FPS Model F1 Flat-Panel Hybrid Speaker System

Sneak Preview

Clement Perry

15 May 2002

Last month I had the pleasure of being given a sneak preview of a new-found speaker system called the F1 from Flat Panel Speaker Inc. I received a call from the one and only Albert Von Schweikert, Doctor Emeritus of Loudspeaker Engineering, after hearing rumors swirling about of a new "killer" system being developed in California based on an innovative Japanese flat panel module. His description of this revolutionary transducer made my mouth water, forcing me to jump on a plane (which wasn't easy for me after 9/11) to hear first-hand. No one has to ask me twice to be the first reviewer to get a "sneak preview" of something new, so off to San Diego I flew. Of course, the beautiful weather and tropical ambiance had nothing to do with my interest, of course. I was also overdue for a factory tour of Von Schweikert Audio, home of VSA Consulting Engineers, Robert Lee's Acoustic Zen Technologies, and Silver Smith Audio (Due to an incredibly hectic schedule I unfortunately never did visit Silver Smith).

As you may know, Von Schweikert has been a transducer designer and system engineer at many speaker companies over the years and is currently the Chief Engineer at EgglestonWorks Audio, among others, as well as his own company, Von Schweikert Audio. Mr. Von Schweikert has won many engineering awards, including Product of the Year (5 times) and Entrepreneur of the Year, awarded by the SBA in 1996.

FPS Flat Panel Transducer

Japanese reissues by companies like Impulse records, Columbia and Blue Note, to name but a few, are regarded by most audiophiles as being the best in their class. My own personal visit to Osaka in December of 2000 only confirmed further why this is so. Jazz, American Jazz at that, maintains a near fever pitch level in appreciation for reasons that I am unaware. The Japanese show an appreciation there like we once did here throughout the 1950's and early 60's. Ever dawn on you why there are such countless valuable pressings in both CD and vinyl available in Japan? Simple, supply and demand. The relentless quest for quality and the appreciation of music and its playback is legendary in Japan. So much in fact, I find it not surprising that a new state-of-the-art transducer would come from Japan as well.

FPS of Japan has spent years developing a new type of flat transducer that greatly reduces the disadvantages of ordinary flat panel drivers. Most audiophiles have heard the various incarnations of electrostatic and planar magnetic designs on the market, and many have had their love affair with this unique type of device. However, many grow tired of the limited dynamic range, lack of truly deep and powerful bass, and locked-into-a-vice type of imaging. The lack of dynamic range is due to the limited excursion potential of a stretched piece of plastic film in a clamped frame; the lack of deep bass stems from front-to-rear cancellation caused by the open baffle. Many large panel designs also beam their high frequencies like a flashlight, so one cannot move one's head more than what seems to be a few micro-inches. In addition, some listeners complain of electrostatic "brightness" or thin sound, lacking in body. The Acoustat panels were also said to have been highly colored, hinting that electrostatics and planar-magnetic speakers are not "automatically" superior just because they have no enclosure or crossover. Indeed, it seems that these may be limitations instead of benefits. The brains at FPS have actually found a way to eliminate their lack of dynamics that have haunted planar drivers for ages.

Engineering Aspects of the FPS Transducer

To eliminate the dynamic range constriction, FPS utilized a rubber half-roll surround, just like cone type drivers use. Indeed, I have been told by the engineers that the excursion potential of the FPS units is approximately 10 times greater than most electrostatic units, enabling extremely high dynamic range potential. In addition, to prevent front-to-rear cancellation of the low range that causes frequency and phase response aberrations, the FPS drivers are loaded into a narrow baffle with a closed back (the rear wave is absorbed by a thick pad of felt). Since the size of the individual FPS transducers is quite small, they do not beam the high frequencies. Indeed, I found the soundstage to be extremely "open" when I walked around the room. I was literally amazed when I heard a direct comparison against the new Martin-Logan Aeon electrostatic speaker system, which appeared to image from inside a closet due to its very limited dispersion pattern. In great contrast, a single F1 speaker almost sounds like a stereo pair, with no muffling off-axis! I remember having to sit in a very small sweet spot with my Maggies, spending many hundreds of hours trying to find a good place for them in my room, to no avail.

