[Review] Audio Grade Sorbothane Isolation Feet and Solitude-ONE Isolation Feet from Elusive Audio

Product: Audio Grade Sorbothane Isolation Feet and Solitude-ONE Isolation Feet
Manufacturer: Elusive Audio - Sheffield, UK
Price: Audio Grade Sorbothane Isolation Feet: from UKP 10.50 per four; Solitude-ONE Isolation Feet: UKP 165 - (Currency conversion)
Reviewer: Richard Varey - TNT New Zealand
Reviewed: February, 2020

Elusive Audio was formed in 2013 by electronic and mechanical engineers with years of experience in the Audio Industry working for HiFi and Electronic equipment manufacturers. They decided that they could make better products in Sheffield and sell them at more affordable prices. As well as a turntable and hi-fi accessories, including cables, they also specialise in vibration isolation. I received samples of both their audio grade Sorbothane isolation feet and their Solitude-ONE isolation feet.

Although I've been aware of Sorbothane for many years, I have never tried it, and hadn't researched the material in relation to audio system improvement. Sorbothane is a patented thermoset polyether-based absorbent polyurethane material. It's a US registered brand name well-known in hi-fi circles. The material is a visco-elastic polymer (it has the properties of a liquid-solid) with a very high damping coefficient, which provides resilient vibration isolation under compression load by absorbing up to 95% of vibration energy. Commercially available since 1982, it was originally developed to treat heel strike injury from sports activities. In addition to being visco-elastic, Sorbothane's properties combine impact shock wave absorption, good memory, vibration isolation, and vibration damping characteristics - it brings a load mass slowly to rest with very low rebound, and short relaxation time. It reduces vibration "noise" transmitted from and to components, and is an effective acoustic insulator. Unlike rubber, it doesn't "age" and harden.

Another common application provides a good way of appreciating the function that is of interest to audiophiles. Drones with cameras are prone to vibration, and good picture quality requires camera decoupling from the motors driving the rotating blades. Without vibration absorption, the video is wobbly and blurred - detail is harder to discern, and it's distracting, making video viewing uncomfortable.

In the audio domain, sound is blurred/smeared and wobbly at the micro level. The massive proportion of vibrational energy absorbed by Sorbothane makes it a very attractive option for mounting equipment that is prone to vibration, such as speakers (cone wobble and wave interference) and disc players with moving parts (reducing tracking errors), and amplifiers with transformers. The heavier the component, the better it is at isolating itself with sheer mass. Motors and other rotating parts are the main culprit in generating micro-vibrations. Lightweight components need isolation and damping.

Important considerations for selecting suitable absorbers are hardness and thickness (i.e. load/weight capacity), since it performs best under a certain load. It's black and "sticky", so gathers dust, but is easily cleaned in running water. It's available in sheets, pads, and bumpers.

The soft version of Sorbothane has been found through trials and customer feedback to be suitable as "audio grade", whilst the harder version doesn't have the same degree of isolation and damping effectiveness in the experience of Elusive Audio.

The Elusive Audio Audio Grade Sorbothane isolation feet are specially selected soft "pastilles", in four sizes. I tried 30 x 14 mm and 38 x 20 mm, the larger being more suitable for heavier components. The suggested load capacity of the smaller feet is 4.5-9 kg for a set of 3, 4, or 6 pastilles, and 8-15 kg for the larger version (3, 4, or 6 pieces). The sample sets of four would isolate components up to 6 kg and 11 kg respectively.

As my speakers weigh 29 kg each, I wasn't able to test this soft Sorbothane with them, and Elusive Audio recommended their Solitude-ONE feet for such an application. It would be suitable for small and bookshelf speakers, however.

Their Solitude-ONE isolation foot has five components. Each is a 48 mm x 12 mm PTFE puck with a 30 mm Steel plate sitting on a 3 mm Sorbothane pad in a recess, all sitting on concentric Silicon rings. A 7.5 mm ball sits in a well in the Steel disc.

This configuration of carefully selected materials is claimed to isolate components in three ways: minimised contact area, vibration damping, and electrical isolation.

Minimal area of contact is effective in isolating a component. The Solitude-ONE uses Grade-G5 Zirconia Oxide ball bearings with a roundness tolerance of ± 0.000005 inch sitting on a precision machined 316 Stainless Steel insert. This is self-levelling when a component is placed on top.

Vibration Damping using two layers of the Audio Grade Sorbothane sandwiched between the Stainless Steel Insert and the PTFE base. The Stainless Steel insert is "floating" on the Sorbothane.

Electrical Isolation is usually overlooked in isolation feet. PTFE is used by high-end cable manufacturers to isolate connectors from each other as well as to isolate the connectors from static build up and EMC. The Solitude-ONE Isolation feet isolate the component from the shelf it is sitting on and so from all other equipment on the rack. The white PTFE bases are also fitted with anti-slip Silicon rings to prevent movement.

The three Solitude-ONE feet were easily placed under my Black Ice Audio Fusion F360 tube preamplifier. I also considered the advice that these may be suitable for isolating my (large) loudspeakers, so that they don't vibrate the floor and walls of my listening room. I placed the smaller pastilles under my Amari LP-32S turntable motor controller, under my Black Ice Audio Fusion F159 tube phonostage and Audiodinamica SUT No. 3, and the larger versions under my Pioneer PD-30 SACD player and Onkyo NS-6170 Network Audio Player.

It turns out that my reference to drone-based video and vibration isolation is very appropriate. Not only are hobbyists and professional camera operators testing Sorbothane and all kinds of apparently similar substitutes, but the results are describable in ways that shed light on the sonic effect.

I've watched video footage with clearer, sharper images that are easier to follow and in which distinct details can be picked out of the total visionscape. Motion is smooth and colours and contrasts are very distinct. High definition, if you like.

This is the result I hear in the sound quality of my listening field with the isolators in place. The sound is cleaner and more attention-grabbing in its realism. Transients are sharper. The sound of the music is more in focus. Think of a radio station when optimum tuning is found. The interference falls away revealing what you want to hear. The mush and fuzz is gone.

I'm not saying that the effect is dramatic. With a system carefully curated over many years, I'd not anticipated any sensational improvement. It's subtle, but discernible. And it's lost when the isolators are removed.

I'm now confident that my loudspeakers' performance would benefit from the addition of isolators. Another addition to the wishlist!

For systems that lack that sparkle and natural life-like presentation, vibration isolation might just be the most cost-effective tweak. And my investigations have concluded that the elusive clean sound can be had by investing in Elusive Audio isolators.

With a pack of four 30 mm x 14 mm at £ 10.50, four 38 mm x 20 mm for £ 16.90, with other sizes available, and the Solitude-ONE pack of three at £ 165, this upgrade isn't really elusive at all.

DISCLAIMER. TNT-Audio is a 100% independent magazine that neither accepts advertising from companies nor requires readers to register or pay for subscriptions. After publication of reviews, the authors do not retain samples other than on long-term loan for further evaluation or comparison with later-received gear. Hence, all contents are written free of any “editorial” or “advertising” influence, and all reviews in this publication, positive or negative, reflect the independent opinions of their respective authors. TNT-Audio will publish all manufacturer responses, subject to the reviewer's right to reply in turn.

Isolation Accessories from Elusive Audio

Stop vibrating!