Legendary Audio Rack

Specifications

• Individual shelf size:  550mm wide x 450mm deep x 40mm tall (22” x 18” x 1.6”)
• Overall size:  620mm wide x 520mm deep (25” x 21”)
• Shelf clearance:  choice of 250mm or 300mm (10” or 12”)
• Weight capacity:  100Kg (200 lbs) each shelf, 250Kg (500 lbs) for the bottom shelf
• Number of shelves:  selectable between 3 and 4 shelves (listeners can start with three shelves and add more shelves later, thanks to the modular design)
• Note:  Ultra Performance Shoes Set supplied at an additional cost

LEGENDARY AUDIO RACK -THE ULTIMATE STATEMENT ON ISOLATION

Design Goals

To provide a unique combination of the following attributes:

• Best quality for the money
• Best resonance control performance in the world
• Aesthetically satisfying rack
• Advanced mechanical structure
• Extreme durability

Technical Features

High end audio equipment racks are not merely furniture to hold equipment. They are an indispensable and inseparable part of a system that extracts the maximum performance from the equipment it houses.

In order for equipment racks to perform ideally, they must be capable of serving three functions:

• Prevent the amplification of vibration, whether by sympathetic resonance of the rack, or the equipment on the rack
• Absorb and eliminate vibrations produced by the materials that make up the rack
• Isolate and absorb external vibration conducted through the air and floor, and vibrations induced in the system’s components by external vibration

As has been scientifically established, resonance is the tendency of matter to oscillate with greater amplitude at specific frequencies, but not at others. These are known as the system’s resonant frequencies (or resonance frequencies).  At these frequencies, even small excitations can produce large vibrations (or oscillations), because the material has very low impedance to those resonance frequencies.  With low quality damping, the resonance frequency is approximately equal to the natural resonance frequency of the system, which is the normal self-evident resonance frequency of a system based on its mass, density, dimensions and internal structure (crystalline structure, or layered structure in Picawood, for instance). 

If resonance is not controlled, audio equipment will have excess vibration at its inherent resonance frequencies. 

The obvious problem is this:  controlling resonance is not easy, because equipment tends to have multiple resonance frequencies, and resonance directions.  And when put in a complex system, these resonances can cause exceedingly high levels of distortion, like acoustic feedback.  Also the resonance frequencies change in accordance with the mass and rigidity of the equipment.  A rack will be asked to work with equipment of every imaginable material, size, mass, weight distribution and susceptibility to vibration induced distortion (like feedback, for instance).

Some audio rack manufacturers argue that installing anti-resonance devices (or active anti-node devices that resonate at a specific frequency to cancel the resonance of the applied equipment) to counteract the anticipated resonance frequencies will tame the resonance of the system and the equipment.  The problem with this approach is that resonance frequencies cannot be predetermined since individual components and racks have multiple interacting resonance frequencies, and the natural resonance frequencies merely change with added mass (weight) and/or stiffness.  The net result of simply adding mass or stiffness is to change the resonance frequency, not to absorb or dissipate it.  An equipment rack maker cannot predetermine how heavy or how stiff the components will be, that are placed on their audio rack (the complex interaction of multiple components, constituent rack components, external vibration, and the floor on which the rack sits will create unpredictable results). 

At the same time, the absorption and dissipation of vibration is critical for the best performance of audio components, since vibration drastically impairs the abilities of high end audio components.  Audio equipment is influenced from two vibration sources:  the first is internally-generated vibration from the constituent parts (every part has its own resonance frequency, and some parts, such as motors, capacitors and power transformers, generate vibration); and the other is the air-born and floor conducted vibrations, forces that act on equipment chassis and the audio rack.

Some equipment stand companies argue that utilizing large damping blocks placed on a rigid frame will work best to absorb and isolate vibration.  However, the damping blocks (being made of polymers or silicon composite) have limited effectiveness. The effectiveness of a given damping puck is limited by the mass and dimensions of individual damping blocks.  The damping blocks employ a type of resilient material, usually a polymer or silicon composite, as a damping material.  Damping block materials have a minimum and maximum weight (the threshold where a material becomes effective, and the point where its mass starts to generate sympathetic vibrations, usually at low frequencies), for the damping material to maintain its damping capability.  If an applied weight is too light to bond firmly to the surface, the damping material does not work.  If an applied weight is too heavy, the damping block’s internal characteristics will start producing sympathetic vibrations, usually at low frequencies.  In addition, damping does not eliminate all vibration:  vibration sometimes requires a more active approach to management, than just damping.

