- Category: General Interest & Interviews
- Created on Sunday, 01 April 2012 00:00
- Written by Garrett Hongo
Speaker manufacturer and designer Albert Von Schweikert has been a respected name in high-end audio for over 30 years. Starting with the legendary Vortex Screen in the late '70s, Von Schweikert has designed numerous speaker lines, for his own company and for many others, including the famous dual-box Von Schweikert Audio Virtual Reality series and the current UniField 1, 2, and 3 speakers. This past year, he launched a completely new speaker -- the VR-44 -- and has plans for a statement model called the VR-77. This past February, over lunch with Albert at a sushi restaurant in Covina, California, I began an extensive interview. Over the next two days, we continued the conversation at a listening session at a nearby dealer, then through a tour of the Von Schweikert Audio headquarters in Riverside, California.
Garrett Hongo: Where did you grow up, and what was it like growing up there?
Albert Von Schweikert: I was born in Panama. My father was German, my mother Spanish. My maternal grandfather, from Barcelona, was one of the engineers on the Panama Canal. My father, whose parents were German, had emigrated to the United States to avoid WWII. He ended up joining the US army as an officer. After being stationed in Panama, he got sent back to Germany to work as a translator. So I grew up in Heidelberg, where the great university is, and, until I was 16, attended German schools and had private music lessons at the conservatory. Music was all around us -- opera, brass bands, and street musicians with accordions, clarinets, trumpets, and a bucket for change.
After we got moved to the States, I went to high school in Florida and got interested in rock and roll. The night before I was supposed to leave for West Point -- an arrangement my father made -- I ran off to join a touring rock band. I could sight-read audition charts and wrote the band’s music. We backed Sonny & Cher and toured with Neil Diamond. This was in Florida in 1965. I ended up being on the road for nine years. We even put out a couple records back in ’67 or ’68, and one got to #1 in a few markets. We called ourselves The Raven and our first big hit, “Calamity Jane,” is on YouTube with a photo of the band. I’m on the far left. Later, I was also the lead guitarist for the Soul Survivors, who had the hit “Expressway to Your Heart” before I joined them.
It was during this time I made my first speaker stack -- a PA system for the band. I went to the library and spent days just skimming everything on speaker design that I could find. I found out that the best speakers were three-ways, not two-ways like the Altec A-7s we had. We bought JBL 15” woofers, JBL 8” full-range drivers, along with JBL horns that were put in ceilings of train stations. I just lashed them into a plywood box at first. But I worked on getting a realistic midrange by building a lot of different crossovers and listening for clarity. I hit upon stuffing the box with fiberglass to eliminate distortion. It was an idea I came up with when I was a 12-year-old kid back in Germany, when my father and I made our own hi-fi. We took a 15” Heathkit two-way we’d assembled and modified it. I stuffed the bass woofer cabinet with my pillow to speed it up and stop it from booming, and put cotton balls in the horn to stop it from sizzling. It worked! From my music background, I knew what music sounded like, and tuned the speaker to suit my knowledge of sound.
Later on, while on tour, I convinced Neil Diamond to use the system I’d built instead of the house PA. After the gig, Diamond said, “Al, you’re okay on guitar. You hit all the right notes, but you’re no virtuoso. When it comes to speakers, though, yours is the best system I’ve ever heard. You should quit music and go into the speaker business.”
I think that was how I first got the idea about building speakers as a profession.
GH: Tell me about your formal training. Was it at Caltech? What about your early experiences in loudspeaker design?
AVS: In my 30s, from 1976 to ’79, I worked in a lab at Caltech. As a project, I measured and built speakers, read a ton of books and articles on speaker and filter theory in the library, and invented crossovers. My particular concern was designing steep crossover points so the drivers in a three-way design wouldn’t interfere with each other and still get a flat frequency response and phase coherence. I went to the lab two or three nights a week, worked my day job selling audio gear at Federated Group, and read things like Siegfried Linkwitz’s articles in the Journal of the Audio Engineering Society about stacking multiple crossovers. After I’d read over 200 books on acoustics, physics, and filter design, I could see a pattern in what all of them said. I found the methodology and mathematical foundation behind what my own experience and intuition had been telling me and became very confident.