The Sum of 72

The most amazing thing about the FPS transducer is the drive system. Each 3" × 4" module that Professor Von Schweikert utilized in the F1 system employs twelve teeny motors! These flat diaphragms have 12 miniature copper voice coils imprinted upon the surface, three across and four down. The voice coils are spiral shaped and are connected to each other by thin trace of copper. A small Neodymium magnet, mounted on a perforated metal plate, drives each voice coil. I was amazed at how strong the diaphragm was. I could literally push it a quarter of an inch without bottoming the unit or stressing the diaphragm! If you have ever seen a Magnaplanar or Quad diaphragm, you know that you can't push on it, as it may become damaged. The clamped edge of a common planar device does not permit high excursion, and worse, the clamped edge causes reflections of energy to "stand" upon the surface when a signal is being reproduced. All said, each F1 speaker system has 72 motors! How's that for instantaneous dynamic response, I thought. No wonder FPS calls their flagship the F1: does that stand for Formula One racing?

Von Schweikert Audio Laboratory

Von Schweikert Audio is located just outside of San Diego, in a large industrial park in El Cajon, California. Von Schweikert's sound room proved to be formidable: 25 ft. wide by 75 ft. long, allowing him to make measurements almost in free space. As Von Schweikert studied to be a scientist, he has all sorts of exotic test equipment and makes measurements that I haven't even heard of. In addition, large tuning panels that are adjustable cover his listening walls; when the tuning panels were in place, the room was somewhat dead and probably very good for making measurements. However, the reverberation was deep and immense when the tuning panels were moved sideways, sounding something like a small concert hall (great for listening). The F1 was in the middle of the room, next to a Martin-Logan Aeon system (one of M-L's latest designs). Von Schweikert's impressive collection of electronics consists of a Linn CD12 compact disc player, a Hovland HP100 tube preamp, and a variety of amplifiers, including my beloved Bel Canto EVo, an 8-watt Single Ended Tube amp from AudioNote and a very impressive sounding 400-watt Spectron digital amplifier. Cables were by Acoustic Zen, one of my few personal favorites, along with some experimental cables by Paul Garner called Verbatim. (Stay tuned for a review on these interesting spiral-wound copper and silver hybrid interconnects and copper foil speaker cables). When I arrived at VSA, Von Schweikert showed me some of the FPS diaphragms and wanted to talk tech, but when he saw my eyes glaze over, he led me to his laboratory and sound room upstairs. In the middle of the room stood the F1 prototype, a slender speaker about 5 feet tall but only 9" wide. The graceful speaker has a swept-back look and is quite interesting (see the photos of the engineering "mule" in their ad on our front page). Von Schweikert's assistant engineer, Kevin Malmgren, did cosmetic design.

Transfixed by F1 Transducers

There are a total of six-FPS (3 × 4") transducers in a vertical line source, along with a dome super tweeter. In addition, there are two 4" midbass "couplers" that Von Schweikert said were necessary to blend the flat panels with the dual 7" cone subwoofers. Sitting outboard and attached by a long umbilical cord was one of the most complicated crossovers I have ever seen. My fellow reviewers know that I am not particularly fond of excess, so the amount of parts boggled my imagination. However, Von Schweikert pointed out that there were four circuits covering four different frequency ranges; much of the crossover is formed by parallel shunts to ground. In fact, very few of the parts were in series with the drivers and the parts quality was excellent. After hearing a description of how the circuits blend the amplitude, phase, and impedance of the various drivers (which is done by sampling the back EMF), I asked about the bass loading.

Acoustic-Turbo™ Bass System

It seems that Doctor Von Schweikert has come up with another variation of his favorite bass loading principle, the transmission line. As FPS calls it the "Acoustic-Turbo," I was dying to know why. Well, it seems that there are three chambers of different volumes, with each chamber expanding into another, something akin to horn loading but not using compression loading, hence the name. The first chamber is small and expands into the second chamber where the lower of the two woofers is loaded. Since the rear wave output of the upper woofer is fired into the second chamber (which loads another woofer), there is a velocity gain created by the expansion. When the upper pair of chambers are vented into the third chamber, there is yet another acoustic gain, further amplified by the Venturi port. Von Schweikert says the measurements indicate that there is approximately a 16 dB gain at 20 Hz compared to a sealed box. This design is patent pending by VSA and will be licensed to FPS exclusively.

How Low Can You Go?

