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Kord Audio Tornado/Vulcan Speakers


As time passes, all techno-logical endeavours involve cyclic processes of differentiation - and then integration.

In the thirties, there were just speakers. In the late sixties, for music alone, a distinct, tri-partite domestic/monitoring/PA divergence of styles emerged. Today, the reverse is occurring - speakers of the 80s are becoming more universal. Rock PA speakers have found use in living rooms and mastering suites. And from the other direction, I suggested in HSR's first issue that some domestic speakers, not normally thought of in terms of monitoring potential, could prove worthy of consideration. Here are two top-flight examples.

Vulcan and Tornado are 2-way speakers, and despite their price, they're still subject to the inherent strengths and weaknesses of any 2-way, infinite baffle or Thiele-loaded design. So the salient question is 'How much can you spend on a 2 drive loudspeaker unit before it becomes apparent that a different type of system (say 3 way, or part horn-loaded) would reap more benefits for the same money?' - a question to be answered later.

Drive Unit



The Vulcan has an 8" bass/mid driver, a Volt unit, designed for Kord by David Lyth, who's also well respected as a PA speaker designer. So Volt units are not only some of the best moving-coil drivers money can buy, but also amongst the few domestic Hi-Fi units that have been developed by someone who's aware of (and sympathetic to) the demands of Rock music.

The bass-mid enclosure is of the infinite baffle variety (a sealed box); compared to a Thiele (pronounced 'Teel') enclosure of equal cabinet size, and using the same driver, this results in an earlier, but more gentle bass roll-off. Power handling capacity in the low bass regions also tends to be increased. If you apply high-level LF (low frequency) signals, or add lots of low bass EQ, the cone will be less likely to bottom (hit the end stops) than in the equivalent Thiele cabinet.

Also in the 'best-money-can-buy' category, the Scanspeak tweeter is an unconventional dome unit, being partially horn-loaded. To readers who've never found dome tweeters convincing on Rock percussion, the Vulcan's tweeter is a revelation, approaching the classic transparent qualities of horns like ElectroVoice's legendary ST350A, or JBL 2309 with crinkle-plate. The basic problem with dome tweeters is that they're rarely designed by people with any cognisance of Rock music, it's potentially large HF (high frequency) content, and the consequent need for the tweeter to handle lots of top-end energy. So most dome tweeters lack sensible power handling capabilities (at least for our purpose), and easily run into compression/distortion. The Scanspeak is, by contrast, at home on a wide range of Rock program, and there's a marked absence of compression at high levels.

Sensitivity



One of the trade-offs we've already encountered in small, passive, direct-radiator designs is low sensitivity. Vulcan is rated at 88dB SPL, but in comparison to similar units of known sensitivity, a higher figure - say 91dB - seems (subjectively) closer to the mark. Of course, it'd be easy to measure the sensitivity, but which of several measurement techniques is valid? In fact, arguing over differences of a few dB in sensitivity figures is pointless, particularly when comparing speakers, essentially because results can vary by 3dB or more, depending upon the measurement and averaging techniques employed.

Just as important is power handling capability, which is 120 watts, indicating a theoretical 109dB SPL maximum output level from the Vulcan. And unlike many similar speakers, the Vulcans remained reasonably sweet when pushed — there's little thermal compression, and with a large power amplifier, say 400 watts, you can expect to achieve short term 112dB mean SPLs.

For any monitoring speaker with circa 88dB SPL sensitivity, you're likely to be driving close to the limits much of the time, and, taking note of the dangers of amplifier clipping as it relates to the driver longevity, an amplifier capable of providing 150 or 200 watts into 8 ohms is recommended, unless you're competent at detecting amplifier clipping, and have the self-discipline to drop the level before damage occurs.