In the beginning, I attempted to design a small two-way speaker that would beat my UK-built Rogers LS3/5A minimonitors. To cross over the 6” woofer with the 1” tweeter I’d selected, I tried using simple first-order crossover filters, as the books indicated that this was the only way to phase-integrate the two filter sections. However, when using them on actual cone drivers, the driver overlap created a “beam” that was not flat in frequency, nor phase coherent off from the main axis. I realized that the only cure for this problem was to eliminate the overlap region by designing a steeper filter set. So I was on my way to develop one of the first crossover circuits that could integrate flat frequency response with phase coherency. I wanted a filter that had the drivers all in phase at the crossover point.
In the end, I was able to build a speaker with the sound of a first-order crossover, yet with the power response of a steep order. To chart the output of my speaker with the new crossovers, I put a big piece of paper on the wall facing the speakers and measured the frequency response at each spatial sector I’d drawn on it. No limiting sweet spot -- the output was even. I called it the Global Axis Network because the emanation of the speaker was evenly distributed.
After my lab experience at Caltech, I applied for a job at Electro-Static Sound Labs, to work for Dr. Oscar Heil. You might call him the Wernher von Braun of acoustics. He invented the JFET transistor and was brought over from Germany at the same time as von Braun. Heil worked in aerospace developing transducers. He also had built his own speakers and drivers almost his whole life, and was famous for his Air Motion Transformer speaker -- the AMT-1. This was essentially a folded ribbon crossed over to a 12” woofer in a floor-loaded transmission-line bass cabinet. The ESS Labs job announcement I answered specified that the successful candidate had to have a Ph.D. in electrical engineering and five years of experience in the industry. I had neither, but got to the interview and convinced Dr. Heil to give me a one-hour verbal test -- to ask me any advanced engineering question he could think of. After about 15 minutes, he gave me the job. I worked on quality control and production protocols for the AMT-1 two-ways. Then I designed a 12” three-way on my own that the company made. I introduced ESS to Fast Fourier Transform analyzers after buying one with my own money. While Dr. Heil concentrated on efficiency and punchiness in the AMT-1, I brought the company a design for a three-way with phase coherency.
After Dr. Heil’s investors closed the factory (his health had been declining), I moved on to KSC Industries and worked for two years in QC, OEM driver manufacturing, and designing crossover boards. I did everything -- woofers, mids, tweeters, and crossovers. Some of my projects ended up in speakers for Polk, Klipsch, JBL, Cerwin-Vega, NHT, and Infinity.
GH: When was Von Schweikert Audio established? What were/are your design goals?
AVS: Actually, I’d been building speakers in my garage for years and selling them to friends. One speaker I came up with was the Vortex Screen in 1979, and I started Vortex Acoustics from that in 1989. An acquaintance, Robert Harley, then a recording engineer just beginning a professional career, had bought an early pair. So did Mobile Fidelity Sound Labs, Sheffield Labs, and A&M Records. When Harley signed on at Stereophile, he published a review of the speaker and we got 500 orders overnight. I sold about 100 pairs by mail order before I realized I needed a dealer network. So, though I had offers to buy the brand, I closed Vortex and worked with Counterpoint Electronics as a consultant, and they hired me out to Lucasfilm as a speaker designer for THX theater systems. It wasn’t until 1993 that I started Von Schweikert Research. By then, I was tired of design and production compromises and wanted full control and a product with no compromises.
My design concerns were basically twofold: 1) to design drivers that were as transparent as possible with the technology available at that time; and 2) to utilize time-aligned voice-coil centers for phase coherency along with new types of filter circuits I had invented to propagate a phase-coherent soundwave. Additional requirements were a flat frequency response, wide bandwidth, low distortion and low coloration, and realistic dimensionality in overall sound.
