Tower speakers on hardwood floors: spikes on discs/coins? Sorbothane/silicone pads? Springs?

[tmuikku]

It's very rarely simple as that, if your speaker happens to have heavy woofer pointing up or down, not so rigid floor as in old farmhouse, and play records on turntable, there might be "serious" problems with this stuff because it could feedback and skip, so fundamental issue. One would need to do something about it, and feet could be one thing. On the orher hand if it's small bookshelf speaker and you stream over BT the problems are something else. And anythig in between.

Point is, if there is an issue one could then address it somehow. Certain type of feet could be a solution for one situation, and problem for another When there is no problem, there is no need to solve it. So, effectiveness of different kinds of feet vary per context and it would be important to understand the situation and what one could do with it, if there is need to do something about it.

 

[MAB]

Thank you for your responses, especially the distortion graphs. My earlier questions were mostly about whether the posited distortion issues could be gleaned from frequency response since no one had posted distortion data yet. (I had also seen a number of accelerometer graphs on other threads, which I found similarly difficult to infer the implications of.)

To me, this is the best and most direct support of the position that feet have little-to-no effect and I appreciate your posting it.

Agreed. The distortion graphs do help to understand what is going on.

I chose the L26 since it is a powerful woofer, like what you will see in a top-shelf floor-standing speaker or sub. If I pick up the cabinet by it's sides while it is playing, I only feel a tiny amount of vibration. If I put my hand in front of the driver, I feel the radiated sound quite dramatically. This is no surprise, speakers are more efficient at vibrating the air than the chassis and cabinet. The cone of a typical 10" woofer cone is ~100g, plus or minus ~50g. Even a lightweight cabinet is 10kg. It's two orders of magnitude difference, consider that a very large impedance mismatch. The acceleration of the cone is primarily being radiated into the room through the cone coupling to the air.

I regret I am not easily able to measure the response and distortion with the speaker suspended above the floor in exactly the same position. It's a hard experiment to do with a large woofer. If I did, I would get the same response as with spikes, elastomers, etc. since such a small amount of energy is actually transmitted through feet of any kind.

 

[Thomas_A]

I measure no differences between feet type:
View attachment 395319

These are tiny distortion differences between spikes, elastomeric feet, and felt pads. Nobody is going to hear these differences even if they are each due to the type of feet. In reality, the few differences are traffic down the hill from me, and my inability to swap feet and return a heavy sub to within millimeters for each measurement.

For a perspective on run to run repeatability, here are two control measurements taken from another location in the room. Each sweep was taken 30 seconds apart, absolutely no setup or mic changes:
View attachment 395326

The speaker-floor coupling thing is such a small order issue compared to room acoustics and speaker placement. If you have feet that allow easy setup and good stability, that matters. Making the feet out of spikes or balls or advanced sound absorbing stuff really plays no role in the sound, unless those feet change the position of the speaker or are so flawed the speaker is rattling around. For many people with thick carpet spikes work great. For people with hardwood floors who wonder what they might be missing with spikes, nothing. Thing is, lots of speakers have very nice feet that allow tilt and other fine tuning which will have an effect and can do good things like tame an overly hot on-axis treble by adding some tilt.

Just to be sure; measuring THD2-9 may not be resolving enough. If you are unlucky, there may be higher order THD which are not masked away by the fundamental.

 

[Chromatischism]

Agree!

Also agree, changes in the floor's resonance definitely change the tactile experience.

That being said... I never know exactly what people change in their setup...
Often people change speaker position, either inadvertently or by not realizing this needs to be controlled for to make valid observations. Especially if a speaker sits at one of the nodal points of a room where small changes in position cause large swings in SPL.
Usually people just fool themselves since our ears aren't good at measuring / quantifying.
The idea that the speaker/floor interface is a big deal in sound reproduction is odd and incorrect, very little energy is dissipated from the speaker's chassis through the feet to the floor. The majority comes from the floor coupling to the acoustic energy in the room.

And thus the type of feet should be chosen for stability, movability, and adjustability of position.

But you can't measure tactile response with a microphone.

