Why should you consider a Von Schweikert Audio speaker for your system?
The goal of each Von Schweikert Audio model is to provide a word-class reference product that can be used for both professional applications and home use. Each model is uniquely endowed with engineering breakthroughs combined with the latest technology in driver design, psychoacoustics, and aesthetic design. For instance, we were awarded the CES Engineering Award for our Global Axis Integration Network in 1996. This crossover design and driver radiation pattern allows the speaker to radiate a "bubble" of sound instead of a narrow beam, allowing 3-D imaging over a very wide space. No more trading chairs for the "sweet spot!" Combined with our rear-firing Ambience Driver for spatial depth, the VR speakers reproduce sound that is incredibly real! Find out why 19 magazine reviewers have stated, "the Von Schweikerts do indeed create Virtual Reality!"
These efforts translate into a true and accurate musical experience that you will thoroughly enjoy whether you are listening to a Bach piano concerto or watching the latest DVD. Stunning realism, holographic 3D imaging, and incredible transparency are found in every Von Schweikert Audio speaker!
How do we design our speakers?
With live musical instruments of course!
We have sophisticated laboratory grade test equipment to measure our speakers just like all the other speaker companies; however, a flat frequency curve does not always mean a speaker sounds real. That is why we use musical instruments such as the human voice, acoustic guitar, snare drum, trombone, harmonica and trumpet to test our speakers. Using a live microphone feed to run the instruments through our speakers, we then invite a listening panel to compare the sound of the original instrument to the sound of our speaker model under test. No Von Schweikert speaker model is released for sale until it passes this critical test!
Build Quality?
All Von Schweikert Audio speakers are engineered to the extreme. Thick wall cabinets, heavy bracing, constrained layered dampening, Analysis Plus wire, and Cardas binding posts are found in every model. Our crossover boards use silver solder, point-to-point wiring and star grounding. The quality of Von Schweikert speakers is surpassed by no other brand available, at any price. No compromises!
Drivers
New technology includes patented Low Distortion Motors for 75% greater clarity. Exotic diaphragm materials including aluminum woofer cones and Aerogel tm midrange diaphragms provide accurate response. Treated silk domes are used on all models with rear-firing fabric Ambience Drivers used on all floor- standing models.
If you are looking for:
- Sonic realism - Find out why our speakers are called "Virtual Reality".
- Accurately tight bass - Extreme engineering results in lots of bass from a small space.
- State-of-the-art transparency - Our speakers are used as references by magazines and studios.
- 3D Imaging - Discover a band or orchestra in your room.
- Liquidity of sound - We have patents on low distortion technology: treat your ears!
- Prestige of award winning designs - 19 reviews state that the VR's are among the best speakers available.
Von Schweikert Audio promises that every listening session will be an emotional experience not soon forgotten!
VR (Virtual Reality) Speaker Design Theory
by Albert Von Schweikert
- The Global Axis Integration Network tm
- Acoustic Inverse Replication tm
My dissatisfaction with the lack of realism in contemporary speaker design has led me on a long quest. Twenty years ago, several experiments I conducted at the California Institute for Technology enabled me to discover several important psychoacoustic principles.
PSYCHOACOUSTICS
The first discovery was that the ear/brain hearing mechanism can sense differences between certain types of sound wave patterns and uses this recognition for identification and spatial localization of sound sources. For instance, an omnidirectional wave pattern consisting of spherical sound waves can be differentiated from highly directional beam waves. A computer in the brain compares data arriving at each ear and computes directional data from arrival times, frequency, phase, and amplitude responses, among other things. This data is stored for later processing, and over a sufficient learning process, becomes an acoustic reference bank. Differences in the data arriving at each ear conveys stereo information, for instance, including spatial localization and timbre recognition of previously heard tones or other sonic sources.
An omnidirectional source radiating a spherical sound pressure wave is comparable to an acoustic musical instrument such as a guitar, piano, or drum. A directional source (read: conventional forward-firing speaker system), however, does not sound precisely the same, nor loads an average listening room in the same manner, due to non-linear frequency response combined with time and phase delays in the off-axis response. These aberrations contribute to warped sound waves that are neither coherent nor accurate to the original spherical waves, and can be easily heard as such, no matter how accurate the system appears to measure on axis. These aberrations are highlighted due to reflected energy from boundaries such as the floor, ceiling, and walls. Although previously documented, these effects were not considered to be of prime importance prior to my research, but had tremendously important psychoacoustic implications, as I discovered.