I’d developed these goals after my experience at Caltech. For a while back at the lab, I’d been stumped about speakers. I’d designed something that measured well but didn’t sound good. This was all using the “black box theory” of speaker design, which insists that the loudspeaker is a device that shouldn’t add or subtract anything. But there are literally no design coordinates to build that black box. This was 1979. Dr. Richard C. Heyser was down the street at Jet Propulsion Laboratory, working on vibrational transducers to let the jet engine know that certain levels of propulsion were overdriving its frame. He worked on telemetry for the Apollo 12 through 16 lunar flight projects, too. Well, he also built audio speakers in his garage, built the first machine that could measure phase (the Time Delay Spectrometry device), and wrote two books on measurement systems and perception. He heard about our lab project and came over. We asked him to evaluate our process, and he told us our measurements didn’t even give 1% of what the speaker was doing. Dr. Heyser said, “OK, what’s good about your speaker, and how do you measure that?”
Well, this stumped us. It was something hard to quantify. For a few nights, my buddies in the lab and I had these bull sessions -- smoking weed, drinking Ripple and Boone’s Farm -- trying to come up with ideas. I fell asleep on the couch and woke the next morning from a dream. I had it: A speaker is really a microphone in reverse! We had to start measuring not the sinewaves -- the output of the speaker -- but what produces the sinewaves on the recording: the microphone itself. The design goal of the speaker is not to be a black box, but to re-create what the mike heard at the recording venue. I needed to study microphones, not speakers.
When I met with Dr. Heyser again, he confirmed my analysis, saying, “You think on a theoretical level -- that’s simple, correct, and elegant.”
I spent the next few months looking at microphone design, querying all the companies, and collecting all their specs, charts, and research documents. So, that’s my simple approach: designing a speaker as a microphone in reverse. Everything else is a search for perfection -- the constant experimentation with materials, using different building blocks.
What I developed out of this, some years later, was the Virtual Reality speaker series, starting with the VR-4, in 1993. It’s “virtual reality in four dimensions” with phase as the fourth dimension.
GH: What is the difference in the field now compared to when you first started out?
AVS: As most speakers are converging toward better and better sound, it’s increasingly hard to differentiate one from the others. These days, some designers believe the solution is to emphasize one aspect of design to the exclusion of others -- cabinet construction, exotic drivers, taking something to the nth degree. I think this is a false path -- to take one aspect and elevate it to the stratosphere. I’ve stayed away from hyperdevelopment in any one area in my designs and stuck with what I think are good, sound engineering values overall.
GH: Have you incorporated any changes in speaker technology since the VR-4 series? In other words, what’s new about your designs?
AVS: Well, we’ve made changes in our evaluation system, first of all. Instead of just me doing all the listening, or informally grabbing guys in the shop and asking them to give me their opinion of a prototype I’ve built, we now use two listening panels I put together to give subjective feedback about how our speakers sound. First, there are formal, organized listening tests conducted by a panel of listeners. We play recorded music on the speakers, and a panel of two or three listeners, myself included, makes evaluations. Second, we incorporate live-music demos and compare them to recorded-music demos using our speakers. We get a few musicians together to play acoustic guitar, a snare drum, cymbals, a harmonica, some wind instruments -- and, of course, singers too. We record it all on a hard drive, using Pro Tools, and listen to the same performance played back through our speakers. Then we make a second set of evaluations where the speaker is altered to more closely match what the original instruments and voices sounded like in that same room.
