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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
rixthetrick's avatar
rixthetrick
1,060 posts
 
@ jchiappinelli  - Lenehan Audio in QLD Australia sell the ML5 floorstanders exclusively with springs, which were developed to be as good as Townshend podiums. The first pair actually shipped with Townshend as the feet some years ago now.


Mike Livine's system extensively uses isolation, often very expensive devices are used. https://systems.audiogon.com/systems/615

pesky_wabbit's avatar
pesky_wabbit
1,183 posts
 
Those who bash springs dont know what they speak about.... I know.....I devised my own method with total success...
Excellent to hear of your successful outcome through careful experimentation. I feel inspired.....
ngiordano
55 posts
 
Was pretty impressed by a guy on youtube from Credo in Switzerland and what he found was spikes attenuated certain frequencies and amplified some , he had all the correct gear to test and sensors and when he put the graph of both tests up when he measured the waves from peak to peak you could clearly see a benifit to using decoupling pucks vs spikes one instance 80% differance, you cant ignore that unless you believe the guy is lying to you, he wasn't trying to sell me anything . I seen GIIA makes the puck with the disk spike combination of both, he didn't test that but that might be worth looking into if you want spikes. I did allot of research and looked at allot of reviews and went with the SVS feet , I need 12 for my dual pb16s SVS and they really do work no BS there , you dont have to break the bank with isolation , I spoke with the head of SVS cause I was getting room boom and this along with acoustic treatments Curtain/ Corner Traps really cut down and cleaned up my bass , once I reran room correction it allowed my gain to come up so you know it worked . Im really happy with the results, without decoupleing your subs your turning your floor into a speaker smearing/ mudding up your bass. 
millercarbon's avatar
millercarbon
12,531 posts
 
The Credo video used a very early generation Townshend Podium that they tried to pass off as a current model. They were for a time a Townshend distributor, until they ripped it off and started selling that instead. They pull a fast one with the graphs, you have to watch real close and go back, as they try and make the Townshend graph look bad when it is better, and theirs look better when it is worse.  

You are right, you do not have to break the bank with isolation. Ordinary springs from eBay for about $30, or Nobsound springs for about $35, perform about as well as Gaia or anything else around that price level. It is really quite astounding just how good ordinary springs can be when resonance is minimized by tuning the spring to the component load. Nowhere near Townshend level but awfully good for the money.
mitch2
4,076 posts
 
It is really quite astounding just how good ordinary springs can be when resonance is minimized by tuning the spring to the component load.
Exactly what I have found.  Use the correct spring constant and appropriate maximum spring load compared to the actual load, apply damping, such as loosely applied thin heat shrink with a hole in it (what I use), or maybe foam inside of the spring, and you should be able to reduce the natural frequency of the damped system to below the audible band.  It was a little more than $35 though because it took me a few tries to get the correct combination of springs.  Other "design" considerations include what spring diameter and compressed height you want, as well as what number of spring coils might work best for the height of spring you are using.  There are lots of choices.  With speakers it is good to know the front (under the baffle) is heavier than the rear due to the weight of the drivers so two different spring constants may be necessary.  Another thing helpful to me is that my main speakers and my two subs all use Sound Anchor stands, which provide a rigid base for the springs to act against.

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