DESIRED AXIAL RESPONSE VS. OFF-AXIS ABERRATIONS
I had developed a small two-way speaker system that exhibited perfect measurements by the existing standards of the day (1976). The design was a Time Aligned two-way speaker using a 6.5" woofer, with first order phase coherent crossovers. The impulse response was pretty good, considering the drivers being used, and the frequency response was exceptionally flat on the axis directly in front of the speaker's tweeter. Yet side-by- side comparisons with an acoustic guitar as a sound source revealed that the prototype lacked an essential realism. One evening, while I was listening to my creation in that magic sweet spot where the music seemed to come together, my wife was washing dishes. I was complaining about my disappointment with the sound quality, so my wife Linda, far off-axis in the kitchen, remarked that the sound was muffled and did not float in the air like the sound of our Hardmann (circa 1899) upright grand piano. This somewhat startled me, since in the narrow "sweet spot" where I sat there did not appear to be problems with muffling nor image recreation.
I then realized that perhaps our ear/brain hearing mechanism somehow compares subtle cues such as radiation patterns, among others, to recognize and identify sonic information. I had recognized, of course, that the sound changed dramatically when I stood or moved around the room, but was not concerned with this behavior since all other speakers I had heard exhibited the same problem! I decided that the brain must somehow compare these subtle cues (like sound wave recognition patterns) to stored information from past experience. Thus the brain knew that the sound from the speaker could not be radiated from a live piano, since the sound waves from the speaker did not match the radiation pattern of sound waves coming from the instrument. Obviously the piano, being an omnidirectional radiator, involved the entire room with its radiation pattern, while my highly directional prototype speaker, did not. Amazingly, listening to one speaker up close did sound highly realistic, much as a very good pair of headphones. It was the directional pattern of the system that was flawed!
I hurried to the lab to conduct a series of off-axis response measurements on a 180-degree horizontal and vertical axis. The results, although dismal as expected, excited me, since the off-axis radiation pattern was clearly non-linear and was perhaps related to the lack of realism I was experiencing! Several years of experiments regarding directivity patterns and driver behavior later proved my theory to have merit. To the layman not schooled in conventional theory leading to a status quo in engineering design, this is not perhaps a surprising discovery, since it would seem intuitive to design a speaker to project sound in the same manner as live instruments!
ACOUSTIC INVERSE REPLICATION
Additional research led to my further discovery that recording microphones encode the musical signal with their overlaying pickup response patterns. After making a series of recordings, using several different microphones, it was obvious during playback that the mics not only had tonal differences related to frequency response errors, but also created different types of imaging patterns. The perception of depth and space was not only dependent on the recording environment and mic placement, but also on the mic's off-axis polar response. For this reason, I decided to engineer an adjustable ambience retrieval system radiating from the rear of the VR speakers, in able to recreate the space and depth heard in the concert hall when the spaced omni method of recording is used.
Thus, a correctly designed speaker system should project the inverse of the mic signal, acting as a decoder to translate the original sound field. I have termed my design for this decoding as Inverse Acoustic Replication tm, and the Virtual Reality series of designs was developed from several important concepts related to microphone pick-up patterns. These concepts are based on the consistent phase/frequency relationships in the polar response pattern of the mics, which was later reverse engineered into the VR speaker systems.
FIRST ORDER VERSUS FOURTH ORDER NETWORKS
Experiments validated the concept of consistent (not the same as coherent) phase vs. frequency linearity in a 180-degree arc around the speaker system, and appeared to work far better than phase coherency limited to the axial tweeter response. As is commonly known, first order crossovers have severe problems with driver overlap, which lead to an effect called lobbing. This problem is related to the fact that the drivers can sum perfectly only on one very narrow axis, since the path length from the drivers to all other axes cannot sum to unity, in either frequency, phase, or transient response! This not-surprising effect is due to the mathematics governing wave transmission and is easily verified by simple experiments or "doing the math."
