Measurement Thread: Measured Effect of Speaker Isolators

[Ethan Winer]

Ethan: One of my concerns was the stability of the table used to support the speakers. I wonder if that impacted the results, especially in the bass region? Would a stack of concrete blocks performed better, or just differently, or would there be no change?

The vendors claim their isolators prevent speaker cabinet vibration from coupling to the surface they rest on, thus preventing that surface from resonating in sympathy. At least that's the claim made by those who claim anything at all beyond vague promises of better sound. So to test that claim we need a surface that can vibrate and ring, versus solid blocks.

JA: Have you any results checking the impulse response (or anything else) of the audio signal from your tests? Or were they solely focused on cabinet vibration?

The REW data file is on my web site, linked in the article. The article shows the impulse responses, and downloading the file lets people view and massage the data any way they like.

--Ethan

 

[DonH50]

Yah, understood, I was just wondering if they did anything differently when on a firm platform. Like any testing, it can lead to an infinite number of related tests, and life is finite...

I saw you REW results, was curious if John Atkinson (JA) had measured the acoustic output or just cabinet vibration in his test (more of an apples to apples'ish comparison to your work).

Thanks Ethan,
Don

 

[Gregadd]

of course a solid foundation would seve as a control.

 

[Purite Audio]

of course a solid foundation would seve as a control.

No surface is really solid when we are discussing vibration, everything resonates it just requires the correct frequency and enough amplitude .

 

[Gregadd]

 

[Argonaut]

Good video . Love to see other measurements besides a thump though. Specifically would be good to know if the device rings on its own. My tractor has no suspension. It is very uncomfortable when I hit a bump. But it then settles instantly. My car has suspension and rides over the bumps nicely but then it bounces up and down a few times before settling. Would have been great for him to play a sweep and captured with and without the stand.

And oh, the last thing he says about your neighbor not hearing your stereo, is false of course. The sound gets out through the air.

Whilst not entirely comprehensive, a little further information re the Townshend Podium.

http://www.hifiplus.com/articles/townshend-audio-seismic-podium/

 

[Gregadd]

No surface is really solid when we are discussing vibration, everything resonates it just requires the correct frequency and enough amplitude .

True.
But Ethan said: "...So to test that we need a surface that vibrates and rings vs a solid block..." That was in response to being questioned about not using a sold surface. See Post #192.
it makes sense. You might want to have a control of a "solid Block" just to nake sure the reults are similar.

 

[Ethan Winer]

The key point is that competent speaker enclosures don't vibrate enough to cause what they rest on to also vibrate. That YouTube video about capturing sound via optical vibrations is really cool - I saw it when it came out a few years ago. But it has no relevance to loudspeaker isolation!

--Ethan

 

[Gregadd]

The key point is that competent speaker enclosures don't vibrate enough to cause what they rest on to also vibrate. That YouTube video about capturing sound via optical vibrations is really cool - I saw it when it came out a few years ago. But it has no relevance to loudspeaker isolation!

--Ethan

If you want to be scientific having a control group is useful and probably required.. I suppose you oculd call the MartinLogan Neolith and NOLA KO imcompetent designs.Our friend Amir found them to to vibrate so bad he culd feel it when he touched them. Customers may want to purchase them for other reasons and seek an aftermarket cure.
I'm gald you enjoyed the video. It does suggest that not only does science alow the detection of vibrations in a speaker before and after isolation but to determine what they sound like. Quite intriguing don't you think?

 

[DaveC]

The key point is that competent speaker enclosures don't vibrate enough to cause what they rest on to also vibrate.

--Ethan

False.

 

[Fitzcaraldo215]

False.

How so, pray tell? Of course, there is the question of what is "competent" and what is not.

 

[Gregadd]

How so, pray tell? Of course, there is the question of what is "competent" and what is not.

If competent is so well setteled you mgiht share that with me or at least tell me where I could find that standard.

 

[DaveC]

How so, pray tell? Of course, there is the question of what is "competent" and what is not.

Every speaker in existence will benefit from decoupling.

Resonances are different from vibration, and while good cabs will be free of resonances they will never be free of vibration and if the speaker isn't decoupled vibration will be transferred to whatever surface it's sitting on. If it's the floor it'll drive the floor... this is not good.

All it takes is getting a pair of IsoAcoustics stands, stillpoints, etc. , put a speaker on it and hear the result. You can measure vibration on the floor around the speaker and I'd guarantee it'll be reduced.

This is in the category of SUPER-OBVIOUS imo... the results of decoupling speakers are easily audible.

You can also look at the speaker cab testing done by JA at Stereophile. Every single one will have measurable vibrations. Some even have resonant modes.

 

[Gregadd]

IIRC Gary did a thread on this some time ago.

 

[Gregadd]

Understanding Coupling/Decoupling

http://www.whatsbestforum.com/showt...ing-with-particular-reference-to-loudspeakers

 

[Purite Audio]

All loudspeaker enclosures vibrate, the job of the designer is to ensure that the vibration dissipates quickly and is not stored leading to resonance.
BBC designs choose a light ,damped cabinet which excites generally at a lower frequency or a more massy cabinet which pushes the resonant frequency up.
Keith

 

[blutto]

All loudspeaker enclosures vibrate, the job of the designer is to ensure that the vibration dissipates quickly and is not stored leading to resonance.
BBC designs choose a light ,damped cabinet which excites generally at a lower frequency or a more massy cabinet which pushes the resonant frequency up.
Keith

....simply adding mass generally lowers frequency....simply adding stiffness generally increases frequency...ergo a more massy cabinet will not push resonant frequency up ( unless of course that added mass contributed a very large amount of stiffness and in that case the frequency could go up )....

Cheers

 

[Purite Audio]

....simply adding mass generally lowers frequency....simply adding stiffness generally increases frequency...ergo a more massy cabinet will not push resonant frequency up ( unless of course that added mass contributed a very large amount of stiffness and in that case the frequency could go up )....

Cheers

Absolutely correct I should have said stiffness , I was just trying to point out the differing approaches to resonance control.
Keith.

 

[blutto]

Absolutely correct I should have said stiffness , I was just trying to point out the differing approaches to resonance control.
Keith.

...yeah, its a real tough one, that....like trying to nail a 3-way cross-over, you spend a lot of time chasing your tail....its complisticated....

Cheers

 

[Ethan Winer]

You can also look at the speaker cab testing done by JA at Stereophile. Every single one will have measurable vibrations. Some even have resonant modes.

Sure, but just because John can measure cabinet vibration with an accelerometer doesn't mean that the vibration is audible. As with all other aspects of audio and fidelity, we can measure much smaller quantities than anyone can hear. Can anyone hear 0.001 percent distortion? Of course not, but that small amount is easily measured. The same for cabinet vibration. I'm not saying there's no loudspeaker in the world that will sound different on an isolating platform. But my measurements clearly show no real change in sound that can be attributed to the devices I tested using a typical competent loudspeaker. So as far as I'm concerned, the burden of proof is clearly on those who continue to believe that isolation affects the sound. As always, I'm glad to change my opinion in the face of hard evidence. Not someone's say-so, but actual evidence.

--Ethan