ONLINE - ISSUE 3
Cheskys System 6.0: A Report From The Edge
(From the PF archives, November, 2000)
As part of Positive Feedbacks continuing interest in "things surrounding audio," we are re-publishing this newly re-written piece by our long-time contributor, Max Dudious. It gives some very interesting details about the Chesky 6.0 surround system that I heard at CES 2001. The reader will have to keep in mind the original publication date of the article, and remember that it was speculative in places when penned. Since this time, DSD multi-channel has made massive and magnificent strides in the realm of fine audio surround sound, and multi-channel SACDs are becoming much more commonplace. This is a trend that I expect to continue and to accelerate in 2003, as the number of SACD titles begins to hit critical mass.
Nevertheless, we believe the profile of the Chesky system is worth covering, so that interested audiophiles can be aware of the issues and alternatives in multi-channel audio. PF Online will be publishing more articles about surround sound and the particular challenges and pleasures thereof in 2003but this helps to set the stage.
I recently heard some of David Cheskys six channel master tapes (actually master discs), through a 6.0 full range system on immaculate gear in the Chesky studio, and was duly impressed. Cheskys sweet System 6.0 is a well-thought-out recording system, and Cheskys playback rig is among the finest Ive yet heard. Kudos and accolades, tribute and encomiums seem in order.
To presume to write "the finest" Id have to spend my life listening to all the contenders, and no one has that much time. Furthermore, the dialectician in me warns it would be impossible to arrive at such a conclusion, for while I was at my lifelong task of listening to state-of-the-art systems, armies of audiophiles would be building new ones. Reasoning from the exclusivity of Cheskys experimental six-channel software, and the general unavailability anywhere except at the Chesky studio of the necessary playback hardware (customized Genex GX8500 Magneto-Optical Digital Recorder CD record and playback, Prototype Muse 6.0 pre-amp and 96/24 DAC), I think Cheskys six-channel system may be one-of-a-kind. Though John Atkinson did audition AT&Ts experimental five-channel surround system at their Shannon Laboratory (See STEREOPHILE, Vol.24, No. 2.), so there are other contenders.
What follows is not a "review" so much as the account of an advance scout whos ridden a time warp out into the audio future and returned to report on the truth thats out there. Theres a new format a-brewing, and it is more powerful than the stereo we now know! It will utilize either SACD or DVD-A (which are, after all, but two different processes for storing and converting digital information to analogue) in ways that will enhance music reproduction, though its hardware will likely be stereo compatible. It is not exactly new, because System 6.0 is based on 5.1 home theater audio technology. And multi-channel audio systems have been around a while, though beset with a range of performance problems. Computer technology has made available sufficient bandwidth to produce an audiophile quality simulacrum of a musical event (in a particular acoustic environment), employing multi-channel full range sound (while eliminating previous multi-channel problems)and the Chesky label has shown the industry how to do it.
The Chesky corporation can likely write off most of its listening room as Research & Development for its new corporate record and playback system, so they spared no expenseas you might expect from a label that stakes its reputation for working at the leading edge of recording art on each new release. Is six-channel matrix a viable format? Thats a tough call. If home theater TV with surround sound is a viable format that the public at large embraces, and it seems to be the first things newlyweds buy nowadays; then, yes, six-channel mid-fi quality sound is a viable format for audio-only. Will the audiophile community, with its higher standards (which has once rejected multi-channel surround sound) embrace this new digitally streaming technology? Thats another tough call. There are those who say System 6.0 offers too little audible reward for the additional expense, that the difference between standard stereo vs. surround sound is not as great as the difference between mono vs. stereo. The market will likely decide.
As the 5.1 system is the basis of System 6.0, (the dialogue and bass channels become the early reflection channels), the hardware and software conversion would be minor engineering adjustments for the manufacturers. The audiophile community could embrace it when enough of the required hardware (six-channel CD players, pre-amps n amps) and software (true six-channel recordings) are available to hear what System 6.0 can do at the local audio boutique.
