关于NXT专利技术 - 行业动态室 - 声学楼论坛

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如今当平板音箱摆在我们面前的时候，我们已没有半点惊奇。因为，科技发展得太快，新东西层出不穷，缤纷的世界已让我们眼花缭乱，处事不惊了。平板音箱以低廉的价格已经“飞入”寻常百姓家，一套2.1的平板音箱只要200余元，其实这是NXT技术的“功劳”。
透视NXT技术
有人称NXT技术是扬声器技术的一次革命。从理论上讲NXT技术的确有比传统扬声器技术先进的地方，它可以解决传统扬声器中存在的许多难以克服的问题。
第一、传统扬声器的中、高频（特别是高频）有较强的指向性，即：扬声器发出的高频率音频信号，在其轴线上的衰减是按照距离增加一倍，信号强度减少6dB的规律进行的。而当偏离轴线时，中低频仍按这个规律衰减，而中高频就不按这个规律衰减了，而变成衰减得更快。因此用传统的扬声器听音时，当聆听者偏离扬声器轴线时，就会明显觉得声音中应有的高频成分少了。而NXT技术则是采用了一种叫做“分布式薄膜”（DM）的核心技术，使一块特殊材料的振膜产生无规则振动，这种无规则的振动效果就像振膜上存在许多方面各异的小高音单元，这样就使得音频的中高频部分无指向性。
第二、传统扬声器的频响与振膜质量有着密切的关系，即振膜质量越大则扬声器的高频特性越差。与第一条中相同的原理，DM技术可以使采用NXT技术的扬声器的高频特性不受振膜质量的影响。
第三、由于DM技术的辐射特性较特殊，振膜在其前后两面所产生的声波相位是同向的，声能是前后叠加的。而不像传统扬声器那样，振膜前后的声波是反相的，声能是相互抵消的，因此，传统的音必须有箱体隔断振膜前后不同相位的振动，以防止声能抵消，而NXT技术的扬声器就完全可以甩开音箱箱体，把它做得非常薄。
第四、由于薄膜材料的特殊性，它可以克服振膜自身谐振而带来的“声染色”，从而使扬声器的声学特性比较平直，声音比较清澈透明。
第五、由于NXT扬声器的振幅非常小，不会使所有的振动元件产生大幅度的非线性振动，因此NXT扬声器的谐波失真也会远远小于传统的扬声器。看着NXT技术有这么多的优点，你是否动心了？是否也同意NXT技术是扬声器技术的一场革命？是否想马上就拥有一对采用NXT技术的多媒体音箱？实际上关于NXT技术的优点这里还没有罗列完，全部讲完你也许会更心动。NXT的驱动技术与传统扬声器技术是采用电磁转换技术，它们最大的差别是振膜的振动方式。
简述“平板”音箱
那么采用NXT技术的音箱使用效果如何呢？说实话，在NXT技术推出之前，大家对此期望较高，但是在产品上市之后，人们却是失望多过于希望，主要是其声音的质量不能让人满意，一是没有低音（200Hz以下的），二是中高音箱比较还是有一定的距离。后来有的厂家采用2.1方式，增加了一个超重低音箱后，低音不足的问题基本得到解决。但是中高音一直还是不理想，直到最近我在市场上见到一款“麦兰”的M-400后，这个印象才稍有改变。但是M-400声称没有采用NXT的专利技术，而是“绕过、改进、发展”了这一技术，从而使声音更好，也不用再向NXT交专利费，使成本更低。我们暂不管此款音箱如何“绕过、改进、发展”NXT这一技术，单就产品的声音的确有不小的进步。值得一提的是，平板音箱的“面板”都会有漂亮的图画，而它们都可以很方便地挂在墙上，这是普通传统音箱所不能及的。
小结
目前在国际市场上，多媒体音箱中应用NXT技术产品做得最好的是美国KWONG QUEST公司，在家用音响中应用得最好的是日本的NEC公司和英国的乐富豪公司。不过我们也注意到，在多媒体音箱的技术上和市场上执牛耳的美国几大家大公司：ALTEC LANSING、JBL、BOSE等企业对此技术还有着其它的看法或态度。另外NXT的产品要进入高级Hi-Fi音响中的时间还会很遥远。

Audio

HiWave?s techniques for excitation of surfaces to produce sound are in use in many applications ranging from turning cars? roof-linings into speakers to improve clarity of audio in a noisy environment, to low-cost toys and games where simple packaging materials become speakers. HiWave offers a range of exciter components providing a variety of output power and form factor options. These exciters are called DML - Distributed Mode Loudspeakers, and create a complex set of waveforms throughout the surface being excited.

Furthermore, HiWave has developed a methodology for controlling modal bending wave activity enabling pistonic action and surface excitation to be combined in a single transducer or driver. This results in a small form-factor speaker drive that delivers uncanny sound quality due to its wide dispersion of sound, and full range response. Listeners have described it?s audio fidelity as ?lifelike? and ?unencumbered by the attributes of speaker mechanics?. HiWave?s family of products utilising this patented technology is called BMR - Balanced Mode Radiator - and are set to transform listening pleasure from small format, low-cost loudspeakers.

Lifelike audio reproduction depends on three separate aspects of the loudspeaker design being optimised - the transducer (or driver), the electronic control system (amplifier and associated signal processing), and the enclosure that houses the driver. HiWave?s Audium amplifier technology is an ultra-low power ?clean-tech? approach to audio amplification where almost no energy is wasted as heat. This means that high audio power can be delivered from a small amplifier chip with no need for heatsinks or forced cooling. The Audium integrated circuits take advantage of the ?peak-to-average ratio? of music and spoken word, where volume peaks are relatively infrequent compared to the normal level of sound. The incoming audio stream is analysed and the the voltage rail is dynamically switched by on-chip boost circuitry from its nominal 1-1.5V up to as high as 32V for maximum audio power, and immediately after the peak it drops back to the low voltage rail once more. The output drive transistors are also on-chip, as is a signal processing stage comprising an array of filters than can be configured for EQ (equalisation) to accommodate the acoustics of the enclosures that our customers choose to house their speaker products in. Combined with the amplifier?s power consumption of only around 5% that of current generation digital amplifier chips, this EQ capability enables our customers to develop new genres of products such as high-quality USB-powered speakers and wireless speakers, with almost any industrial design form factor available to the developer?s imagination.

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