B.M.C. Audio Arcadia 喇叭

[Leo Yeh]

在今年2012的CES上，B.M.C.發表的第一對喇叭讓我非常驚豔，有著非常傑出的表現，現在官方有進一步的新聞稿
Arcadia是bi-poloar設計，喇叭正面與背面的單體完全一樣，使用自家特製的單體與外接的分音器
使用陶瓷為基礎的箱體，其也是此系列3對喇叭首先發表的第一對，預估價格約在USD 39,000

單體
two 6.1-inch Kevlar-Honeycomb-sandwich midrange drivers
an Air-Motion ribbon tweeter with a massive motor in conjunction with a light diaphragm
Two 11-inch Kevlar-Honeycomb-sandwich woofers with multi-magnet

http://www.bmc-audio.com/







B.M.C. Audio announced the Arcadia bi-polar floor standing loudspeakers for audiophiles, built with custom drivers, external crossover, in a ceramic-based cabinet. It is their first model in an anticipated series of three new speakers.

In developing the Arcadia, B.M.C. Audio didn't simply assemble a collection of off-the-shelf parts -- it profoundly re-examined how speakers best work. As a result, the Arcadia is as technologically sophisticated as it is stylishly designed. The three-way speaker sparkles with daring innovations -- from its bi-polar balanced configuration and ceramic-composite cabinet to custom-made drivers; plus an external crossover for each speaker system offering an impressive 28 jacks for ultra-flexible & upgradable connections for one or multiple amplifiers, the woofers and midrange drivers, and the Air-Motion tweeters.

Most conventional speakers, for example, project good depth of image in the center of the soundstage, but much less so at the sides. The Arcadia's bi-polar design, which features the same driver set on the rear as it does on the front of the cabinet, dramatically improves the listener's impression of depth at the left and right sides of the soundstage, making the soundstage more complete and realistic.

The Arcadia is also a balanced speaker. Both front and rear baffles feature two 6.1-inch Kevlar-Honeycomb-sandwich midrange drivers and an Air-Motion ribbon tweeter with a massive motor in conjunction with a light diaphragm for superb acceleration and high sound pressure capability. Two 11-inch Kevlar-Honeycomb-sandwich woofers with multi-magnet drives at the sides of each cabinet deliver impressive air movement.

B.M.C. Audio Arcadia Woofer

The speaker's striking cabinets are constructed of an exclusive, innovative ceramic-compound B.M.C. calls Megalith. In development since 2002, this is a dense, acoustically optimized amalgam of several aluminum-oxide-based ceramics with multiple grain sizes held together with complex acrylic binders. Unlike Epoxy or phenolic binders, the Arcadia's acrylics remain stable for decades.

The cabinet's advantages include an absence of base and midrange coloration, greater stiffness, and a lower internal energy loss than is possible with any cabinet made of wood. Resonance-free and rigid, the cabinet is also free from the effects of humidity and thermal elongation. In fact, the fusion of its parts is more like chemical welding, so that its elements react as a single, seamless piece. Three thin raised panels on each of the cabinet's sides emphasize its graceful verticality, and create a slim profile that helps the speaker comfortably fit in most living rooms.

B.M.C. Audio Arcadia External Crossover
The crossover, uniquely, is external, and weighs 37.5 lbs. Being external frees it from internal sound pressures, and makes it easy to upgrade with future solutions designed to improve the sound even further.

B.M.C. Audio custom designed all the Arcadia's drivers. They feature honeycomb-Kevlar cones that are light, stiff, and free of resonance and coloration. Rather than use the traditional single magnet per woofer, B.M.C. Audio embedded each Arcadia woofer with 6 magnets arranged in a ring. This yields an exceptionally dense magnetic field for long linear excursion range of 0.27 inches.

Also unconventional, B.M.C. Audio custom crafted all the Arcadia's key elements, including its large air-inductors, inductance-free polypropylene capacitors, unique polystyrene 'by-passers'. Metal-film resistor arrays replace the usual MOX or wire resistors for superior precision and sound quality.

Arcadia applies a sealed construction process, avoiding bass-reflex resonances and significantly improving bass precision. The power of the drivers, and the cabinet's low energy loss, more than compensate for any loss of oomph in the sound. Each cabinet stands 47.2 inches high by 20.4 inches deep by 11.2 inches wide at the base, tapering to a narrow width of 7.7 inches at the top. Despite its relatively compact dimensions, each speaker weights 198 lbs., excluding the crossover.

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Also notable, and unusual, is that the cabinet is made from a mold, which means the color is not applied later but added directly into the mix and solid all the way through for a non-glossy finish. A bonus of the process is that scratches can be buffed away without worrying about ruining the surface. B.M.C. applies a transparent lacquer for a high-gloss finish.

Price and Availability
The Arcadia speaker is available from Aaudio Imports, its North American distributor, in a black or white satin or high gloss finish at a suggested price under $39,000/pair.

[167]

高音是德国Mundorf的气动高音（Air-Motion ribbon tweeter ）

[francisleung]

看過Leo Yeh兄的资料，覺得Arcadia的設計有兩點與我的構想吻合，故此在這裡談—下。
1. "28 jacks for ultra-flexible & upgradable connections for one or multiple amplifiers" 我計了多次才估到。每邊前、後共六個中高音，另加兩個低音。(3x2)x2+1x2=14 jacks, 即七對正負。從表面看，每邊可用六單聲道(六對正负)或是單—聲道擴音機推動(一對正负)。—聲道推—單元是我所喜歡的做法。BMC的網頁没有揚聲器，故此不能查證我的估計。德國公司很少這樣遗忘的。
2. "a narrow width of 7.7 inches at the top" 單元是6.1吋，所以木邊只有0.8吋 (2x0.8=7.7-6.1)。窄的邊板是减少diffraction, 從而改善擴散。我的中高音line source都是—吋。
另外顺帶談—下其它的。
Air Motion Ribbon Tweeter。這款高音我不認識。我知道aluminium tweeter( 我—直用開), 是利用磁鐵的正負極使它發聲。Air Motion Transformer 我知—點點。是Heil所發明，專利巳過期，故此近年很多人做，我聽過示範的有Volent 和FAL(日本京都)，但都是中音，是壓缩單元缝的空氣來推動外圍的空氣。這個用air motion 來推動ribbon的高音，我就不知道是怎樣操作。
BMC的DAC, 我在它的網頁看到是用Burr-Brown 1792. 我燒毁了的舊DAC亦都是用1792A (多了個A)，聲音還可以。

[Leo Yeh]

The Air Motion Transformer is not from Mundorf, even if it might look similar. This tweeter is made especially for us, according to our specification, with very strong neodymium magnets.

If you need any further information, please feel free to ask.

Best regards,

Michael

[Leo Yeh]

B.M.C. Audio Arcadia Bipolarer Megalith-Lautsprecher: Download (1,3 MB)

[Leo Yeh]

B.M.C. Audio Arcadia Bipolar Megalith Speaker: Download (1,3 MB)