Our approach to address the above resonance and vibration problems is:

• Reduce exciting forces at their resonance frequencies (tune to prevent individual resonance frequencies from being excited)
• Increase damping to decrease resonance amplitude
• Direct the vibration away
• Change system stiffness to change/tune resonance frequencies
• Isolate components from external vibration
• Incorporate dynamic/active absorption

Design and Structure Features

Reducing excitation forces at resonance frequencies 

  

We also employ a method to maximally damp the supporting pillars that support the shelves.  We fill the precision-milled duralumin pipe with the dried white pebbles, and insert a Picawood section in the middle of each pillar structure.  Picawood is the 250-ton ultra-compressed Birch plywood that has maximized vibration transfer and rigidity, while maintaining the preferred vibration characteristics of Birch plywood. 

Directing the vibration energy for quickest draining

 

Vibration is directional.  It flows from a large surface to a narrow surface, and from a light pressurized area to the heavy pressurized area.  One popular application of this directional tendency is the spike and cone.  The vibration flows from the large and less pressurized area of the cone to the narrow and more pressurized point of the spike’s tip. Utilizing this tendency, spikes and cones are widely used to drain vibration energy and isolate the applied equipment.

Our audio rack system is carefully designed to direct the flow of vibration for the quickest exit from the audio components.

The directional flow of vibration:

• The shelf holding the component absorbs vibration from the chassis of the component (made of multiple noise sources), and converts the vibration to heat through the action of the sand reservoirs.
• The remaining unabsorbed vibration travels horizontally along the layers of the Birch plywood.
• The Wing Extension Rods at the four corners pass the vibration to the pillar structures.
• The pillar structure absorbs and eliminates vibration through the action of various sized white pebbles inside the pillar cylinder.
• The remaining vibration is further passed to the Picawood Pillar Interface. The Picawood Pillar Interface absorbs and eliminates the vibration, while passing the vibration further down the pillar structure.
• The base of the pillar structure absorbs vibration from the Picawood Pillar Interface.
• The last remaining vibration is drained to the base through the Pillar spike and Ebony-wood footer.

Changing system stiffness to change resonance frequencies

Unlike other audio rack makers who adopt a purely rigid structure, our approach is a mixture of rigidity and compliance. Though stiffness is an excellent way of transferring energy, it always has a resonant frequency, and will send reflections up and down the length of the rigid structure if nothing is done to absorb, damp or transfer the vibration somewhere else.  While the audio rack maintains structural integrity to hold the weight of audio equipment and to avoid rack-induced sympathetic vibration, our rack system allows a certain degree of mechanical compliance.  This compliant design is achieved through the Extension Wings at the four corners of each shelf, and the modular design by which each shelf is laid upon another shelf, through the pillar stacking mechanism. This compliant design is much more effective than a purely rigid system in dissipating vibration, and isolating components.

The picture above shows the spike for each pillar, the cup, and the Ebony buffer disk that goes between the spike and the cup.

Vibration that comes from above, travels through the spike at the pillar base, and through the Ebony buffer disk. The cup transfers that energy to the underlying structure.

Isolating equipment from external vibration

The audio rack, and the equipment is holds, are affected not only by air-bone vibration (acoustic vibration), but also by the room floor that holds the bottom feet of the rack.  The rigid design of many audio racks is weak in combating the structural vibration of the room environment such as the room floor.  However, our audio rack achieves room isolation through its modular design, the multiple buffering and damping mechanism between shelves, and the sand reservoir within each shelf. 

Super Tuning Shoes:  A Firm Foundation for Ultra Performance

A set of high performance tuning shoes is supplied to lay the firm foundation for the Legendary audio rack.

These shoes feature adjustable height, and are housed in a Picawood base.  The Picawood base provides outstanding resonance and vibration control (absorption).

The photo of the Silver Edition super shoe, DS4

(Accompanying cones are respectively the PWC04 Gold and the ALC04 Black from left to right)

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