Loudspeakers: Place them on spikes vs damping feet? - AVS Forum | Home Theater Discussions And Reviews
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Old 07-26-2017, 01:04 PM - Thread Starter
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Loudspeakers: Place them on spikes vs damping feet?

Hi,

I just wonder what is preferred to put on the bottom of loudspeakers - spikes or damping feet? What results in the best sound quality?

For example, see:
Spikes: Soundcare Superspikes: http://www.soundcare.no/products.htm
Damping feet: Sonic Design: http://www.sonicdesign.se/sdfeet.html

Intuitively, it seems like weight matched damping feet would be better, since it should isolate the speaker vibrations from speaker to the floor better. As for spikes, won't any vibrations be propagated onto the floor anyway, even if the "spike-to-spikestand" area is very small, since there is still a mechanical coupling?

And is there any difference what is best depending on if the speakers are placed on hardwood floors or carpet floor?

Finally, is there any science to back anything regarding this up?

Any info would be much appreciated!
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Old 07-26-2017, 01:34 PM
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Quote:
Originally Posted by Fjodor2000 View Post
Hi,

I just wonder what is preferred to put on the bottom of loudspeakers - spikes or damping feet? What results in the best sound quality?

For example, see:
Spikes: Soundcare Superspikes: http://www.soundcare.no/products.htm
Damping feet: Sonic Design: http://www.sonicdesign.se/sdfeet.html

Intuitively, it seems like weight matched damping feet would be better, since it should isolate the speaker vibrations from speaker to the floor better. As for spikes, won't any vibrations be propagated onto the floor anyway, even if the "spike-to-spikestand" area is very small, since there is still a mechanical coupling?

And is there any difference what is best depending on if the speakers are placed on hardwood floors or carpet floor?

Finally, is there any science to back anything regarding this up?

Any info would be much appreciated!
Yes there is science, you generally want to decouple the speaker from the floor. The spikes are really for carpets. It's especially important for subs. Svs sells special footies for that and includes them in their higher end subs. You need something like that on any hard surface, less so if carpet is involved.

Yet this is avsforum, so there will be people that will tell you the opposite!

I use something like what you linked to for most of my speakers, just cheap rubber, but the svs subs have the isolation pads.
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Old 07-26-2017, 01:43 PM
 
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Neither affects sound quality. Spikes are best on carpet, to give a better grip, although they're not that much better than rubber feet. Rubber feet are best on hard flooring. There's no need to isolate a speaker to keep it from causing the floor to vibrate, because it can't. High level low frequency sound waves may cause the floor to vibrate, so isolating the speaker so it won't be vibrated by the floor isn't a bad idea, but that's accomplished with very inexpensive rubber feet. Claims made by manufacturers and sellers of either for magical improvements in sound quality are just as valid as those made by manufacturers and sellers of expensive cables.
Required reading:
http://ethanwiner.com/speaker_isolation.htm

That's the science of it.
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Old 07-26-2017, 01:52 PM - Thread Starter
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Originally Posted by gregoryperkins View Post
Yes there is science, you generally want to decouple the speaker from the floor. The spikes are really for carpets.
Hmm... but won't spikes couple the speakers even more to the floor, if it's a carpet floor? Because then the spikes will get in touch with the wood floor beneath the carpet, instead of the carpet acting as isolation between the speaker and the wood floor beneath the carpet?

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Originally Posted by gregoryperkins View Post
It's especially important for subs. Svs sells special footies for that and includes them in their higher end subs. You need something like that on any hard surface, less so if carpet is involved.
So on a hard surface, damping feet are preferred over spikes?

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Originally Posted by gregoryperkins View Post
Yet this is avsforum, so there will be people that will tell you the opposite!
Ok, it will be interesting to hear that too. Especially if there is some science/logic behind it.

