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Wilson Audio: WAMM Master Chronosonic

مصاحبه زیر را مجله ی "Stereophile" با آقای "Dave Wilson" مدیر کمپانی ویلسون اودیو درباره ابر بلندگوی "Chronosonic" انجام داده است:

Wilson Audio: WAMM Master Chronosonic

On December 8, 12 days before an embargo on the news was lifted, I visited Wilson Audio in Utah. The occasion was the launch of the WAMM Master Chronosonic loudspeaker. Given its limited-edition production run (70 pairs), oversized dimensions (approximately 86" H with spikes x 26" W x 36.5" D), and high price ($685,000/pair), Wilson Audio's ultimate speaker is not slated for dealer and audio show demos. Instead, the only way prospective customers, dealers, and select press can experience Dave Wilson's magnum opus—the culmination of well over three decades of loudspeaker development—is to journey to the Wilson residence in Provo and hear either the WAMM P2 Prototype or, soon, the WAMM Designer Proof that will take its place and become the company reference

After a lengthy factory tour (report to come) with Sheryl Lee Wilson, who has been at Dave's side for longer than their 50 years of marriage; their son, Daryl Wilson, who has taken over management of Wilson Audio; and John Giolas, Director of Marketing, we indulged in a quick lunch and headed up to the Wilson residence. There I discussed the design of the WAMM with Dave Wilson

 Wilson Audio: WAMM Master Chronosonic

Design and Philosophy
"Frankly, I designed the WAMM Master Chronosonic for me as a tool, and as a thing of beauty," Dave told me. "It was never designed as a product; I intended to build a limited number of them for friends of Wilson who chose to acquire them

The WAMM's driver configuration consists of

Front Firing Drivers
• 1x 1" Convergent Synergy Tweeter (version 5) developed for WAMM
• 2x 4" Upper Mid (8 ohm) developed for WAMM
• 2x 7" Lower Mid used in several Wilson Audio products: XLF, Alexx, Alexia, Sasha W/P 2, Yvette, and Polaris
• 1x 10.5" Upper Woofer developed for WAMM but first released in the Alexx due to the very long WAMM development cycle
• 1x 12.5" Lower Woofer developed for WAMM but first released in the Alexx due to same

Rear Firing Drivers
• 1x 1" Convergent Synergy Tweeter (version 5) developed for WAMM
• 1x 4" (16 ohm) developed for WAMM

All internal wiring is by Transparent. Each driver's wiring has a custom twist ratio whose sonic differences are both measurable and audible. Twist ratios may change when the same driver is used in different model loudspeakers

You'll note that the Alexx is mentioned at least three times in the driver description. Truth be told, Daryl was developing the Alexx at the same time Dave was perfecting the WAMM Master Chronosonic. During my visit, either he or John commented that the Alexx is, in some respects, a smaller (and less finely adjustable) version of the WAMM. At one sixth the price, I might add

The WAMM's imposing driver array is but one aspect of its uniqueness. Wilson claims that the design achieve an unparalleled degree of time alignment between frequency ranges, with a time-coherent presentation that clarifies information usually smudged by other loudspeakers

"The placement of the drivers relative to each other affects the synchronicity of the alignment of the leading edge of the transient," Dave said. "Our patent on how we achieve time alignment dates back to 1984

He then explained that sound travels approximately 0.135" in 10 microseconds. Above 5kHz, 10 microseconds lies at the threshold of what humans can detect from a multi-driver loudspeaker when the waveform's leading edge is not aligned properly. At lower frequencies, somewhat larger misalignments can be tolerated

Dave claimed that speakers that just have flat front baffles fixed at an angle of 90° to the vertical can have an error of hundreds of microseconds built into them. "100 microseconds, for example, is 1.3 inches," he said. "That's a lot

To address audible timing incoherence, the WAMM's "upper-frequency mechanisms allow for adjustments down to about 2 microseconds." Dave promises nomograms—I had to look that one up—that will be based on 1) the speaker’s distance from a seated listener’s ears; 2) the distance of that listener’s ears from the floor; and, equally important, 3) the time the signal takes to be passed through all upstream electronics and cables

