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Sonic Design - damping feet

Clap your hands and...damp yer feet!

[Italian version]

Product: Sonic Design SD damping feet
Manufacturer: Sonic Design - Sweden
Approx. price: standard edition - 29 Euro/$ SEK (8 feet) + 12 Euro/$ (shipping)
Audiophile edition: 64 Euro/$ (8 feet) - CD edition : 15 Euro/$ (5 feet) + 12 Euro/$ shipping
Reviewer: Lucio Cadeddu

[Sonic Design]

Damping feet, once again. I can't help but admit it's my fault. Yes, once you start reviewing these items, they start to invade your room and put themselves under everything which seems HiFi related.
So, ladies and gentlemen, guys & gals, here are the Sonic Design SD damping feet for loudspeakers from Sweden. Good news? You bet! There's always something new to be excited of (?). Now, the name tells the whole story: these damping feet were originally meant and designed for loudspeakers then, testing 'em under amps and CD players, the Sonic Design guys started to think at different versions to suit everyone's needs (CD players etc.).
First of all, the standard version: these are the least expensive of all, and meant to be used under loudspeakers of different weight, 4 different "compounds" are actually available: the softest ones to accomodate loudspeakers under 12 kgs (multiply by a factor 2 to get the weight in lbs, you damn non-metric dudes :-) ), from 12 to 28 kgs, from 28 to 50 kgs and finally from 50 to 100 kgs.
More or less these are the same "ranges" used for the G-Flex's or the Vibrapods feet, both tested here on TNT-Audio.
But Sonic Design pays an extreme attention to make you get the perfect damping solution, so their advice is to weigh the front and the rear of the loudspeaker, so to choose the right compound for the given weight.
This makes a lot of sense, since the front of a loudspeaker, normally containing the drivers, is heavier than the rear.
To get the perfect damping, you just need to put a good digital scale (the same your wife uses to control her weight) under the front baffle and then under the rear. To get proper measurements, make sure nobody's home and your neighbours are out for dinner (YES, they DO have a social life, ever noticed that?).
Don't get me wrong, you're an audiophile...a pretty weird animal for them. There's no need to make 'em aware of the curious and hard to explain fact you've just put your loudspeakers on a Weight Watchers strictly low-fat diet :-))))

The Sonic Design crew claims their feet (well, not literally, their SD damping feet :-)) reduce the transmission of vibrations, helping to get a cleaner and less coloured sound. Furthermore you should also be able to transmit less noise to your neighbours.
Well, when I listen to my favourite Music (Pearl Jam's Binaural right now, and pumping) my neighbours' main concern isn't caused by the vibrations I transmit downstairs through the floor. It is their doors rattling, I guess :-0

The SD damping feet have two sides: the rough one should face downwards while the smooth one should be kept in contact with the cabinet of the loudspeaker.
Now, the SD feet are even available in a thicker "audiophile version" (no gold plating here, thanks). These Audiophile feet are not only thicker but they have a lower resonance frequency (claimed, 7 Hz) while the CD edition feet are thinner and come in a 5-units package, so to better balance the uneven weight of players with a center of gravity off the geometrical ideal center.
These CD feet are available in different compounds, the weight range is: 5 kg, from 5 to 10 kg, from 10 to 25 kg.

We've been playing with them for a long time (too long, actually, sorry for the delay) and we have tried to test them almost anywhere. Right now they have found their favourite place under my power amp.

Clap your hands and...damp yer feet!

The question is always the same: do they work? And the answer is still the same: it depends. Under bookshelf loudspeakers they work pretty well, though sometimes it seems the sound becomes a bit too soft and plushy.
The usual problem is their use under heavy and tall floorstanding loudspeakers. Let me spend two words on this issue.
ANY damping/decoupling device I've tested under heavy floorstanders has caused the same troubles (I'm referring to Vibrapods, G-Flex's etc.): under the violent accelerations of the woofer the cabinet becomes to rock (and roll :-)), back and forth. No, you don't notice it, but it happens.
The softer the feet, the wider the oscillation. Yes, it is true that the amount of vibrations transmitted through the floor are much less, especially when compared with spikes, but while the cabinet may vibrate up and down (causing reactions, when on spikes) it also vibrates back and forth (action-reaction principle: the woofer moves forth, the cabinet moves back). And if you put a tall floorstander on soft feet, this movement affects the precision of the virtual image, the macrodynamics and the phase response.
Every time I've tried a "soft" approach with floorstanders (especially if very tall) I got the same results. Cleaner mid-high range but worse dynamics and imaging.
I'm sure the SD crew doesn't agree with this BUT!!! if the action-reaction principle they claim to use works in the VERTICAL direction (vibrations that go TOWARDS the floor) it works equally well in the horizontal plane (i.e. back and forth). And don't forget the woofer moves horizontally, not vertically!
More or less, it is the same principle that causes many "tall" cars to oscillate wildly on tight corners (Mercedes Class A being the most "notorius" case). And it is not surprising the Mercedes guys have solved the problem with stiffer suspensions, lower and wider tires (plus the famous electronic ESP control). And it is not a surprise that race cars use ultra-stiff suspensions.

