Hi Fi in the Arena: The Concert Sound of the Grateful Dead

First published in The Absolute Sound, Issue 89. Copyright © 1993 by Absolute Multimedia. Reprinted with permission.

[Note: this article was published more than 15 years ago, and since then, concert audio equipment has evolved quite a bit, especially in the area of digital audio. Healy's comments on digital audio are now historical in perspective, yet remain interesting.]

The other night I experienced the finest large-scale High-End audio system I have ever heard. It shattered my preconceived notions of what the state-of-the-art in High End sound reproduction is capable of.

This system was clean from fewer than five Hertz (according to its designer) to beyond the range of human hearing. Never at any time did I hear distortion. The stereo imaging was pinpoint and extremely accurate, with no bunching, "hole-in-the-middle," or problems at the extreme left and right. (This was accomplished with no room treatment whatsoever.) The tonal balance was almost without flaw (though the highs were slightly too prominent at close range), simply that of the instruments it was reproducing, especially drums, cymbals (which were reproduced with a purity which had to be heard to be believed), and gongs. Its reproduction of the lowest bass was unparalleled—the bass from the Infinity IRS woofers is feeble by comparison. The same can be said about this system's dynamic capability: It could reproduce a clean 120 dB at distance of over 50 feet. Soundstaging? The depth was almost perfectly accurate compared to the locations of the instruments on the stage, and the speakers were capable of generating width in excess of 100 feet. There was an excellent balance of direct-to-hall sound.

It was easy to see the instruments on the stage. Not "see" the instruments, see them. Most important, the emotional connection between the listener and the music—the ability to convey the emotion and feeling inherent in a musical performance being the measure of a truly great High End system—in my opinion was absolute, total, complete.

The stereo to which I am referring is the Grateful Dead concert sound reinforcement system, heard at the Nassau Coliseum in Long Island, New York.

I know. Live rock concert sound is usually terrible, right? The equipment doesn't come remotely close to the fidelity afforded by good High End gear. The volume and distortion levels are painful. The mix is indistinct, and the acoustics are horrendous, with gross amounts of echo.

The Grateful Dead sound system is a dramatic exception to the rule. It is a dramatic exception to the rule. It is so good that only the finest High End systems I've heard even come close to it, and the parameters of bass extension and clean power, home High End systems are Tinkertoys by comparison. Never have I been so blown away by amplified sound. Depth, width, stereo image? 120dB at below 20Hz? The ability to hear every detail in the mix? A religious experience from 18th row center. Especially when accompanied by the music of the Grateful Dead: transcendent in the truest sense of the word. The Dead can hypnotize with their music, interlocking the polyrhythmic percussive complexities of Mickey Hart and Bill Kreutzmann, the syncopated, weaving guitars of Bob Weir and Jerry Garcia (whose solos just go out there, seemingly into infinity), the simultaneous rhythm-against-melody bass playing of Phil Lesh, the sonic seasonings of keyboardist Vince Welnick, combined with multi-part harmonies singing lyrics that are among the most meaningful written, speaking directly to the heart of the human condition. Listening, one forgets space, time, and surroundings. The saying goes, "There is nothing like a Grateful Dead concert." It is a profound truth.

We had to find out how the magic was wrought.

First, a quick digression. The Absolute Sound is based upon the premise that the sound of live, unamplified music occurring in a real space is the only valid reference with which to judge the quality of reproduced sound. I think it is time to expand the premise somewhat. While it is true that the sound of an unamplified instrument is a know reference (though there can be variables involved, e.g., different violins sound different from one another, and the same violin can sound different in different rooms) the sound of some amplified instruments can also be known reference. Most musicians familiar with electric instruments will tell you that the sounds of certain electric instruments are immediately identifiable, whether live or recorded. Nothing else in the world sounds like a Hammond B-3 organ played through a (tube) Leslie cabinet. The sound of a Fender Stratocaster electric guitar is so distinctive that, not only is it easy to tell which pickup setting it's set to, regardless of amplifier, but one can hear a difference between a Stratocaster with a maple fingerboard (brighter) and one with a rosewood fingerboard (mellower). Indeed, experts can distinguish different brands, even vintages, of amplifies, 12-inch guitar speakers, different types of power tubes, and so on, to the most minute degree. (Guitarist extraordinaire Eric Johnson says he can hear the differences between different brands of batteries in his effects pedals!) Such specific knowledge of the sounds of amplified instruments can form the basis for accuracy of a sound reproduction system. Such is the philosophical basis for my determination that the Grateful Dead's sound system is one of superb fidelity. Especially when one considers that the Dead also play many acoustic instruments on stage whose sound was easily determined to be faithfully amplified.

