Isolating Feet for bookshelf speakers worth it ?

[terrycym]

Correct!
So all the energy from the room is coupled into the speaker and the energy from the speaker is room.
Try using a stethoscope on the speaker cabinet when playing music and listen to what is there.
Likewise, and vibrations caused by passing traffic outside your house ends up in the speaker cabinet.
The Townshend solution as well as the inner tube attempts to isolate this link.

 

[Julf]

I think the 'theory' of spikes is that the sharp 'point' provides so little contact area that 'energy' cannot get through or past it.

I think that is an example of magic thinking.

 

[eka]

I had speakers on a bookshelf with the result that that shelf was resonating to the touch. Then I bought these Moongel pads: https://www.thomann.de/gb/smile_moongel.htm (about 10 euros) and placed them under the speakers. Now the speakers float on the gel pads with a resonant frequency of about 5 Hertz and no vibrations seem to be coupled to the shelf anymore.

 

[terrycym]

It may be magic thinking but it certainly isn't any mechanical engineering covered in my degree course.
Also, for it to work (couple) correctly, good luck with getting all 4 spikes to be in perfect contact with the support at the same time.

 

[John Phillips]

I think the 'theory' of spikes is that the sharp 'point' provides so little contact area that 'energy' cannot get through or past it.

I think that does not work. Keith Howard's experiments with spikes for Hifi News are summarised here: http://www.audiomisc.co.uk/cones/speak.html. Keith was rather surprised how effective spikes were at transmitting vibrations compared to the isolation he measured from "small rubbery feet".

My own professional experience in semiconductor research labs is that pneumatic air-springs (sometimes with damping for the spring/mass resonance) are effective at isolating vibration-sensitive equipment. In a non-professional environment, compliant ("rubbery") mountings ("feet") would be a less expensive equivalent.

 

[mr sneff]

I bought a set of these to put under my Audience THE ONE speakers, which I find to be very effective.

 

[terrycym]

Just look at high magnification microscopes isolation.
Loads of examples - here's one...
https://www.newport.com/f/nikon-microscope-isolation-platforms
Notice how they DO NOT use spikes between the microscope and the bench. Mind you, what does the medical industry know?
I would image that something like this would be rather interesting when placed under speakers? Obviously, a different, larger solution would be required.
You can see where Max gets his ideas from? Maybe?

 

[JensenHealey]

I think that does not work. Keith Howard's experiments with spikes for Hifi News are summarised here: http://www.audiomisc.co.uk/cones/speak.html. Keith was rather surprised how effective spikes were at transmitting vibrations compared to the isolation he measured from "small rubbery feet".

Exactly, hence I wrote 'theory'! And Keith Howard's first paragraphs go on to explain that 'theory' before the debunking. I have read this 'theory' so many times in the hifi press over decades. Many folks still have spikes on every shelf in their rack - is that really the right way to go? Surely most racks would work better with Sorbothane or similar pads as shelf supports? Or the shelves could be a constrained layer damping composite rather than MDF / Wood / Glass?. Last time I had a rack, the shelves (Thin MDF) were supported on small rubbery blobs, that sat on metal frames underneath each shelf. Then the whole rack was spiked to the floor.

FWIW I have no spikes or cones in my system. The speakers sit on rather springy metal folded metal tubes and rock about rather freely. These stands were designed by the speaker designer - whether they are 'correct' I do not know. The stands then sit on new soft carpet and underlay, with concrete flooring under that. In a basement, so no wooden floors problems, nor transmission from other parts of the house coming in either.

 

[Tarzan]

Under my Audionote ANK-LX are Atacama Gel pads ( good VFM) for what they do, in the hollow portion of the pad l placed Blu-tac to hold the speakers to the
stand, under the stands themselves l use Vauxhall Viva valve springs and these work a treat for buttons, because l have the music room floor from hell.

 

[JensenHealey]

There must be Vauxhall somewhere that is looking for those!

 

[awkwardbydesign]

I had speakers on a bookshelf with the result that that shelf was resonating to the touch. Then I bought these Moongel pads: https://www.thomann.de/gb/smile_moongel.htm (about 10 euros) and placed them under the speakers. Now the speakers float on the gel pads with a resonant frequency of about 5 Hertz and no vibrations seem to be coupled to the shelf anymore.

I would be rather surprised if they had a single resonance, which anyway would depend on the speaker's mass. But I've bookmarked them, as they look useful.

 

[awkwardbydesign]

It may be magic thinking but it certainly isn't any mechanical engineering covered in my degree course.
Also, for it to work (couple) correctly, good luck with getting all 4 spikes to be in perfect contact with the support at the same time.

Quite easy with these new-fangled adjustment screws!

 

[Lee T]

If anyone else hasn't mentioned Atacama gel pads, these are the best option for shelf mounting
Eliminate all vibration from surroundings
google user reviews, pretty much sums them up.

