Building a Legacy--Interview with Bill Dudleston by Tom Nousaine

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I first met Bill Dudleston in 1985. He and his partner, Jake Albright, drove to Chicago to pick up a pair of loudspeakers that I had reviewed. The speakers, now evolved into the Legacy Classic, sounded quite good, but what distinguished them from the competition was their furniture-grade

Since then, Legacy’s line has expanded to 12 models and the company has grown into a major player in the high-end speaker market by pioneering direct marketing and sales. In the process,. Legacy has developed a fanatical following among customers, thanks to the quality of its goods as well as to an extraordinary level of customer service that is several layers deep.

TN.

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How did you become interested in audio?

I really can’t remember ever not being involved in audio. My first memories in audio were of taking my grandmother’s stereo apart and putting it back together again or messing around with the phasing of a Capehart phonograph. When I was 12, I built a working radio, hand-wound tuner and all, from directions in a science hook.

My heart was always in audio, and my passion developed naturally. As a teenager I had three or four open-reel tape recorders. I would record anything I could. My first Akai recorder had sound-on-sound, which, of course, had delay between the tracks. So I mixed down things with slap echo like Sam Phillips and Elvis.



How about your training?

My degree is in chemical engineering, which requires an understanding of fluid flow and thermodynamics, plus an appreciation for mechanical and electrical engineering, in addition to chemistry. I think this background gave mean edge in acoustical modeling of polar patterns and in understanding phenomena such as mutual coupling.

Many models don’t treat sound as an expanding wave front but more like bullets bouncing around the room. If you drop a rock a bridge, you can see an expanding wave.

Sound works more like that. The fields overlap nicely, and the chemistry really helped with diaphragm technologies, surround adhesives, and the like.

What did you do after college?

I worked for a few years as a process engineer during the energy crunch. M job was to fine-tune chemical processes to decrease energy consumption. After that I supervised a digital research lab for an agrionics company, where I created calibration algorithms by using linear regression methods.

But these jobs just weren’t emotionally gratifying. I was working eight to ten hours a day in the lab and then coming home and modeling loudspeakers. I also built a lot of furniture and did a lot of woodworking.

Woodworking is a tedious process that re quires a lot of planning, patience, and manual labor. Just like scientific research. Starting a loudspeaker company put all the things I loved in life together for me.

It sure seems like you have done an excellent job of blending the art of constructing fine furniture with designing good-sounding loudspeakers.

The Legacy line in ‘86; the company now makes a dozen different models.

Almost all of my designs begin with acoustical parameters, leading to a certain driver layout or baffle width. From there you have to conceal your work and encase it in something you would want to bring into your home. When I think back about de signing the Whisper system, I remember the concept percolated for about 15 years. I had to get m head together on what I wanted to do with the directivity; another six months was spent on optimize the radiation pattern (using Speak software at that time).

But the final cosmetics were the biggest challenge—making the loudspeaker look like something you would want in your home. Initially the Whisper looked like two surfboards stuck in the sand, one behind the other.

The finished speaker looks like a monument or something. The front grille is shaped as a gemstone emerald cut to convince a woman it’s something she would want in her home. The Whisper is our most popular model among women. They actually encourage their husbands to buy them, if you can believe that. I actually had one guy in California, a decorator, who bought one just to look at it. He didn’t even want an amplifier.

When did you start professionally in the audio business?

That’s a tough one. I’ve recorded everything from sound effects and ceremonies to classical performances. I was around 20 years old be fore I did anything that was commercially viable.

How did you first get involved in building loudspeakers?

It was an economic thing. In high school I always made things for myself. I built my first bicycle. I built my first radio. At that time there was a loudspeaker I was rather fond of, the Dahlquist DQ-10. It was a touch inefficient and didn’t go too low, but I liked what it did right.

But I couldn’t justify spending that kind of money with college coming up, so I built my own. They were my first serious speakers, and I ended up winning a science award for them.

Were they just copies of the DQ-10?

No. The design was influenced strongly by the DQ-10, but I used different drivers and wound up doing things differently. This was all before Speaker Builder magazine was available. Amazingly, back in the ‘70s there was little information available at the local library, and you couldn’t pull anything down from the Web, so there was a lot of cut-and-try going on.