 

[Thomas_A]

Thank you for your responses, especially the distortion graphs. My earlier questions were mostly about whether the posited distortion issues could be gleaned from frequency response since no one had posted distortion data yet. (I had also seen a number of accelerometer graphs on other threads, which I found similarly difficult to infer the implications of.)

To me, this is the best and most direct support of the position that feet have little-to-no effect and I appreciate your posting it.

Distortion data (if you are unlucky). With hard feet vs. weight-adapted sylomer pads, speaker on a bench.

 

[MAB]

But you can't measure tactile response with a microphone.

I totally agree, the tactile sense through the floor is a significant part of the experience. Concert halls with seating on floors made of wood vs. concrete is a great example.

But the majority of the floor's tactile response is due to the driver coupling with the air in the room, which drives the floor. The coupling of the speaker to the floor through the feet is a minority of what drives floor vibrations. Change the feet as much as you like, the speaker isn't radiating enough energy through the feet to make all but the tiniest difference. That is what I showed in the measurements. Others show this when they make measurements as well.

I am really in strong agreement with you on the tactile experience of the floor vibrating. It's just that it vibrates because of the sound-field, barely any vibration is due to the speaker sitting on the floor.

 

[Hear Here]

the shows I go to for enjoyment certainly benefit from the sound crew at the event making measurements, and people who made any sound reinforcement gear making measurements, or in some cases where the sound sucks not so much

You really should go to live events where you can listen to musical instruments and not to loudspeakers. But please leave your microphone and PC at home - just enjoy the performance and leave it at that.

 

[Hear Here]

As bad as our hearing is in midrange frequencies

Chromatischism replied:​

What? Since when? Midrange is our strongest area.

You have quoted someone other than me. Please take care to attribute you quotations correctly. Thanks

 

[Chromatischism]

But the majority of the floor's tactile response is due to the driver coupling with the air in the room, which drives the floor. The coupling of the speaker to the floor through the feet is a minority of what drives floor vibrations.

Then why do single-sided subs deliver so much more tactile response than a dual-opposed sub of equivalent construction? This is well-known, and I have experienced it myself on my subwoofer journey. The force-cancelling of the dual drivers is the cause of the reduction in floor vibrations, despite having double the cone area. Even smaller subs from the same company produced more tactile response than the larger dual-opposed sub, despite having 4x less power. Everyone has different priorities, but I didn't care for dual-opposed as much. I felt it took too much away from the experience. I will tell you, they are excellent for dorms or restrictive apartments.

 

[kifeep]

Distortion data (if you are unlucky)

I guess I’m a different kind of unlucky. My noise floor is higher than 60dB below fundamental. Or maybe I’m just not playing loud enough.

 

[MAB]

You really should go to live events where you can listen to musical instruments and not to loudspeakers. But please leave your microphone and PC at home - just enjoy the performance and leave it at that.

You lecturing the wrong person.

You have quoted someone other than me. Please take care to attribute you quotations correctly. Thanks

He was quoting me, but out of context, and somehow tied you up in his response.

The correct context was a comparison of human hearing to a microphone... Compared to a microphone, our ears are incredibly insensitive in the midrange, and even more incredibly insensitive in bass frequencies. You both missed the point. And there is the entire psychoacoustics part of perception, but I am not sure it will be a useful discussion given some of your other comments.

 

[Thomas_A]

I guess I’m a different kind of unlucky. My noise floor is higher than 60dB below fundamental. Or maybe I’m just not playing loud enough.

It is really not related. You will hear this. Noise floor at 1 kHz?

 

[antcollinet]

It was patently clear

The effects of perceptive bias always are.

 

[Hear Here]

You lecturing the wrong person.

He was quoting me, but out of context, and somehow tied you up in his response.

The correct context was a comparison of human hearing to a microphone... Compared to a microphone, our ears are incredibly insensitive in the midrange, and even more incredibly insensitive in bass frequencies. You both missed the point. And there is the entire psychoacoustics part of perception, but I am not sure it will be a useful discussion given some of your other comments.

I'm not suggesting that the difference in bass rendition of speakers with Gaia feet compared with spikes can't be measured. What I'm simply saying is that I can clearly hear the difference in the detail and clarity of the bass. Is that difficult for you to understand? It's akin to bass from a boom-box compared with good quality hi-fi - although not so pronounced or obvious!