"Transit time can be significant when you're talking about this critical degree of time resolution, and can be ascertained using propriety techniques," he said. "In the low frequencies where many solid-state amplifiers have very close alignment, a vacuum-tube amplifier may lag by about 50 microseconds. With the WAMM's adjustability, that variable can be normalized. If we know a particular amplifier's "time profile", we can derive the appropriate custom alignment. We've looked at six different amps so far, but we are just getting started

One pair of WAMM P2 prototypes will eventually be permanently mounted at one end of a small, narrow padded room in the Wilson factory, with a permanently affixed microphone at the other end. Here, when essential timing information is not supplied by manufacturers, Wilson Audio will measure an assortment amps and/or cables and determine their timing profiles. In cables, of special interest is the delay time in various ranges, eg, the high frequencies relatives to the upper midrange to the lower midrange and to the bass

"Speed is not a main arbiter of quality; it's just a characteristic," Dave said. "The WAMM Master Chronosonic system gives an unparalleled degree of precision of alignment. If you were to start with an MQA recording and play it with the speaker time aligned for cable and amplifier speed in the various ranges, you'd be getting pretty outrageous sound, clean as a whistle

"It's about time; it's all about time. Flat frequency response, low distortion, extended bandwidth, and accurate timing synchronicity are equally important. It's nice if you have phase coherence, but it is not necessary. What I'm interested in is the synchronicity of the leading edge of each note. If you were to look at what 10 microseconds is on our measuring scale, you'll see that our adjustable driver positioning dissects that line. We are truly splitting hairs

He then referred to the sound of the timpani used by the Vienna Philharmonic, which have a lot of upper-range harmonics. A single roll on the timpani will excite not only the woofer, but also the midrange and tweeter. If those drivers are not time-aligned, he claimed there could be hundreds of microseconds difference between the drivers

Microsecond accuracy, it seems, is essential to reproducing, not only the sound of instruments, but also the sound of the hall. "Most audiophiles would think that the perfect speaker for this type of thing would be a single diaphragm electrostatic, with no crossover," Dave said. "But research shows that a 1.5m-high dipole electrostat, with a single driver positioned 5m away from the listener and with the listener's ear at half the speaker height, will have a temporal spread of 650 microseconds. That is completely unacceptable, but it's what people are accustomed to thinking is good time coherence." (MartinLogan and Quad lovers are not going to like reading that.)

Dave also said that while our hearing range decreases with age—high frequency sensitivity may roll off above 6kHz—timing sensitivity remains strong, with maybe only 10% loss with age. "There were several people I built the original WAMMs for who were in their 80s, and who could hear the timing, because it's not linked to high-frequency extension," Dave reported. "And my guess is that the ear is less sensitive to timing in the lower frequencies


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Hard or Soft
Before listening began, there was one question I was dying to pose. If I had $1000 for each time a speaker manufacturer has made a point of contrasting his hard-dome, ultra-hard-dome, or super-ultra-hard-dome tweeter with Wilson's soft, silk-domed tweeters, I'd have enough money to buy a pair of Alexxes, which cost $109,000/pair. Hence, I asked Dave and Daryl, "How can your tweeters have anywhere near the resolution of hard-dome tweeters that have taken years to develop

Dave: "I do find it interesting when people look at things in terms of speed. I've been in this field a long time, since the first solid-state amplifiers came out and were considered better than tubes because they were faster. If someone has a problem with silk-dome tweeters but they play vinyl through vacuum tubes, there's a certain inconsistency ther

"In the final analysis, it's what you like. One of the things about a soft diaphragm is that when it goes into break-up mode, it breaks up softly and gradually, like soft clipping. A rigid diaphragm has some real benefits, especially if it's light, but when it goes into break-up mode, it's harsh. With speakers with wide dynamic range, the drivers can be driven really hard. That's one reason I don't use 6dB/octave crossovers, because I like wide dynamic range in the speaker

Ultimately, there's no absolute answer, only different perspectives. In the final analysis, which do you like

Daryl: "It's almost like judging a car on the basis of 0-60 performance. Speed is only one parameter. It's a good question, but it's not the only question. Hence we asked what other characteristics are absolutely necessary for what we're trying to achieve

?Jason: Has Wilson Audio ever experimented with beryllium tweeters

Dave: "This is the second generation of WAMM prototypes we've had in this room. The first generation, which we called P1, looked roughly the same, with no paint and different metal, and it had a beryllium tweeter. After living with it, we took it out and replaced it with silk

