Speaker Spike Philosophy


This is a learning exercise for me.

I am a mechanics practitioner by training and by occupation, so I understand Newton’s Laws and structural mechanics and have a fairly effective BS-detector.

THE FOLLOWING THINGS PUZZLE ME, and I would be glad to hear from those who believe they understand so long as the responses are based on your actual experience or on sound mechanical arguments (or are labeled as conjecture). These are independent questions/musings, so feel free to weigh in on whichever ones you want, but please list the number(s) to which you are responding:

  1. Everything I have read recently ("Ask Richard" (Vandersteen) from 15 Feb, 2020, for instance) seems to indicate that the reason for speaker spikes is to hold the speaker fixed against movement induced by the drivers. I have seen in the past other explanations, most employing some use of the term "isolation" implying that they decouple the speaker (from what?) Evidently the "what?" is a floor that is fixed and not moving (let’s assume concrete slab foundation). So to decouple the speaker from the floor, which is fixed, is to . . . allow it to move (or not) as it wishes, (presumably in response to its drivers). These two objectives, "fixity" and "isolation" appear to me to be diametrically opposed to one another. Is the supposed function of spikes to couple the speaker to "fixed ground" so they don’t move, or is it to provide mechanical isolation so that they can move (which I do not think spikes actually do)? Or, is it to somehow provide some sort of "acoustic isolation" having to do with having some free space under the speaker? Regarding the mechanical isolation idea, I saw a treatment of this here: https://ledgernote.com/blog/q-and-a/speaker-spikes/ that seemed plausible until I got to the sentence, "The tip of a sphere or cone is so tiny that no vibration with a long waveform and high amplitude can pass through it." If you have a spike that is dug into a floor, I believe it will be capable of passing exactly this type of waveform. I also was skeptical of the author’s distinction between *speaker stand* spikes (meant to couple) and *speaker* spikes (meant to isolate/decouple, flying in the face of Richard Vandersteen’s explanation). Perhaps I am missing something, but my BS-detector was starting to resonate.
  2. Spikes on the bottoms of stands that support bookshelf speakers. The spikes may keep the the base of the stand quite still, but the primary mode of motion of such speakers in the plane of driver motion will be to rock forward and backward, pivoting about the base of the stand, and the spikes will do nothing about this that is not already done by the stand base without spikes. I have a hard time seeing these spikes as providing any value other than, if used on carpet, to get down to the floor beneath and add real stability to an otherwise unstable arrangement. (This is not a sound quality issue, but a serviceability and safety issue, especially if little ones are about.)
  3. I have a hard time believing that massive floor standers made of thick MDF/HDF/etc. and heavy magnets can be pushed around a meaningful amount by any speaker driver, spikes or no. (Only Rigid-body modes are in view here--I am not talking about cabinet flexing modes, which spikes will do nothing about) "It’s a simple question of weight (mass) ratios." (a la Holy Grail) "An 8-ounce speaker cone cannot push around a 100/200-lb speaker" (by a meaningful amount, and yes, I know that the air pressure loading on the cone comes into play as well; I stand by my skepticism). And I am skeptical that the amount of pushing around that does occur will be affected meaningfully by spikes or lack thereof. Furthermore, for tower speakers, there are overturning modes of motion (rocking) created by the driver forces that are not at all affected by the presence of spikes (similar to Item 1 above).
  4. Let’s assume I am wrong (happens all the time), and the speaker does need to be held in place. The use of feet that protect hardwood floors from spikes (Linn Skeets, etc.) seems counterproductive toward this end. If the point of spikes is to anchor the speaker laterally (they certainly do not do so vertically), then putting something under the spikes that keep the spikes from digging in (i.e., doing their supposed job) appears to defeat the whole value proposition of spikes in the first place. I have been told how much easier it is to position speakers on hardwood floors with the Skeets in place, because the speakers can be moved much more easily. I was thinking to myself, "yes, this is self-evident, and you have just taken away any benefit of the spikes unless you remove the Skeets once the speakers are located."
  5. I am making new, thick, hard-rock maple bases for my AV 5140s (lovely speakers in every sense), and I will probably bolt them to the bottom of the speakers using the female threaded inserts already provided on the bottoms of the speakers, and I will probably put threaded inserts into the bottom of my bases so they can be used with the Linn-provided spikes, and I have already ordered Skeets (they were a not even a blip on the radar compared to the Akurate Exaktbox-i and Akurate Hub that were part of the same order), and I will end up doing whatever sounds best to me. Still, I am curious about the mechanics of it all...Interested to hear informed, reasoned, and reasonable responses.
linnvolk
Spikes under speakers is another cure in search of a disease - to borrow a medical metaphor. I am unaware of any speaker that is affected by woofer/driver motion. Another marketing ploy to get the gullible and insecure to spend more money!
You have a pretty good grasp of the basics of vibration control. At least in terms of- yes the mass of the speaker is so great compared to the moving mass of the cones, etc the cabinet isn’t going to move hardly at all. So holding it fixed isn’t really relevant. But if we were going to try and hold it fixed the last place we would do it is some dinky spikes way at the extreme far end of a lever arm. So you got that part pretty good.

