The Equipment
Although the twin woofers on the DC-X have the familiarly-shaped and positioned felt pads, it seemed to me that the drivers themselves were not the 'old' fibreglass-coned units I'd enjoyed on the original DC-X and sure enough, Wilde confirmed via e-mail that the drivers fitted to my review sample had Kevlar 'composite' cones. He was keen to point out that although these drivers look similar to drivers used by several other famous loudspeaker manufacturers here in Australia and overseas, they've actually been made to VAF's own specifications. Specifically, they have a T-shaped pole-piece and a high-temperature voice coil with former venting.
Venting the coil through the former is a well-known technique, but fairly unusual to find in loudspeakers selling at this price. Even more unusual is that instead of venting the coil above the spider, VAF vents underneath it. This enhances the centring effect of the spider, but means the driver also has vents in the frame below the spider, so the heat can escape. The beauty of this system is that the spider acts as a kind of 'air pump', moving hot air away from the coil much faster than would otherwise be possible.
VAF rates the bass driver(s) at 210mm because this is the mounting hole diameter, but the Theile/Small diameter is somewhat smaller, at 173mm. This puts the effective cone area at 235cm2. However, because the DC-X uses two woofers, the available cone area for the bass is 470cm2. So, if VAF had used a single bass driver, it would have had to have had a Theile/Small diameter of 244mm to move the same amount of air (all other parameters being equal), which would equate to about a 280mm driver.
Displacement isn't only about diameter, however. Cone travel must be factored in to the equation, and here VAF claims an extraordinary linear excursion of 9.5mm and a total potential excursion of 22mm. The result is a linear displacement of 1100cc. The drivers are fully magnetically shielded, and the ABS chassis has six 'legs' that are strong enough to provide enormous rigidity, yet thin enough that they don't interfere with air flow behind the driver.
VAF doesn't just use the output from the front of the bass drivers. It also harnesses the energy from the rear of the cones, in a split bass-reflex arrangement, with the lower of the two woofers vented through a front-firing (145 x 71o) port and the upper driver through a rear-firing port (123 x 71o) located high on the rear panel. In the DC-X Generation IV, VAF says it has also concentrated on ensuring minimal acoustic propagation through the woofer diaphragms. In many speakers, but particularly those without internal baffles and proper damping material, higher-frequency sounds generated from the back of the cone travel into the cabinet, reflect from the rear panel, then travel into the room through the thin cone material. This is highly undesirable. In the DC-X Gen IV, sloping panels behind both drivers ensure high-frequency sounds are deflected downwards into the cabinet, where they're absorbed - mostly by VAF's 'Hypersoft III' foam.
The multiple (there are three) sloping internal partitions do more than separate the top and bottom sections of the cabinet into different volumes and act as deflectors. They serve a third role by contributing to the rigidity of the cabinet, which in turn reduces resonances. If a cabinet is at all resonant, it will create sound energy in the room that will detract from the fidelity of the drivers. Because of the partitions (and the other bracing), the VAF cabinets are effectively acoustically 'dead'.
The two tweeters are 25mm diameter soft-dome designs driven by neodymium magnets. VAF has obviously been following (or, knowing VAF, taking part in) the research into the problem of compression in tweeters using neodymium, because the magnets on the VAF T25DTH1 tweeters have very large heat sinks attached to ensure the magnets are adequately cooled. (For those not in the research loop, neodymium is such a powerful magnetic material that you don't need nearly as much of it as you would if you used ferrite. What this means is that if you have two equally powerful tweeters, one using ferrite and the other using neodymium, the ferrite magnet will have almost ten times the surface area of the neodymium magnet, and therefore can stay much cooler because there's more surface area to dissipate the heat. Why do you want the tweeter to stay cool? Because magnetic materials become less efficient as they get hotter, so as the tweeter heats up, its output will fall, so the high frequencies will gradually become attenuated. More insidiously, the heat generated on peaks will cause compression, limiting the treble dynamics).
Despite the use of dual chambers to load the DC-X Gen IV, the speakers have a fairly straight-forward two-way crossover, albeit divided into completely separate high-pass and low-pass sections, so the two woofers are driven in parallel via the low pass section and the two tweeters in series via the high-pass. The crossover components are hard-wired to each other, and all component's are glued to one of the internal partitions. All the inductors are cross-mounted so there's no possibility of interaction between the magnetic fields, and all capacitors are good-quality Bennics. Thick, multi-strand wires from the crossover run to each of the drivers, where they're soldered to the terminals, rather than using the inferior tag connectors employed by most speaker manufacturers. The same thick wires also link the crossover to the rear terminal plate, which sports two pairs of heavy-duty, gold-plated multi-way banana-capable terminals.
VAF is justifiably famous for its range of kit loudspeakers, and so when you see a pair of DC-X Generation IVs in the flesh, you'll see the finish and construction is so good you may be tempted to mutter under your breath 'I can't believe it's a kit'. This is because the DC-X isn't a kit. VAF sells it fully built and tested, complete with an individual test report, and with a full three-year warranty, for $2,499 per pair. (Though if you can't pick them up from VAF's factory in Adelaide, you'll need to add in an extra $80 to cover freight to your front door.)