Quote:
Originally Posted by gregoryperkins View Post
I use something like what you linked to for most of my speakers, just cheap rubber, but the svs subs have the isolation pads.
Sounds like you're using some kind of damping feet then. What type of floor do you have?
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Old 07-26-2017, 02:01 PM
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Both carpeted and hardwood. I don't have any floor standers on the carpet, just a sub without the special pads. I use some sort of pad at a minimum, rubber o-ring feet on ones that have spikes. I could probably replace the spikes, but it seems to be fine. The SVS subs were playing deep and the small rubber feet are not as good as the pads or so says SVS.

https://www.svsound.com/products/sou...olation-system

This is what I use below the spikes on hard floors

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
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Old 07-26-2017, 02:14 PM
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Ideally all the energy of the drivers would go into moving air to create sound and not the cabinet or anything else. If the cabinet is moving, that is taking away direct radiated energy, and adding unwanted energy (e.g. cabinet rocking and resonances). In practice what you do is unlikely to have any audible impact, but if you take the position that the drivers ("cones") themselves should move and nothing else, then you want to couple (not decouple) the speakers to the floor unless the floor moves more than the cabinet (extremely unlikely). Helping to keep the cabinet rigid by coupling the speaker to the floor (which presumably has much more mass than the cabinet) makes sense to me. Ages ago I measured the impulse response of a few speakers to see if there were differences among variance feet/coupling to the floor. The measured response was a hair better when the speakers were rigidly fastened to the floor but nothing was audible in tests we ran IIRC. Decoupling (e.g. on spring or viscous rubber feet) allowed more cabinet movement that hurt measured response.

Many other variables, like cabinet and floor/wall/ceiling resonances, floor material, and so forth can influence the results, of course. However, as a rule of thumb and general guidance, my advice is always to tightly couple the speakers to the floor or whatever the speakers are sitting on. If the floor exhibits resonance and vibration in response to the speakers, or the speakers are sitting on a desk or something that vibrates itself, then decoupling may make sense, but IME that is the exception for home audio systems.

Short version: what Bill said.

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Old 07-26-2017, 02:52 PM
 
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Originally Posted by DonH50 View Post
Helping to keep the cabinet rigid by coupling the speaker to the floor (which presumably has much more mass than the cabinet) makes sense to me.
+1, though in most cases it's neither easy nor practical to do so.
Quote:
small rubber feet are not as good as the pads or so says SVS.
What would you expect? Truth in advertising?
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Old 07-26-2017, 04:07 PM
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Quote:
Originally Posted by DonH50 View Post
In practice what you do is unlikely to have any audible impact, but if you take the position that the drivers ("cones") themselves should move and nothing else, then you want to couple (not decouple) the speakers to the floor unless the floor moves more than the cabinet (extremely unlikely). Helping to keep the cabinet rigid by coupling the speaker to the floor (which presumably has much more mass than the cabinet) makes sense to me.
I kind of agree with you that it is usually not a big deal but while the assumption that spikes are coupling the speakers firmly to the floor and soft feet are not seems intuitively correct, it is in fact fundamentally wrong in most cases! While spikes feel stiff, they are actually acting as fairly stiff springs. If anything, spikes move the membrane-box-floor resonance system into a higher Q, higher frequency realm, than sensibly dimensioned soft feet does, essentially creating a "tuning fork" with resonance frequencies that may well reach into the audible range.

Soft feet on the other hand will typically have a resonance frequency in the single digit Hz range so while soft feet will not prevent the speaker from moving, in the audible range the movement will be comparably small, linear and non-resonant. With spikes, however, the resonance frequency will not seldom be pushed up into the audible range, causing frequency dependant excessive movement compared to soft feet.

