Albert Von Schweikert's Traveling Mr. Wizard Show

Inspired by Watch Mr. Wizard, a children's science show that aired on American TV 1951–1965, loudspeaker designer Albert Von Schweikert brought his updated, all-ages loudspeaker installment to Orinda, CA last weekend. Presenting to members of the newly constituted San Francisco Audio Society, who packed SFAS Events Goddess Leslie Lundin's newly renovated listening room, Von Schweikert and his grandson, Devon Von Schweikert, enabled attendees to compare the sound of various midrange drivers and enclosure materials.

"We could measure it, but instead we'll listen and see what we like best," Von Schweikert told attendees. "After all, everyone has a different spin on what drivers to use. And since 95% of today's engineers don't believe in time alignment, we'll discuss its benefits and trade-offs. Finally, we'll pretend to build a cabinet together."

First off, Von Schweikert asked if there is a defined goal for a loudspeaker. The correct answer, proffered by SFAS head honcho Alón Sagee (below), is to serve as a "reverse microphone," conveying precisely what the recording engineer captured with his or her microphones.

Ancient History
Then he reminisced a bit about how he initially stumbled onto the path of loudspeaker design. Von Schweikert's five-decade romance with loudspeaker design began at Cal Tech in Southern California, where he and fellow students attempted to build a loudspeaker. The initial model, he confesses, sounded terrible.

Enter speaker pioneer Richard C. Heyser (1931–1987), the former president of the Audio Engineering Society whose research on audio and acoustic measurement techniques resulted in nine patents, including one for time-delay spectrometry. "Do you want to make a speaker that measures good or sounds good?" asked Heyser. Spurring on the students to investigate how they could get a speaker cone to reproduce fast transients, Heyser inspired Von Schweikert to examine different driver and cabinet designs, as well as resultant room interactions that contribute to 60% of a system's sound.

Von Schweikert asserted that since every loudspeaker has colorations, the best mastering engineers learn to listen beyond and through their favorite speaker's colorations. Unintentionally providing evidence of same, he acknowledged that when the Von Schweikert Unifield 2 loudspeakers he had intended to tote to the demo were sold out from under him by an eager dealer, he was forced to bring a pair of Unifield 1s that had hardly any hours on them.

"I'm not overly concerned about the sound even though it sucks," Von Schweikert admitted. "Every loudspeaker is a trade-off," he said, as he played a track from Psalms, Reference Recordings' superb outing with the Turtle Creek Chorale. Happily, the rest of the system, which included an EMM Labs DAC 2X and Conrad-Johnson 140Wpc tube amp, helped soothe the ears of those who had formerly questioned whether loudspeakers even need break-in.

Returning to his history lesson, Von Schweikert noted that in 1954, when RCA Labs and Western Electric were competing to build the best movie theater speakers, Harry F. Olsen, Chief Acoustical Engineer at RCA, noted that the high-pitched sounds of Fred Astaire's tap dancing were not all of a piece with the lower pitched sounds. His solution was to crank the horn tweeters back and forth on a track until he could achieve time alignment between woofers and tweeters. This Von Schweikert demonstrated by positioning two 2" VIFA full-range drivers (100Hz–20kHz) atop each other (below), and moving them forwards and backwards until the sound aligned and what we heard seemed natural rather than hollow and nasal.

Then came the opportunity to listen to four very different midrange drivers. The first, which is used in both the Von Schweikert VR-44 and a number of Wilson Audio models, has a paper cone. Although the naked driver can sound harsh when unmounted in an enclosure, it also offers an extraordinary amount of detail.

Next came, in no particular order, a polypropylene driver that provided a very deep hall sound (as from a rear hall perspective) but less detail; an Audax driver with a cone made from very stuff, resin-impregnated carbon fiber; a very expensive Accuton ceramic cone driver ($600/wholesale), whose fragility was proven when Von Schweikert discovered his was cracked during shipment; the world's only push-pull planar magnetic driver, which the Japanese use for noise cancellation in subways; and a driver with a magnesium cone that is ceramic-coated to stop it from ringing

Cabinet Materials
"No single speaker cabinet material works optimally by itself," said Von Schweikert as he pointed to two very different materials. The first, designed with the aid of computer modeling, consisted of an outer core of MDF and a layer of artificial granite (crushed gravel and resin), bonded together by Plasticene non-drying adhesive. The artificial granite side also had a final layer of soft foam to absorb resonance and prevent reflections within the cabinet.

"This is better than any single material anyone uses, especially when braced internally," Von Schweikert claimed.

To make his case, he then presented a far more expensive sheet of aluminum. Acknowledging that both it and the MDF/artificial granite/foam sandwich would sound very different when formed into a cabinet with adequate bracing, he then proceeded to hang both materials from separate frames. After asking for a volunteer, SFAS member Vince Suave struck each material with a small tack hammer. Designers who use aluminum in their cabinet designs may cry foul—I personally have yet to hear a Magico or YG Acoustics loudspeaker that rings—but there was no question that, in this particular demonstration, Von Schweikert's layered material sounded far more inert and resonance-free than the aluminum.

Summing Up
"What has your 50 years of speaker building taught you about crossover design?" one attendee asked Von Schweikert at the end of the demo.

"The crossover is the heart of the speaker," he replied. "There are many ways to configure it; some are better than others. All good sounding crossovers have two things in common: high-quality parts, and the ability to disappear to the point that you can't hear them.

"Over the years, I've developed my own circuit architecture, which is unique to VSA speakers. Our patent-pending Global Axis Integration Network enables the drivers to create what I call a 'bubble of sound' rather the typical 'beam of sound.'" When questioned about this after the demo, Von Schweikert referenced something he said at the start of the presentation: "I like to be able to hear 3D sound all over the room, not just in the sweet spot.

"I doubt I've invented anything in my whole life," said Von Schweikert with genuine modesty. "I'm just a good assembler of ideas."

SFAS Events Goddess Leslie Lundin hosted the Von Schweikert event

corrective_unconscious's picture

I have never seen a review with lateral dispersion or polar response charts to show this bubble of sound from this sort of crossover. It would be interesting.

Pat McGinty used to have a finished speaker rig allowing him to move the tweeter back and forth and thus demonstrate time alignment, but some people claimed the methodology could be altering cabinet diffraction or lobing as the position changed. (In other words, the same validity questions the report here raises about the demonstration of cabinet materials and damping.) This was back before production type speakers came with adjustable heads, as we see from Focal and Wilson and Vienna Acoustics, etc.

Mr. von Schweikert has always had a slightly different assessment of time and phase alignment from the old Thiel and from Vandersteen, in that he thinks the threshold of audibility for delays is around the four or five millisecond mark.

I'd love to get a good pair of VR2 speakers on the used market; they always seemed to occupy a real sweet spot in the floorstander market.