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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
pindac's avatar
pindac
2,864 posts
 
I have never set out on the path of placement of Speaker on Sub Plinths and Footers with a Science for what I am doing in mind.

I started out with Steel Mounts for Two Way Speakers, and then ended up filling the Steel Mounts with Kiln Dried Sand and this evolved over many years into variations of configurations of materials.

Today at hand are a selection of Materials to create different configurations of Mounting for a Speaker, beyond the immediate available Flooring.

A Willingness to periodically trial new discovered Materials as continued Investigation has resulted in increased material options over time.

I know today I am attempting to manage a energy transmission and attempt to use this management of energy transmission to allow for a Speaker Presentation that is most pleasing to my own unique preferences.
I use what is learned from these experiences and take them on board for all of my Devices Mounting requirements.  
In many cases there is more of a attenuation created through a materials exchange, it can be perceived as more of a change to a devices flavour other than a improvement.
That is about the extent of the Science used today in my participation.   
clearthinker's avatar
clearthinker
1,582 posts
 
Morning Miller.  Boing boing!

A spring so unstiff that it is compressed to half its free length by the mass of the speaker is certainly going oscillate all day long in response to the cone/membrane movements in the speaker and the air moved by them, as well as air movements in the room.

Happy listening to the distortion created.
pragmasi
212 posts
 
A spring is an energy store, a bit like a capacitor, so where does that energy go?.. Either back into the loudspeaker or into the floor. So the problem hasn't really been dealt with by using a spring on it's own, it will need further engineering or tuning to ensure the energy is dissipated benignly. If you end up spending a lot of time or money trying to fix the problems introduced by your 'solution' then there's a good chance you
didn't choose the right one in the first place.
Compliant materials like acoustic foam etc. are more like resistors - they are designed to transfer most of the energy into heat and so don't require any further 'tuning'. They don't always look great and they're difficult for manufacturers to make a big profit on (because everyone knows they're just buying slabs of material), but they do the job just fine. However there may be a problem with stability if your speakers have a high centre of gravity. 
audioman58's avatar
audioman58
4,170 posts
 
Look at Wilson Audio for example look at their substantial spikes heavy duty 
and use 3/8th thick threads most spikes are not only thin butthe threads are abut loose ,I always use Teflon tape to absorb as well as remove any play in the spike 
Ihave outriggers which is a great solution if you don’t have a substantial foundation. Iso acoustics makes some very nice ones for hardwood floors ,
and adapters for ones with rugs. They truly do solidify the speakersbass,as well as focus . Just thinking your house as being on on pegs .for sure to start buy a roll of Teflon tape at any hardware store and wrap the threads 3-4 wraps going 
in the direction you will be threading in , if stand mounts throw a bit of spray foam 
In thebottom , then dried play sand ,I also bought50 lbs of graphite coated lead shot ,then after shaken compacted with a small woodblock then sealed with plumbers putty then put the top plate on ,much better focus, sound city sell pretty decent outriggers for under $300 a pair.
rixthetrick's avatar
rixthetrick
1,060 posts
 
@pragmasi - the enclosure deforms with transient energies (ballooning inwardly and outwardly), and then (hopefully) returns to it's natural shape within milliseconds. Play some loud deep bass music and put the back of your hand gently moving it on different panels of the speaker enclosure to feel it for yourself.
Instead of passing that wave of energy onto another component or the substrate, it aught to compress the spring and decompress the spring.
It will probably not do it perfectly, but like a car it aught to smooth out the ride so to speak. Isolation done correctly, simply works.

I could blather on, however, I'm eagerly waiting for wokeuptobose's experiment. Something many of us have done, and so we'll see what he posts. Because so many of us already hear the difference, I don't think he's going to need more than minutes to be impressed.

Millercarbon, if he doesn't want to try the springs, yeah I'll have them back.
By the way nice write up, the concept surely isn't that hard to understand??
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