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Old 07-26-2017, 04:25 PM
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That does not match my experience but backgrounds differ. IME/IMO, the idea is not to play with the physics of springs and such, but rather to tightly couple the speakers to the floor so they are more tightly coupled to a larger mass. There is not a "tuning fork" type of effect IME. You'd have to get the floor vibrating at a high frequency and the opposite is generally true. Ideally the spikes would not act like springs at all, and most of the ones I have seen do not, excepting certain brands that are actually spring-loaded or comprised of layers with the aim of decoupling rather than coupling and happen to have pointy ends. But the interaction among floor, spikes (or whatever), and speaker cabinet and drivers is part of what makes any arguments like this complicated. Certainly if the floor is vibrating, or desk or whatever as mentioned earlier, then decoupling may be more appropriate. There are always exceptions.

As for higher Q, that is likely true for the spikes themselves, but they are a small part of the overall mass and have minimal impact on the total system's resonance. Your argument seems to be that using spikes allows the entire speaker system to vibrate at higher frequency and thus enter the audible range. IME that simply does not happen, though it could conceivably render the impact of a cabinet resonance worse. The counter, that decoupling with soft feet leads to lower resonant frequency, seems reasonable but then the cabinet is "rocking" in response to low bass signals, footfalls across the floor, and other low-frequency inputs. Potentially causing some sort of doppler distortion, one of the arguments made for spikes long ago (I am no longer an AES member but the papers should be there). Most speaker manufacturers recommend spikes based upon that research and their own tests (I assume). I do not understand your "non-resonant" comment; it seems to me that you are shifting the resonance frequency lower and, by using soft feet that allow the speaker to move, increasing the amplitude. Soft feet also exhibit frequency-dependent response.

In any event, debating this seems a poor use of engineering expertise and time. Use whatever you feel sounds best to you. IME, spikes provide better measurements and better sound. - Don
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Old 07-27-2017, 01:24 AM - Thread Starter
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Quote:
Originally Posted by DonH50 View Post
IME/IMO, the idea is not to play with the physics of springs and such, but rather to tightly couple the speakers to the floor so they are more tightly coupled to a larger mass.
But the spike manufacturers argue that since the spike point is so small, the vibrations do not propagate onwards to the floor. I'm not sure how they have arrived at that conclusion, since the speakers are still mechanically coupled to the floor, even though the area of the spike point is very small. But anyway, they seem to want to achieve de-coupling, not coupling.
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Old 07-27-2017, 01:36 AM - Thread Starter
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Some measurements and science below.

Soundcare Superspikes



Note that this is not normal measurements of sound from the speakers. Instead, see measurement method below.

Measurement method:

"A calibrated loudspeaker has been fed with a sinus wave on each frequency level. The loudspeaker has been placed upon a calibrated pressure sensitive microphone. For each frequency the signal is fed through the loudspeaker and the output level is adjusted to specific level which is referred to as 0 dB. Then the spike is placed between the loudspeaker cabinet and the pressure sensitive microphone. The same signal with the same output level is used. The level from the microphone is then measured. The direct sound through air from the loudspeaker to the microphone is never measured louder than –30 dB for any of the frequencies. The curves will therefore show the approximate transmission of energy from loudspeaker cabinet through the spike and down to the microphone."

More info and details here: http://www.soundcare.no/measurement.htm



Sonic Design damping feet



"Sinus signal 125 Hz to the speaker (top), floor movement below, using soft feet. Floor signal magnified 2 x."





"Sinus signal 125 Hz to the speaker (top), floor movement below, using spikes."

More info and details here: http://www.sonicdesign.se/sdfeet.html
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Old 07-27-2017, 04:04 AM
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Originally Posted by DonH50 View Post
That does not match my experience but backgrounds differ. IME/IMO, the idea is not to play with the physics of springs and such, but rather to tightly couple the speakers to the floor so they are more tightly coupled to a larger mass. There is not a "tuning fork" type of effect IME. You'd have to get the floor vibrating at a high frequency and the opposite is generally true. Ideally the spikes would not act like springs at all, and most of the ones I have seen do not, excepting certain brands that are actually spring-loaded or comprised of layers with the aim of decoupling rather than coupling and happen to have pointy ends. But the interaction among floor, spikes (or whatever), and speaker cabinet and drivers is part of what makes any arguments like this complicated. Certainly if the floor is vibrating, or desk or whatever as mentioned earlier, then decoupling may be more appropriate. There are always exceptions.
Well, the thing is that while a normal spike is hard and seems very stiff to the touch the material it is made of still has a modulus of elasticity and hence the spike will act as a spring in the mass-spring system created by the speaker, the spikes and the floor.

