Review

Esoterix Complete Review - Australian Hi-Fi - Australia

01 May 1996

It's not hard to pick a Krix from the pack. Just look for the speakers that have perfectly matched, hand finished veneers (and that includes the rear panel!) state-of-the-art drivers, properly implemented crossover networks, superb instruction manuals and incredibly solid cabinets.

The only real problem with following these instructions to the letter is that you'd still be left with a fairly lengthy list of heavy-weight contenders, which would include some of the most famous names in hi-fi. However the coup de grace, is that you should now add price into the selection process. Et Voila, le Krix!

The Equipment

Lest I have given you the wrong impression, Krix speakers do not hail from France nor, unlike many 'Australian' loudspeakers, do they incorporate French drivers! The company is all-Australian, operates out of South Australia, and uses drivers from several regions, but primarily from Scandinavia. Other than drivers, which it doesn't make, Krix is one of the few Australian companies that makes everything in-house. Cabinets, crossovers...you name it.

The reasons for this have to do with quality and pride. Scott Krix (Head of the companies design team) is proud of all his speakers, and very conscious that his family name is emblazoned on the grille of every one. He maintains that having complete control over one's product is the best way to guarantee quality.

You only have to look at an Esoterix 1 MkII cabinet to realise that Krix has put a great deal of thought into the design. For example, although it's a floor-standing speaker of impressive dimensions (955 x 225 x 433 mm) it has been supplied with its own 'pedestal' and just the right amount of backwards tilt to put the tweeter at ear level for a normal seating position a normal distance from the speakers. Perhaps more importantly, this means that when you're further away, and therefore probably standing, or seated on some higher chair (perhaps a dinner table) the tweeters will still be aimed correctly.

However, the cabinet's construction is not merely for technical reasons, aesthetics also play a part. The pedestal, for example, tends to break up the 'bulk' of the speaker, making it more visually attractive. Krix has also cleverly put a tiny gold trim between the main body of the cabinet and the front baffle, as well as deliberately contrasting the cabinet veneer with the baffle veneer. All these elements combine to ensure the Esoterix 1 MkII is not only functional, but also makes for an attractive piece of furniture.

As should be obvious from our photograph, the Krix is a three-way design. The reason for the widely-spaced drivers may not be immediately apparent. The midrange driver is positioned immediately above the tweeter to ensure that instruments whose fundamental frequencies travel through the crossover frequency (at a nominal 2.2 kHz) do not appear to 'shift' physically in space. However, it's the accurate placement of harmonics that is perhaps even more crucial, because few musical instruments can produce notes at or above 2.2 kHz. It is these harmonics that give acoustic instruments their characteristic 'tone' or sonic characteristic, so it's absolutely essential that harmonics should appear to issue from the same apparent point-source as their related fundamentals. (It is important to remember that if instruments did not produce harmonics, you would be unable to tell a flute from a violin. And it is only because each instrument produces its own unique set of harmonics, that we are able to tell a Stradivarius from an Amati, or a Maggini).

The bass driver, on the other hand, is positioned so it can take advantage of the proximity of the floor, to provide some acoustic loading, and also so the bass driver can operate from its own unique bass-reflex environment, the main chamber of which is differently damped to the sub-chamber that backs onto the midrange driver and tweeter. (Note however, that the midrange actually operates from a totally sealed plastic tube, and the rear of the tweeter is sealed, so what is in this sub-chamber affects only the bass driver, and not the midrange and tweeter).

The bass driver is made in Norway. Rated by Krix as having a diameter of 210 mm, Australian HI-FI's super-accurate tape measure put the effective cone diameter at 155 mm, giving an effective cone area of 188 cm2. We couldn't determine the origin of the 210 mm specification, because the diameter including roll surround is 182 mm, and the overall diameter of the frame is 215 mm.

The bass driver's cone is made of polypropylene, and the surround of rubber; in other words, materials which are inherently environmentally stable-even in Australia's difficult climate. (Regular readers of Australian Hi-Fi Magazine will already know that roll surrounds made from foam which is most of them will eventually rot and disintegrate in most regions of Australia).

The basket is also impressive. It's made from magnesium, rather than flux reducing steel, and is cast, rather than being pressed. According to Krix, it uses a T-shaped magnetic circuit and a voice coil that's 39 mm in diameter. The cable connecting the bass driver to the crossover is un-branded, but tremendously thick and will carry more current and voltage than the bass driver could ever possibly require. Krix says the copper in this cable is oxygen-free and there's not a spade-lug in sight the wires are silver-soldered to both the driver and the crossover.

The crossover is not mounted on a PCB, but is instead completely hardwired, which would be quite a project, considering the component count includes five hand-wound inductors (three ferrite cored, two air cored), eleven (count them!) capacitors (mostly bi-polar electrolytic types), and eight wire wound ceramic resistors. The crossover complexity is caused at least in part by the fact that the Esoterix 1 MkII is tri-wirable/tri-ampable. One suspects a little overkill here, because although most audiophiles of my acquaintance either bi-wire or bi-amp, I know only one diehard (hello Bob!) who tri-amps. Still, it's always nice to know you can tri-amp...even if you don't want to!

