LOUDSPEAKERS

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go to: Contents | Features | Bookshelf, Stand-Mount and Desktop | Floorstanding | Editors' Choice Awards Kevin Voecks • Revel What are the particular challenges and trade-offs of designing a small loudspeaker Which sonic qualities are you primarily trying to optimize, and which qualities are you most willing (or compelled) to give up The challenge of maximizing the fidelity of a small loudspeaker is an instance in which what appears obvious is indeed the case. Low-frequency extension and output capability make up almost the entirety of the challenges that are particular to small loudspeakers. As is the case with any loudspeaker, one need only look to the applicable physics to understand the challenges and trade-offs. Also in common with all speaker design, too narrow a vision will result in a speaker that isn’t as good at the total task of fidelity as one built with an eye toward the total result. For example, the low-frequency bandwidth could be greatly extended if you ignore output capability and sensitivity, but that would not result in a very useful speaker. A superior design must keep all characteristics that contribute to fidelity in balance. After selling high-end audio in high school, the quest for higher fidelity led Kevin to Massachusetts for a formal engineering education. He founded Natural Sound, a high-end audio store, with a fellow student who remains a Revel dealer. With virtually any high-end brand at his disposal, it was evident that loudspeakers were at the same time the most important and most flawed part of the audio-reproduction chain. After spending time doing research into high-end loudspeakers, Kevin joined Mirage as chief engineer, followed by becoming chief engineer at Snell Acoustics. A call from Sidney Harman asking him to found a new loudspeaker company of the caliber of which Mark Levinson was known for electronics, with the resources of Harman International, resulted in the formation of Revel in 1996. Do you have your own design techniques that maximize the performance of small designs First and foremost in the small speaker category is to optimize every aspect that contributes to extension and low-frequency output capability, while of course also staying true to what we have learned about full-range sound quality. I am extremely fortunate to be able to work with an outstanding group of engineers, including specialists in transducer design. Being able to model and design every component in the system, from spiders to surrounds to diaphragms, is absolutely essential to achieving the best possible complete loudspeaker system. Instruments such as the Klippel analyzer are instrumental in wringing-out the best possible performance from the transducers. It should go without saying, but probably bears stating that “tricks,” such as designing a high-Q system with a midbass peak to simulate real bass, are not acceptable. Neither of course is tilting the overall response or limiting the high-frequency extension in order to seem more balanced in a speaker attempting to claim fidelity. Has your design work on larger loudspeakers informed your approach to stand-mounted ones Using the results of our researchers, we have a sophisticated understanding of which aspects of sound quality are most audible— and which are not. That is critical to making informed choices in the hundreds of decisions and tradeoffs that are part of every design. Having access to high-resolution anechoic chambers allows us to properly characterize both the transducers and the transducerenclosure combination to allow high-precision filter (crossover) synthesis. A good example that applies to any size loudspeaker is resonances. Our research group has determined the threshold of audibility of resonances, which have been shown to be a critical aspect of high fidelity. We take pains to be sure that resonances— regardless of the source—are reduced to the level of inaudibility in all of our loudspeakers. This is the reason that we use stiff diaphragms that push the first mode (resonance) well above the crossover frequency to make them inaudible in all Revel loudspeakers. Speaker Designer Roundtable 32 Guide to High-Performance Loudspeakers www.theabsolutesound.com previous page NEXT page
go to: Contents | Features | Bookshelf, Stand-Mount and Desktop | Floorstanding | Editors' Choice Awards One of the most important findings of our research group is the critical importance of the far off-axis response being similar to the onaxis response. This relates to our research on the audibility and psychoacoustic significance of reflections. We learned that the first sidewall reflections are of the greatest sonic significance, and that it is usually a speaker’s far off-axis response that contributes to these critical reflections. That means taking a very unusual approach to design that places great weight on matching the response up to 60-75 degrees off-axis with the on-axis response. The importance is clearly proven in blind listening tests, as matching the response results in a seamless characteristic that makes reproduced music much more believable. This has led to generations of high-frequency waveguides that match the off-axis characteristics of the tweeter to the midrange (or woofer in a twoway design). Position-independent, double-blind listening tests are an essential part of any loudspeaker design. Any audiophile knows that moving a speaker changes its perceived character as its interactions with room modes and boundaries change. The problem cannot be solved by placing speakers in close proximity with one another, as they still cannot be in the same place at the same time, and the presence of one very close to the other will influence the sound of both. Our use of a high-speed speakermover is really essential to compare two loudspeakers, as is the double-blind process Speaker Designer Roundtable in which no one is aware of the identification of the speaker under test. What, if any, sonic and technical advantages do small two-ways have over larger multiway systems In my opinion, the characteristic that is most appealing to listeners who prefer small twoways over larger loudspeakers is, in fact, a coloration, although one of the very few that can be defended. I am referring to the lack of natural masking that occurs when lowfrequency sounds are present concurrent with midrange and high-frequency sounds. Since that natural masking is present in the original signal if it is a “real” acoustic event, the lack of masking is by definition a distortion. It does often make the midrange sound cleaner and more-detailed, which is the reason that I think it is defensible. However, it should be acknowledged as an artifact—however pleasant it may be. and you’re there Close your eyes and you’re there. Building on our award-winning AR series, Sony ES speakers recreate the experience of hearing music performed in a live venue. Hand-crafted from Scandinavian birch selected for its acoustic resonance, the single cabinet, two-enclosure design gives you unparalleled low-frequency isolation. The I-Array tweeter system delivers a true-to-life listening experience. And the result is beyond words. Because You Care About Music Learn more at www.sony.com/ES 33 Guide to High-Performance Loudspeakers www.theabsolutesound.com www.theabsolutesound.com ©2013 Sony Electronics Inc. Sony and the Sony make.believe logo are trademarks of Sony. All rights reserved. Reproduction in whole or in part without written permission is prohibited. All other trademarks are trademarks of their respective owners. previous page NEXT page NEXT page SS-NA2ES
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LOUDSPEAKERS

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