Being primarily an up-market domestic speaker, Vulcan exhibits the very low colouration typical of the best speakers in this class. In particular, 'suck-outs' (sharp yet audible dips in the frequency response, a common problem with all cone drivers in the high midrange region) have been judiciously filled in, and the whole mid/top response is free from any obvious colouration or falsification. This unfortunately draws attention to the one unbalanced parameter in the sound, namely the bass lightness. If you're used to large speakers with extended LF (low frequency) response, the Vulcans will sound light, or bright, when used without EQ, and sited away from walls. Yet because the low bass drops gently, and in a regular fashion, without significant peaks or dips your ears will quickly compensate for most of the error. It's rather like wearing blue-tinted spectacles; after a day, your eyes wi|l accommodate the 'colouration', and the world will cease to take on a blue complexion.

Nevertheless, mid/top-heavy sound, however uncoloured, can be uncomfortable at high SPLs. Apart from the customary options of placing the Vulcans close to the wall (which is actually the recommended position), or against the corners of the room, or EQing to put back some of the missing lower octaves, there's another option at this price level - subwoofers. Here, you bring a large diameter driver into play at frequencies below, say, 100Hz, solely to handle the low bass. Because LF sound lacks natural stereo information, readers using purist microphone techniques can get away with a single, mono subwoofer - but that's another story. Instead we put the idea into stereo practice, using a pair of Turbosound TSW18 woofers below 80Hz. Obviously this is a more expensive set-up, but it's still well under three figures, whilst offering results commensurate in many respects to elaborate systems costing many times the price. Not surprisingly, Kord aim to introduce passive subwoofers as an optional extra late in 1984.

With the speakers sitting about 1 metre from the wall, room integration was outstanding, and within reason, results are good wherever you sit, or stand, though an on-axis distance of 10 feet/3 metres gave optimum results in the 12' x 14' listening room. This suggests that the Vulcans would be at home in a larger room, but beware of SPL limitations. At the same time, there's a distinct transition into a more intimate acoustic closer up - at six feet or so - which offers a useful contrast for some purposes.

The Tornado



Tornado is the top model, one up from Vulcan, and again, it's a two-way design. However, the enclosure is substantially larger, and the bass loading is of the Thiele (vented) variety, hence more bottom end sensitivity. Accordingly, the room-integrated response is substantially flat down to 34Hz, (as with other speakers, the frequency response graphs taken in the anechoic chamber aren't particularly relevant to the bass developed in practice - a room-integrated response curve gives a better indication of what you'll actually hear below 500Hz) and so bass lightness with the Tornado is much less in evidence, if not altogether abolished. With this correction, the tonality comes into balance and it becomes easier to focus on other aspects in the midrange for instance. This is fortuitous, in theory at least, because the Tornado's Volt driver (also 8" but a different model) features an exotic plastic cone for reduced break-up. This should improve the midrange clarity and detail, but ironically, the pulp-cone of the Vulcan's Volt driver performs so well that the difference is relatively subtle: both are simply excellent performers.

The bass is also improved - subwoofers aren't necessary (although they're always welcome if you can afford to be extravagant) and only a touch of bass EQ or some corner-mounting should be enough to convince you that there's enough bass. In this, and other respects, the Tornado's relationship with heavy roots-reggae was a good sign. There was a valuable revelation of fine detail which customary heavy-duty systems tend to obscure, and yet the Thiele-loaded bass/mid driver didn't get into problems at the bottom end. Of course, using the Tornados as a main reference for monitoring reggae is ill-advised. Much weightier speakers are needed to handle raw roots music, and higher SPLs, but if you're fortunate enough to contemplate Tornados as a second, auxilliary reference, they'll be fine - just cut the low bass to avoid overexertion in the bass driver. And by all means play your reggae records through them.

Meanwhile, improvements in the bass and mid are mirrored in the treble. The tweeter hasn't changed - it's simply that with the harmonics relating back to more accurate fundamentals, the top takes on the 'silky', ethereal quality that's indicative of the best tweeters - the ones that you don't hear, because there are no obvious tonal abberations to focus on.

Like the Vulcans, the Tornados weren't fussy in a small room as regards listening position, although close-up listening was less desirable - a distance of about 8 feet/2½ metres seeming about optimum again. Imagery was also larger, more spacey, a 'big' sound. The Tornados have the ability to project sound from acutely defined (if virtual) points of 'tension' in space. The fact that the stereo imaging was found to be superior in some respects to a 3-way system costing over £2000 shows that the much advertised theoretical advantages of (less elaborate) 2-way speakers are very real.

