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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
sokogear
1,097 posts
 
@mitch2 - The R500s weigh 48 lbs and the discs are 1square inch (1.125 inch diameter)) with 4 spikes, so 12 psi if you assume the force is evenly distributed throughout the bottom of the disc, which is not possible as the disc gets thicker as you get near its center where the spike fits. If you assume the part hitting the floor with force is the size of the indentation, then you are talking about an area of .0128 sq. Inches (.25” diameter) for a force of 937 psi.

I would argue the area is even smaller, about the size of the tip of the spike which I can’t measure without lifting the speaker, which I am not going to do. Let’s assume it is 1/3 the size of the indentation (it’s probably less) so diameter is .0833” for a force of 2200 psi or 317K psf!

I am sure digging the spike into the floor would be better sounding (not sure by how much), but grinding up up oak floor is a non starter. The way I have it probably sounds better than if I had the spike digging into carpeting that has padding under it.

in any case, I am sure that if I had my 4 discs sitting on top of a Townshend platform, the sound would improve (I have one under my turntable and it was an incredible improvement, but my 10 lb table is a lot more susceptible to vibrations than my speakers are). However, the platforms cost more than my speakers (after close out discount) - so that’s a non-starter.

in the cost no object world some posters reside, around $2K for speaker platforms is a rounding error, but for us regular guys with low 5 figure systems, it is substantial. That being said, $10K+ speakers should include stands that optimize their sound or build it into their cabinet designs live Vivids and KEFs do.
bachemar
14 posts
 
bachemar,
Imagine you are an audiophile. No, wait, too hard. Nevermind.

@millercarbon I’m really curious as to why it would be so hard?  Is it the rational and common sense approach to understanding the impact of various footers on vibration suppression is too hard to comprehend?

Or could it be, because I called out that your preferred method - Springs, are you know.. “springy”, and would not be be best at damping vibrations.  The spring action would just add their own color or even potentially, resonance to the vibration. Springs might be good at suppressing vibration transmission (from one send to the other), but this is a different application altogether. 
linnvolk OP
90 posts
 
<soapbox on>
I am really not interested in seeing personal slights.  My OP was a set of technical inquiries.  Was hoping to see mature technical responses.  Most replies thus far have been.  Seeing the beginnings of a departure from that here.  This is a highly subjective subject.  I heard it best from my dealer earlier today.  A lot of this is "witchcraft,"  (please read on)  by which he did NOT mean that there were not valid physical explanations for what is going on.  He was honestly stating what I agree to be a fact, which is that:

1.  There are things that make a difference.
2.  Not all will hear the difference.
3.  A given difference may or may not be simply perceived (as opposed to real).  In other words, some things do not make a difference.
4.  Some will find a given difference "good" and others will find the same difference "bad."
5.  For the most part, our understanding of what is really going on physically, acoustically, and psychoacoustically in these differences is incomplete, sometimes vastly so.

I don't care to see others' audiophilic manhood called into question because of opinions/preferences on the above (or anything else for that matter). 

Back to the dealer.  This dealer has never attempted to sell me isolation equipment, though he certainly has it for sale.  He believes in it.  When I asked him about the topic today, we had the discussion summarized above.

He has a regular stream of folks coming through his door hawking the latest and greatest bits of kit.  In most cases, he puts it in his reference system and has the team give a listen.  If he and/or they find it to be helpful, they may start selling it.  If they find it not to be helpful, they do not sell it (I gathered most things fit this category).  He does not sell anything that he does not believe improves SQ.  He sells pricey Symphony plinths, and high-dollar power and speaker cables out in plain sight, none of which I intend to buy.  Today.

He is a firm believer in trusting your ears.  Not his. 

He also has a good grip on the twin realities of budget constraints and limitations on what any given client can hear.  His flagship system is $275k, but I am going in for a paltry $17k myself to update the electronics behind my AV 5140s, including going Aktiv (Exakt), and to put a modest system in my garage so I can have music while spending time there.  This is perhaps more than I should be spending, but I suspect it will be my last large expenditure.  I am 58, and the last time I spent serious money on audio was about 20 years ago.  I needed to get into the 21st century this time (streaming), and have chosen a path that should be incrementally upgradeable.  I have spare drivers for the speakers, which I like a lot.

I bring this dealer up to say that I like his approach:  Don't judge.  Help others.  Know your stuff (he does--he was involved with Jack Renner in the early Telarc recording sessions (Fennell, etc.)).  Know your clients (if you are a dealer).  Don't belittle others just because you know a lot and have a great pair of ears.   
<soapbox off>
sokogear
1,097 posts
 
+1 @linnvolk  Most of the belittling involves @millercarbon, who does know a lot, but sometimes doesn’t understand some of your points above. Your dealer sounds like a good guy. Everybody’s hearing, taste, and priorities/budget are different.

I don’t think $17K is a small amount to be investing though. However, you’re around my age and hopefully your expenses (payroll) are shrinking and the amount of time you have to enjoy your system is increasing, so you will benefit more from it now.

One point- not sure if I would invest much in a garage system unless it is climate controlled or you live somewhere like San Diego where the weather doesn’t get extreme. I’m sure our equipment doesn’t like 30 or 90 degrees or worse. I have a Bose wave clock radio that I move down into the garage when I wash my car. Not great sound, but strictly background music. You could do something like that (portable boom box type set up) and either put more into your main system or trim your expenditure.

Enjoy!
linnvolk OP
90 posts
 
@sokogear, thanks for the advice. Garage is in Houston area and is not climate-controlled, but it is an attached garage.  It did not get below 32 F when we had our recent snowpocalypse with temps dipping (just) into the single digits. Summers here are hot and humid. We will see how it goes. I doubt the garage temp gets above 90 F (?). The larger issue is wood dust—this is my wood shop, and while I use hand tools whenever circumstances permit, a fair amount of dust gets generated nonetheless. 
The investment is fairly modest: BlueSound Node 2i, NAD C316BEE V2 (40 Watts), and Klipsch RP-600M.  About $1700 drive-out. I am all ears if anyone has ideas about protecting it from dust. (No discussions on dust-collection systems, please.). 
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