Daryl: "We've experimented with diamond, beryllium, and titanium. We see the trends, for example, a beryllium tweeter coated with diamond dust to add rigidity. But the question we ask is, what sounds more real? Does it have the ability to mimic the experiences we've had in the Musikverein, Staatsoper, and Concerthaus? Does it fool your mind when you close your eyes, and make you feel as though you're in that hall? Those are the questions we ask. There are a lot of designers with great and noble products, but they ask different questions than ours

Dave: "This applies equally to the composite we use for our drivers. We've spent an awful lot of thousands of dollars going to Vienna and Cleveland, as well as to the Mormon Tabernacle and Abravanel Hall right here, and listening closely

Daryl: "We've walked around in the halls during rehearsals, taken notes, and discovered which seats we liked the most. Then we came home, and developed the drivers we use now

We then spent an hour or two listening to the WAMM.P. (Given that the pair I heard was one of the company's prototypes, whose appearance differs somewhat from the Designer Proof pair that will reside at the Wilson residence, I was asked not to take photos. Hence, our photos are limited to those supplied by Wilson.) I say "an hour or two," because I really have no idea how long I listened. Dave wanted to illustrate the speaker's strength via several analog and digital tracks of his own choosing before I began to play my stack of SACDs and CDs. (I had hi-rez files with me, but we never got to them.)

The quality of the system could not be faulted. We're talking a Basis Inspiration turntable with Basis Vector 4 arm and Lyra Etna SL cartridge; ARC Ref Phono 2 phono preamp, John Curl/Studer A80 30ips, ½" analog tape deck, dCS Vivaldi v 2.02 DAC and transport, VTL 7.5 Series III preamp, Dan D'Agostino Momentum M-400 monoblocks, and Transparent Opus Gen 5 interconnects and Magnum Opus Gen 5 speaker cable

Once listening began, I was, in a sense, out of time. All I know for certain is that I was discovering so much that was new and rewarding about the recordings and artists I love, and I remained in the sweet spot of the Wilsons' huge living room—39' L x 29.5'W x10.5' H (lowest) to 16.5' (peak), with Polycylindrical Diffusors on the descending ceiling slope opposite the speakers—for as long as they would have me

At first, seated 13.5' from the loudspeakers, I had to make some mental adjustments to fully appreciate Dave Wilson's magnum opus. There was far less brilliance to the sound than I'm accustomed to. Partly, as I've discovered at home, that has to do with clean power, which reduces brittleness. (There was no power conditioning in the equipment chain.) Dave has paid particular attention to his home's electrical wiring, with all the ground legs attached to the same "phase leg" of the panel etc. The room has several dedicated lines, including two dedicated 240V lines that each has its own breaker, and several more dedicated 120V lines

Once I had acclimated to the fact that, due to the combination of power source and heavy rugs, draperies, and padded furniture, the sound in the Wilson living room was most akin to the sound in a dry hall that emphasizes detail over color and reverberation, I experienced revelation after revelation. On that old standby LP Cantate Domine (Proprius), I became acutely aware of the resonance and natural decay of voices in acoustic space. Soundstage depth on an SACD performance of Stravinsky's L'Histoire du Soldat (Pentatone) was similarly amazing

I also could hear total clarity between extremely rapid drum slaps on Mickey Hart's CD, Kodo Mondo Head (Red Ink). The beats were so fast, and so clear, that I was literally startled. (It seems Mickey lived near Dave at one point, and invited the Wilsons onstage for a few of his shows.)

I listened to many more recordings, but I took no notes during my final listen, to Lorraine Hunt Lieberson's "As with rosy Steps the morn" from Handel's Theodora [], which is best heard on her incomparable Handel recital (Avie SACD). Aware that I had been privileged to hear one of the world's finest and most accurate presentations of what artists and recording engineers hoped to share with music lovers, I ceded the sweet spot to Sheryl Lee Wilson as an act of thanks

What More Needs to be Said
As a proof of concept, the WAMM Master Chronosonic is destined to serve as lasting testimony to Dave Wilson's pioneering work. Although it's a shame that so few people will have the ability to enjoy it for more than a single afternoon, we mere mortals can at least console ourselves that its technological breakthroughs have trickled down into the Alexx, which Michael Fremer will be reviewing for Stereophile in the New Year