Which is not to say of course, that you can't buy them as a kit if you want. In fact VAF offers two different kit versions of the DC-X Generation IV. For a shade under $2,000 VAF will supply all the component parts of the speakers, including ready-assembled cabinets and pre-wired and tested crossover networks. All you need to do is solder a few speaker wires, position the ports and foam damping and screw in the drivers and speaker terminal plate. If you fancy yourself as a cabinet-maker, or you wish to get a cabinet-maker build you a pair of custom cabinets in some exotic finish, VAF will sell you the plans for the cabinet, plus a complete set of parts, for $1,149. Remember, however, that if you are building your own cabinets, you need to follow the plans exactly, otherwise the design will not perform to specification.
Before you race out and commission a cabinet-maker to build you a custom cabinet, I'd suggest calling VAF first, because my understanding is that although the standard 'ex-factory' finishes are American Oak, Black Oak and Australian Jarrah, the company is more than happy to provide cabinets in just about any veneer or finish you want. Founder Philip Vafiadis once told me that so far as timber veneers are concerned, he's more than happy to provide any veneer that's available in Australia, and that he has already built speakers in all manner of custom painted finishes in matt or piano gloss, so you can have any paint colour you like, including metallic finishes.
Listening Sessions
It's best to be sitting down when you listen to the VAF DC-X Generation IVs. This is partly because if you're not, you'll likely be knocked off your feet by the sound quality (or at least go a little weak at the knees!). If Roy and HG were reviewing these speakers, they'd no doubt say 'the sound is HUGE' and they'd be right, because the bass response is enormously powerful, more like live sound than recorded sound. But by powerful I don't mean that the bass is in any way exaggerated, or that it has the usual 'buy me' hump at around 100 Hz that many manufacturers deliberately build in to make their speakers stand out in a showroom A-B demo. On the contrary, the DC-X Gen IV has bass that's perfectly balanced and tonally realistic, but is delivered in such a way that it simply seems much more 'powerful', as if it's an unstoppable force rather than just 'bass'.
The other reason you need to be sitting down is that the tweeters have been deeply recessed into the front baffle in order to get them time-aligned with the bass/midrange drivers. This means that if you're standing in front of the speakers, you won't hear the full, unimpeded output from the topmost tweeter until you're at least two metres away from the speaker cabinets. In my listening sessions, I arranged my seating so my ears were at exactly the same height above the floor as the midpoint between the two tweeters (900mm) and satisfied myself that this height gives the best sound. Co-incidentally (though more likely it's been designed this way) this is the height your ears will be if you're of average height and sit on any standard lounge chair, sofa or settee. As it happens, the exact ear height isn't critical - I heard pretty much the same sound quality when I ducked my head down lower and when I kneeled on the sofa to get my ears up high. So although 900mm is certainly optimum, there's a pretty big vertical window where the sound quality is identical.
And if the vertical window is big, the horizontal window is positively panoramic. You can sit way off to one side of the DC-X Gen IVs and still get perfect treble, with no roll-off at all. You also get a perfect stereo image. It seems that VAF's angled tweeters really work! The difficulty for me with the angled tweeters was where to 'aim' the speakers: parallel with the back wall, or so that one tweeter was aimed at the listening position? The answer turned out to be counter-intuitive because in my room, I achieved the best performance with the speakers toed in to intersect at the listening position, even though this meant I was facing neither tweeter head-on! I'd recommend this position because for me, it returned extended highs, glorious stereo imaging and a palpable sense of three-dimensional space when listening to properly recorded CDs.
I experienced a great sense of this space listening to Lisa Miller sing (and play guitar) on her album 'As Far As Life Goes', and it's a great album to boot. Listen out particularly for Garrett Costigan's pedal steel on 'Til I Get It Right' and the title track. For the bass, you might care to listen to the deep bass impacts that emanate from Downsyde's 'Gifted Life'. This bass is 'studio enhanced' to be in-your-face, but the VAFs reproduced it with ease, even at lease-breaking listening levels (though I think it's a pity that those who like Downsyde's music have to endure the lacklustre production values!)
Good live concert sound is always a great test of whether a loudspeaker passes the 'being there' test, and you'll get no better concert than is captured on Manu Chau Radio Remba (Virgin). The excitement is present right from the first track, and there are 29 (count 'em) absolutely fabulous tracks of high-energy South American music on this CD. The VAF DC-Xs delivered the almost-subliminal bass with such tight control and such depthy power that it almost seemed not to emanate from the speakers at all.
Piano sound is difficult for any loudspeaker, both because of the percussive nature of the instrument and its enormous range. Once more the VAF shone, such that I was able to distinguish the differences in sound between the two Steinway Ds Ronald Farren-Price plays on his 'Moonlight Sonata' CD (Move). The piano sound is rich and cohesive, perfectly captured on this recording, with a level of detail that will have you playing the 'pick the piano' party trick as well.
Would the VAFs handle grungy rock? It's a question I answered in the affirmative after listening to the raw, eccentric, eclectic and decidedly curious sounds of The Electric Soft Parade. Turn up the volume and wait for the Noise Police to arrive (or, more likely, the Drug Squad)! You certainly won't have to fear for the speakers: If they can handle this, they can handle anything...