Along with staff Deadhead Peter S. Barry, I made a return trip to the Nassau Coliseum and interviewed Dan Healy, the—yes—audiophile mastermind responsible for the systems' superb sonics. Dan Healy goes back to the Dead's origins, has been mixing their live concert sound for over a generation, and is also responsible for much of the band's equally excellent recorded sound.

This is a man of such ability that he (with help of Don Pearson) was able for the Grateful Dead's One From the Vault series of re-issued classic performances, to take an eight track mix with "immense" amounts of leakage on each track (resulting in severe phase cancellation and time smear) and, with the use of a B&K 2032 FFT Analyzer and TC Electronics 1280 delay unit, remix the tapes with a "nearly perfect" stereo image. (In fact, they were able to determine that, back on August 23-24, 1968, the Dead's equipment had been set up in a location approximately one foot different the second night that it was the night before!) Dan Healy was not lacking in insight, wisdom, or opinions—many of which reinforce the truisms of High end audio—and many which contradict them. The truly High End sound we were so overwhelmed by was hardly the result of chance. We met with Dan and his technical right hand man, Uwe Willenbacher, at the sound board during a sound check before the fourth show of a sold out five night stand.

***

FD: Dan, first tell us how you and Uwe work this setup.

DH: Uwe's the guy responsible for the [sound] booth. He's my interface with the equipment. I could [set it up] all myself, but, years ago I discovered that, when it comes to the creative self, if you spread yourself too thin...what would happen would be, I would come to the show five hours early, and noise out the system [run pink noise through the system and measure the spectral response, in order to determine the frequency response of the hall and equalize the sound system to compensate for peaks and dips in the room's response] And all too often, by the time the show started I really didn't give a damn what the show sounded like because of fatigue.

So we split the gig into two pieces—the structural half, and the "painting" half, the "architectural" half. Uwe breaks out the equipment and sets it up. He's the second in command over the entire sound system. This requires full knowledge of audio as well as full knowledge of computers—which he is really crack at—he's also in charge of the stage crew and the stage setup.

We design each setup for the particular hall. We use auto CAD (computer aided design), an architectural drafting program. We scan in the dimensions of the halls—literally, the architectural drawing—so we can set up the sound system "in the computer" before we set it up in real life. The software can also run tests—dispersion, amplitude, and frequency characteristics, standing wave characteristics.

FD: The reflectivity, reverberation time and so on...

DH: Right. What we really use it for is [to determine the] 3dB down points and so on, so we know how to overlap the speakers. What we call a 3dB down point is really a figure for the worst case; we allow ourselves a plus or minus 1-1/2 dB variance in the SPL [sound pressure level] at any point in the room.

That's [determined] before we even leave home. When we get to the hall, it's up to Uwe to see that [everything is] interpreted and installed right. The rigging is based on the computer-determined points. Then I come in and determine how many speakers to put up, in what arrays, how much curve and how much tilt and so on in order to get everything to converge properly with smooth coverage throughout the room.

FD: What are the tolerances involved?

DH: When it's all working the way it's supposed to, it's within plus or minus an inch or two.

FD: How do you do your measurements?

DH: I do scale drawings before the fact. When we get to the hall, everything references off a stake that's in the front center lip of the stage. Everything is measured from that, so the stage is vectored out on angles from that [which is] known and predetermined. They literally take a transit and set it up just as if you were surveying, and you take that pole and go [to the location points]. But you have to use surveying tools. You can't use a tape measure—you have to be serious about it!

FD: One thing that struck me about your sound. Audiophiles are always talking about three dimensionality, soundstaging, and layered depth. Most concerts, the sound is horrible...

DH: Yeah, it's not even worth discussing.

FD: You're lucky if you hear anything even close to a reasonable frequency response. You take it as a given that properly set up High End equipment can give you better sound than even a recording studio. Here, I heard better sound quality than, maybe, any High End system I've ever heard!

