Sistemas Metalcone de fabricação recente

MJ Acoustics is rapidly becoming a big deal in the world of British audio - but there's more to the brand than its well regarded subwoofers. They also make complete speaker systems, like this one, which I've lusted after since spying it at the recent London Heathrow hi-fi show.

As soon as I clapped my eyes on it, I wanted to indulge myself and asked if HCC could be first in line for an audition. The company agreed, and here we are. Ladeez and Gennelmen, may I introduce the Subliminal home theatre speaker system, married to MJ's new and very cunning MkIII version of its Reference 1 subwoofer!

For boxes that look small and slabby, they come in some of the weightiest for- size cartons I've ever encountered. The Subliminal S1R front speakers stand just short of a metre tall and have big wooden bases. They're made of thick MDF with a furniture-grade veneer on the surfaces, and solid timber end-pieces to match the wood of whatever veneer you have. They're only 104mm deep, yet enclose a long transmission line organ pipe type enclosure within. They weigh a ton, and yet are packaged in pairs, fully assembled - there's no Ikea-style screwing-on plinths to contend with.

The carton is filled with polyurethane custom-cut packaging and even that weighs a good bit when empty. To unpack, you'll need a mate's help. Unfortunately, I don't have any, so had to manage on my own. Thankfully, I weigh a ton myself so was able to sort of grab on, lean back and generally lever the things into position.

The Subliminal S1R has a single hole underneath and sports a single speaker post cup on its rear. The enclosure has but one 4in aluminium coned loudspeaker driver in its face under that neat cloth grille. The shiny cone is surrounded by a very soft and compliant surround that allows the driver to play way down to 40Hz in this cabinet, and 55Hz in the smaller monitor-shaped product, called the Subliminal S1RM, as in er, monitor.

The other three enclosures in this 5.1 system are smaller, costing £500 each compared to the £2k per pair for the tall S1Rs. Again, there's a single port out the back, which is the mouth of another transmission line enclosure. Famed for making small drivers deliver the most disproportionately huge amounts of bass versus their surface area, these T-L boxes need to be vast versus their driver's cone area, so even a simple 4in can wake the dead with low frequencies.

So we know transmission line speakers make deep lows, but how do they make the highs? For they most assuredly do: bright, transparent, fast even. With a reach that goes 2,000 cycles above our theoretical 20kHz limit of high-frequency hearing, these speakers can be easily paired with Super Audio CD and DVD-A hardware.

The speaker units themselves owe some of their creation to Ted Jordan, one of the fathers of modern hi-fi transducers and drivers, as the use of actual cone flex is part of the HF response. Above a certain point, the cones vibrate within themselves as well as acting like a low compression piston for the bass tones.

The product uses no caps, no coils and no resistors. There's nothing inside but silver soldered wire to connect the speaker leads up to the driver; this results in a purity and clarity which appeals directly to the sensitive midband hearing zone. Vocals are remarkable, detail is utterly pin-sharp and the weight of bigger sounds is inescapable.

Stereo version

S1RM

The S1RM's adopt a transmission line cabinet design and they have no electronic crossover. A single 4" full-range driver with molecular vibration technology is used to provide frequencies between 40Hz - 22KHz. The driver flexes throughout the frequency range to produce crisp, clean treble frequencies without being sharp or cheeky and tight rigid bass register frequencies.

Reproduction of female vocals is detailed and enjoyable to the ears, unlike many two-way speakers where the tweeter can make a feminine vocal sound harsh and too bright. Mid range frequencies have excellent definition and provide a wide sense of depth and display superb stereo imaging.

With its aluminum die-cast chassis, "Controflex" metal foil diaphragm and unique spider that attaches to the cone's center via a light metal tube passing axially through the magnet, the JX92s is very special.


Rather than extending HF reach via a Whizzer cone in Lowther-fashion, Jordan uses a dustcap-tweeter dome that's driven not from its own butyl suspension, voice coil or motor but the surrounding cone area of the woofer to which it is affixed - hence the Controflex* designation. It points at very sophisticated materials-science flexure patterns that, in a nutshell, allow the driver's center to act in relative independence as a dome tweeter, distinguishing it from the discrete separation of coaxial driver designs.

*Controflex veja: http://www.novacon.com.br/audiogmar.htm

In Ted Jordan's own words: "Basically, whereas conventional designs endeavour to make the cone as rigid as possible, we accept the fact that it is impossible to maintain this rigidity throughout the audio range. At high frequencies, the cone will flex. We have chosen to work with this deliberately. Our cone profile has been developed to control this flexure such that the effective cone diameter decreases progressively with rising frequency. The ratio between effective diameter and frequency has to be closely defined to match the characteristics of the radiation resistance imposed by the air load. This approach has to be used in conjunction with a specially designed low-mass voice coil but in effect the centre of the cone becomes its own tweeter."

As the published response curve indicates, extending flattened LF reach below 100Hz requires clever cabinet reinforcement. Today's review subject, the Konus Audio Essence loudspeaker, thus uses a quarter-wave triple-folded transmission line. It also incorporates classic instrument-tuning techniques, 3/4-inch resin-impregnated MDF construction, real wood veneers and associated specialty curing with a 6-layer lacquering process. To optimize this driver's response in the absence of the usual electrical network compensation circuits? It cost designer Sead Lejlic endless trial-and-error iterations. Simply, computer modeling can't predict what cabinet shop trickery is required to smoothe and extend frequency response with MDF alone. Understandably hesitant to give away hard-earned secrets, our Bosnian cabinet tuner and European distributor for 47Lab instead smirkingly invokes the 5th. He trusts that our ears will either embrace or reject his solutions. In the latter case, design disclosures won't remedy such reactions. In the former, they'd do little to enhance our enjoyment save for allowing copycats to short-circuit their own learning curve.

Projeto precursor:

Labirinto acústico: http://www.novacon.com.br/audiogecld8.htm 

O duto de abertura fica na parte traseira .

Como no protótipo temos um labirinto de três vias com  ¼ de comprimento de onda A abertura no fundo tem área semelhante à do alto falante.

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