Later, my more serious designs came for a different reason. I always felt I could build a better speaker than I could buy at any reasonable price. Didn’t you feel that way, too?

Things aren’t the same for an amateur now. I used to feel confident I could make speakers better than I could buy. It’s difficult to do that today except with really big subwoofers. But how did you get into speakers as a business?

Something really reached me at the University of Illinois. We fit parameters of ideal gases to predict the behavior of a specific gas. It wasn’t until my fifth year that I realized you have to use a polynomial far more complex than we were using—and one fit ting a lot more parameters—to even approximate the behavior of real gases.

That taught me a lot about the oversimplification of Thiele-Small parameters. I re member having my Sharp pocket calculator and using handbook values to crunch numbers, only to find the measured response of real speakers varied wildly from the calculations because we didn’t consider many influences that occur with loudspeakers, like box loss, room gain, and floor bounce.

I really didn’t start building loudspeakers as a business. My interest just kept taking me that way. I didn’t build a loudspeaker to sell it. But whenever I built a loudspeaker system, somebody would want it. Then I would build another one. Eventually I just quit my job and started my own business.

With your partner, Jake?

At the time my father-in-law, Jake Albright, was a just-retired contractor who had been very successful. 1-le was a very good partner who saved me lots of steps in the business practice. It was 1983 when I really started looking at the business side of things, fore casting and so forth. When it’s just your own engineering time and your own labor, you can neglect what the real costs are. The ad vantage you have when you start that small is that you can do many variations on a product. In fact, during the first two years, most of the improvements resulted from solving vendor and supply problems. When you receive 15 variations of a woofer, pretty soon you get to know that design. That taught me the importance of reliable suppliers.

What was your first product?

The Legacy-1, a speaker that has become the Classic in our current line. It’s a floor- standing tower about 42 inches tall. We did enough things right on that speaker that it stood up well over time and through sever al design iterations.

In 1985, that speaker leaned backward. I was impressed with your candor when I asked whether that was a time-alignment trick.

Yes, I remember that. The back tilt was be cause there were so many drivers on the face that the speaker would tend to fall for ward unless small feet were added to tip it hack. I actually optimized the crossover phasing for that tilt.

How many did you sell that first year?

We sold about 20 pairs. Because of the amount of time it took to build them, that was probably a good thing. But there was enough financial activity for me to quit my job.

In the beginning I had to decide between getting more test equipment and buying parts in greater volume. I had an agreement with my wife that there would be no borrowed money. So I spent a couple of months installing car stereos to use up parts so I could buy larger hatches of parts and keep my test equipment, too.

So you made a foray into car stereo. Didn’t you also have a retail outlet?

Absolutely. My first building and wood shop actually had a four-car installation hay. It’s a test bay now, but then things were a lot cruder. One of my first products was a cabinet for hatchbacks, the Road Rocker. Ironically, Loyd Ivey of MTX used to summer in Springfield, Illinois, and hang out at the same Icy Root Beer I did. He has since parlayed that fuzzy box thing in the hacks of cars into a multimillion dollar business. That’s something I would not want to compete in today, that’s for sure. I think I put $300 worth of parts in the first box. It was internally amplified, too.

The company was originally called Reel to Real Designs. Where did that name come from?

Reel to Real was more studio-influenced; I was doing a lot of live recordings at the time. That was the shingle we operated under then, but the product line has always been called Legacy.

One of the things I am very proud of is our involvement with the Stradivari Violin Society, a nonprofit organization that is dedicated to the preservation of the world’s finest instruments. The Society uses Whispers as its reference system.

I have also built loudspeakers for studio purposes. In fact, our Focus developed out of requests from recording studios. They all had their high-level systems and wanted a loudspeaker that would play at 130 dB but at the same time retain the tonal and imaging characteristics of our Classic. So we made a much more dynamic loudspeaker, the Focus, It will do 115 dB at 20Hz!

At 1 meter?

Yeah, it really will. With three 12-inch woofers per side, it should.

How many speakers did you sell last year?

In the thousands, yet we are still production-limited. I won’t say it’s a problem; in a way it’s actually a blessing. For more than 10 years we have had a waiting list, just like one would wait for a Steinway piano or Stradivarius or another handcrafted product. But we are proud to say that most of the time the wait is under six weeks and typically about four.