Ultimately 6.0 should prove a boon to the dealers, who will have to employ all their expertise in set-ups, (phase matching, cabling, physical placement, sound pressure metering, level setting) an essential value-added service the mail-order houses cant offer. Proper set-up is required for optimum System 6.0 function. SACD vs DVD-A will be an interesting competition to watch during the next few years, before the consumer electronics industry settles on a standard format, because either format could be compatible with the 6.0 system. The six-channel pre-amp would have to have one or the other formats DAC built in; or, perhaps, one of each.
The Chesky System 6.0 could be replicated in homes on a much more modest budget than a recording studios, and even in lived-in rooms it would produce pretty good sound. For guys who really care, well... there is virtually no upper limit to performance. Dedicated rooms, soundproofing, acoustic treatment, with the best 6.0 CD players, matched speakers, matched electronics, and cables can take the listener to audio heaven in the room above the garage, or in the basement. The 6.0 system could also be a blessing to audiophiles forced to listen in smallish rooms, with more modest accouterments, say six monitor-sized, or small DAppolito configured speakers with (or without) a subwoofer. The technical capability (enough bandwidth) finally exists to transform a smallish room into an acoustical approximation of whichever recording venuesmall, medium, or large.
The Chesky surround configuration
Cheskys six-channel system has two "front" speakers, two "high" speakers, and two "rear" speakers. The front speakers, arranged as a standard toed-in two-channel system, give you the first direct wave-form of the sonic event, the most information. The high speakers are somewhat off to the side but equidistant to the listening area, up six or seven feet on tripods, toed in and down (in, fifty-five degrees, and down, till theyre aimed at the seated listener). Since each room has differing ceiling height, hence its own acoustic, this will be subject to trial and error until the sweet spot is located. The rear speakers are likewise equidistant from and aimed at the back of the listeners head, and are similarly toed in and "ear-tuned" until everything clicks into place. Trust me, youll know it when you hear it. The listener gets an approximation of the direct sound, the ceiling and near side wall reflections, and rear wall reflections as they occurred in the original recording venue, whatever its size. The soundfield floats (adjustably, to taste) somewhat off the floor.
Since sound travels about 1100 feet per second (the only constant in audio), the differences between different sized home listening rooms will be a small percentage of, say, the distances involved in a symphony hall. Listening in a small room (ten by fifteen feet or less), compared to a medium room (fifteen by twenty feet), compared to a large room (thirty by fifteen feet or more) will introduce a difference of only five to ten, maybe fifteen milliseconds. Those are very small delays compared to those in a recording venue (symphony hall) that might be more than seventy feet across, and equally high (seventy milliseconds up and another seventy down), and perhaps two hundred feet long (similarly, two hundred milliseconds out and another two hundred back, about .4 of a second). Not to mention the natural acoustic decay that ranges from around one second (recital halls), to around two seconds (symphony halls) and sometimes three seconds or more (cathedrals, The Royal Albert Hall). So System 6.0, theoretically, could be set up in any adequately sized room, with modest gear, and it would be impressive. In a room as large as the Chesky studio (29 x 15 x 12) and with immodest gear, it is mind-boggling.
With first class speakers and electronics (silky smooth Verity Parsifal speakers, and matched Muse amps that can be tweaked for accurate level tests), the effect is drop-dead gorgeous. Since the special, British made, SoundField MKV microphone array is hung just behind and above the conductors podium for recording classical music, the listener is transported near that spot on playback. It is the closest thing to being on the podium. For all you guys who like to conduct with "air baton," this is definitely nirvana. For the rest of us rockers, it is the playback system that puts us in the best seat in the house, virtually first row front and center, inside the performance (the night club, the recording studio, inside Miles Daviss whisper mute, or Jimi Hendrixs pickup, for that matter), but not quite.
