Speaker Spike Philosophy

" This new learning amazes me Sir Bedevere. Explain to me again how sheep’s bladders may be employed to prevent earthquakes."

@wokeuptobose, I am keen to hear a report from your upcoming experimentation; I do hope you will post back to this thread or at least put a link here.  Thanks!

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.

@aschuh, that would be quite true if the force were static.  In your example, that force is reversing direction 60 times per second.  No problem for an 8-oz woofer cone.  The displacement (vibration) response of the 100-lb sub in rigid-body mode at that frequency will be of very small magnitude as it is nowhere near the natural frequency for that mode.  Whether there is enough magnitude to matter and whether the magnitude is attenuated by the use of spikes or springs (and whether that attenuation is good, bad, or indifferent) IMHO would best be addressed by running the test and using your hands/ears...or accelerometers.  For the accelerometer testing, please hire my company, have them spend several days on testing (I will write the test report), and send @ausaudio the bill.

@ausaudio,

You caught me in some less-than-clear writing.

The second quote is based on a tacit assumption that we are talking about hard floors.  This is what I have, and I tend to default to it without necessarily giving the reader the appropriate cues.  My bad.  The point here is that putting spikes on a speaker that would otherwise be sitting directly on a hard floor does nothing to help the stabilize the speaker against the rocking mode.  They actually will destabilize this mode, because the spikes have to be inboard of the periphery of the speaker base in order to have something to screw into.  This reduces the footprint and thus the resistance to rocking.

The first quote addresses, as stated, the case of tower speakers on thick carpet.     It is equally or even more applicable to bookshelf speakers on stands (which are likely a more top-heavy arrangement). In this case, the speaker will want to rock back and forth on the springy carpet, pivoting about its base, due to the carpet's compressibility.  Here, using spikes lets you bridge across the mushy carpet and get "seated" on hard floor.

I agree with your accelerometer statement.  My life is not long enough nor my pockets deep enough to head down that road.  Though not part of my practice area, my company could actually do this for several thousand dollars. 

I think the "hand on speaker test" with some thumping bass would provide a substantial clue regarding whether spikes or springs are either one changing the game as far as speaker vibration is concerned.  I suspect that neither will show any difference in that test, though here, as in listening, perception bias will play a part unless you enlist at least one other person in a blind test so that you do not yourself know which is which.  Even there, the speaker on springs will have some perceptible wobble in response to just your touch which you won't be able to ignore/forget.

@mijostyn, I wonder if what you are feeling with hand on speaker is primarily flexible modes being excited, which locking the speaker to the floor will not really attenuate.

Spiking the speaker to the floor (if it actually works as intended) would restrict the translational fore-aft rigid body mode, but it would do little about the fore-aft rocking mode. I suspect both of these modes for most speakers are in the sub-1-Hz range. I am skeptical that any true acoustic benefit of spikes derives from them actually anchoring the speaker to the floor, though their ability to keep the speakers from walking might be valuable.

Have you done the "hand on speaker" test both with and without spikes (same music, same electronics, same everything, except with/without spikes)? I have not, but my intuition tells me that you may feel no difference(?) I would put the same question to the "spring and damper" crowd.

Based on anecdotal evidence from others and the differences in opinion regarding the physics involved from experts (Richard Vandersteen and others), I suspect that:

1. There may be some real difference (better or worse) in SQ between the manifold options (including doing nothing).
2. It is difficult to know whose grip on the physics (if any) is correct.
3. It is difficult for me to entirely reject that perceptions based on bias will unavoidably be mixed with perceptions based on true acoustic reality--and I mean *anyone’s* perceptions. The ability to conduct a true blind A/B/C/etc. comparison between options, realistically for real humans, is limited at best, especially for heavy floorstanding speakers.
4. The truth regarding the physics is, and likely will remain, both complex (much more than "gotta keep the speaker from moving" or "gotta let the speaker move") and elusive.
5. Experimentation with one’s own ears (but see Item #3) and equipment would be the most profitable path forward, to the extent one wishes to invest in the experiments. Personally, I have way too many other interests, including a soon-to-be-seven-year-old, to invest much more in this particular enterprise--at least until my new system is set up and I start itching to mess with it all.
6. For tower speakers on thick carpet, spiking through the carpet it to whatever floor is underneath may be a good idea for stability against toppling.

As Einstein said, “It can scarcely be denied that the supreme goal of all theory is to make the irreducible basic elements as simple and as few as possible without having to surrender the adequate representation of a single datum of experience.” (often misquoted)

Thanks again for all the input.

@ausaudio, I agree with the light finger pressure at the upper back edge of the speaker, to ID rigid body rocking response.  As for rigid body translational response, the bottom of the speaker might be better.  I don't know though if we can conclude that what we feel in either location is free of flexural modes, though it ought to be more free than anywhere else on the speaker.  Best to place accelerometers at multiple places and post-process for modes; the rigid-body components should be easy to identify for an experienced dynamicist.  Glad you are paying for all this.

Has anyone else considered that the area of the driver creating the sound pressure wave also meets with resistance from the air it's moving, both inside and outside of the enclosure (assuming it is used in such a fashion).

@rixthetrick, yes.  See OP Item 3.

<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, 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.). 

Anyone who has taken physics (which includes anyone with an engineering degree) should know what Coulomb friction is.  It may be more widely understood than not.  But we digress...

I guess MC is right about some things, although I don't think anyone is as smart as he thinks he is.....

Perhaps not, but he may have spent more time trying different things than most(?)  I certainly will not be doing as much, myself.