DH: We should take you outdoors sometime. This is mediocre compared to what we can do outside. We can do halls better than anyone else in the world, but you should hear what we can do outside. It'll dazzle you!

FD: What kind of microphones do you use?

DH: I've used them all. The latest state-of-the-art, vintage Neumanns and RCAs, you name it. Sometimes I'll change vocal mikes three times during the course of a tour. There aren't any microphones I'm really satisfied with. I think there's room for another generation of microphones before they bottom out on the physical limitations of the technology. I think you'll see this in the next year or so. I may be more outspoken than most, but I think that any engineer that's been engineering for any length of time would, if they told you the truth, admit that one of the biggest letdowns in the whole audio industry is microphones.

FD: People put so much emphasis on the reproduction of sound that they don't pay enough attention to the production of it. Once the sound hits the microphone, you've already made the potential for perfect reproduction impossible.

DH: You got it.

FD: How about an audiophile question: What type of cable do you use?

DH: We use oxygen free copper. Made to our specifications—it's more rugged than most. It also has a good capacitance specification—about 13pf per foot. The cable used in the snake [the long cable connecting the control systems in the sound booth to the amplifiers on stage] has even less capacitance, about 6 pf per foot. I'm sure all the "hi-fi" guys are advocates of that sort of thing...essentially, non-inductive speaker cable. Although I think these considerations applied to a three foot length of [interconnect] is a little bit ridiculous.

FD: The whole High End cable industry is built around differences in cables and connectors and things like that. Valid to a point, but a lot of it is just an attempt to take advantage of people who want a new toy every couple of months.

DH: That's marketing. I can understand that. Why not?

FD: But no manufacturer wants to reveal his trade secrets.

DH: That's because a lot of considerations are debatable as to their validity. You can't really prove [whether one design is better than another], so if your opinion is [that] it makes your sound system groovier, then go for it! Although the differences in cables tend to be outweighed by the much larger differences in the rest of the equipment. If you want to [improve the sound of your system] there are so many other things you should attack.

FD: Where we were sitting, we could HEAR soundstaging and layered depth.

DH: Oh yeah, it's all there. Sometimes, on a really good night, when I'm in the mood for it, I'll fool with the time delay and create holographic effects and things like that.

PSB: How has this setup evolved from the old "Wall of Sound?" [The legendary, humongous sound system from 1974 which featured skyscraper-like banks of woofers, midranges, and tweeters. It lasted only a short while because of the impracticality and expense of touring with it.]

DH: That was a sort of breadboard. When I started out [in the mid-Sixties], the sound systems were really crude. They were basically public address systems. They were designed for voice, and music wasn't really part of the consideration. I began adapting Altec Voice of the Theatre boxes—which were developed by Bell Labs back in the Twenties for talking pictures. They were still fairly crude, but they were better than what people were using at the time. I used to go to rock and roll shows where there were just two folded horns on either side of the stage!

FD: Like those Atlas sound metal horns on poles.

DH: Yeah, that kind of s**t! By 1970, I had absorbed all the knowledge that had really been turned up, so it was time to develop some new ideas. There were a lot of questions we were asking that hadn't been answered. Like arguing over the distortion in a piece of wire or a connector and stuff like that. The f*****g audio world would look at you like you were nuts if you said s**t like that back in those days! They considered it unimportant.

It was time to carry things [to a new level]. Filters—we would sit around and argue the merits of a Bessel filter vs. a Butterworth filter—which one sound the best. My EQ here is all time corrected. Because I have to use such severe amounts of EQ, it would normally severely smear the time. so we use inverted all-pass networks that are included in the EQ programs, so when you write a filter in—the equalization is computer-controlled—it nullifies the time smear by writing in an all-pass network that's inversely proportional to the applied EQ.

FD: Otherwise, the amount of phase shift would destroy the time relationships of the musical signal and the integrity of the stereo image.

DH: Oh, this system will pass square waves! Even the snake has got time correction on it. That thing is 350 feet long!

We began severely questioning what was going on in the field of sound reproduction because we needed answers! That led us to the Wall of Sound, which was basically R and D for [today's efforts]. The purpose of that system was to define distortion, distribution, and dispersion; find out what happens when you stack arrays of speakers. All based on the theory that the optimum speaker is infinitely small, infinitely loud, and infinitely flat. Taken from there, obviously, every time you stack speakers, you're compromising. Well, we're talking about stacking dozens. Hundreds! And no one really offered any information about what to expect. Nobody had any information about what to expect. Nobody hand any hard core data. So we used that system to map and chart all facets of dispersion-related distortion, electronics related distortion, logistics of mechanical dispersion.