Nevertheless, if you do try different things and compare you will hear there are indeed real differences. Just about any spike or cone will be better than what you are planning on doing. Will tell you why in a minute. For now just accept that whatever you can imagine, I have done it at one time or another over the last 30+ years and not only with speakers, but everything else from the amp to the conditioner to the freaking step down transformer under the floor.

The best solution of all, and for all of these, is springs. Why? Because: ringing.

No matter what we do, no matter how rigid or massive, no matter if it is wood or concrete or carbon fiber, it is gonna vibrate. Look at my system. That rack is solid concrete, 4" thick cast concrete shelves with 1" of sand and 4" solid granite. The legs are cast concrete. People will say you don’t need this or you don’t need that because: concrete floor. Such people are so full of it they don’t even know. Concrete transmits vibrations just fine. I know from experience. https://systems.audiogon.com/systems/8367

Each material has it’s own inherent vibration characteristics, the speed and frequency it vibrates at best or most, and also the ones it vibrates at least or damps. The vast majority of vibration control on the market today (or ever) is nothing more than people played around to find a combination of materials that resulted in a favorable or benign acoustic signature. Hard to explain, maybe even harder to understand. But play around with these things enough you will hear it.

The speaker (or other component, they are all the same) does not need to be held rigid. Quite the opposite. It needs to be free to move, and as independently of the environment as possible.

Why? Because when the component is the only thing vibrating then the vibrations it generates settle down so much faster. Any coupling to the environment, be it a shelf or floor or whatever, and it will set the whole system to vibrating, and those vibrations will take a lot longer to settle down.

This can actually be seen via a seismograph on a speaker. https://youtu.be/BOPXJDdwtk4?t=8

The key element in all of this is that the spatial information that tells us precisely where a sound is coming from is extremely subtle and low level. Ordinarily the ringing created by the speaker/room vibration system smears a tremendous amount of this detail. When something as effective as Townshend Podiums are used they break this ringing feedback cycle resulting in a tremendous improvement in clarity and detail.

I can tell you from actual experience the plan you have will be no better, and maybe even worse, than nothing. Bolting maple to the bottom of the speakers will only add a little mass, but not very well damped mass, so it will mostly add smearing. Putting spikes under it will not help at all. Better in fact to put the spikes on the speaker, and the maple on the floor. You can experiment if you like. Most guys sorry to say come here pretending to ask but really already having their minds made up. Hope that’s not you. I am not kidding. That idea is not good.

Springs are so much better a solution that even dirt cheap Nobsound springs are better than just about anything else you can do. They aren’t perfect. They require a bit of experimentation to determine the correct number of springs to tune the sound to what you want. Then more experimentation and tweaking to get them level. But in terms of price/performance they will beat just about anything.

About the only thing they will not beat, not even close, are Townshend Podiums. These are engineered with just the right amount of damping to tune out the tonal aberrations that would otherwise be a problem with springs.

I tried all this stuff. That was your requirement. I actually did it all. Springs are way better than anything else- except Townshend. Podiums under your speakers will open up the sound stage deep and wide, with so much detail you will wonder if it really is the same speakers. Truth of timbre will be like a whole component upgrade.

Notice the one guy in the video said they had what they thought was a room problem with bass modes. I had the same thing. Was just about convinced I was going to have to break down and try bass traps. Put Podiums under my Moabs, hey where’d that bass resonance go? There is still some room resonance, but it is so much less it is hard to believe. I am now convinced a huge amount of what we consider room acoustic problems are really rooted in the speakers exciting the whole room to vibrate by not being properly isolated on springs.
I am a Electrostatic Speaker user for many years and in the past few years have used occasionally a Three Way Floor Stander.

To get the best from the Floor Standers during earlier occasions of use I have used various Sub Plinths,
that in the end become a Two Tier Sub Plinth,
using a highly compressed Chip Board as the Base Tier, that is Spike Foot coupled through Carpet to a Concrete Screed Floor.
A 40mm Thick Granite Slab is the Top Tier, that is Spike Foot Coupled to the Chipboard.

