Friday
Oct172008

Speaker Technologies

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The_Maxell_Blown_Away_Guy

50+ advancements in loudspeaker design

Roy Johnson's most important speaker breakthroughs from those 50+.

 

Time-coherent soundfields

To hear the original waveform, which contains all the musicality and entertainment, the sounds from the woofer and tweeter must recombine at your ear as if there was only one driver emitting the sound. For this, they must move synchronously, as one unit.

This can only be accomplished when the drivers are well-behaved naturally, requiring only the simplest ‘first-order’ crossover circuit -- the only circuit design that allows the low and high signals to pass through with no distortion in the time domain.

You will discover additional benefits: You will stop reaching for the bass and treble controls and worrying about the quality of an album or soundtrack before you buy it. You will want to hear everything you own -- and watch hundreds of movies -- for the first time...again.

 

Adjustable_Tweeter

Adjustable drivers

Since you may sit or stand anywhere, our speakers are adjustable to focus the time-coherent sound axis to your position regardless of speaker location. In our two-way models, the tweeter adjusts from front to rear. In our three-way speakers, the midrange and tweeter adjust independently and together as one unit.

 

Controlled dispersion

The sound you hear from a speaker is a mix of its direct sound and reflections from its surface, the floor, wall behind, and sidewalls. All of our speakers are designed to deliver a dispersion pattern that smoothly narrows with increasing frequency and decreases abruptly to the sides and rear. Far less sound is sent to nearby surfaces so you hear everything more clearly even when the speakers cannot be optimally placed -- and even when you are in another room.

 

Direct-delivery treble

You hear less ‘speaker’ when the tweeter itself is capable of producing a uniform tone balance across the treble with no help from reflections off the cabinet surface or its own surface. We take it to the next level by mounting that tweeter outside of the woofer enclosure, so that its sounds freely expand into the room. It is always a strange sensation at first to see the speakers but hear that the sound has nothing to do with them.

 

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The most simple crossover circuits

When the quality of the drivers allows the simplest crossover circuit to be used, then only a single inductor keeps highs out of the woofer and a single capacitor keeps lows from the tweeter. Those two components can then have ‘mirror image’ values that offset the inductor’s rising impedance-with-frequency with the capacitor’s falling impedance-with-frequency. Your amplifier does not ‘see’ either the inductor or capacitor, because the ‘Balanced-Phase™’ of those two opposite electrical components cancels out their differences and leaves only what seems to be a perfect Y-adaptor for the bass and treble of the signal.

 

Internal resonances prevented

When any speaker enclosure has an internal dimension exceeding about 18", no acoustic lining will absorb the tones with wavelengths longer than 4x18", or 72". This is because the air molecules at these tones from that low-voice range and on down are not moving back and forth very fast. Thus, they have little velocity to be ‘scrubbed off’ by acoustic-absorption materials and they begin to echo inside, forming resonances and cancellations at different frequencies. The simplest way to counter their formation is to introduce a baffle across that longer cabinet dimension having carefully-calculated openings to break up those waves. The mathematics behind our baffles were based on the Golden Ratio, so that no whole-number multiple of a wavelength (1/2, 1/3, 1/4...) is allowed free passage from one end of the enclosure to another. The result is a far less ‘boxy’ sound, with much more clarity and greater pitch definition, especially on complex music and soundtracks.

 

Pouring_marble

Marble-composite cabinets

Q-Stone™ was developed over a 10-year period before being introduced in the Europa in 2001. It is a blend of marble dust and resins that are then cast in specially-designed molds. Q-Stone™ produces enclosures that are extremely rigid and non-resonant in shapes that provide the best possible dispersion of sound, without reflection. ‘Q’ is the symbol for the tendency of something to ‘ring.’ A low ‘Q’ has the least resonance. More about our marble casting process >

 

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Wood_faceplate

Cabinet-edge
defractions prevented

Because reflections from the face of a cabinet are harmful to the sound, especially in the voice and treble, they can be absorbed and diffused. They also can be avoided altogether. The multi-dimensional curves to all our Q-Stone™ enclosures were calculated to let the enclosure ‘get out of the way’ as soon as possible, for the least reflection at any listening angle. The speakers disappear even more and you enjoy a much wider range of music and soundtracks.