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As for higher Q, that is likely true for the spikes themselves, but they are a small part of the overall mass and have minimal impact on the total system's resonance.
It is not the spikes mass that is of concern, it is the compliance of them that is the concern.

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Your argument seems to be that using spikes allows the entire speaker system to vibrate at higher frequency and thus enter the audible range. IME that simply does not happen, though it could conceivably render the impact of a cabinet resonance worse. The counter, that decoupling with soft feet leads to lower resonant frequency, seems reasonable but then the cabinet is "rocking" in response to low bass signals, footfalls across the floor, and other low-frequency inputs. Potentially causing some sort of doppler distortion, one of the arguments made for spikes long ago (I am no longer an AES member but the papers should be there). Most speaker manufacturers recommend spikes based upon that research and their own tests (I assume). I do not understand your "non-resonant" comment; it seems to me that you are shifting the resonance frequency lower and, by using soft feet that allow the speaker to move, increasing the amplitude. Soft feet also exhibit frequency-dependent response.
Well, that's where you and the laws of physics disagree. Using sensibly dimensioned soft feet will create a resonance frequency of the speaker-feet-floor resonant system that is so low in frequency that it will never be close to beeing excited by audio frequencies. The system will be predominantly in the mass controlled region in the full audible range, so the movements of the speaker will be very small and the vibration transfer to the floor will be very small in the full audio frequency range. Using spikes, however, there is a real risk creating a resonant system that will have its resonance frequencies up in the audible range (say in the several hundred Hz region), either by the speaker itself or by the high compliance of the spike exciting the floor when hitting a system resonance.

I can't actually think of any good reason for using spikes under speakers!

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Old 07-27-2017, 04:16 AM
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But the spike manufacturers argue that since the spike point is so small, the vibrations do not propagate onwards to the floor. I'm not sure how they have arrived at that conclusion, since the speakers are still mechanically coupled to the floor, even though the area of the spike point is very small. But anyway, they seem to want to achieve de-coupling, not coupling.
Yes, the notion that spikes and cones act as "mechanical diodes" is an absolutely absurd audio myth that has been around for decades. Newtonian physics will apply even for speaker spikes!

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Old 07-27-2017, 05:53 AM
 
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Originally Posted by Fjodor2000 View Post
Some measurements and science below.
Fake science.
Quote:
Note that this is not normal measurements of sound from the speakers.
And that's why it's fake. What matters is what you hear, not what might be heard by dust mites inhabiting the space between the speaker and the floor. The method employed by Ethan Winer in the link I previously posted is the correct procedure.
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Old 07-27-2017, 07:22 AM - Thread Starter
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Fake science.
I think you're going a bit too far here. They clearly explain the measurement methodology they used, and make no attempt at claiming it is "normal" sound measurements.

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And that's why it's fake. What matters is what you hear, not what might be heard by dust mites inhabiting the space between the speaker and the floor.
They do not claim otherwise, do they? The vibration measurements from the speakers that they measure is of course still of interest. After all, that's that they are trying to minimize, so they want to measure how well their products succeed in that. To what degree it has an effect on the sound is of course what's finally of interest though, and I do agree it would be nice to see measurements from them on that as well.

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The method employed by Ethan Winer in the link I previously posted is the correct procedure.
I agree that is useful too. And even that test did show an effect on the sound from spikes and damping feet. Sure, he got an effect from just raising the speakers too. But "max change in frequency curve" does not necessarily mean "max improvement in sound quality". The question is how well each of the setups he tried matches the "ideal frequency curve"? I don't think his test answers that, because that "ideal frequency curve" is unknown in his test.