What do you mean when you say “hand-crafted”?

Until 1995 everything was entirely done by hand: hand-plunge-routed, hand-sanded.

To this day the only thing automated is baffle-plunging, using a CNC router. Anything that involves veneers, crossover manufacturing, or tuning of the product is done by hand. Lots of labor. Our Whisper cabinet alone requires 108 man-hours.

Is there something more to it than just the quality of the finish?

Automation can, of course, provide comparable tolerances and accuracy, if not better. The real benefit of the hand labor is the selectivity of it. For example, if you are laying out veneer on a pattern or selecting hard wood to brace the uprights, you can select out the knots and hand-cut it, making sure the left speaker will look like the right.

From a consumer’s standpoint, the benefits of handcrafting will definitely be in the product’s finish. There are seven steps of hand-rubbing and polishing the cabinetry. It’s definitely the slow point in the process. In most companies this would be the area where people would try to get the wheels to turn faster, but that’s not our formula. Just like a number of companies that have survived for a long time, such as McIntosh, we appreciate why we are in our niche. We just continue to do things the way that has proven successful.

Are you ever about it? I once heard of a company that refused a large order because it didn’t think a piano-black finish would do justice to its speaker.

Remember, I started this business to satisfy myself; that’s as straightforward as I can put it. But over the years I’ve learned the value of relationships with customers. If there is a Legacy difference, it’s that we listen to the customers’ needs. For example, recently we had a customer who said he wanted our Focus speaker on a Whisper-style oval base. Our cabinet shop handcrafted it for him. We have had quite a few people with requests like that. While we try to be realistic about it, we don’t like to use the word “no” when it comes to customers.

So, if I were to buy Legacy speakers, I would have a good chance of getting a pair that is unique or unusual in some way?

It definitely can be done. There s a little longer alt on something like that We ye done things like curly maple for customers. In fact, we’ve added curly maple as a new custom finish this year.

The added cost to the company is higher than you would expect when you factor in the space required to lay out and store the custom materials. But the real cost is in what other companies consider a break of efficiency: Could you have built four that day instead of two?

Speaking of how your company differs from others, tell me about your distribution system.

I think there are a lot of myths about it. I see a company advertising that it was the first direct-marketing company in the speaker business. We weren’t the first, and we started three or four years before that company.

What I can tell you is that direct marketing would, at first, appear illogical in selling speakers. Who’s going to buy something he can’t hear? We swam up stream and still do. In the early years we offered free shipping to the customer; we were willing to bet you would like our loud speaker better. Our early ads said: “Go find your favorite loudspeaker, or even the best speaker you can find anywhere, and we will ship you ours. If you don’t like it, send it back!”

We were able to achieve a 98% success rate doing that. Direct marketing wasn’t some thing we happened into. Direct marketing was what allowed us to build a better speaker, by investing more in its construction.

At the time we started, there were 450 loudspeaker manufacturers. If we were going to make any noise we had to have a demonstrably better product—not just in audio terms but in furniture terms and in customer service. Customer service is one thing that separates us from the pack.

Can you be more specific about what customer service means to you?

Customer service is following up after the sale, answering questions before the sale, giving advice in areas where you might say that there’s nothing in it for Legacy except establishing a good reputation. The biggest difference is what happens when someone calls us about a possible loudspeaker or audio system purchase. We can take him through a show-and-tell sheet, which is a room diagram, construct a model of his room on a screen or a sheet, or send a form to fax back. We’ll discuss speaker placement in the room and what widths and heights are required. For example, when someone buys an on-wall speaker he often doesn’t know the height of the wall over the door way. We’ll go through all the details. Basically, more than anything else, it’s about personalizing and understanding individual needs.

This may seem like a stretch, but we’ve had people say, “I want to buy a pair of Classics, but I have a problem. My left speaker is going to have to sit on a hearth, so I need 4 inches cut off it.” I have actually adjusted crossovers and retuned the cabinet to compensate for that 4-inch difference in height.

At what cost?