 

Durable, fine-grain finish

Texture-Kote™ is our adaptation of a tough industrial paint, shot through a specialized spray gun that produces a fine pin grain, black-leather texture. It does not fade.

 

Reflection-free tweeter environment

First seen in our Continuum 0.5 Center Channel/Shelf speaker, and later the Aperture, we designed a unique arrangement of angled wool-felt and acoustic foam baffles to surround the tweeter to absorb all sounds headed into its labyrinth, so that all you hear is the direct sound coming straight from the tweeter. It was necessary to allow the Aperture to be placed completely into a bookshelf, so that no upper-range tones could be sent to all the nearby surfaces. The sound is much cleaner and multiple voices on soundtracks are far easier to follow.

 

Resonance-free bass

Ideally, all but the very lowest bass tones should be directed away from the rear of the woofer to never return. When a long transmission-line tunnel is placed behind a woofer, the idea is to absorb all the middle-bass and high-bass tones as they travel along -- by an acoustic stuffing usually of wool -- so they cannot come back to resonate with the woofer. However, all conventional transmission lines have reflections that cannot be absorbed -- most notably, the one tone with a wavelength three times shorter than the main length -- which happens to be right in the middle bass. The "Anechoic Transmission Line" design connects a shorter transmission line to a longer one, and the resulting path-length difference completely cancels this resonance.

 

Bi-Port

Efficient bass ports

First used in the Eos and Eos HD, our Bi-Port™ technology allows twin bass port openings to be placed in the front of the enclosure where they do the least harm to the air-pressure support that the remaining solid front of that enclosure must give to a smaller woofer. That frontal surface area is needed so that the woofer can maintain proper tone balance in the low-voice and high bass ranges, regardless of the speaker’s position in the room. Yet, on the inside of the cabinet, there is only one prime location for the intake of those two ports, so the Bi-Port™ design merges their two intakes into one large, aerodynamically-shaped opening positioned at just the right spot to take in the pressure changes coming back to it from all parts of the enclosure’s interior.

 

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Resistive-vent

Resonance-free
enclosures for midrange drivers

Any midrange driver has its own low-frequency resonance because it has a moving mass (the cone) bouncing off a spring (its suspension and/or the air in its sealed chamber). Even when this natural resonance occurs far lower than the midrange driver’s lower crossover frequency, it still affects the action of the crossover circuits’ filtering, and makes life a little less pleasant for the amplifier. While it is possible to damp this resonance by adding more parts to the crossover circuit, that solution is never good for sound quality. Instead, we were the first to successfully adapt a resistive vent to a midrange enclosure that optimally damped this resonance mechanically, before it begins. Think of it as an ‘air brake’ to the motion of the cone, allowing the midrange driver to operate in a resonance-free environment. The amplifier also sees far less energy returned to it, because none is being regenerated. This vent is used in all of our three-way speakers.

 

Multi-layer wood cabinets with composite foundations

We could cast a large woofer cabinet out of Q-Stone™, but who would or could lift it? When wood must be used, we glue different types and thicknesses of MDF wood together with non-resonant adhesives and combine that with Baltic-Birch, multi-ply hardwood plywoods. To prevent torsional and shear vibrations of the cabinet, all corner joints are painstakingly inlaid and overlaid, and then some are overlaid again with another layer of MDF. The base of some enclosures has an interior reinforcing lining of epoxy/marble compound for the utmost rigidity and stability. Remember that nothing should move but the woofer’s cone -- so it is a little disconcerting to hear and feel everything in the house shaking while your hand remains still when placed on the cabinet.

 

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