How shape/material of speaker footers impact their effectivness

[Cosmik]

I would have thought that the ideal is for (1) the cabinet to not vibrate at all, and (2) for no energy to be transferred to the structure of the room (except via the air).

Presumably you can achieve (2) with aircraft electronics suspension mounts or whatever, but this may actually increase (1). With a stiff mount to the floor, you get closer to (1) but with an increase in (2) - if the floor is not concrete.

Intuitively, a really heavy enclosure throughout its structure (and not just lead weights in the base) improves (1) and (2) in all circumstances.

And if the enclosure itself is also heavily damped, would this not help also? The sand-filled enclosure wall sounds like a good idea.

 

[RayDunzl]

material

Sorbothane

 

[Fitzcaraldo215]

Ive taken measurements of the rooms acoustics using XTZ Room Analyzer and there was 1 bump at 39hz or so that was cured with a -3.5db cut worth of PEQ and another bump at 168hz or so that also only required a small cut of PEQ

My current footers are a combination of the factory Spikes and a set of Herbies Audio Lab Titanium Decoupling Gliders. Thus far this combo appears to have reduced bass boom/rumble in the room and to a greater extent reduced the vibration felt thru your feet when sitting in the room.

I thought I explained my intention of the post fairly clearly but to recap, I am wondering if an even better approach exists that would achieve more of the same results that I found when slightly Decoupling my speaker and how the shape and material used in the footer/footers/platforms ...etc can change its effectiveness to work as either a coupling or decoupling device.

Have you measured various footers with XTZ, and is there indeed a consistent noticeable difference with/without?

You know I am a skeptic about subjective listening evaluations of stuff like this. Since you use XTZ, I would think that any useful benefit would show up in measurements. If it did not, I myself would not trust my own impressions through my ears or through my feet.

 

[Nightlord]

Weight matched soft feet so the resonance of the system is way below the music range. Preferrably a speaker weight a factor 1000 more than that of the moving weight(inkl the 'trapped' air). This is generally a problem for subwoofers that seldom achieve more than a factor of 200.

Have used a seismograph app in my iPhone on my speakers and it is flatlines while playing music. The sofa table 5 meters away vibrates noticably at the same time - and the coupling is by air only.

It's so un-intuitive that this works so well, since you can easily rock the speakers with a finger, but the frequency of that push is, when you think of it, extremely low - thus below resonance.

I even have my surround speakers in the cinema on weight matched soft feet - I may be the only one who've done it. The speaker designer himself hadn't done it for any theater room he'd designed even.

 

[fas42]

Fas it doesnt matter if the corners are locked into position, the other panels will still vibrate doing their own thing.

Next week I will measure a speaker baffle panels vibration, rigidly bolted to a stand and with squidgy sorbothane pads and we shall see how it changes

Yes, but subjectively the panels vibrating is much less of a problem than if the box is free to "bounce" - every experiment I've done has produced better sound if the most rigid parts of the cabinet are clamped, weighted down, locked into position - indirectly this reduces some of the vibration of the panels, because the overall structure of the cabinet is under a different set of stresses. Some time ago I mentioned doing an exercise clamping a small monitor on top of metal stands with a belt, at an audio friend's home; the results were clear, the tighter the tension of the belt, the more the frame of the speaker was tied to the frame, becoming one with the stand - the greater the improvement. More impact, tighter bass, greater soundstage, better clarity - all pluses, no minuses.

 

[fas42]

I have tried Nightlord's approach of using soft footers, but for my speakers this has never worked - once a bit of volume is asked for the sound just falls to pieces, becomes a blurry mess ...

 

[Nightlord]

I have tried Nightlord's approach of using soft footers, but for my speakers this has never worked - once a bit of volume is asked for the sound just falls to pieces, becomes a blurry mess ...

Could be that you have the wrong feet, if the resonance point of the system is too high, then of course it won't be a good idea. So don't write of the principle on a failed experiment, unless you've mananged to measure the resonance frequency and found it to be in the 3-5Hz range.

In many cases the speakers are front heavy and then you need different feet front and back.