But here’s the most exciting thing. We’ve implemented new technology in the midranges we use and the way we use them. For 25 years, I’ve built traditional three-ways with the classical mid, woofer, and tweeter crossover points. The new technology, first used in the UniField 3 and now applied to the new VR-33, VR-35, and forthcoming VR-44, employs a full-range driver for the mid and adds a woofer harmonically tuned to the mid that augments the bass. We use a supertweeter to augment the upper treble and hypersonic range. Again, the mid is run full-range! Instead of cutting the signal into three sections according to frequency, I’m running the mid as a full-range driver and augmenting the signal at bass and treble with subwoofers and supertweeters. And extending crossover points to places where you can’t hear them -- woofers at 80Hz and below, tweeters at 6kHz on up. Essentially, what we’ve done is take the R&D from the UniField 3 and apply it to the VR-33, VR-35, and VR-44. I want them to sound like one-way speakers.
The VR-44 on display at RMAF 2011.
GH: For those not familiar with the UniField 3 speaker, which you developed in 2008, can you talk about what it is and what breakthroughs you thought it accomplished, particularly for Von Schweikert Audio?
Most of the great reference speakers available -- all multi-ways -- have some sort of problem with driver blending. Electrostatics and other types of panel speakers sound transparent and coherent due to their one-way design, lack of cabinet resonances, and lack of crossover distortion. I tried to invent a new type of speaker system wherein all of the standard trade-offs could be nullified by using some new technique. My solution was to use a single, full-range driver and augment its frequency extremes by adding a passive subwoofer below 80Hz and a ribbon supertweeter above 8kHz.
The single full-range driver cone is hand-built in Japan out of five different types of fibers that are nonresonant, very rigid, and light in weight. This driver has a response from 67Hz to 17kHz, so very little augmentation is required to make it sound like a big, full-range speaker system. It sounds as coherent as most electrostatic designs, since the crossover points are inaudible at 80Hz and 8kHz. It has a very high degree of dynamics and “life.” The ribbon supertweeter has an airy, detailed sound that captures the upper harmonics of most musical instruments, and has a tone quality that’s quite sweet, even though it goes up to 50kHz. Finally, the 7” subwoofer is mounted in a quasi-transmission line that has flat response to 30Hz. It easily handles high power up to 200Wpc.
The UniField 3 was also my first cabinet design to employ a 3"-thick sandwich composed of three different materials laminated together. The three materials have Q factors that differ by a factor of 2.7, so that, when they resonate, they do so at different frequencies that cancel each other. It’s quite simple to design and inexpensive to fabricate. Our Triple-Wall Laminate cabinet is as effective as solid aluminum sheets used in speaker cabinets that cost three to five times more.
GH: Will you tell me a little bit more about your newest designs?
AVS: The VR-33 entry-level model ($3750 USD per pair, factory-direct) is a boundary-loaded design, to be placed close to or against the wall in order to save space in the room, but, most importantly, to have at least one defined boundary that we can count on for placement purposes. The VR-33, along with the higher-quality version called the VR-35 Export Deluxe ($7995/pair), has a soundfield that is designed to be as large as the wall behind the speakers, but in fact can fool you into believing your room has disappeared. The rear-firing, 10” subwoofers in these two models use the wall behind the speakers as a “platform” to reflect the bass pressure, resulting in a uniform bass response almost anywhere in the room. As the sidewalls of these two models are angled, the sound pressure from the front driver array -- consisting of twin 6” full-range drivers with a ring tweeter in their center -- is encouraged to form a uniform pressure wave that is directed to the sides, rather than wrapped around to the rear. This technique is called “controlled directivity” and is well known to engineers who develop pro-application speaker systems, but is hardly ever used in high-end audio systems. Most speaker designers feel that their customers have large, empty rooms and can place large speakers far into the room. This is fine for a small percentage of audiophiles, but most have smaller rooms and have to deal with furniture, walk-through traffic, and non-symmetry issues. For these audiophiles, a wall/boundary-loaded speaker design is the key to good sound and keeping their marriages intact.
Check back on June 1, 2012, for Part Two of my interview with Albert Von Schweikert.
. . . Garrett Hongo