Thus the measured polar vertical off-axis response, for instance +/- 180 degrees, of speakers using first order crossovers will typically exhibit amplitude dips and peaks of up to 18dB caused by the lobbing effects caused by uneven path lengths and will have severe phase distortion as well. The ear/brain hearing mechanism can easily hear this effect, due to reflected response from the room boundaries even though the listener may be seated on the perfect axis. Not amazingly, the ear is far more critical than any type of test equipment yet devised, so these effects cannot be ignored on a psychoacoustic level, especially in a normally reverberant living rooms where the off-axis response dominates the perceived frequency and phase response.
OFF-AXIS PHASE VS. AMPLITUDE CONSISTENCY
I have termed my method of enabling consistent phase vs. frequency behavior Global Axis Integration tm, since my design constructs a consistent polar response both in the amplitude and time domains, both horizontally and vertically. Not only does this radiation pattern enable the listener to perceive well-balanced frequency and harmonic integration from almost anywhere in the listening side of the room, but also enhances sound-stage imaging over a 180 degree axis horizontally and 70 degrees vertically. This is especially important psychoacoustically, since the ear/brain hearing mechanism responds favorably to this reconstructed sound wave pattern.
This Global Axis Integration method consists of a carefully engineered radiation pattern created by front and rear driver arrays. Proprietary circuits form steep 24 dB acoustic crossover slopes at specially selected frequencies without the penalties of induced ringing and excessive phase delay. These slopes are necessary to limit lobbing effects and non-linear off-axis response, and actually enable the consistent phase behavior necessary between drivers. The architecture of the circuitry resembles first and second order filters combined with Zobel conjugate compensators in parallel. By using a minimum of high quality parts in series with the drivers, the sound remains transparent, yet the control over phase and amplitude can be corrected with the paralleled Zobel circuits.
LISTENING VS. MEASUREMENT CORRELATION
Long-term listening sessions have shown very good correlation between the engineering target-response patterns and perceived musicality. Although initially I listened to the designs using high quality phonograph and tape sources, I later designed a test using live music sources to compare to the speaker output. In a large room, with sonically absorbent panels in the middle of the room, we compared the sound of an acoustic guitar at one end of the room being replicated by the speaker at the other end. We used several expensive mics and a tube preamp for these tests, and alternated between different kinds of portable instruments, such as brass, chimes, snare drum, trumpet, saxophone, harmonica, and of course, the human voice. In the beginning, circa late 1970's, we were humbled by the lack of realism in our original designs. Over the years, by conducting research into the distortions and colorations caused by the drive units, circuits, and enclosures, we were able to eliminate or greatly reduce the factors that contributed to the sonic colorations.
Critical evaluation of these new engineering principles by several magazines has resulted in highly favorable reviews and comments. Although not an exact inverse of the mic signal, the AIR and GAIN designs use psychoacoustic principles to work with the listening room. Ambience retrieval, imaging clues, and soundstage transparency are combined with wide band frequency response, low distortion, and ultra low levels of coloration. This combination of engineering goals has resulted in unprecedented levels of realism not achieved in competing speaker designs, regardless of cost.
NEW DRIVER TECHNOLOGY
My latest research has concerned the cone material and motor. Driver manufacturers continuously develop new cone materials in their search for the holy grail of perfect measurements. For instance, the new metal cones have fantastic stiffness and "punch" for bass frequencies, but unfortunately do not fare as well when used in the midrange and treble ranges due to high Q peaks. On the other hand, old materials such as paper have been upgraded with composites such as carbon fiber powder, Kevlar threads, or plastic compounds injected into the paper when the cone is being formed. One such formula termed Aerogel by Audax of France is an especially promising cone material for midrange reproduction, having the best Young's Modulus we have tested. Although many materials have been tested for treble reproduction, including metals, ceramics, paper, plastic film, and others, the plain-Jane fabric dome has seemed to remain at the top of the audiophile's list for smooth response.
New motor technology has been discovered and implemented in many of our new products. The distortion caused by the voice coil moving in a non-symmetrical magnetic field has been greatly reduced by new mechanical designs of the pole piece, shorted-turn voice coils, and new magnetic materials. We have found that up to 75% of the previous distortion has been eliminated, leading to greatly improved transparency.