 

[fas42]

Could be that you have the wrong feet, if the resonance point of the system is too high, then of course it won't be a good idea. So don't write of the principle on a failed experiment, unless you've mananged to measure the resonance frequency and found it to be in the 3-5Hz range.

In many cases the speakers are front heavy and then you need different feet front and back.

I'm curious whether the footers you used were essentially elastic only, or did they have viscoelastic qualities?

 

[March Audio]

Yes, but subjectively the panels vibrating is much less of a problem than if the box is free to "bounce" - every experiment I've done has produced better sound if the most rigid parts of the cabinet are clamped, weighted down, locked into position - indirectly this reduces some of the vibration of the panels, because the overall structure of the cabinet is under a different set of stresses. Some time ago I mentioned doing an exercise clamping a small monitor on top of metal stands with a belt, at an audio friend's home; the results were clear, the tighter the tension of the belt, the more the frame of the speaker was tied to the frame, becoming one with the stand - the greater the improvement. More impact, tighter bass, greater soundstage, better clarity - all pluses, no minuses.

How much do you think the mass of your speaker cone moving (at 90deg to) is going to make the mass of your speakers "bounce"?

The speaker panels will be vibrating through forced excitation from the drivers and their own natural frequencies.

Do you realise that a typical stand will also be vibrating regardless of how tight you couple the speaker to it?

Now if you stick a massive weight on top of the speaker, yes you will change its stiffness etc, however you need to quantify the effect. You could even be shifting resonances into a more audible area.

I'm afraid Fas, as we have seen so many times before, your experiments are meaningless.

 

[March Audio]

I have tried Nightlord's approach of using soft footers, but for my speakers this has never worked - once a bit of volume is asked for the sound just falls to pieces, becomes a blurry mess ...

Then, as has been mentioned, you had the wrong soft feet. They have to be correct for the mass.

 

[Nightlord]

You've all done the experiment in physics. Attach a weight to a spring and yo-yo it with different speed (=frequency).

If you do it slow, the weight follows your hand. This is below resonance.
If you increase then at a certain point the weight will be moving quite a lot and in reverse to your hand. This is the resonance point.
If you keep increasing it will slow down to virtually standstill while the spring absorbs all the rapid movement. This is above resonance point.

So the question is... Do you want to push the resonance point higher or lower? If you tighten up the speakers connection to the room - you are making the system stiffer... So the resonance point will go up.
If you couple the speakers loosely, the resonance point will go down. - And the frequencies above it will not be exciting any resonance - or movement.

 

[March Audio]

Ive taken measurements of the rooms acoustics using XTZ Room Analyzer and there was 1 bump at 39hz or so that was cured with a -3.5db cut worth of PEQ and another bump at 168hz or so that also only required a small cut of PEQ

My current footers are a combination of the factory Spikes and a set of Herbies Audio Lab Titanium Decoupling Gliders. Thus far this combo appears to have reduced bass boom/rumble in the room and to a greater extent reduced the vibration felt thru your feet when sitting in the room.

I thought I explained my intention of the post fairly clearly but to recap, I am wondering if an even better approach exists that would achieve more of the same results that I found when slightly Decoupling my speaker and how the shape and material used in the footer/footers/platforms ...etc can change its effectiveness to work as either a coupling or decoupling device.

I have had a quick look at the Herbie site. I'm hoping you are going to tell me those pads are compliant, as the description gives me the feeling they are quite solid. BTW the choice of metal for the cone wont make a jot of difference. I am also a bit confused by their testing mentioned at the bottom of the page and the numbers in the table. They reference a testing standard ASTM E90 "Standard Test Method for Laboratory Measurement of Airborne Sound Transmission Loss of Building Partitions and Elements" so I'm not seeing the relevance.

Simply you will need an appropriate compliant coupler (correct durometer) on the feet for the mass of the speakers and isolation frequency. Difficult to be more specific. Be extremely cautious regarding any products designed for hifi.

 

[Deleted member 65]

Changed the original spikes on my Evolution Acoustics MicroOnes resting on suspended wood floor to these, no going back to spikes on my floor.