It’s on the order of $150 for a modification like that. We are in a field that has perhaps the world’s most persnickety customer. Not only are there a variety of “religious” beliefs going in, like tubes versus solid state, but we also have subjective coloration preferences and a host of other considerations. The secret of customer service and dealing with individuals is listening. It’s important to get them to relax. You have to listen to what their needs are.

Have you ever had dealers?

In the early years we experimented with dealers, but there is an implied value in going to a dealer. Remember, this business was started by a guy who longed for that one- on-one customer contact. In the early years, I saw dealers more as a barrier because the customer always came back to us with questions anyway.

On the distribution side, direct marketing seemed to offer many strong advantages in terms of customization of the product. It would have been impractical for a retailer to inventory 12 products in eight different finishes. But we have worked with a number of installers who bring us their customers’ needs. This year we are looking to add a few more installers. In recent years our line has expanded so broadly that very little customization is required.

How do you test or tune your speakers?

Tuning is quite an involved process. One reason is that we use multiway crossovers. For example, if you are building two-ways, you can grade woofers and tweeters, batch them together, and off you go. When you’re going with a four-way, things get a bit stickier. We also grade and batch raw drivers by impedance curves and so forth. But in final production, we null the first speaker in a pair against a “mother” (a reference unit) and then match the second speaker to the first. It’s an intensive process; we spend 45 minutes to an hour on every pair just manually testing and tuning.

That’s different from driver selection, isn’t it?

Driver selection is done earlier. It’s a culling process of rejecting drivers we find unacceptable, even if they con form to the manufacturing spec.

But grading drivers alone won’t get you there, because of the overlapping and under-lapping going on with three-, four-, and five-way designs. To get those speakers pinned down so that their polar patterns are all tilted and phased properly is difficult. Anyone who has looked at driver impedance curves knows how reactive drivers are, and to use steep slopes and lock these drivers in is not an easy thing to do.

By the way, we batch our woofers by f_s (resonance frequency). Midrange drivers are checked acoustically as well as electrically. We reject about 15% of the mid range drivers after buying from the highest quality vendors we can find. We test them with frequency sweeps and by listening to complex tones like piano and voices for high order harmonics.

Doesn’t failing your listening tests mean that the driver will fail the frequency response test?

You can find drivers with normal-looking response and impedance specs, but when playing music their voice-coil leads may be a little too short or the voice coil may rub

How about tuning the finished product?

That’s where I was going earlier. First we check all the switches and controls, making sure all the binding posts are tight and everything is operating properly. Then the tuning begins. We place the speakers side by side, aimed in toward a microphone at 1 meter, while inverting the polarity on one speaker. We remove the crossover from each enclosure and match the two loudspeakers by adjusting the crossover to get the deepest acoustic null we can. What’s beautiful about this technique is that the difference plot we get indicates any errors precisely.

There are five to twelve attachment points in every speaker where we can trim values. We typically change a choke or a capacitor or tweak resistor values before the speakers are ready to go out as matched pairs.

When you find errors, which speaker do you fix?

The final pair must be qualified against the mother, so we fix the one that deviates from the mother. But there are times when you can’t tune the errors out. Because our tolerances are very tight, it’s sometimes better to replace drivers. It’s particularly touchy in the midrange; the top and bottom seldom require any bending.

Let’s change gears. Do you consider yourself high-end?

To me, high-end is high-performance audio, and I certainly consider Legacy products to be very high performance. And we are not inexpensive.

As far as fitting into the chemistry of the high end, well, the high-end audio industry is a bit bizarre, to say the least. There are some incredible products being sold out there, and right next to them is some guy selling magic rocks and glow-in-the- dark interconnects. That part I don’t see our company fitting into. We tend to be a lot more practical and hope we have our feet planted a bit more firmly on the ground.

I can’t fault the industry for its style. The biggest problem is its reluctance to move forward when real technology is available. Our industry now is paying a price for not being as progressive as the computer industry in the late ‘80s and early ‘90s. The consumer could have been benefiting more from DSP digital higher-efficiency amplifiers, and so forth. For that part of the high- end industry, I am saddened.

But the consumer is the boss. Between the home theater push, which is a healthy thing, and the push in computer technology, high-end audio is waking up. A lot of manufacturers are scrambling to build much better products. That’s a good thing.

It seems like much of the high end is trapped in two-channel.