The Materials chose in the Sub Plinths were selected from a variety of used materials.

The Speakers were seated directly onto the Granite and as an alternative seated with onto the Granite with Spike Coupled Feet.

The Speakers were at their best 'in my view' when the Spikes were used as feet.
When used during this time period, I also had a selection of Dumbbell Weights seated on the top of each Speaker Cabinet.
I recall that by moving the weights off centre into different positions had the effect that I would refer to as a attenuation and could produce a very slight change in how the sound is being perceived.

Very recently I reintroduced the Speakers into the System, they were allowed to see the light of day after a long term storage and used in the New Listening Room Space I have recently created.

I worked my way methodically through their Setting Up and settled for the above set up.
It was for myself, being perceived as being correct in many ways, the result being,
the Speakers were much more impressive in the New Room, when recollections of their previous usage were taken into account.
I am yet to add the Weights to the Top of the Cabinets

I had a opportunity to trial the Speaker Set Up a little further, using a change to a footer, the good impression they were making was a stimulus for the extra investigation.

I had produced similar things for others in their Home Systems and the impression made was enough for those who experienced to create similar Set Up using either Townsend or Gaia Footers

I Seated the Speakers onto Audio Technica AT-616 Pneumatic Feet and was left thoroughly captivated, the effect on the SQ was not expected.
The impact they were having on the SQ was quite noticeable and further enhanced my already good impression.

I have one more trial to undertake, which is to protect the AT 616 Top Surface and Place them under the Speakers Spiked Feet.

I will say the Spiked Footers under the Speakers when used on the Two Tier Sub Plinth Set Up is allowing for a imaging and Soundstage with a defined edge. ( A Electrostatic Mimic )
 
The AT-616 have blurred the edges ’very slightly’, giving a richness to the presentation with a noticeable weight underpinning the performers.
The Soundstage is now perceived without a Boundary and the experience has that added effect of being more honest / believable. ( This has made such a impression on me, afgter Twenty Plus Years of Electrostatics, they are now in Storage, allowing for myself to get the most from this Set Up )
I fully concur with @millercarbon. An alternative to springs is the Symposium Svelteshelf on rollerballs. Whatever you put under the speakers if they are floorstanders, should be relatively thin, otherwise you need to lift your seating position by a similar amount to get adequate vertical allignment. Also note that bass performance is likely to decrease with increasing distance from the floor.
The problem with springs is if they deflect they must rebound. And they of course have their own resonances when they do. So they must be damped. Try driving a car without dampers. So the damping is very much more critical than the spring in its design. Which is why the dampers on your car cost 100x more than the springs. The problem with dampers is they often have their own resonances. Some springs are damped by having trapped air escaping through a hole. For anything other than the lowest of frequencies this is a disaster because the viscosity of the air is both the reason why any damping at all happens and the reason why you are left with another spring in the form of compressed/decompressed air in the damper. And guess what, that air spring has its own resonance... so most spring/damper combos left this long ago and moved to oil based, because oil doesn’t compress and doesn’t add yet another resonation to the system. But the problem with uncompressible liquids is that they are more viscous than gasses, meaning you need a reservoir, seals, etc and this all eats into your profit margin. The next problem with the spring/damper combo is what is the range of frequencies it can deal with. As an engineer you can probably do the maths. Car spring/dampers can cope with low frequency deflections well, but can not cope with high frequencies at all. This is why your car has pneumatic tyres as well, where the air is another spring and the rubber of the tyre has a damping effect.  The different spring rate of air in tyres to the spring/damper on the axle is a problem and why the fussy have lower profile tyres - it minimises the air spring conflict of the tyre.  And the smallest of vibrations (road texture) is handled in the rubber touching the road alone.
So the issue for audio is - what are the frequencies that are thought to be a problem? Where are they coming from? Are they in the range a spring can react to? If so, can that spring be damped so as to not make the problem worse? Is that damping adding new resonances and again making things worse?

The products marketed seem to me to have very low frequency spring rebound indeed, and have air damping which at higher frequencies will themselves become springs, not dampers.  I can not see how at the high frequencies and low amplitude of audio-caused vibration they can have any effect - I think any effect is due to the mountings and fixings (like the bushes on car suspension, which are vitally importance for isolation because they deal with higher frequencies which no car spring/damper can deal with) and not the springs. 

I’d like an engineer - mechanical - to tell us here i) whether there is a spring that is effective in the range of frequency and amplitude deflections thought to be relevant to audio through speakers, ii) how such a spring if it exists should be damped, iii) whether a spike or BluTac has solved the problem already!