During the demo, Kevin, the mechanical engineer at Von Schweikert Audio, compared the F1 to the Martin-Logan Aeon (which uses a metal 8" woofer in a sealed air suspension cabinet), playing several "mondo-bass" cuts I have heard in the past. In fact, I highly value deep bass thanks in part to the pretty incredible ROC 2002 subwoofer from Talon audio. Well, simply stated, the F1 simply destroyed the Aeon (and most other speakers I've heard lately) in the deep bass department. The F1 bass was not only deep and very powerful, but was so fast and clean that it defies the imagination. Although the F1 sounds as tight as a sealed box design, the speed and transient response were far more dynamic and also had amazing clarity. I could hear the fingerprints on a bass player's hand as he plucked an acoustic string bass on the song "Hush Now" on Three Blind Mice. Also, there was a tremendous difference in the dynamic range of the F1 compared to the Aeon, from bass to treble. The Martin-Logan sounded very constricted, shallow and compressed, while the F1 sounded like it was connected to some sort of gimmick device like a dynamic range expander! Von Schweikert feels that dynamic range is one of the most overlooked specifications to be addressed in modern speaker design. Von Schweikert uses blind ABX testing, so that when he and his listening panel audition a new design, no one knows which speaker is playing. In this case, there was no question of which speaker was the most realistic, since the efficiency and dynamic range of the F1 was absolutely incredible. Comparably priced, this, in my opinion, did not spell good news for Martin-Logan.

Midbass Couplers

When first approached by FPS engineers to design their loudspeaker, Von Schweikert told me he was not certain that he would be able to blend the incredibly fast and transparent planar drivers to a cone subwoofer system with 100% success. However, using the twin 4" couplers did the trick. He explained,

"The deep bass integrates completely with the hyper-transparent flat panel midrange units. The transient response of the two 7" woofers is not as fast as a half-dozen FPS transducers, as the directional patterns of the two driver types are not similar. The large woofers behave as a point source, with bass pressure wrapping around the speaker while the line source of flat panel transducers radiate a vertically oriented beam wave. The differing radiation patterns result in dips in the 90 degree off-axis horizontal frequency and phase responses, so the 4" midbass couplers allow a transfer of the radiation pattern and the frequency response laying between the deep bass and the midrange."

Rarely have I heard vocals as natural and clean as the many driver F1, with nary a hint of coloration.

Although the FPS panels go to 20 kHz, Von Schweikert says "they are somewhat inefficient at that range." Therefore, Professor Von Schweikert utilized a 1" silk fabric dome super-tweeter to enable the F1 to reproduce 25 kHz "air" and sheen from violins (his favorite instrument) as well as cymbals, bells, and chimes. When comparing the high frequencies of the F1 to the Martin-Logan, I was amazed how much "there" and "air" the F1 possessed, allowing cymbal harmonics to rise vertically! On violin solos, the F1 had more bloom and fullness compared to the electrostatic. In fact, on some recordings, the M-L sounded somewhat thin and bright, while the F1 sounded full, rich, and highly musical.

Comparing the midrange, especially with the human voice, completely sold me on the F1's flat panel transducers. Although the Martin-Logan is no slouch on voices, the electrostatic tends to favor high frequencies, especially their harmonics. The M-L was often overbearing in the upper midrange, even with Von Schweikert's highly musical playback gear, while the F1 sounded much more full-bodied and rich; so much so, that I was musically seduced. However, the F1 was not overly warm or thick, which is a big faux pas found in many speakers.

Art? Science? Or Sci-fi!

All in all, the F1 appeared to have many strengths and a high degree of what I can only call "magic" due to its seamless driver integration, wide and open dispersion, and incredible bass punch. No matter where I stood in the room, the F1 sounded fantastically "real" as well as highly enjoyable. Was the F1 a scientific breakthrough, as I would believe from seeing the FPS transducers, or was it art and/or magic?

Since this is a sneak preview and not a full review, I won't go any further except to say that the F1 is far superior to the Maggies I owned a few years ago. As well, the F1 "blew away" the Martin-Logan Aeon so badly that I suspect the F1 will be soon rated in the "Super Speaker" territory. Of course, only time will tell…..

Lastly, I am quite skeptical of the many driver and complicated crossover loudspeaker since being swooned by the Talon Khorus no-nonsense minimal approach. That duly noted, there is something very special in this F1 design that is purer in heart regardless of complexity. Most rewarding is its target price. I'm told the F1 loudspeaker is going to be priced for the real "Joe" Audiophile at around $7,000. Can you imagine, a loudspeaker that rivals the huge $70,000 Pipe Dreams in multiple-driver-count-per-enclosure, uses a new driver technology that is simply breakthrough, only stands 47" tall, yet costs less than seven grand? See FPS in Room 625 at Stereophiles' Home Entertainment Show at the NYC Hilton Hotel May 30 through June 2. I will be there.

Hey, Christmas may be coming very early this year.