One of the biggest problems in the pursuit of high fidelity is establishing what exactly is in the signal and what the reproduction equipment adds to that signal. Essentially, this is ‘distortion’, and many forms of distortion are euphonic, in that they change the sound in an attractive way, almost by making up for aspects that get lost in the reproduction chain. As long as the distortions are harmonious, we don’t seem to mind them and even – in the case of valve electronics – positively love them. Valves are, of course, transparent in ways that transistors aren’t, but few would argue that they produce a linear tonal response.
According to Townshend, playing music through speakers on spikes is much like plucking a ruler in a vice, and the whole cabinet resonates as a result. If you have your speakers spiked to concrete, that resonance is at about 100Hz and about 50Hz on wood or carpet. Putting spikes under a speaker gives it a faster, sharper sound that has greater immediacy than a speaker on rubber feet for instance. The sharpness that spikes bring to the sound, according to Townshend Audio, comes from a separate, but perhaps more insidious, issue of microtremors, which constitute the background noise that you see on seismographs. These are constant tiny earth displacements of between 1 and 10 microns, which we don’t feel because they are too small. However, to a 25mm tweeter playing a signal at 5kHz at 35dB, which has a resultant amplitude of 0.7 microns, a displacement of 10 microns is huge. So these microtremors are bigger than the movement of a tweeter and often that of a mid/bass driver, too.
Townshend Audio has been making products that break the link between speakers and ground borne vibration since the 1990s, and these have been constantly refined. Earlier this year, Townshend came up with a whole platform ‘Podium’ solution that might not offer a great deal more isolation than its predecessors, but does the job in a way that is much easier to install: the previous Seismic Bars needed careful placement under a speaker in order to get it standing vertically in both fore/aft and side-to-side planes, and with heavier loudspeaker designs, this proved a challenge.
The Seismic Podium adds a mere 2cm to the height of a loudspeaker. This is important not just for obvious centre-of-gravity reasons, but because boundary proximity affects low frequency performance, so raising a speaker up too far will make for a leaner bass than originally intended. The Seismic Podium is also rather more professionally executed and finished than earlier designs. The central footplate is designed to withstand the abuse of spikes, but in most cases you are better off just placing the speaker on the platform ‘bareback’. The Podiums have adjustment for floor level and some adjustment for weight displacement. This last is useful because the weight of many loudspeakers is not evenly distributed.
Seismic Podia are available in a range of five sizes for speakers weighing between 12kg and 240kg, while for bigger speakers Townshend can make custom versions. You need to specify weight in particular because it’s the combination of mass and spring strength that provides the isolation. Next time you’re waiting for a train, have a look at what sits between carriages and bogeys – large examples of damped springs. I don’t know about you but I wouldn’t want long train journey with spikes in place of those springs!
The effect of putting a speaker on the Seismic Podiums is quite dramatic. I did the demonstration to the guys from DALI recently when they brought round a pair of Epicon 8 speakers for a forthcoming review. They couldn’t quite believe the improvement in coherence and timing it wrought, and the extent to which the sound is able to escape the boxes. Then there’s the bass, which is suddenly incredibly articulate, three dimensional, and powerful. This is true of every speaker that I have tried on these bases, and the irony is that the sound is faster and more fine detailed than it is with spikes. There is none of the edginess and emphasis on leading edges that spikes produce, yet there is greater immediacy. In all honesty, I’d say you don’t know how good your speakers are until you isolate them from the floor.