FD: Before the early Seventies, there was no such thing as a rock concert sound system. It evolved with the evolution of rock and roll.

DH: Right. All the people who worked with me throughout the years are the ones who wrote a lot of the chapters in that book. A lot of famous people, theoreticians, notorious audiophiles were involved.

FD: Such as John Curl.

DH: John Curl, for one. He's probably the papa of all picky audiophiles! That guy scrubs the resistor leads on resistors before he solders them into a circuit card! He claims the [oxidation on the leads] make the sound distort. And he's probably right!

FD: His equipment is quite good.

DH: I have nothing but wonderful things to say about the man. Same with John Meyer (of Meyer Sound), or Ron Wickersham...Owsley Stanley...a lot of people used the Wall of Sound as the launching pad to form their own companies.

I'll tell you where it all started. We were young hippie kids. Often times we couldn't rent equipment, or good equipment. We always would up with s**t stuff and leftover stuff to play with. We were very ambitious—we knew we were going places. So we began taking our own money and buying equipment. We basically thumbed our nose at the Establishment, who were really not very helpful or very contributive to our situation. It's only been in the last ten or fifteen years that the Grateful Dead has been venerable. Before that, we were considered renegades and outlaws!

However, during all of this time, we've probably done more to further concert sound than any other organization in the world, and probably most of the other organizations put together. The band was willing to put tremendous amounts of their money back into the equipment. That Wall of Sound cost millions of dollars! It was a means to an end for them to have the opportunity to play through [a system] that was truly worthwhile, because they, too, shared the dream of, "Wouldn't it be nice if we could go into one of these places and play music and have it be a truly great experience for us as musicians, as well as for the audience." It was a common goal between the band, the sound freaks, and the audience. It was fortunate that a bunch of genius-quality sound freaks got together and decided that we'd forego your own personalities, at least for a period of time, and collaborate. It yielded a tremendous amount of information that we now use. If nothing else, we found out what we didn't want to do. It's like all breadboard situations—the more flexible something is, the less expedient it is. Flexibility is paid for by the cash of expediency. That's just a reality of life. If you want something that does 20 different things, then it's not going to be as streamlined as the thing that does only one thing.

We were the first ones to start using time alignment. Direct coupling. Getting rid of capacitors. Do you know that this sound system is direct coupled?

FD: I can't believe you guys have the nerve to do that! What happens if somebody trips on a cord?

DH: It's decoupled going into the power amps.

FD: Oh, okay! (Laughter) I was picturing the worst...

DH: I've caught my sound system on fire! Literally burning. You put a rail of DC into a loudspeaker, and you get a bonfire! So, now it's decoupled in that one place. But the rest of it is DC-coupled. In a normal sound system you might go through as many as 20 series capacitors. This system has one series capacitor. All the preamps, the [mixing] console, the line drivers are all servoed to get rid of DC offset. There's an op amp in the feedback loop which senses any offset and feeds in an inverse signal which nullifies any offset.

FD: When did you first go stereo?

DH: Years ago. I've been a stereo freak for years. You can just do so much more with the image. Mono is just to limiting. I did the center-cluster thing for a while. There's a lot of people who think that's the way to go. It reduces you to one point source, which does eliminate a lot of standing wave and echo problems; at the same time it's much more boring. For me, this stereo configuration is one of an intentional compromise for the purpose of [what I want to do]. Sometimes, absolute purity isn't exactly what you want. You want to be able to have the flexibility of absolute purity but you also want to be able to pervert it somewhat if it's in the best interest of art.

FD: The stereo image: How to you maintain it?

DH: The left and the right [channels] sound absolutely the same. When I equalize the system to the room, I have two banks of equalizers, one for each channel. We electronically match them by using the B&K Spectrum Analyzer. We electronically match every filter, one at a time, so that they have absolutely the same frequency response, bandwidth, and so on. This preserves the stereo image throughout the frequency range.

FD: This room seems fairly symmetrical.

DH: Not really. All it takes is a vomitory here or there that's not in the same place on either side and, then there's a bump somewhere [in the frequency response] that isn't on the other side.

