Review

KDX-C, KDX-M & Seismix 5 Complete Review - Australian Hi-Fi - Australia

01 Feb 2000

Readers who over the past twenty-seven years have become familiar with Krix’s admirable habit of giving its speakers names (almost always ending in ‘x’) rather than model numbers might be forgiven for thinking this South Australian manufacturer has taken a backwards step by calling its first complete, integrated home theatre speaker system ‘KDX’. The letters KDX stand for Krix Digital eXperience, and for a complete five-channel system, you need a pair of main speakers (KDX-M), a centre channel (KDX-C) and a pair of surrounds, for which Krix recommends you use a second pair of KDX-m speakers. For the deep bass, you have a choice between the Krix Seismix 7, Seismix 5 or Seismix 3.

KDX-M/KDX-C

For some years now, since the introduction of Dolby surround sound in fact, we have been telling readers that the three front channels in a home theatre speaker system should use identical drivers. Very few of the systems we see, however, ever fulfill this basic criteria. We’re pleased to be able to report that Krix has got it right. The KDX-C is almost identical to the KDX-M – same drivers, same cabinet, same everything. Well…not quite everything. The crossover network in the centre channel is very slightly different, partly to compensate for the horizontal orientation, which tends to increase the bass output. If you are using all three speakers in a vertical configuration (as you might if you use a video projector rather than a conventional TV) you should replace the KDX-C with a single KDX-M.

The bass/midrange drivers a paper-coned drivers, which are attached to a cast magnesium basket by a rubber roll surround. All the cones are doped, which reduces the propensity of paper cones to be hygroscopic and also makes the cones more physically robust. The use of rubber is also to be admired, since rubbers are far more durable that the relatively fragile foam surrounds used by manufacturers unfamiliar with Australia’s harsh environmental conditions. All drivers also use a double-magnet assembly that is shielded, so that any of the speakers can be put near a television. Although Krix rates the bass/mid drivers at ‘5 inches’ (sic), the overall moving part of the cone, including the roll surround, is 110mm and the cone diameter itself is just 92mm.

Krix uses the same 25mm soft dome tweeter in both the mains and surrounds, positioned directly midway between the two bass/midrange drivers, D’Appolito style. In the KDX-M, the nominal crossover point is 1.6kHz, as against 1.5kHz in the KDX-C. The tweeter is also shielded.

The cabinets (which are beautifully finished, because Krix makes all its own cabinets, in what is probably Australia’s best equipped factory) measure 435 x 185 x 280mm and weigh 8 kilograms. This weight comes about both because of the weight of the two bass/midrange drivers and because Krix is using 17mm thick MDF for the cabinets. The enclosure is bass-reflex, with the port venting to the rear. The nominal impedance of both systems is 8 ohms.

Seismix 5 Subwoofer

Krix’s Seismix 5 powered subwoofer is virtually a carbon copy of the award-winning Seismix 7. It’s only when you place them side by side that you realise the Seismix 5 is physically smaller (though at 430 x 575 x 415mm it could hardly be called ‘small’). The bass driver is nominally 300mm in diameter, with a corrugated paper cone. (Out tape measure put the diameter of the driver, including the pleated surround, at 290mm. The effective cone diameter is 245mm, for a cone area of 471cm2.) This driver has a huge 50mm voice-coil, which is wound on a Kapton former that moves in and out of a 4kg magnet assembly. This is driven by a low-distortion (0.03% at 160 watts) power amplifier that Krix rates at 200 watts. Associated with this amplifier circuit are a clipping protection circuit and short-circuit protection.

Like all sensibly designed subwoofers, the Seismix switches itself on and off automatically, using signal sensing at the audio input. The input itself is actively filtered, using a variable 3rd order low pass filter, with a 45-95Hz range. A single phase switch is provided that can adjust signal phase by 180 degrees. The two controls are located on the front panel with the volume control, above three LEDs that show the status of the in-built limiting circuit, and power (on/standby). One problem with mounting this panel on the front is that it is underneath the grille cloth, so you can’t see these LEDs while the grille is on, neither can you adjust the controls. The rotaries are ‘set and forget’, but we’d like to keep a weather eye on those LEDs!

Listening Sessions

Installation went smoothly, though when it came time to mount the centre speaker in a real installation, we realised the rear-firing bass reflex port on the KDX-C somewhat curtails installation flexibility, particularly if you have your TV mounted in a shelving system. The size of the KDX-C also means it may have a somewhat precarious perch if you place it atop your TV. Alternatively, if you try to perch your TV on top of the KDX, you’ll have to provide additional support for the set behind the speaker, as well as allow space for the rear-firing port to ‘breathe’.

Not that we ever had any doubts about the importance of timbre matching, particularly across the front channels, but if we did, a few moments listening to the Krix KDX system would be all we’d need to allay them. The coherency and uniformity of the front sound stage was simply exceptional. One of the first discs we fired up was Denon’s fabulous multi-channel version of Beethoven’s Third Symphony (Eroica) plus Chopin’s Piano Concerto No2 in F Minor (Op 21) {Denon DEG-02001}. The entry of Vladimir Krainjew (piano) is a revelation, because you really get to hear a real piano, centre-stage, not a piano that appears to be as wide as the full stage, or one whose sound is compressed and one-dimensional.

We do sometime have doubts of the necessity for surround speakers to be identical to those in the front channel, primarily because they’re operating with a different acoustic loading. However, listening to the Krix KDX, there’s no doubt that when you used matched speakers, the surround effect is considerably enhanced. Curiously, this is not so much with movies, where the surround effects tend to be environmental (wave noises, trees rustling and so on) or in-your-face (explosions, jet fighters) but with music, where the focus and overall sound field seems smoother and more natural with matched speakers.

The Seismix 5 proved to be more than capable of filling the room with thunderously loud, deep bass, which served to reinforce a niggling feeling that the flagship Seismix 7 might be a bit of overkill in the average Australian lounge room. If you can’t shake the walls and rattle the windows with the Seismix 5, you’re not really trying.

Conclusion

With its history steeped in commercial cinema applications (the company is one of the world’s leading suppliers of commercial cinema systems) Krix was always going to be perfectly placed to extend its expertise to the home theatre market, and this KDX system proves it has made the transition effortlessly.

- Australian Hi-Fi Best Buys - Australia , Greg Borrowman

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