Tukan's are quite well damped but the shelves are not & will happily bounce along with your music, at least this way you hear the speaker as intended.

 

[Konteebos]

I think that the real theory behind spikes (an not the pseudo science about mechanical earths etc) was to make sure that the speaker was stable and stationary, so that the only thing that moved was the cone. As you can easily rock any speaker that is sitting on carpets, the spikes were intended to eliminate this. Of course, the spikes will transmit vibrational energy into the floor so there is a trade-off - is it more important that the speaker body is immobile or that the vibrations are not transmitted into the floor? My own experience has been that it is better to isolate.

 

[Nic Robinson]

Doesn't it depend on the type of floor? In the case of a concrete floor you're essentially "earthing" the speaker's vibrations as they're not going to move the floor. In the case of a wooden floor, the vibration of the cones would, via the speaker's body, excite the floor to some extent, if the floor has any movement in it. Similarly and empty free-standing shelving unit might be more susceptible to vibration than one fully loaded with books or records - built in inertia. All this assumes the speaker can't rock (hence spikes). I was advised many years ago to put bookshelf speakers in 3 nuts in a triangle, which prevents movement in either plane relative to whatever it's sitting on.

Whether any of that has much audible effect is another question.

 

[awkwardbydesign]

[

Doesn't it depend on the type of floor? In the case of a concrete floor you're essentially "earthing" the speaker's vibrations as they're not going to move the floor. In the case of a wooden floor, the vibration of the cones would, via the speaker's body, excite the floor to some extent, if the floor has any movement in it. Similarly and empty free-standing shelving unit might be more susceptible to vibration than one fully loaded with books or records - built in inertia. All this assumes the speaker can't rock (hence spikes). I was advised many years ago to put bookshelf speakers in 3 nuts in a triangle, which prevents movement in either plane relative to whatever it's sitting on.

Whether any of that has much audible effect is another question.

Concrete will vibrate. Our floor is concrete, and speakers solidly mounted on it would transmit vibrations into the brick wall and cause resonances in the bedroom above. Springs (ala Townshend) stopped that. We now have solid oak glued to the concrete, which presumably would have helped back then.
It would seem that some speakers in certain circumstances benefit from different isolation/coupling treatments. I suspect some cabinets like to be coupled at certain frequencies and decoupled at others, depending on what they are mounted on. And although spikes couple, do they do so equally at all frequencies? If not that would explain the mixed results; likewise the foam, etc, decoupling systems. Of course there is plenty of marketing involved, which muddies the waters.
As far as I can see (or hear?) only tuned devices truly decouple, and then only above their resonant frequency. Which means matching them to the weight of the speaker. Most so called decouplers are actually absorbers (Sorbothane, gel, etc) in the main, with diffuse resonances, if any.
At least that is how I see it.
BTW, I think paper-back books would be worth experimenting with. Multiple layers, non resonant materials, varying thicknesses and incredibly cheap. 4 for 99p at our local charity shop. And if you have the energy, cut them into smaller pieces for feet!

 

[Nic Robinson]

[

Concrete will vibrate. Our floor is concrete, and speakers solidly mounted on it would transmit vibrations into the brick wall and cause resonances in the bedroom above.

Very certainly didn't happen in the 3 houses I've lived in with concrete floors...but it will vary between buildings I guess.

 

[Tony L]

I think the 'theory' of spikes is that the sharp 'point' provides so little contact area that 'energy' cannot get through or past it.

Spikes on speaker stands first arrived as a perfectly logical method to obtain a solid footing on a carpeted floor, i.e. the spikes would pierce the carpet and underlay and allow accurate levelling of the stand on the floorboards, concrete or whatever lay beneath so the speaker didn’t wobble about as light-weight stand-mounts are very prone to doing. All the marketing huff, bluster and pseudoscience arrived a good bit later and can be viewed as revisionism in most cases IMHO. I certainly remember them being referred to as ‘carpet piercing spikes’ or similar in the early days as that is what they were for.

 

[awkwardbydesign]

Very certainly didn't happen in the 3 houses I've lived in with concrete floors...but it will vary between buildings I guess.

Very true. Our bricks here in Plymouth seem to have a high granite content, and it may depend on what us under the concrete too.
All of which emphasises why I think the results of coupling/isolating are so mixed; one size does not fit all, and trying to insist that one is right and the other is wrong is doomed to failure and frustration.

 

[BLACKMASS]

I received the 'Sonic Design' feet a couple of days back. I swapped the Sorbothane domed pads out for them this afternoon.

I've only listened to one album so far but initial impressions are very good. The music seems more focused. As I say early days.

Slightly OT. My speakers are on a side board with granite chopping boards underneath.

Just wondering if slate might be an improvement?

Sorry to the OP for going OT.