There is a certain magic that occurs in the two-channel demonstration where you synthesize a phantom center image from a mono feed. That is a wonderful phenomenon—hence the success of stereo. Multi- channel doesn’t have to be seen as a detraction from stereo, however. You can always go back to two-channel.

One thing I’ve found is that the advantage of adding a center channel is difficult to talk about to a customer until it’s been demonstrated. For example, if I take our Marquis center channel—which is timbre matched to the Whisper—I can convince a centered listener that he has heard the same thing twice when I switch the Marquis on and off. You don t notice anything until you move a few feet off center.

Then consider the history of stereo perspectives and listening angles. The first stereo most people owned had speakers attached to a portable phonograph and spaced only 24 inches apart. But if you think about Blumlein stereo and ORTF recordings I think the ma listening angle is 5 degrees off the noses axis. That makes a total 110 degrees included angle. Back in those days wider speaker spreads were very desirable.

But an audiophile today often places his speakers 5 feet apart and sits 10 feet away trying to maintain a strong center image There s not much benefit in adding a center speaker in a situation like that When you add a center speaker you can and should spread the others farther apart


ABOVE: Geoffrey Fusi and master builder Tetsuo Matsu.

Speaking of angles, you’ve done some interesting work on directivity control. How did you get started on that?

Directivity control is not something that came to me quickly I had to be hammered over the head for 25 years before I under stood the need for it.

I think back about my early analog sys tern and how we would buy phono cartridges with 20 or 25 dB of separation at 1 kHz and amplifiers with 80 dB of separation We think of channel separation as if it were significant at the front end of the sys tern But the minute we get to the speaker we stop talking about it The same is true for signal to noise ratio.

If your phono cartridge picked up ghosts as it tracked along as can occur with multi path in FM radio it would seem unacceptable. But when you listen to a loudspeaker system you get the original program material that was recorded plus your room s imprint on it.

Eventually I realized that we need to improve the signal to noise ratio of the over all system more signal less room. The goal should be to hear the recording halls environment not your own We have to understand that what we pick up at each ear is purely two dimensional—amplitude modulated over time The matrixing is all done by the brain.

Let me illustrate. Cover one ear and listen to someone speak. Everything sounds too reverberant. Then remove your hand and it all snaps back to normal. That’s because the brain is able to correlate and lock onto the information common at both ears.

A good loudspeaker setup should leave you with a you are there perspective not they are here. We need to minimize the influences of the room. In the Legacy product line you will see that as the speakers become more complex they are getting larger and have more piston area. This lowers distortion and improves directivity control. Our Focus has a strong midrange null in its out put toward the floor to minimize floor bounce effects and the Whisper takes the concept to the next level by doing it horizontally as well.

The Whisper system has the narrowest wideband directivity of any speaker I know of today It’s desirable to keep the radiation angle close to 45-degr., so that we can keep the left more left and the right more right This was readily achieved at high frequencies by orienting our ribbon driver sideways and loading the dome into a foam throat. But as the frequency drops we have to work a different trick At 1 kHz the wavelength is 10 times longer than at 10 kHz so its a different ball game Trying to wave guide that and avoid the problems of a horn meant using different tools.

Different tools?

We built an array of five identical cone drivers one in the center two above and two below Then we worked with the spread to optimize the radiation angle both vertically and horizontally Ultimately we set up a di viding network so we could hear the four outer drivers the one in the center or all five. What we discovered wasn’t what we expected. First of all four drivers were far more precise than a single one because they formed a larger source that behaved some what like a parabolic antenna in reverse to. The thing that was most bizarre was that the perceived loudness was greater for the four drivers than for one even when the levels were matched The ear can lock onto the four more readily than the one That is be cause we are constantly trying to use our two ears to maximize the signal to noise ratio. Reduced reverberant energy is perceived as an increase in signal to noise ratio.

We understood this phenomenon better when we noticed that from an adjacent room the sound was noticeably softer when four drivers were playing The relative amount of reverberant energy had dropped.

What approach did you take in the Wins per s woofer section?

