Turntable Isolation Platform

The problem

Structure borne vibration from floor and air affects virtually every piece of audio equipment, but its effects are most damaging to the tiny signals read and processed by source components such as turntables. Any forces affecting these signals will be magnified through the amplification chain, so it is desirable to eliminate as much as possible at source.

Vibration enters audio components via the feet & the chassis, with effect of reducing clarity, smearing detail and distorting frequency response. Eliminating this structural resonance in audio equipment results in instantaneous audible improvements; including an increase in soundstaging, improved imaging and  smoother more natural tonal balance.

Man in a white lab coat says: The material which provides superior isolating properties is Sorbothane. Sorbothane is the brand name of a synthetic viscoelastic urethane polymer which combines some  properties of rubber, silicone, and elastic polymers. Its main application is as a shock absorber in sports shoes and vibration damping in hi fi.

As a patented material manufactured under license, it is fairly expensive for what it is, but cheap compared with its’ effect in improving the performance of much more expensive equipment.  An alternative to Sorbothane is wood – in the form of oak cones, and similar function isolation platforms such as honeycomb construction Torlyte from Russ Andrews.  Wood is also expensive- it doesn’t grow on trees, you know.

The importance of acoustic vibration is such that one wonders why the manufacturers of hi fi electrical equipment don’t build damping into their components and systems as standard. The answer I suspect is that they are 100% focussed on electrical components, and do not recognise the role of anything else in determining sound quality, such as casework vibration or  interconnects. It’s not clever enough for them.

The solution

I added the isolation platform manufactured by Avid. Conrad Mas knows what he is doing and I trust his judgement.

The test result

Hi fi aficionado Man-in-a-Shed and I  A:B tested the turntable with and without the platform may be a dozen times, with one record I use a lot for evaluating change, Azymuth’s Equipe 68, from the album Lest We Forget. The tonal range, instrument placement and dynamic stereo mixing of the track is a joy. If something is happening this will usually ferret it it out.

Things were happening but it turns out this record wasn’t the best choice. The music is largely electric instruments and a digital transfer. A clue to its effectiveness of the platform was to be found in few acoustic instruments on the track – cymbals, shakers and other percussion. These promptly gained detail and improved stereo imagery, but electric piano remained stubbornly electric piano – it didn’t have any detail to reveal, nor did electronic bass.

The acid test – I preferred the music  overall with the platform but it was hard to pin down why, and by how much, and whether the gain was worth it?

Fatigue with the Azymuth tracks twelfth hearing  suggested a switch to an a Columbia Six Eye, Miles Davis in Person at the Blackhawk. Just acoustic instruments in a perfect analogue vintage pressing. A serendipitous choice.  This time in an A:B test the isolation platform made an immediate impact. Miles trumpet stepped forward centre stage by a foot, and the supporting rhythm section seemed to retreat by a foot. Davis was fully the star performance of the show, the timbre of the horn becoming more affecting and emotional. Briefly I mourned the loss of some bass, but to the advantage of the whole performance. This is closer to how it was meant to be.

Why it works

Having established what effect the platform had –  the important bit – time for some reflection on how and why. Better control of vibration – in effect, of taming the bass register, was allowing the middle and higher register to “breathe more easily”. The impact was to catapult Davis’s trumpet – all  mid and upper register –  to the fore. The whole balance of the music tilted towards greater lead instrument articulation and imaging, offering detail and realism. Better controlled bass was more tuneful and less disco-in-the-basement.

“Lifting a veil” is the cliché people often use describe such effects. The analogy obscures why it is happening. There is no veil, just extraneous micro-vibration which blurs the underlying information-carrying  signal. The thing strangling the all-important mid and upper register is poorly controlled bass. Bass energy is drowning out other signals, all going down the same piece of wire. Control that bass energy and greater clarity benefits everything else.

The platform was declared a success.

Its getting kind of crowded on the staging, but fortunately the Avid plinth is rectangular and can be turned sideways, so the World Designs phono-stage power supply  just fits neatly next to it.

Icing on the cake, the Avid  turntable power supply below benefitted hugely from double sorbothane 30mm  discs under each foot, with the phono-stage unit and supply both given 12mm sorbothane hemispheres under the feet, completing the isolation of the vinyl system. The resulting improvement in bass control  has yielded significantly more detail in the mid and upper register. Delightful, and a fraction of the cost of a “better amplifier”. Definitely  several notches up on the Enjoyment factor.

Plinth supplied by Analogue Seduction, Sorbothane courtesy of Ebay, pleasing retro-cushion from IKEA.

LJC (with help from Man-in-a-Shed)