The midrange driver is also made in Norway, and also uses a cast magnesium chassis, polypropylene diaphragm and rubber roll surround. Although the effective cone area of the midrange driver is not particularly significant (though it should not be too high, of course), we were interested to discover that once again, we could not measure the 120 mm diameter claimed by Krix, with the driver having a total moving diameter (cone plus roll surround) of 112 mm, and an effective cone diameter of just 92 mm. The frame itself is not circular, but the smallest dimension is 133 mm, and the greatest, 149 mm. The wires connecting the midrange to the crossover are relatively thin, and appeared to be some type of silver-coated copper. Despite the smaller diameter of the wire, it is soldered to the terminals of the speaker. The rear of the midrange driver fires into a tubular plastic subassembly that tapers to a small rounded 'point' at the far end. This tube is stuffed with Australian merino wool, a material that's far superior to fibreglass in every respect. Although Krix's literature appeared to me to intimate the damping is pure wool, it's in fact only 90 per cent pure. The remaining 10 percent is an artificial polyester fibre.

The tweeter used in the Esoterix 1 MkII issues from the factories of ScanSpeak. It's a D2905, a 28 mm textile dome type that uses ferro-fluid to assist with damping, cooling and efficiency. The same silver-coated wire is used to connect the tweeter to the crossover and, once again, Krix has elected to silver-solder the wire at both extremities.

Nominal crossover frequencies for the Esoterix 1 MkII are 340Hz and 2.2kHz, and Krix says the filters are: "Designed to exhibit acoustic 1st and 3rd order slopes."

At a time when cabinets are becoming thinner and thinner, with 12mm even 9mm wall thicknesses appearing on some famous foreign brands, I was encouraged to learn that Krix cabinets are as thick as or thicker than they ever were, with 25mm board being used not only for the front baffle, but also for all panels. Not satisfied with this, there's also internal cross-bracing and reinforced corners. Internally, the bottom portion of the cabinet is filled with expanded, open-cell (but high-density) foam. At the top, as mentioned previously, the cabinet is filled with the 90/10 Merino/polyester mix. Due to the thickness of the cabinet, and the weight of the crossover and drivers, I was not surprised to find each cabinet weighing in at around 30 kg.

The terminal block at the rear of the cabinet is massive holding, as it does, three pairs of huge, gold plated five-way speaker terminals to facilitate tri-wiring. If you only want to bi-wire, or use just the one set of wires, the terminals can be joined with thick, flat sections of gold-plated metal, which is provided. Above the terminal block are two bass reflex ports, each one of which is stuffed with a low density, open cell foam vent plug, to allow more accurate bass tuning in the event that your room places some constraints on speaker positioning. Krix says the Esoterix 1 MkII will perform best without the vent plugs in place, and with the speakers positioned 400 mm from a rear wall. If this puts the speakers too far out into your listening room for your liking, the solution is to push the speakers back towards the wall (but never closer than 150 mm) and insert the resistive vent plugs, to tame the level of bass reflecting from the rear wall.

Wherever you look on the Krix, you can see attention to detail. The wires from the subassemblies are glued to prevent air leaks, all three drivers are gasketed before being attached to the front baffle and wires are colour coded to avoid confusion. The drivers, although they're affixed with screws rather than the more expensive bolt/captive nut arrangement, are fixed with star headed screws, rather than inferior posidrive types.

This attention to detail is perhaps nowhere more evident than in the information Krix provides with each pair of speakers. You get a performance graph (MLSSA), specifications a plenty, helpful information about where to best position the Esoterix 1 MkII's in your room and an extremely useful four-page brochure titled 'A Guide To Safe Operation' which clearly explains the mechanism of amplifier clipping and how it (adversely) affects loudspeakers and may result in damage that would not be covered by warranty. The brochure also clearly explains how incorrectly setting your tone controls can also result in loudspeaker damage.

Listening Sessions

Positioning the Krix Esoterix 1 MkIIs correctly could take a little time, and require some rearrangement of the larger items of furniture in your room, but I'd wholeheartedly recommend you apply yourself, because the effort you put in will be amply rewarded.

In particular, ensure the rear-firing ports are not damped in any way (such as by a curtain or drape) and that they 'fire' into identical materials (that is, not a window for one speaker and a brick wall for the other). I'd also recommend not using spikes with these Krix speakers, because I thought bass performance was slightly more melodic and warmer without spikes.

I also felt that performance was marginally improved with the speaker grilles removed, though the difference is so slight that if you have small children or sharp-clawed cats, I'd play it safe and leave the grilles in place.