The question of ambience
Even the best of two-channel systems, those that retrieve a pretty good amount of ambient information, often leave their keepers seeking a greater spatial sense, more specific sound staging, or center fill, or recording venue boundaries. Though good (usually tubed) amps and good dipole (usually electrostatic) speakers do a terrific job of approximating spatial cues, they are usually limited in dynamic range. The six-channel system gets all that ambient information through regular woofer/tweeter speakers. It gets you the spatial information of dipole speakers with the zotz (or startle-ability) of dynamic speakers. No more trade-offs. No compression. Minimum phase error. No artificial home-theater format trying to do a job for which it was [not] designed. Cheskys System 6.0 seems like one dynamite answer. More than a few multi-channel formats have come and gone, never capturing their place in the market. While a few were four discrete channels, many were electronically derived, echo and delay generated artificially from the original two channels and then fed to the rear channels. Their adjustments did create the illusion of small, larger, and great space, but that came at the expense of phase anomalies. Not any more. Cheskys sweet 6.0 system is a true, discrete, uncompressed, six-channel, minimum phase error, full-range, audiophile quality, audio-only system, with six signals passed through a six-channel preamp, into six separate channels of amplification, into six separate but equal speakers, and its the real deal.
In addition to the music, what we hear in a good hall is spatial information, and what we often dont hear in our listening rooms is the illusion of that space. Of course, the selection of the recording venue is crucial. Some halls are better than others. Some halls have a sonic thumb print so distinct, its orchestra begins to capitalize on that characteristic sound and slick management programs music that will show it to good advantage. If we studied the architectural drawings and acoustical data we might understand how Chicagos forward Orchestra Hall is likely responsible for the Chicago Symphony Orchestras mighty brass sound; how Philadelphias drier Academy of Music is likely responsible for the Philadelphia Symphony Orchestras ravishing string tone. It has become a recording engineers maxim that the hall is 90% responsible for the quality of the recording. That some halls are just too harsh, or too boomy is evidenced by the periodic pleas to tear down Avery Fisher Hall and start over, as Maestro George Szell suggested when it was new. Some stereo recordings (CD and LP) do capture a lot of the illusion that were sitting in a room much larger than our home; and some capture the venue so well that we can tell when we are listening to a recording from Amsterdams resonant Concertgebouw with its 2.0 second decay, or Philadelphias Academy of Music with its 1.35 second decay.
Recording in stereo, it was largely hit or miss if the spatial element would be well captured, though some recording engineers did it better than others. Robert Fine and Wilma Cozart Fine for Mercury, and Kenneth G. Wilkinson for EMI, to name but a few. The engineer had to do a good job, get everything just so, to catch the acoustic of the venue. While most of the formulae were known, his equipment had to be friendly, and our listening rooms had to be so too, in order to pull off the illusion of a large space. That was for two-channel. Six-channel recording was designed to take most of the guess work out of the engineering process.
The Chesky recording system employs two pairs of Blumlein arranged microphones set up in a single isosceles tetrahedron (equilateral pyramid) module designed decades ago by the late Michael Gerzon, and known in the UK where it is manufactured as the SoundField MKV microphone. It is set up to capture the depth (x-axis), the width (y-axis), the height (z-axis), and the omnidirectional reference pressure (w), in a configuration designed to minimize phase error between the microphones. In the hands of Cheskys gifted recording engineer, Barry Wolifson, it does a great job.
Now I might ask (ever in service of dialectics), how could it not sound good with the high quality of Cheskys playback system? Veritys Parsifal speakers are known for their glorious electrostatic-like midrange, while Muse amplifiers are known for their tubelike liquidity, their shimmering open highs. To which Id answer, even a man who is pure in heart and says his prayers by night, can botch a recording when the phases clash and the moon is full and bright. In other words, in stereo it was possible to foul up and there are many recordings that used incorrectly spaced omnidirectional microphones testifying to that. Their soundfields might foreshorten, or their stereo soundfield collapse into mono as the result of trial and error engineering. But if you have good artists in a good venue, a good recording engineer will most likely get everything onto disc using the Chesky system. Less is more in the K.I.S.S. (Keep It Simple, Stupid!) system. The only concession Chesky is willing to make is to the vocalist fronting a band whose lead voice would be drowned out without a spot mike. So one of the beauties of the system is, it seems nearly bulletproof once you get the hang of recording with it. Clinging to the optimism that resides within each of us, I want to believe that the next generation of recordings will be of nearly universally high quality, whoever the engineer, though I know there will be a range of good, better, best.