The bass section was the real holdup I had built a woofer behind the woofer dipole prototype around 1991/92 so I could feed them the same signal but play with the phasing and frequency shaping to peck away at the rear radiation—a synthetic di pole if you will I also experimented with the physical spacing What I learned is that a dipole has some pretty desirable characteristics, with one strong exception: the low-frequency rolloff rate.

The ultimate downside to the dipole, however, was that it still engaged the room to some degree at low frequencies. My goal became to squash the figure-8 pattern into something that looked more like an infinity symbol, to steer more intensity front and rear, creating a tighter pattern.

A bell went off in my head. I remembered a paper by Harry Olsen, from back in 1972, I believe. When I first read it I had wondered why anyone would ever want to do this. Why would anyone want to build a high-directivity low-frequency cannon? But here I was searching for one.

I built the design but found there are some things in the paper that don’t seem to work. It took about a year of building Whisper prototypes before I began to have an idea of what was really happening with it. Olsen was trying to tell us something there.

The Whisper is not a second-order gradient design, then?

I prefer the term “differential”; I would like to reserve “gradient” for microphones, where it really has meaning. I have built prototypes with as many as six woofers front to hack. What works for two works even better with more drivers. But there’s no free lunch. There’s a power penalty: For every 3 dB of power in your budget, you are getting only 1.3 dB of it hack in on-axis radiation; the rest is lost creating the strong nulls to the sides.

What’s the speaker’s low-frequency bandwidth?

It’s extraordinary, with adequate piston area—quite usable down to the resonant frequency of the driver itself and with good directivity control. Overall, it’s a pretty sensitive system, but the rolloff at very low frequencies is pretty sharp, too. The Whisper system also has six poles of electronic equalization with adjustable bass damping. So the system has a 22-Hz low-frequency cutoff, but it’s adjustable. If you use a sub- woofer, you will be better off moving that upward to 38 to 40 Hz. You’ll still get all the directivity-control benefits, and when you drop below 40 hz you are talking room pressurization anyway. You don’t need directivity control down there, where reflections are in-phase; you just want to fill the bucket.

Do you see a change in the way people approach audio today?

Yes. For test marketing, I watch my daughter’s habits. Though 11, she is already a teenager today—a girl on the go. You have to be able to take your stuff from room to room and floor to floor, and you gotta be able to show your buddies. It’s in formation-swapping.


ABOVE--- The Classic is a direct descendent of the Legacy-1, the company’s very first product.

And one of the most frequent questions I get from people is: What are the trade-offs when you go from a two-channel to a multichannel system?

Hey, there are no trade-offs!

Exactly, but one of the main questions is what’s best for surround speakers: bipole, dipole, cardioid, or a conventional mono- pole? (I hate that term, “monopole.”) The answer is that 12 monopoles wrapped around you would work just fine. But given that we don’t have 10 to 12 surround speakers, I think we can arrive at a darn good compromise by using two to four bi-poles.

I don’t care what kind of surround you get—just get it. Not having surround is the compromise.

I saw Armageddon; the amount of hard steering going on is—well, there are things that arc clearly localizable in the surrounds. Things can be hyped, but many of those things can add to the naturalness in audio reproduction. With music, I love having the crowd to the sides and rear instead of behind the perf where two—channel puts them.

I’ve had a multichannel system as far hack as 1975. Anyone who has experienced immersion just can’t live without it. It takes your walls out. It takes the room away. That also ties into the value of high directivity in the front planes. With surround, you can get the immersion effect without compromising clarity.

A while back, Legacy merged with Allen Organ. How did that come about?

As we became more and more successful, my partner began working his way out of the business. I have always been interested in customer contact but, frankly, never the financial side.

Finally, at 75 years of age, Jake told me he was ready to retire, and I had to make a decision. One option was to sell the business outright, but my heart was still in it. I felt that Legacy had grown to a point where we were ready for the next step. Jake’s retirement just underscored that.

So I began looking for a technology partner. The Wall Street Journal had just published a column on Legacy and our level of customer service—a “come to the cornfields of Illinois and find out how customer service is really done, the old-fashioned way” kind of thing. That article triggered a response from a musical instrument manufacturer, the Allen Organ Company, a company I probably would not have considered otherwise. They invited me to visit, and I was absolutely blown away.

