Hip Joints© are small devices that act as footers (i.e., adjunct feet) for audio and video components. Their purpose is to provide isolation (in the horizontal and rotational planes) from performance-degrading vibrations that would enter components through their feet. Each Hip Joint© is comprised of a small disk with a curved depression in the top. A steel ball bearing sits on top of each Hip Joint in the depression. Used in sets of three, a component is placed atop a set, so it is lifted off its own feet and is supported only by the Hip Joints©. This results in the component having a bit of horizontal play, with the curve of the depression assuring the component will always return to its centered position.
Modeled after the slip plate bearings used under skyscrapers in earthquake-prone areas, Hip Joints© have a resonance (i.e., a propensity to vibrate) at a frequency well below the audio range. This subsonic resonance creates a low-pass filter that inhibits the passage of frequencies higher than the resonant frequency, and thus acts as a vibration block (in the horizontal and rotational planes), preventing damaging vibrations from passing through to your components.
For best results, Hip Joints© should be placed to form the largest equilateral triangle that will fit beneath the component they are supporting. Some users place one Hip Joint© under the front of a component and two under the back. Others place two under the front and one in back. As long as they form the largest equilateral triangle that will fit beneath the component they are supporting, the arrangement doesn't matter.
|A Metric Halo ULN-8 on Hip Joints©
|A closer look