If your ears aren't better at telling your brain what sounds good than your microphone and PC, I genuinely feel sorry for you. There's little point in listening to music if you feel your ears aren't telling what you should be enjoying. Just go out and listen to and enjoy as much live music as you can and cease worrying what your measuring kit may make of it.

Same applies when listening at home. Enjoy what your ears and brain interpret as exciting and realistic music. It's really that simple. Great music delivered by great kit will measure pretty well, but let your ears and brain dictate your purchases from the vast selection of kit out there, and pay less attention to what others or your PC may say you should be buying.

Taking measurements has its place, but perhaps most usefully in making the most of the kit you have in your home. Measurements may well suggest the effects of different speaker placement, adding / removing carpets, curtains, etc and these may well add even more to your music enjoyment.

 

[Thomas_A]

I measure no differences between feet type:
View attachment 395319

These are tiny distortion differences between spikes, elastomeric feet, and felt pads. Nobody is going to hear these differences even if they are each due to the type of feet. In reality, the few differences are traffic down the hill from me, and my inability to swap feet and return a heavy sub to within millimeters for each measurement.

For a perspective on run to run repeatability, here are two control measurements taken from another location in the room. Each sweep was taken 30 seconds apart, absolutely no setup or mic changes:
View attachment 395326

The speaker-floor coupling thing is such a small order issue compared to room acoustics and speaker placement. If you have feet that allow easy setup and good stability, that matters. Making the feet out of spikes or balls or advanced sound absorbing stuff really plays no role in the sound, unless those feet change the position of the speaker or are so flawed the speaker is rattling around. For many people with thick carpet spikes work great. For people with hardwood floors who wonder what they might be missing with spikes, nothing. Thing is, lots of speakers have very nice feet that allow tilt and other fine tuning which will have an effect and can do good things like tame an overly hot on-axis treble by adding some tilt.

Just a question, did you investigate distortion orders separately above >4th order?

 

[MAB]

Just a question, did you investigate distortion orders separately above >4th order?

Yes, to 9th harmonic.
There is really nothing. I can post when I get home, I think I still have the data open in REW.

There just isn't enough energy transmitted to the floor via the feet, unless you mess things up and find a resonance. For instance I have measured elevated distortion with spikes on a hard floor, only to discover one of the spikes wasn't firmly in contact, fixing the spike fixes the elevation in distortion.
Compact subs that are tall and narrow, or passive radiator systems that don't use dual radiators for force-cancelling can walk at high volume making noise. Spikes help those circumstances, but the real problem is poor/cheap design. I have made many passive radiator systems, I tend to use dual opposed, not because of the sound or change (measured or imagined), but because of the walking.
I imagine a cabinet so flimsy with a driver so heavy that it exhibits changes with feet. But this is my imagination, I am yet to observe.

If you believe that there is a large amount of energy in speaker chassis vibration, then the feet and composition may matter. The problem is, there is just not enough energy. For sure you can stick an accelerometer on a plinth with a driven speaker on it and measure a difference in vibrations, yet not measure on single bit of difference in the sound field. The team who did the review really made a fantastic apparatus to measure vibration. If the reviewers had taken a moment to put their hand on the vibrating plinth, they would have said to themselves "this is in no way enough energy to change the sound either directly or through re-radiation". If the vibrational energy was two orders of magnitude higher, it would matter. And speakers would be considerably less efficient.

 

[Thomas_A]

Yes, to 9th harmonic.
There is really nothing. I can post when I get home, I think I still have the data open in REW.

There just isn't enough energy transmitted to the floor via the feet, unless you mess things up and find a resonance. For instance I have measured elevated distortion with spikes on a hard floor, only to discover one of the spikes wasn't firmly in contact, fixing the spike fixes the elevation in distortion.
Compact subs that are tall and narrow, or passive radiator systems that don't use dual radiators for force-cancelling can walk at high volume making noise. Spikes help those circumstances, but the real problem is poor/cheap design. I have made many passive radiator systems, I tend to use dual opposed, not because of the sound or change (measured or imagined), but because of the walking.
I imagine a cabinet so flimsy with a driver so heavy that it exhibits changes with feet. But this is my imagination, I am yet to observe.