I had pictured a stodgy old church organ company. I get out there, and I see 15 channels of DSP and 15 channels of amplification with digitally adjustable acoustics. I’m not talking about just delay or reverb, I’m talking interplay between the channels.

They could synthesize an entire environment! I later discovered that Allen had pioneered DSP for music applications, working with Rockwell around 1970. And its plant is not far from Morristown, New Jersey, where Bell Labs invented PCM 50 years ago [as of late 1997].

I also hadn’t known that I was going to meet three generations of Dutch craftsmen there who could help with the manufacture of our product. Now all the rosewood on a Whisper baffle is laid up at Allen. Some Focus pieces are made up at Allen, too. And by combining laboratory facilities, we have become even more rigorous in our methods.

Working through Allen’s network of musical instrument dealers, we now have audition sites for our products in many parts of the country. Pilot sites in Dallas and Atlanta, for example, offer multiple show rooms dedicated to demonstrating Legacy products. The people who run these sites are musicians, and they have well-trained technicians on staff It all fits together pretty naturally.


ABOVE--The Impulse Legacy’s 200-watt/channel integrated amp

What about listening rooms? What are your thoughts?

The biggest improvements we will see over the next quarter-century will come through the application of DSP. We’ll still need speakers with flat power response and properly oriented lobing patterns, but the room transfer function can he broken down into certain frequency bands. My way of looking at it is to break it down into three parts, the three R’s of playback. First, there’s a reinforcement zone from DC to 35 to 40 Hz or so, where reflections are in- phase. Then there’s the heavily resonant zone, up to about 300 Hz, where rooms typically induce large response swings. Above that, you transition into the reverberant zone. DSP will help us deal with these different room characteristics most intelligently.

We have learned and benefited from the work at SigTech, which shows that it takes tons of power to compensate for a high-Q resonance and that if you try to compensate for high-Q resonances, you just create new errors at different locations.

At the lowest frequencies, we should treat the pressure in that zone as pressure and adjust it accordingly. There is plenty of ad vantage to more piston area down there, be cause it lowers distortion and provides a better-damped system. But you are not going to get a “faster” system—30 Hz is 30 Hz.

That’s cycles per second. If it were faster, it would be a higher frequency. People always talk about woofer speed, hut to steal an al ready coined phrase, “If a woofer were fast, it would he a tweeter.”

As we move into the resonant zone, effects become very position-de pendent. I’m not sure that folks fully understand the nodal and anti-nodal behavior from floor to ceiling. Even listener height will affect performance.

How, in your opinion, will multi channel play out here?

Discrete channels will afford us more control and better separation. With stereo loudspeaker playback, channel separation in a room is typically less than 2 dB over the frequency range of human speech, com pared to about 6 dB in free-field. That’s one of the advantages of a center channel that may not be obvious. A center-channel speaker is higher above the floor and farther away from other boundaries than the other channels. You have to love it.

I have come up with a simple system for adjusting rear-channel speakers. I wheel my chair around and equalize while looking at the back wall. This prevents me from over riding the natural head-related transfer function. Try to get things to sound like the front channels when you’re facing the other way.

I use the term “fog” or “mist” to describe spatial envelopment. In a good, misty environment, I should feel moisture evenly on my skin no matter where I sit.

We did a rear-channel demonstration in Dallas this year. No processors or anything, just a pair of left and right wall-mounted surround speakers. We demonstrated them operating in-phase and out-of-phase. Out- of-phase just shoves the walls out. And when you shut one off, you have no problem localizing the sound as left or right.

One way to avoid surround localization is to make sure the speakers are above the plane of your ears.

Absolutely. When you do that you are also creating support slightly behind you, in what I call the “bald spot” area. I am also working on a new system that detects diagonal conditions to gate an overhead speaker to enhance flyover effects and provide better continuity.

You’ve seen lights with a parabolic shade that flood the room with light. I’ve built quite a few speakers like that and fired them at the ceiling to “illuminate” the room with acoustic ambience. That idea may turn into a new product as well.

Also see: All About Paradigm Loudspeakers

Adapted from 1998 Audio magazine article. Classic Audio and Audio Engineering magazine issues are available for free download at the Internet Archive (archive.org, aka The Wayback Machine)





 

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Updated: Saturday, 2016-03-05 9:15 PST