Stack Audio AUVA 100

There is an ancient philosophical paradox known as ‘sorites’ or ‘the paradox of the heap’. Imagine a heap of sand, now keep removing grains of sand. At one point, it ceases to become a ‘heap’. Logically taking away that last grain of sand didn’t solely cause the cessation of ‘heapiness’; adding a few grains of sand once more will not restore it to being a heap. The sorites paradox hangs on the vagueness of its predicates.

The heap paradox doesn’t count in audio because we’re an obsessive lot. To us, a heap is precisely eleventy million grains of sand, no more, no less. And it is against that obsessiveness that companies like Stack Audio set out their store. The Stack Audio AUVA are made to replace the spikes of loudspeakers, with the AUVA 50 for the more svelte speaker, the AUVA 70 designed for most models and the AUVA 100 a perfect choice for the huskier transducer up to 275kg. I used the latter with my pair of Wilson Audio Duette II.

Into the AUVA

If you upend a pair of loudspeakers, you’ll find one of the myriad combinations of spike diameter, thread, weight loadings and even number. Theo Stack recognised that although the same basic properties apply throughout, making three sizes of AUVA (and a wealth of different thread sizes and diameters) means almost every floorstander, stand-mount stand and even spiked bookshelf speakers can be accommodated.

Why replace the spikes? First, think about what spikes try to do. There is a lot of stray vibration energy in a loudspeaker that is best removed. A spike is a hard coupler, effectively ramming the points of several into the floor, and letting the sheer mass of the house absorb any vibration. It’s proved popular, but it’s not that effective. There are other ways of absorbing or dissipating that vibration, perhaps the best-known of which are the Townshend platforms.

The clue is in the name for Stack Audio; AUVA stands for ‘Audio Vibration Absorber). This is a very different way of removing that pesky vibration. The pod is a hollow vessel filled with loose particles of different materials, including tungsten powder. Vibrational energy transmitted through the spike thread hits this chamber of particles and is dispersed as heat energy. Think of this a little like the Styrofoam ‘peanuts’ that act as packing protection. Their job is to collide against one another in the box, thereby absorbing any external impact forces. The energy generated by cabinet resonance (in AUVA’s case) or the back of a courier’s van (in the Styrofoam setting) is dissipated as heat.

What’s more, just as if you shake a box with a product protected by Styrofoam peanuts you can hear them gently rattling around, if you put your ear to the AUVA and give it a little shake, you can hear the loose particles rustling. This is deliberate.

This isn’t the only thing going on inside the AUVA foot, but the rest is hidden behind pending patents and protected by ninja death squads.

With one end of the AUVA neatly screwed into the vibration-making loudspeaker, the other side of the pod can be fitted with a pad or three tiny carpet-piercing spikes. These are not for vibration dissipation, but to root the speaker in place.

Not my first rodeo

I expected the AUVA 100 to do something, but this is not my first anti-vibration rodeo. I’ve long since gone away from spikes and adopted the Townshend Seismic Isolation Podium to keep vibration at bay. Also, although the choice of cabinet and stand materials in my trusty, now discontinued Wilson Duette II meant a lot of internal resonance and vibration was already dealt with in camera. So, while the AUVA 100 will do something, it will be an at best a nuanced difference given the setting.

Or so I thought. The Stack Audio AUVA 100 profoundly impacted the loudspeaker’s performance. The music was more energised, more engaging and had considerably better separation and space around the instruments. But that was just the start.

It didn’t matter what recording I played through the AUVA-equipped loudspeakers. In all cases, the same thing happened. The midrange sprung out at you, almost like a two-way loudspeaker suddenly became a three-way. Vocal clarity, articulation and projection improved considerably. This is extremely impressive when listening to someone already praised for their diction and projection (the tactical nuclear vocal cords of Joyce DiDonato, for example). Similarly, treble kinks – however mild – are ironed out, allowing a smoother race through the upper registers.

You might expect the biggest change to the bottom end and would not be disappointed. The AUVA 100 feet tidy up the definition and precision of bass notes, even in a loudspeaker that traditionally gives good bass for its size. The improvement is more about ‘control’ than ‘depth’, but it makes the un-AUVAed loudspeaker’s bottom end sound almost ‘one-note’ by comparison.

In essence, the AUVA 100 does everything the Townshend Seismic Isolation Podium does for the sound but often does it better. I found the deep bass notes of Trentemøller’s Chameleon, the subtle interplay of cello and mandolin in Yo Yo Ma’s Bach Trios and the fast, twitchy electro of Orbital to have greater snap and precision on the AUVA 100. The Townshend had the edge in scale and depth, the two were neck-and-neck in the tonality sweepstakes, but the Stack edged it in bass definition. That’s a first!

Feet don’t fail me now!

They might look like big Oreos or hockey pucks, but a lot is going on inside the Stack Audio AUVA 100. I’ve been trying to resist saying this, but they don’t put a foot wrong.

Those of us used to other methods of vibration control systems in loudspeakers might be surprised just how much more can be removed from the loudspeaker by using the AUVA isolators, and just how much better the results can get. And as for those who have never tried anything apart from the spikes that come with the loudspeaker… are you in for a treat!

Price and Contact Details

• Stack Audio AUVA 100 Isolator £1,240 (for 2× four isolators, as tested)

Manufacturer

Stack Audio

www.stackaudio.co.uk

+44(0)1626 249005

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