Carbide Audio Carbide Base Footer Update

“The footer has been further optimized to be 13% shorter, yet have a 280% increase in height adjustability. With 3/4” (20 mm) of adjustability it’s not just leveling of equipment that’s possible, but also rake angle and tweeter height tuning when used under speakers.

A new red Super Heavy ViscoRing™ is also now available for racks which supports up to 800 lbs (363 kg) per set of 4.

Vibrations induced from loudspeakers can turn the surfaces of a room into unwanted sound radiating sources. Vibrations can also induce noise in the output of sensitive electronics such as turntables due to the phenomenon of microphony. The patent pending design of our Carbide Base audio isolation feet isolates these vibrations in all directions when placed under your audio electronics and loudspeakers.” 

Separate upper and lower portions are designed to optimize vibration isolation and dissipation in vertical and horizontal directions.

 

The upper portion is machined out of aluminum billet to accept a specially formulated viscoelastic member called ViscoRing™. The ViscoRing™ acts as a damped spring supporting the equipment while isolating it from vertically oriented vibrations. It is replaceable depending on the intended supporting weight range.

 

The lower portion comprises separate machined stainless steel sections. 18 exceptionally tough zirconia ball bearings and 3 viscoelastic elements are incorporated to enhance horizontal isolation and damping. The bottom is threaded to facilitate nearly 3/4″ (20 mm) of height adjustment. It can also optionally accept the 3 provided spikes to pierce through carpet.

When it comes to viscoelastic materials providing isolation, more is not necessarily better. It is the low ratio of surface area supporting weight to the surface area free to bulge outward which is important. The term for this ratio is Shape Factor. The lower the Shape Factor, the greater the potential degree of isolation.

 

Carbide Base audio isolation feet implement viscoelastic materials with Shape Factors far lower than previous designs. The large tubular shape of the ViscoRing™ maximizes the surface area that is free to bulge. This yields a Shape Factor around half of the lower limit traditionally used for elastomer isolators. The low shape factor is made possible by the patent pending design of the Carbide Base footer. Ridges selectively brace the ViscoRing™ to stabilize it under compression and shear while leaving a substantial surface area free to bulge.

Carbide Base footers can be optionally mounted to equipment and loudspeakers with the supplied screws in metric thread sizes M4, M6, M8, M10 and imperial sizes #8-32, 1/4″-20, 3/8″-16, 1/2″-13. The screws are standard flat head machine screws allowing easy substitution for a different thread size or length. A removable nylon insert is provided for smaller diameter screws. This avoids the need for proprietary threaded studs as used by the competition.

 

A machined stainless steel jam bolt is provided to thread in behind the screw to hold it into place. The jam bolt has a top threaded hole to optionally upwardly mount one of the included spikes to rigidly contact the underside of equipment. The jam bolt can also be removed to provide a cavity to captively hold a loudspeaker floor spike.

All Carbide Base footers are the same size. Each is optimized for the weight of your equipment by choosing among the 4 available interchangeable ViscoRings™. The recommended supporting weight range with each ViscoRing™ installed is shown below.

 

While some isolation devices require different versions for different weights, a single version of the Carbide Base footer can support a wide range of equipment weights by simply replacing the installed ViscoRing™.

Transmissibility is the ratio of vibration energy transmitted into one side of a Carbide Base footer (such as from a loudspeaker) to what is being applied to the other side (such as the floor). A transmissibility less than 1 is represents vibration isolation which is desired. Anything greater than 1 is an amplification of vibrations.

 

Most passive vibration isolators exhibit an amplification of vibrations at frequencies near the resonance frequency of the device. The unique design of the Carbide Base footer minimizes this amplification and confines it to frequencies around the lower threshold of human hearing. Low frequencies are important to isolate as they travel with little impedance throughout the room and equipment as structure-borne vibrations.

Loss factor, or tangent delta, is a measure how much vibration energy is dissipated through a conversion to heat due to the phenomenon of hysteresis. A loss factor of 0 indicates a perfectly elastic material where the oscillating force of a vibration occurs in-phase (at the same time) with the accompanying deformation of the material. A loss factor of 1 indicates a perfectly viscous material where the force and deformation are exactly 90 degrees out of phase resulting in total dissipation of vibration energy to heat.

 

The viscoelastic materials utilized in Carbide Base footers are engineered to have an exceptionally high loss factor over a wide frequency range. The gray ViscoRing™ has the highest loss factor, followed closely by the blue, black, and red ViscoRings™ which can support incrementally higher weights. For reference, natural rubber has a loss factor of about 0.05 across most audible frequencies.

The vibration dissipation ability of a Carbide Base footer is significant enough to measurably subdue resonances in equipment being supported. The graphs below show low frequency vibrations in the panels of a test loudspeaker enclosure as measured using a calibrated accelerometer. Dips and spikes in panel acceleration indicating resonances are effectively damped when the same measurement is taken with Carbide Base footers placed under the loudspeaker.