Construction



We'll look at the mechanics of both models together, as they're essentially identical in this regard. With their Hi-Fi pedigree, the Vulcan and Tornado can't fail to score highly for their external finish in the less fussy (?) home studio field. Cabinets are 100% veneered (no bare chipboard showing at the back) in real American walnut by a famous, fine English cabinetmaker. Drivers on the other hand are finished anodised with Allen machine-screw fixing, in the best Japanese tradition!

The enclosures are also heavy and substantial with considerable internal bracing of the panels. Both are desirable qualities in accurate speakers. More important for some readers though are domestic considerations, the high aesthetic qualities of these speakers will help to allay some female misgivings about their cost, and the space taken up by sound equipment in the home...

Connection to the power amplifier is with high quality, 4mm binding posts, which will also accept banana and bunched-pin plugs and make good contact with these. All internal connections are soldered. The crossover plays a large part in the Tornado's and Vulcan's integrative abilities, neither speaker sounding like a collection of drive units. It also accounts for the excellent imaging and total absence of audible 'suckout' effects in the difficult 1kHz to 5kHz region. The secret is an asymmetric pair of slopes - one unit rolls off at -12dB/octave, the other at -18dB/octave. By careful design, the overall acoustic output of each unit thus approaches 24dB/octave, and a phase-coherent relationship between the drivers follows. Both designs are certainly free from the usual -12dB/octave and -18dB/octave response anomolies, namely an audible response dip (or peak, depending on polarity) and displaced imaging/no integration between units. Having made the crossover sound quite elaborate, I should stress that it uses few components; inductors are air-cored, the capacitors are plastic film types for the top end, and reversible electrolytics are used in the bass filter section. Designer Mike Fox had previously used expensive plastic film capacitors here, but found that electrolytics (which are easier to source) could be used in the bass end without detriment to the sound, provided they were carefully selected types.

Lastly, the general sturdiness of the fixtures inside the cabinet, and the fact that all the screws employed are either retained with paint, or are very tight suggests that both the Vulcan and Tornado would be at home on the road: providing your flightcasing has foam to protect the exterior surfaces from injury, these speakers will clearly stand a lot of rough travelling.

Conclusions



Summing up, both the models reviewed here exhibit SPL limitations making them adequate for some purposes, but not for all. But then the demand for monitoring loud often stems from a need to perceive details in the sound, so to some extent the SPL limitations are compensated for by the very high level of accuracy available from both models. Here, they are equal in this analytic regard, (if not better) to top-flight studio monitors at three or four times the price.

In a nutshell, the Vulcan and Tornado are befitted to readers who are concerned with the fine details in sound as opposed to overall textures.

Shortform Specification

Vulcan Tornado
Power rating 120 watts 150 watts
Sensitivity @ 1w @ 1m 88dBSPL 88dBSPL
Frequency response (anechoic) +/-2dB over 160Hz to 20 kHz 100Hz to 20 kHz
Room integrated response substantially flat at 52Hz 34Hz
Impedance 8 ohms 8 ohms
Size (H x W x D) 20" x 10½" x 9¾" 23½" x 10½" x 11"
(508 x 266 x 247mm) (600 x 270 x 285mm)
Price per pair, (including VAT) £399.00 £557.00


The Vulcan and Tornado are available ex-stock from leading Hi-Fi dealers, or direct from Kord Audio Products Ltd., (Contact Details). For a limited period of 28 days from the date of this issue's publication, Kord are offering a special 15% discount to HSR readers.



Next article in this issue

Active Speaker Systems


Home & Studio Recording - Copyright: Music Maker Publications (UK), Future Publishing.

 

Home & Studio Recording - Dec 1983

Donated & scanned by: Mike Gorman

Review by Ben Duncan

Previous article in this issue:

> TC Electronics Parametric Eq...

Next article in this issue:

> Active Speaker Systems


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