Ready to rumble

Stoke seismograms 10

Have you ever noticed that your system sounds better later in the evening, that it becomes more revealing and effortless ‘round about midnight’? If so you may have wondered why and you wouldn’t be the first. There are a number of possible causes, the most often cited being that most people turn off their TVs and other electric devices later in the evening, so there is less demand and less noise being injected onto the mains. There is also less ambient noise because there are fewer cars and lorries being driven around, something that is more of an issue in built up areas. But late night improvements are felt even in rural areas where population density is low, so there must be other factors at work, and Max Townshend thinks he has put his finger on what could well be the most significant one. Seismic activity.

We tend to think of this as being related to earthquakes but a look at the British Geology Survey site reveals that seismic activity increases significantly during the hours that people are out and about. If you look at the seismogram for Stoke (shown above for December 10th, 2014) you’ll notice that levels begin to rise around 6.30am and don’t calm down until after 11 in the evening.  The range of movement varies from 10 to 100 microns, not much perhaps but considerably more than the circa two microns of movement that a 165mm speaker cone has to move to produce 2kHz at a sound pressure level of 80dB (at one metre).

bW 804 with bars.9

If you consider that a good percentage of that seismic activity will travel through a building and thence into your loudspeakers it’s not hard to imagine the masking effect that it will produce. This energy is essentially low in frequency but can be anything from 1Hz upwards. Townshend’s isolation devices claim to keep out energy above three Hertz when you have the right springs for the weight of loudspeaker.

Townshend has always sought to explain why his loudspeaker isolation products make so much difference, and this would seem to be a feasible answer. I have recently been trying Seismic Speaker Bars under PMC fact.8 speakers and have been shocked at the benefits that they accrue. The noise floor drops dramatically and the speakers ‘disappear’ from the soundstage. Close your eyes and it’s hard to point at them because the image is so strong, it’s so three dimensional and convincing that it seems unrelated to the position of the speakers. Equally impressive is the way that overhang is reduced and timing precision increased. It’s not a small change by any means, in truth it’s akin to a loudspeaker upgrade representing at least a 50% increase in price.

The irony of this is that spiking a loudspeaker improves its connection to the seismic activity, what you hear with spiked speakers is a combination of seismic and signal induced energy, and in the case of wooden floors you get low frequency energy from there as well. So seismic activity has a crude reinforcement or loudness effect that is clearly appealing. But take it away and you get a much cleaner, more revealing and relaxed sound that is less distorted. Even when distortion is euphonic or appealing it’s still distortion, it’s still getting between you and the music.


bW 804 with bars.7

I have been talking to people about this of late and discovered that the benefits of speaker isolation are becoming better appreciated. I visited a fellow reviewer recently who had massive speakers on Seismic Bars, his system sounded significantly better than it had done for a long time. I mentioned it to PMC who have done some experiments and come to the conclusion that the benefit increases with the size of the speaker. Smaller speakers are lighter and decoupled to an extent by stands (albeit often with spikes) so perhaps they are less sensitive. Paul Messenger has also had extremely good results with Townshend isolated Bowers & Wilkins 800 Diamonds as well as PMC IB2SEs.

This is not a coincidence, it’s the beginning of a revolution, the kick out the spikes and float the speakers revolution. It’s a pity that isolating speakers in a stable fashion (that doesn’t raise them up too much) is so tricky, it has taken Townshend a few decades to get it right, but the Seismic Bars are definitely the neatest way of doing the job. If you want to hear music without a mask of random vibration I strongly suggest you give it a try, you will be surprised.

Jason Kennedy

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