections comprise the usual line level stereo RCA Phono inputs and are joined by not only a pass-through output for daisy chaining additional subs (how rich do you feel?), but high pass outputs for stereo users wishing to feed a bass managed signal back to their power amplifier. There is a toggle switch for selecting either a 80Hz or 100Hz for the high pass signal. This is a real plus in my book, because not only do you remove the onerous, distortion laden task of bass from your speakers, you also get to apply the EQ of the DD+ to a wider range of the generally affected bass, which has a massive impact on bass quality. These In/Thru/Hi-Pass outputs are mirrored by a set of balanced connections and joined by speaker level inputs to complete as fully featured a set of inputs as you will see on a domestic subwoofer.

Custom install is covered by not only a 12V trigger but an infra red extender input (should the infra red remote control 'eye' on the front be obscured), plus R232 in/outputs for integrated system control. Finally, there is a Ethernet port to facilitate firmware updates. Phew! It's finally time to let the DD15+ stretch it's legs.

Velodyne DD15+

Listening - Music

So, given that we have a subwoofer with unparalleled system integration controls, very effective room integration EQ, distortion quashing servo control and a base line of huge SPL output delivered through a large, well engineered driver, then something weird is going have to happen for this not to be a humdinger. I wasn't disappointed although it's worth noting, in the vein of all MkII reviews, what current DD Series owners should expect. Indeed, there was a day during the review period when a DD15 was on hand for a direct comparison, so this comparison is not uninformed.

In terms of music, there's nothing I can really fault. Bass is extended, even and taught down to subterranean levels. Kick drum has an enormously satisfying kick that hits you square in the chest, if you have the opportunity to wind the wick up. I would argue that's as much about being a sealed subwoofer, simply because leading edges of transients arrive more instantaneously and crucially, let go and disappear as quickly. Sealed subs simply describe the transient nature of a dynamic impact more accurately and a kick drum, however apparently simple, is a tactile experience of exactly the sort that is hard to replicate in a believable manner. The DD+ does, superbly.

This finely defined dynamic attack is matched with a taught rendition of pitch that makes it a joy when listening to my, by now hackneyed, Paul Simon demo of 'Diamonds On The Soles Of Her Shoes'. Few subs combine the attack and tonal definition of the rapid electric bass guitar, plus the ability to drive the room in a way that gives the performance a tangible, immediate reality. It takes the shoddy demo beyond being well done, into feeling near live and I speak as a bloke who knows drummers and used to play (badly) bass guitar. Live bass has an immediacy, an electrifying quality, if not depth, that is hard to reproduce and the Velodyne DD15+ gets closer than anything I've heard.

This ability is underpinned by profound extension, matched by only a few box subwoofers of any size, that I've heard, to plumb the depths necessary to deliver believable church organ. Okay, you can deliver the deepest stops harder and lower, but you will either have a coffin sized box in your room, or have knocked holes in your wall to install multiple 15" free air drivers to do so and, lets be honest, that's not a practical reality for 99% of people and/or homes. You will, however, feel your room modulated in a way that gives a more than passable impression of the massive expanse of a church acoustic which expands the soundstage in all directions way beyond your speakers. This is a trick oft ignored when speaking of the dark arts of sub bass, but one that a really good subwoofer can deliver, even if the music itself lacks any overtly deep bass content. The acoustics of a room need really deep bass to be accurately portrayed, even if you're listening to a string quartet and this is a subwoofer that excels in this area.

Velodyne DD15+

Listening - Movies

So, musically we're dealing with a sub that is about as spot on as I've heard for all practical, non real estate re-modelling purposes, but as far as I'm concerned, a truly great sub has to shift gears and cope with movies as well.

This is where it gets interesting, especially when comparisons with the original DD15 are brought into the equation. Up to this point, I'd be lying if I said I thought there was a lot of differences, in practical use, between the two with music. A few bass test tracks played at ridiculous levels might start to hint where the extra time, effort and money has gone but (action) movies lean more heavily on such bass delivery.

The same DD taught, rigid grip on texture and tone lends the scenery of the multichannel movie world an extra layer of tangible reality. Simple things like vehicles driving by in street scenes have a real world presence that is devoid of overblown bloom and it's quite distracting if you start listening for it. It's a real sod for making you think a car door has just closed outside of your house too. The wife has been regularly duped by most of my subs for years, but this time I found I was the one doing the nonchalant walk, returning from a curtain twitch. Oh! The shame, but a demonstration of the tactile reality the DD+ has.