When I tried to get some particulars out of David, he cracked foxy, but he did say, "The outputs of the capsules can be matrixed into two, four, six, or many more channels. Think of this as Three-D Blumlein ... You can manipulate in post-production and all ambience channels can be tweaked to the producers taste. There are no rules, and just as there are many ways to do a stereo recording, there are just as many variations with multi-channel. We are at the dawn of this medium and we must experiment to see what works best."
The sound of 6.0
What does it sound like? Great! It sounds just great. It doesnt sound like those old multi-channel set ups where the instruments entered the sound field like bits of shrapnel in an aerial dogfight, flying at us like B-17 tail assemblies that made us duck in 3-D movies. The Chesky 6.0 system sounds like a reasonable reproduction of the music in its original venue. The instruments are well placed in acoustic space, and you can hear the spaces between the instruments better than on really fine stereo. David at the control board took me through a recording of trumpet player John Faddis and his jazz group playing some standards. I listened to that in two channel (stereo) for a while before he added the two rear channels (quad); then, finally he added the high channels to make it six-channel (System 6.0). Next I heard David Johansen and the Harry Smiths. Then he played excerpts from a piano-cello duos chamber music recital, and finally excerpts from his own Oratorio with full orchestra and chorus. With each sequence from stereo, to quad, to System 6.0 the sound got deeper, the panorama got wider, instrument location got more precise, instruments rounded out, and there was a more convincing and more involving reproduction of ambiance. The music seemed to float in the air, in front, in back, above, and around the speakers (which curiously seemed to have no relationship to the sound). The speakers became pieces of furniture in the room as decor, certainly not the authors of this amazing sound field. I still felt like I was seated in the audience, first row front and center, but I wasnt thrust among the instruments in the annoying way of the old quad playback systems.
System 6.0 seems a bit sensitive to the amps and speakers that are used in it. For a while Chesky had Lamm amps on the front channels, with McCormack DNA-2 amps on the rear and side channels. He told me he went to all Muse amps because some subtle phase shifts were occurring, that he could hear. For similar reason David wanted to have all of the speakers in this array from the same manufacturer, with the crossovers using the same shaped knees, with the capacitors, resistors, and chokes all of the same matching design. This would insure minimal phasing errors. If the speakers had some errors, at least theyd be the same ones. Since time alignment is crucial, great pains were taken to see that the speakers were exactly placed.
Having said that, Im sure people will eventually find all sorts of amps and speakers in the attic and put them together, which will amount to post-production re-engineering (because it will introduce various anomalies), and write that I was wrong, and the whole enchilada wasnt worth the time. But, in theory, if not in practice, and in the perfectionist mode, you can see how it might be advantageous to have a systems approach here. Same model amps, same model speakers, equidistant. Ive started to notice packages for home theater audio advertised from one manufacturer, so the idea already has its adherents. Check your Sunday supplement. What remains to be seen is the industry-wide standard, audio-only format selection, and then the manufacture of six-channel CDs and CD players.
And in the future ?
Will six-channel audio be on its way soon? Has David Chesky gotten the drop on the industry by being among the first to recognize the potential and to begin recording in this format? He has, being who he is, set up [El Monstro] system in his studio. He has taken the idea of "surround sound" to a level previously un-imagined, and, being a musician, Chesky has harnessed the technology in service of the music. Is it technically feasible? Yes. Is the sound a big improvement? Yes. More immersive, lifelike, and involving. Will the audiophile community embrace this new format? The jury will be in the marketplace. There are always some guys ready to do whatever needs to be done to get great sound.
What is the likely time-line for availability to the public? When Jack Kennedy asked his panel of scientific advisors how long it would take to put a man on the moon, the answers ranged from ten to forty years. It took nine. I dont know how long it will take to get six-channel CDs and CD players into the stores. I predict it will be faster than we now imagine. Not because the manufacturers are rapacious; but because (owing to unforeseen developments) technology always moves faster than we expect. Rather than "sometime in the indefinite future," Id say "sometime in the indefinite soon." If the industry were to agree on one format, or a redundant DAC system, it could be real soon. The manufacturers are already getting their ducks in a row.
Somethings coming. When it arrives we should thank David Chesky for accelerating the process.