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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
noromance's avatar
noromance
9,821 posts
 
Check out my thread (our thread!) on springs from last year. Lots of good stuff in there.
https://forum.audiogon.com/discussions/springs-under-turntable
elliottbnewcombjr
5,469 posts
 
It’s about transferring weight to smaller area, achieving greater lbs per sq. inch. Good concept, can make a small speaker heavy.

I’ve done spikes, ... gave them away.

Big or medium speakers (or small speakers on sand filled stands) are heavy enough to put on 3 wheels (more weight per wheel than 4) (3 do not need leveling wherever you move them).

Put rear corner blocks not touching floor, just a bit shorter than the rear wheel height to prevent tip-over when moving. Tilt: corner block touches floor.

Move them here and there, find, then use the perfect location for one person (need marks, I have a grid wood floor luckily).

I listen alone and with 1 or 2 friends, when 2, I want good imaging
You can easily adjust toe-in for a wider center for 2 people, push back into the corners for lower volume listening, i.e. when expanding the dining room table, large crowded parties, ...



ebm
9,311 posts
 
WOW i did not know that.
linnvolk OP
90 posts
 
Thank you all for the considered and well-crafted replies. All of them. I got something useful out of each one, and greatly enjoyed the morning read. I expected a much lower signal-to-noise ratio than I received from you guys--my mistake.

I am not willing to pay for Townshend Podia at the moment. I am, however, willing to spring for (pun intended) Nobsounds and may piddle with some damping ideas in combination. I still need to build fairly rigid bases for the AV 5140s because their footprint is too small to be sufficiently stable against topling (and this will get worse--to what extent remains to be seen--with the addition of springs). The Linn factory bases went missing long ago, and I don’t think they were "all that" to begin with.
pragmasi
212 posts
 
My understanding is that whether you use spikes or isolation pads etc. the aim is to minimise the transfer of energy from the loudspeaker to whatever it is standing on. Spikes aim to closely couple the loudspeaker to the floor by concentrating the mass on the points... I guess if you bolted the speakers directly to the floor that would have a similar effect. The other approach is to isolate the loudspeaker from the floor by placing some kind of compliant material between the speaker and the floor to absorb the energy.
In my case I have floorboards on joists which have their own harmonic resonances so I put my speakers on isolation pads. Another approach that might work for suspended floors is mass-loaded vinyl (as long as the floor can take the weight), I have used that with some effect when recording drums.
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