Where the new boy starts to show its class is in the headbangers favourite quality - sheer output. Assuming you balance your sub to match your speakers and not just to bend the room when someone on screen opens a letter (you know who you are...) and assuming the speakers can play at Dolby/THX Reference levels, then plenty of subs can match those sorts of levels. The differences are to be found in maintaining those levels with descending frequency. If the original DD15 could be found out, then it was in that last octave between 30, down to 15Hz. Okay, its limits were broadly as a result of the servo limiting distortion, but it couldn't quite pulse the room with infrasonic pressurization, so big bass drops tended to tail off a bit early compared to some of the bigger ported boxes.

Fast forward 8 years and the DD15+ offers twice the driver throw and an additional 6dB(SPL) of output. Incidentally, in raw output terms, that equates to the old DD18 and, indeed, the new DD12+ is claimed to match the old DD15 in this regard. The servo still caps distortion, and most of the time, I still found little difference between the two generations of DD/DD+ sonically. But an extra 6dB over the DD15 - at the bottom end - is analogous to having bought two of the older subwoofers and, in use, the DD15+ feels like you have. All of the dexterity and control is now underpinned by a thunderous bottom octave

Master & Commander - The Far Side of the World is a reference that has fallen from favour with time and perhaps over-familiarity, but the cannon exchanges are, frankly, stunning. The initial concussive kick is now backed up by a real sense of being assaulted by the following wavefront of explosively decompressing air. It sounds similar, but it feels like much bigger guns are in use. The autobot slow-mo barrel roll in the original Transformers movie delves that little bit deeper and hangs on that little bit longer to sustain the effect closer to its room-wobbling conclusion. I've only heard it done better by multiples of subs, or ported boxes several times the size and they fail to match the DD+ in many other areas, so it's a fair trade in my book. These massive bass events are less than 1% of your viewing, but probably 100% of what you show your mates and the DD15+ requires no excuses.

Velodyne DD15+

Negatives? Mercifully few and far between. There was a slightly odd occurrence when running the internal test tones (too loud) that caused a hard edged rattle to be heard. It was more like a digital input clipping, rather than a mechanical rattle, or amp clipping. I was entirely unable to replicate it the following day when running the test tones from the supplied CD at even higher levels, so I put this down to ham fistedness in the excitement of the moment.

It is also indicative that the massive setup flexibility can also make it somewhat daunting and, perhaps, a touch confusing, even to those less than green in the subject. There are two auto setup modes labelled 'Auto' and 'Self' - one of which uses the internal test tones, the other requiring the CD. One EQs the sub alone and the other takes into account integration with the speakers. I can understand why both EQ options are handy, but feel that the internal test tone generator of the sub should be enough, even if it means running a pair of stereo RCA interconnects back to the amplifier to feed a full range signal into the amp's bass management. This is scratching around to find some hairs to split though.

Other than that - as a user of external EQ software - I would like to see 0.5Hz increments in the steps between filters. The difference made is small and, to be fair, not needed by the DD setup, but for those willing to tune out room modes using a 3D plot, the extra 0.5Hz resolution can make the difference between nailing a mode on the head and only just missing it, especially at the upper end of the sub's pass band, where peaks are narrower. This is a sub you can cross very cleanly at frequencies much higher than the multichannel mandated 80Hz, so it's not just a box ticking exercise and it is entirely possible for Velodyne to implement within the current firm/software. Its incluson won't affect 99% of users, but it would be nice for those of us who think (obsess?) over going that extra yard.

Velodyne DD15+

Verdict

10
AVForumsSCORE
OUT OF
10

The Good

  • Superb performance
  • Finish from the very top drawer
  • Compact size relative to output
  • Versatility in integration

The Bad

  • Setup can be daunting
  • Ordinary wood finishes don't look quite as lustrous as the Ebony option

Velodyne DD15-Plus Subwoofer Review

Flawless build, and more flexibility than you may even want, is underpinned by epic bass in quality, depth and quantity. You can eek out more of those last two but the subwoofer that does it will take up enough of your front room to park two DD15+ subwoofers in, so that solution is a compromise in another respect. For me, it's the fact that the DD15+ gets you so far into the same territory, in such a respectably sized package and manages to take other aspects of its performance right into the high end. This is a reference level product, whatever you listen to and whichever room you choose to do it in, the DD15+ can be made to work. Superb.

Reference Status

Scores

Sound Quality

10

Build Quality

10

Value For Money

.
9

Verdict

10
10
AVForumsSCORE
OUT OF
10

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