 

[fas42]

How much do you think the mass of your speaker cone moving (at 90deg to) is going to make the mass of your speakers "bounce"?

The speaker panels will be vibrating through forced excitation from the drivers and their own natural frequencies.

Do you realise that a typical stand will also be vibrating regardless of how tight you couple the speaker to it?

Now if you stick a massive weight on top of the speaker, yes you will change its stiffness etc, however you need to quantify the effect. You could even be shifting resonances into a more audible area.

I'm afraid Fas, as we have seen so many times before, your experiments are meaningless.

You may recall that my initial experiment, done 30 years ago, was using an extremely heavy, sand filled concrete column, which was pinned to the concrete slab of the house. I did the tight coupling of the cabinet to that stand using Blu Tack, and then severely mass loaded on the top of the cabinet again - each increment moved the sound further from cheap, monkey coffin sound towards large scale, clear, tight presentation - if the latter was distortion, then give me more of it!

When I listen to the vast majority of other audio setups now it's basically junk sound - tiny, trapped in the carcase, falls apart as soon as the volume is pushed - it's Asian mini car nonsense, not worth listening to beyond a cursory appraisal.

 

[fas42]

You've all done the experiment in physics. Attach a weight to a spring and yo-yo it with different speed (=frequency).

...

OK, but you still haven't said whether the material had any viscoelastic character - IOW, inherent damping qualities.

 

[cjf]

I have had a quick look at the Herbie site. I'm hoping you are going to tell me those pads are compliant, as the description gives me the feeling they are quite solid. BTW the choice of metal for the cone wont make a jot of difference. I am also a bit confused by their testing mentioned at the bottom of the page and the numbers in the table. They reference a testing standard ASTM E90 "Standard Test Method for Laboratory Measurement of Airborne Sound Transmission Loss of Building Partitions and Elements" so I'm not seeing the relevance.

Simply you will need an appropriate compliant coupler (correct durometer) on the feet for the mass of the speakers and isolation frequency. Difficult to be more specific. Be extremely cautious regarding any products designed for hifi.

Yes in terms of the Herbie cups the material that the Spike itself rests in is metal and the metal part is then fused onto the Herbie foam/sponge or whatever you want to call it material. The soft material can be deformed if you press your finger nail into it so there is a fair bit of compliance but not enough to cause it to squish down dramatically as long as the speaker doesnt exceed the weight limits they list per cup. My speakers (150lbs /ea) are well under the weight limit one cup can handle.

What are your reasons for not believing that various metals/solids have differing speeds of sound propagation? The science proving this appears to be in abundance after a 5sec search on our friend Google.

 

[fas42]

Just found an interesting article on "what spikes do!" - http://www.audioholics.com/loudspeaker-design/speaker-spikes-and-cones-2013-what2019s-the-point. I agree with much of the material in that ... overall, my mantra is stability, stability, stability.

 

[Nightlord]

OK, but you still haven't said whether the material had any viscoelastic character - IOW, inherent damping qualities.

I don't have the foggiest, but it would seem safer to say yes than to say no as a material without would probably be impossible.

 

[March Audio]

Yes in terms of the Herbie cups the material that the Spike itself rests in is metal and the metal part is then fused onto the Herbie foam/sponge or whatever you want to call it material. The soft material can be deformed if you press your finger nail into it so there is a fair bit of compliance but not enough to cause it to squish down dramatically as long as the speaker doesnt exceed the weight limits they list per cup. My speakers (150lbs /ea) are well under the weight limit one cup can handle.

What are your reasons for not believing that various metals/solids have differing speeds of sound propagation? The science proving this appears to be in abundance after a 5sec search on our friend Google.

Please tell me about the differences between the metals cited and what practical relevance that would have in this application. What practical difference between 6 and say 4km/s in a material a few mm thick?

 

[March Audio]

Just found an interesting article on "what spikes do!" - http://www.audioholics.com/loudspeaker-design/speaker-spikes-and-cones-2013-what2019s-the-point. I agree with much of the material in that ... overall, my mantra is stability, stability, stability.

Problem is that the stand is not infinitely stiff and has its own natural frequencies. Make the connection to the floor as solid as you like.