If you believe that there is a large amount of energy in speaker chassis vibration, then the feet and composition may matter. The problem is, there is just not enough energy. For sure you can stick an accelerometer on a plinth with a driven speaker on it and measure a difference in vibrations, yet not measure on single bit of difference in the sound field. The team who did the review really made a fantastic apparatus to measure vibration. If the reviewers had taken a moment to put their hand on the vibrating plinth, they would have said to themselves "this is in no way enough energy to change the sound either directly or through re-radiation". If the vibrational energy was two orders of magnitude higher, it would matter. And speakers would be considerably less efficient.

Thanks. If you still have the files (spike and elastomer) I would be glad if you could share the files as well. As I’ve stated several times, there is usually nothing to find, in most cases. The overtones that radiates from floor and other objects are usually masked by the speaker distortion. In the example with the130 Hz fundametal the distortion is found in ≈ 5th-15th harmonics.

 

[Chromatischism]

There just isn't enough energy transmitted to the floor via the feet, unless you mess things up and find a resonance.

This really depends on the speaker, obviously. I expect vast differences out there. How much does it take to be noticeable, I don't know. But the differences are obvious with subwoofers. And let's be clear: the tactile experience combines with the audible to create a different experience. When we get more tactility, the sound is perceived as more powerful. So we are into psychoacoustics now.

 

[MAB]

This really depends on the speaker, obviously. I expect vast differences out there. How much does it take to be noticeable, I don't know. But the differences are obvious with subwoofers. And let's be clear here: the tactile experience combines with the audible to create a different experience. When we get more tactility, the sound is perceived as more powerful. So we are into psychoacoustics now.

It seems to also depend on who is making the claim.
Some say opposed subs have audibly obvious differences from non-opposed, I have heard people say the bass is tighter, deeper, more tactile, less bloated, has less group delay (whatever they meant by that...), etc. You claim less tactile. And all sorts of reasons are given. I just never see data. More tactile bass is measurable, so is tighter bass., and all of those other descriptors. All are easy to measure. It would be nice to see data that clearly shows dual opposed is different than two co-located non-opposed drivers.

 

[Chromatischism]

Some say opposed subs have audibly obvious differences from non-opposed, I have heard people say the bass is tighter, deeper, more tactile, less bloated, has less group delay (whatever they meant by that...), etc. You claim less tactile. And all sorts of reasons are given. I just never see data. More tactile bass is measurable, so is tighter bass., and all of those other descriptors. All are easy to measure. It would be nice to see data that clearly shows dual opposed is different than two co-located non-opposed drivers.

My position is that all of those descriptors are psychoacoustic manifestations stemming from the completely inert cabinet not transmitting anything physically to the room.

I heard it myself with Rythmiks.

2xF12

2xG22

2xFV15HP2

Despite all the extra cone area and amp power, the G22s felt less tactile than the F12s. Yet the output headroom at all points was greater. Yes they outdid the F12s in midbass, of course. But down low, even to below 10 Hz, they didn't move the room or the seats like the single-driver subs, and especially not as much as the FV15HP2s. Not even close. You FEEL the FV15's and it puts you in the movie in a way that the others can not. It's the same with music. When you don't have any tactile feedback, you only have the tones emanating from the drivers, picked up by your sense of hearing. Because that's all you have, you focused on them more intently—and along with the sealed design, is recipe for people claiming "tighter" bass.

But I think you can hear through it and there isn't the difference people think there is.

I make adjustments to achieve the same overall system balance no matter what subs are in here, and I can tell you that's nonsense. The sealed subs aren't actually "tighter" than the vented versions, but they may seem that way at first if you don't have as much low end support from the ports. Once you run the same house curve, the audible sound is the same (despite the overall experience being different). The group delay on the vented sub begins below the threshold of audibility, and the enclosure is essentially sealed in the upper part of its band. People simply get less low end without the ports and no room shake with the dual-opposed drivers and it combines to feel "tighter" and "more accurate". There may be something to the air movement but I haven't been able to pin that down (not actually feeling the air blowing, but some kind of force created by the ports—theory only at this point).

These differences are real and are reasons to choose one or the other for your situation and priorities. It just isn't what people think it is.

That's my 2 cents.