Also the problem with Ethan Winer's test it introduces other components into the equation, like the characteristics of the room used. He mentions that himself as well, saying e.g. "You'll notice response changes below 30 Hz, about 35 dB down, which might be air flow noise from my heating system." and "You'll also notice a deep null in all of the graphs at 155 Hz. This is due to "floor bounce" whereby sound from the speaker goes directly to the microphone, but the same sound also arrives at the microphone slightly later after bouncing off the floor.".

If he would have performed the tests in an anechoic chamber that would more or less have eliminated such room characteristics. But then the question is whether an anechoic chamber is really representative of an actual room in this case, since its floor and walls are isolated so they cannot resonate and propagate the vibrations that spikes and damping feet are trying to reduce onwards anyway.

So I can see why the manufacturers of spikes and damping feet would like to take such room characteristics out of the equation, to isolate the effect from only the spikes and damping feet. Having said that, I agree that "normal" sound measurements would be nice to see as well, even with a disclaimer saying that it was measured in one specific room, and that those results may vary.

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Old 07-27-2017, 07:30 AM
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Bolt your speakers to the floor....
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Old 07-27-2017, 07:42 AM
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I have used something called "Tip Toes" on (all) my floor standing speakers for years (see sig); it's essentially an inverted pyramid/cone. You place 3 under each speaker (3 points make a plane), providing a solid "coupling" to the floor (the room is carpeted); the affect (to me at least) is a "tightening" of the bass. People used them on turntables, etc., but I'm not sure where to get them anymore.
Bottom line: I think you should use some of "coupling" (especially on carpet) with any floor standing speaker.

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Old 07-27-2017, 08:33 AM
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http://www.essenceelectrostatic.com/...peaker-spikes/



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Old 07-27-2017, 08:43 AM
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My Revel F208 speakers came with spikes that have pointed (for carpet) or rounded (for tile) ends. I first used nothing and had the speaker's base flat on the floor. I felt the bass was not tight so I got some SVS isolation feet (https://www.svsound.com/products/sou...olation-system) and installed them. The rubber is too soft and the speaker was not stable, it rocked. Not safe.

I installed the Revel spikes, rounded end down on my tile floor on concrete slab. The entire speaker sounds better, not just the bass. Everything seems tighter and more clear.

I worked as a professional recording and live sound engineer for over 30 years, so I trust my ears.

Try options and use what sounds best to you.

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Old 07-27-2017, 10:00 AM
 
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Essence™ Tip-Toes Speaker Cones.. minimizing early reflections

That ad copy writer must not have the slightest notion what early reflections are. I guess he saw the term somewhere, and figured 'what the heck, might as well stick that in the ad too'. I'm surprised he doesn't say that they'll cure cancer as well.
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Old 07-27-2017, 10:22 AM
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Just passing along the info related to post 17. Don't shoot the messenger.



If you can’t explain it simply, you don’t understand it well enough – Albert Einstein
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Old 07-27-2017, 10:46 AM
 
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Just passing along the info related to post 17. Don't shoot the messenger.
I didn't say you were responsible for it, just pointing out the nonsense contained within.
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Old 07-27-2017, 11:06 AM
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I misunderstood since you quoted "me" (the link). I am not responsible for what's contained in the verbiage.




Personally, when I purchased my sub a very long time ago (20 years maybe?), it came with both round padded feet (for bare floor) and spikes (for carpeted floors). Since I had carpets, I used the spikes as directed by the instructions. The sub hasn't been moved since. And.... to be honest, I wouldn't know how an "early reflection" presents itself.