FD: When do you trust your ears, as opposed to the machinery?

DH: Every time. Everything that I do is tempered by what I hear with my ears. There are frequent times when the analyzer will say something that your ears just don't hear. Or conversely. In the end, the ear is the final judge.

I've known so many people who are insistent in going by the book, and you go in front of their speakers, and they just sound like s**t. And they insist that it's correct because [the measurements indicate it]. If it doesn't sound good, what's the point?

FD: How much of the equipment is off-the-shelf, and how much of it is dedicated hardware?

DH: Nothing is really "off-the-shelf." It's all modified and all rebuilt.

FD: You've eliminated most of the capacitors (in the equipment).

DH: Nothing is stock. It's modified both for physical endurance and for electrical "spiffing." There's a lot of things the audio industry does that they don't consider "violations," like...not only do they use capacitors, but they'll use tantalum capacitors. That to me, is a gross violation!

So we take out that kind of circuitry and put servo circuitry in its place. And in a lot of places in the circuitry, they'll use a capacitor to block, say 20 microvolts of DC offset, but we know that doesn't hurt anything, so we'll just run it. As long as there's not a tremendous amount of gain involved.

FD: So you're going for the least amount of componentry in the signal path.

DH: I'd have a straight wire between the microphone and the speaker if it were up to me. We use that as our model, and then get as close to that as practicality will enable us to.

FD: Which is?

DH: Direct coupling, no more gain that you have to have—the chain is really streamlined. The microphone goes through the microphone preamp. The [mixing] board is mostly passive. Then there's a combine stage, and then an output stage. Only three gain stages to get you out of the board. Then there are the line driver stages, and they have a little bit of gain, but they're mainly for buffering. The signal comes out of the board and goes into these filters, which are active. There's a stage in each one of the filters, but they're all direct coupled servo, no capacitors there, and the line driver is really a current converter, because it has a .01 ohm output impedance. The best way to nullify inductive disorders of the snake and stuff is to have the source impedance as low as possible. And then we also have all-pass networks on the snake, so you can pass a 1000Hz square wave into the mike preamp and measure it at the power amp, and you'll get a perfect square wave.

PSB: How did you find the transition from analogue to digital?

DH: It's likely that we're going to be digital by this time next year. I want to get rid of the analogue EQ. I'm getting to the place in my career where I'm really beginning to savvy how to deal with sports arenas and places with crappy acoustics. The way you have to do that is, you have to be able to deal with extremely articulate and extremely severe equalization. Analogue filtering just doesn't afford you that. You can't get steep enough filters without running into other problems, instability problems and things like that. So, the only real way to get the EQ that I think is going to make hockey halls sound like concert halls is by being able to digitize the signal, and then have a central processor run EQ programs. The problem so far is of course finding A-to-D and D-to-A converters that are agreeable to us sonically, and the other problem is being able to run enough information fast enough through the processor to be able to derive in a real time basis the equalization curves that we're looking for. Although there are some 20-bit A-to-D and D-to-A converters that are actually getting to be formidable.

One of the problems is we're stuck with S/PDIF [Sony/Philips Digital Interface] and all of the industry standards which have seriously curtailed the sampling frequencies [among other things]. So when you buy [digital hardware], it's usually based on being compatible with DAT players and CD players and crap like that. We want [hardware that is] much faster. We don't have to have drastic anti-aliasing filters. We want single-channel instead of dual-channel A-to-Ds, of much wider bandwidth. A megacycle sampling rate, rather than 44 kilocycles.

FD: What don't you like about the sound of today's digital hardware?

DH: When digital was first introduced, there were limitations regarding how quickly the chips could sample. The lowest speed the manufacturers could realistically use was about twice the highest audio frequency they wanted to use. And if your sampling frequency is less than twice your highest audio frequency, the two will "see" each other and beat together, and form artificial harmonics, which are forms of distortion. Even at twice the supposed highest audible audio frequency, this happens.