So, to cut a long story short, I don't like soft feet under floorstanders, period. This doesn't mean you can't like their effect. After all this is a fine-tuning, you may decide it suits your needs better than spikes, for example.
The SD feet work very well when used under electronics, such as CD players, preamps, integrateds and power amps. The "smoothing" effect is often welcomed, the mid-high range becomes sweeter and more refined while the bass gets heftier. The effect on "imaging" may vary from component to component. Thanks to the smoother high range the 3D image often becomes wider though sometimes less precise.
Under turntables their effect has to be carefully evaluated since they can affect the resonance frequency. Just try and decide.

Summarizing, the main pluses of the SD feet are: low cost, ease of use, good and noticeable impact on sonics, tuneability.

Some advice

Avoid loading excessive weight on the SD feet, choose the right compound for your needs! You can permanently damage the damping structure and loose any sonic benefit. On turntables and tall floorstanders evaluate carefully before buying.
Have in mind that their sonic effect is somehow complementary to that of spikes: if your system sounds edgy and unbearable these feet may easily cure the problem.


Nothing much to complain here. The SD feet are honest and clever accessories, they don't promise you a miracle, but get the work done, if decoupling/damping is what you're after. In my humble opinion their effect on floorstanders is questionable, to say the least. They are not the solution to every problem, NO ACCESSORY is, after all.
Finally two words about their "living room acceptance factor" (LRAF): the Sonic Design feet aren't exactly cool and if you consider the various flashy colors they come in, their impact on a nicely furnished room could be relevant. Anyway, this is just my opinion, look at them and judge by yourself. I'm Italian, after all, and Italians are always concerned with style and good looks :-)


The Sonic Design feet are an excellent and inexpensive alternative to costly hi-end accessories. Easily tuneable to suit everyone's needs they could be considered THE SOLUTION for any damping/decoupling action you may need into your HiFi system.

A big thank you to Sonic Design for having sent us these interesting accessories.

© Copyright 2000 Lucio Cadeddu - http://www.tnt-audio.com

Manufacturer's comment

There are two main issues covered. We seem to agree on the first issue: The reviewed feet fulfill their task to isolate vibrations, which is advantageous for a variety of equipment.
The second issue is where we have the disagreement: Would it be better to have floor standing loudspeakers standing on stiff spikes (with a resulting resonance frequency in any direction within the bass range) or, on the other hand, would it be better to have them standing on very soft feet (with a resonance frequency in any direction well below the frequencies reproduced by the loudspeaker)?
We plan to make measurements that show the vibration levels of floorstanding loudspeakers using spikes compared to SD feet and publish the results on the Internet. In the meantime we encourage anyone to investigate which vibrates more when playing music.
This can be done by scientific measurements. One could also simply put a finger lightly on the speaker baffle, turn up the level and feel what setup vibrates/shakes/moves the loudspeaker the most.

Such measurements vere actually performed for an article in 1989 by the editor of the scientific and objectively oriented Swedish magazine 'Music & Audio technology'. The results were very clear. The cabinet moves substantially more (>10 dB) when placed on spikes compared with ultra soft feet!
The author (Ingvar Öhman) pointed out that loudspeakers reaction forces are primarily to be found in the frequency range above driver resonance, i.e in the membrane mass controlled range of each driver.
Below resonance the forces generated by the driver motor find their counterparts in the suspension of the driver rather than in forces from cabinet inertia.
The impression you get of soft feet when you try to rock the cabinet with your hand will therefore be irrelevant. This also goes for the sports car comparison.
Ingvar Öhman also pointed out that the main task for super elastic feet is to be elastic, not to add damping. An infinitely elastic foot with no damping (i.e. hoovering loudspeaker) will guarantee the cabinet motion to be 1000 times lower than woofer membrane motion if a 1000 time weight ratio is by hand.
With spikes cabinet motion is always higher, often many times higher. In some cases Ingvar Öhman have measured more than 20 dB increase near horizontal spike/cabinet resonance (often between 20 - 50 Hz).
The only exception he found was when a subwoofer with very heavy passive radiator was used, since such a speaker does generate extreme reaction forces near fh (~20 Hz). Such a speaker can sometimes benefit from spikes if they couple the cabinet to the floor to a high enough frequency.
The structural vibration in the building when spikes are used might still make the neighbours to prefer super soft feet though! :-)
Per Arne Almeflo - Sonic Design

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