The sound of the Esoterix certainly benefits from extended running-in, to a greater extent than any other speaker I have listened to this year, in my opinion. I don't know whether this is because the drivers Krix is using have particularly stiff suspensions, or if it's something to do with the 'dynamic damping' system Krix claims to use, but the end result is that a non-run-in pair of Esoterix 1 MkIIs is chalk, and a run-in pair is cheese, the difference in sound is that dramatic.

I also found that even when fully run-in the Esoterix 1 MkIIs took a few minutes to come to full bloom each and every time the amplifier was switched on. Once again, I'm not sure of the reason, but I suspect the complexity of the crossover might have something to do with it. Whatever, if you want to impress your friends from the outset, play a track or two before they come into the room to listen. (And, just in case readers think it was the amplifier warming up that changed the sound, it wasn't. I checked this by the simple expedient of leaving the amplifier on and disconnecting the loudspeakers, then reconnecting them after several hours...so it's definitely the speakers. Obviously, this small operational quirk will not affect listeners who leave their amplifiers on permanently.

Optimally positioned, run in and warmed up, the bass performance of the Esoterix 1 MkIIs is something else again. I found the quality of the bass to be more reminiscent of a perfectly-tuned transmission line enclosure than of a bass reflex enclosure. I tend to find that the bass sound issuing from bass reflex enclosures can sometimes tend towards 'tubbiness', where one imagines a slight acoustic roundness on notes. This just doesn't happen on a good transmission line it's a hard, flat stomached bass that seems to warn pianists to make lefthand errors at their peril, and for bass guitarists and double bass players to play like their replacements were waiting in the wings. And, as I said, the Esoterix 1 MkIIs' bass has all those sonically-desirable transmission line enclosure qualities it's tight, it goes deep, there's absolutely no doubling and the tonal control is exquisite.

The acoustic crossover from the bass to the midrange is perfectly seamless, even from quite close distances, and I never had any sense of there being two drivers involved. The midrange itself is pure and accurate, no matter whether it's being driven hard, or idling along in the late hours of the evening. Strings sounded beautifully real with the Esoterix.

High frequencies were glassy and extended, with flutes, violin harmonics, and percussion sounds being reproduced with surprising realism. I never had any sense of the upper harmonics being restricted, or made dull, and performance was as good off axis as it was on axis. In terms of overall sonic balance, I think Scott Krix has struck an excellent balance between the sometimes too-clinically dry sound one hears from top-end British loudspeakers and the equally slightly too live sound preferred by US speaker manufacturers. Which is not to say that I think the Esoterix 1 MkIIs fall exactly in the centre in fact I think the sound is skewed slightly towards the US sound. That is, a bit brighter.

What will no doubt impress listeners right from the start is the ability of the Esoterix 1 MkIIs to resolve the spatial position of instruments albeit only on properly-recorded CDs of acoustic instruments. When listening to orchestras, one can easily point out the positions of the various instruments and, when listening to Handel's Messiah, for example, I didn't have to think twice about the relative positioning of the four soloists in fact I could actually hear them approach the microphones! Given this kind of precision, positioning the players in smaller 'classical' ensembles (quintets, quartets) and jazz ensembles (trios, quartets) was a breeze.

Another area where the Esoterix 1 MkIIs proved their superiority was in their ability to create an excellent facsimile of image height. Indeed they were so good at this that I wondered whether the unusual driver spacing was the major contributor to the effect. I would certainly recommend taking image height factor into account when auditioning, however, I should point out that you will get best image height performance only when you are seated at least four metres from the speakers and, unfortunately, most of the audio showrooms I've seen aren't big enough to allow proper auditioning at this distance. If you listen too close, the illusion of height seems to diminish.

Despite Krix's recommendation, I personally preferred the overall sound balance of the speakers without the acoustic plugs, and when they were only 150 mm from the rear wall. Obviously this will depend on the size and acoustics of your room, as well as your own personal tastes, but it does prove that one should not blindly follow manufacturer's recommendations when it comes to positioning.

And speaking of manufacturer's recommendations, Krix recommends "amplifiers up to 200 watts RMS" and here I'd agree totally. In fact, with these speakers, it's a case of the more power the better. They're not efficient and, because they don't really go below 5 ohms, you don't get much advantage from a high current amplifier. I'd suggest a minimum amplifier power of at least 60 watts RMS per channel and I'd prefer something in the region of 80-110 watts. Of course, if you can afford a 200 watt per channel amplifier, buy one by all means, but this may be gilding the lily a little for average domestic applications.

Conclusion

My Macquarie dictionary defines the word esoteric (from which the name of this loudspeaker is surely derived) as being "understood by or meant for a select few". If this is indeed the case, I guess I can't agree, because I think everybody deserves to have access to the type of sound quality the Esoterix 1 MkIIs can provide and in this case, because of the very reasonable asking price, they can!

- Australian HiFi - Australia , Greg Borrowman

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