But twice the frequency was about all the technology would permit when the manufacturers locked in the standards, so severely sharp, 24, 36, even 48dB per octave brickwall filters are used, and they're horrible. They cause phase shift, introduce distortion, and disrupt the linearity of the signal well into the audio frequency range. So there's an inherent problem with the existing standard. No matter what you do, you're stuck. The answer to the problem would be if you used a sampling frequency which was ten times your highest audio frequency. Then the lowest sampling harmonic and the highest audio harmonics would still be so far apart there wouldn't be a problem with beat frequencies producing distortion [or brickwall filters introducing problems]. Increasing the sampling frequency is the only way that the lack of distortion and improvement in sound quality that guys like you and I demand is going to be achieved.

At any rate, that's the next step we're about to take. We feel that, assuming we can get our hands on hardware currently under development that can operate at the clock frequencies that we want, computers that can operate at that speed, and get 20-bit conversion that we feel passes the musical test, [in conjunction with] parallel processing with computers that have the horsepower to operate in real time, [we'll be able to achieve acceptable digital sound].

FD: The cymbal sound—it was extend, grainless, transparent-whatever audiophile buzzword you want to throw around—that's something I've never heard in any other live concert system.

DH: Well, most [sound contractors] use piezo tweeters in their [speaker] cabinets. I took them out and threw them away, I can't bear the sound coming out of them, it's simply bursts of random noise! They're just disgustingly awful. So I take them out and equalize the midrange horns [to extend into the high frequencies]. Each cabinet [made by John Meyer] has two [custom made in Switzerland] 12-inch drivers and a midrange horn. They'll go out real far, as long as you don't put too much [level] through them. John Meyer designs and builds his own diaphragms, and they're much better than [most]. His horns are much better tuned than most. They don't have huge peaks and bumps. This is a horn-loaded system, including the 12-inch drivers. The crossover and electronics are Grateful Dead home brew. This [speaker system] is very unique to itself, and it really has to do with being an audiophile for a lot of years and listening to a lot of things. I've redesigned everything to be High End, swift, full-range.

FD: What do you listen to at home?

DH: I don't have a sound system at home.

FD: How about the guys in the band?

DH: I don't really know. Some of them do, some of them don't. Bobby (Weir) has a nice system. Jerry (Garcia) doesn't. Phil (Lesh) has a nice stereo...I don't know what anybody else has. Speaking for myself, there isn't a system that's groovy enough that I'd want it in my home.

FD: You just slapped a lot of our readers in the face!

DH: Well, I don't want to...

FD: No, that's all right! I've said myself—a lot of these $20,000 preamps, and stuff...

DH: I've got all that stuff. John Meyer gave me his $20,000 preamp—in fact, I was using it as a line driver in this system for a while. I like the sound of [John] Curl's stuff. Electronics are easy. My main beef is speakers.

There's something about every speaker system that I don't like. I hung out with that guy who does the WAMM speakers...

FD: Dave Wilson.

DH: He's a nice guy, and he does well, and I know he really has intense faith in his stuff, but—they don't do anything for me. To him, that's it. I used to hang out with the Infinity guys...

FD: Arnie Nudell and Cary Christie...

DH: Yeah, in the old days, when they were in Santa Barbara, and they would sit around and pull their goatees and smoke their pipes and have long discussions about [the merits of various speakers]. I used to hang out with a guy named Jeff Cook, one of the most formidable audiophiles in the world, I think. He had a small scale system called Sound Storm, and he and I were [among the first] who started that really critical listening stuff. We used to have fun with all these [High End] honchos by having blindfold test, and we found that most of those people that sat around and went on trips like that couldn't pass them. The ones that could, could. There's a lot of things in audio that people worry about that aren't important, and a lot of things that people don't worry about that are important. When I say things like I do, I'm not trying to crash or crush anybody. I also don't think that that's grounds for giving up trying to design and build great equipment. I would rather hear a bad speaker with a good amplifier than a bad speaker with a bad amplifier!

FD: Trying to get to the point where you had a system which could literally reproduce live sound is what everybody's ultimately aiming for.

DH: The closes thing I ever heard was that ion speaker...

FD: The Hill Plasmatronics?

DH: No, a guy named Mack Turner, Jeff Cook, and myself were doing some experiments. Unfortunately, they're hopelessly inefficient, and probably won't ever work, but...they were impressive. We did a little bit of playing around with the flame speakers, but the ion ones were impressive! They just weren't loud, and of course they yielded deadly...

[At that point, Dan was called to the stage by Bob Weir, the question of flaming and deadly speakers (of the un-grateful variety) left in the mists of audio legend.]