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Old 07-27-2017, 11:13 AM
 
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Early reflection is another term for reverberation, which has a very short arrival time difference between the direct and reflected wave. The other end of the scale, with a very long time between the direct and reflected wave, is an echo.
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Old 07-27-2017, 11:27 AM
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Thanks!
I guess I have neither in my room! Woo-Hoo, woo-hoo, woo-hoo.......
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If you can’t explain it simply, you don’t understand it well enough – Albert Einstein
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Old 07-27-2017, 11:32 AM
 
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You have early reflections, if you didn't the room would be anechoic, totally dead. Some early reflections are necessary for ambience. But too much isn't a good thing. If you can tell that it's there it's probably too much.
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Old 07-27-2017, 11:38 AM
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Oh, okay. So it can be good or bad.


Whatever I have or don't have, I like my system and the "nits" are not important to me. Does that make me a bad person?


My goodness, I provide a link and get raked over the coals.



If you can’t explain it simply, you don’t understand it well enough – Albert Einstein
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Old 07-27-2017, 01:29 PM
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Well, the thing is that while a normal spike is hard and seems very stiff to the touch the material it is made of still has a modulus of elasticity and hence the spike will act as a spring in the mass-spring system created by the speaker, the spikes and the floor.

It is not the spikes mass that is of concern, it is the compliance of them that is the concern.

Well, that's where you and the laws of physics disagree. Using sensibly dimensioned soft feet will create a resonance frequency of the speaker-feet-floor resonant system that is so low in frequency that it will never be close to beeing excited by audio frequencies. The system will be predominantly in the mass controlled region in the full audible range, so the movements of the speaker will be very small and the vibration transfer to the floor will be very small in the full audio frequency range. Using spikes, however, there is a real risk creating a resonant system that will have its resonance frequencies up in the audible range (say in the several hundred Hz region), either by the speaker itself or by the high compliance of the spike exciting the floor when hitting a system resonance.

I can't actually think of any good reason for using spikes under speakers!
The modulus of elasticity of the spikes is not the issue here, it is how well they couple the speakers to the floor. We are arguing about two completely different things. If the feet are soft the speaker cabinet can react in response to the sound energy. If the cabinet is tightly coupled to the floor (forget spikes, say they are bolted rigidly to the floor) then the drivers would have to move the entire floor in addition to the cabinet. Yes, it is stiffer that way, so the frequency would go up, but the overall movement should also be much smaller due to all the added mass. The caveat is that, if the floor moves, the speaker moves, too. On a bottom-level concrete floor that is probably of no concern; on an upper wooden floor that is not properly anchored (like in some old houses I have seen that have warped joists and minimal underlayment) it could happen. Either way I really doubt the effect is audible.

This is where I wish I still had AES access, or at least the data from the decades-old tests, but OTOH it is probably not worth the effort since we seem to be at opposite ends of the ring. I'd come out fighting, but would rather just go get a drink.

"After silence, that which best expresses the inexpressible, is music" - Aldous Huxley
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Old 07-27-2017, 01:45 PM
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, but OTOH it is probably not worth the effort .., but would rather just go get a drink.
1st round on me.
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Old 07-27-2017, 03:28 PM
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The modulus of elasticity of the spikes is not the issue here, it is how well they couple the speakers to the floor.
The compliance of the spikes will define how well the speakers couple to the floor. I don't disagree with bolting speakers to the floor will couple them to the floor real good, but I am saying that spikes do not couple speakers to the floor especially well, they risk creating resonances in the audible range and due to the coupling they transfer way more vibration energy to the floor than a sensibly dimensioned soft foot. If coupling the speaker to the floor is what you want, spikes (as they normally are engineered) are still a stupid design!

I know we're probably splitting hairs here, but if controlling cabinet vibrations (and hence making the speaker perform optimally) is the goal, then decoupling is by far the best choice. Coupling the speaker to an arbitrary floor using spikes will make the floor part of the resonant system, making the speaker cabinet vibrations behave different depending on what surface it rests on. Decoupling, on the other hand, will remove the floor from the equation, making the cabinet behave in a predictable way on pretty much any reasonable surface.

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