Speaker De-coupling

[QMuse]

Have you tried moving the speakers to a different location to see if they still resonate? They don't have to be moved to a final position, just moved for testing. You may just have an unlucky placement issue.

You will have a really hard time trying to find optimal speaker position based only on your hearing - looking at waterfall charts is a much more acurate and faster way to do that.

 

[Siwel]

The most effective method to tame resonant peaks is room EQ. If you can hear resonances during sweep they are there with music as well but masked with other tones so they are harder to hear. Can you post waterfall chart for left and right speaker?

You will have a reall yhard time trying to find optimal speaker position based only on your hearing - looking at waterfall charts is a much more acurate and faster way to do that.

I don't have a mechanism to do that....I can do FFTs and SPL. To repeat, I don't think chasing the airborne component of this is the solution. This is a mechanical transfer of energy. Update: I ordered some of the pads Kal linked to....everything I needed was under $50 and can be returned. If they work I will certainly report back. If they don't it may mean taking more Draconian steps including reevaluating my whole setup's geometry but if I can avoid that........

Now I have to reckon how to make the whole thing work on a thickly carpeted but relatively flexible floor.

 

[QMuse]

I don't have a mechanism to do that....I can do FFTs and SPL. To repeat, I don't think chasing the airborne component of this is the solution. This is a mechanical transfer of energy.

If you do that same sweep with REW it will be able to show you watterfall graph. acoustic resonance is always about mechanical transfer of energy. Your speakers go deep and loud, if they are near the ccorners they wille excite pretty much all resonant room mode that exists in your room so identifying those frequencies and EQ-ing them is the only effective solution. This happens in pretty much every room with large speaers, not only yours.

 

[jhaider]

I've looked into Sorbothane (one of my first notions) and just as you say it's another very inexpensive material solution...

One thing about Sorbothane, even “non-staining,”...isn’t. At least it WILL stain hardwood floors. I would assume carpet as well.

 

[Siwel]

If you do that same sweep with REW it will be able to show you watterfall graph. acoustic resonance is always about mechanical transfer of energy. Your speakers go deep and loud, if they are near the ccorners they wille excite pretty much all resonant room mode that exists in your room so identifying those frequencies and EQ-ing them is the only effective solution. This happens in pretty much every room with large speaers, not only yours.

Thanks Q, I understand that it's all mechanical but trust me, these speakers are not in corners and won't be going there. I'll post a picture of my setup here for you. Note: The subs are not in the location seen in the photo....they are asymmetrically placed but were moved into visual symmetry for the photo for "visual appeal." . The perspective of the photo is a little off too....the speakers are about 48" from the side wall and a somewhat lesser amount to the front baffle from the rear wall.

 

[Siwel]

One thing about Sorbothane, even “non-staining,”...isn’t. At least it WILL stain hardwood floors. I would assume carpet as well.

I'll turn off the lights and listen with my eyes closed. This always makes a mess go away fast and effortlessly!

 

[QMuse]

Thanks Q, I understand that it's all mechanical but trust me, these speakers are not in corners and won't be going there. I'll post a picture of my setup here for you. Note: The subs are not in the location seen in the photo....they are asymmetrically placed but were moved into visual symmetry for the photo for "visual appeal." . The perspective of the photo is a little off too....the speakers are about 48" from the side wall and a somewhat lesser amount to the front baffle from the rear wall.

Such speakers will excite room modes even if you put them both in the middle of the room.

Here's how it looked with my left speaker before correction (when it shaled my entire listening sofa):

And after:

 

[Dogan]

^That may well be but it would be a shame to have to move the mains out of their existing location as it's optimal for other characteristics. I have played with all the elements of placement for both the mains and the subs and have settled on a combination I like. I'm not stubborn so I take your idea as having value but it would be great not to have to reset the whole idea of the thing.

Problem is, I suspect shifting locations enough to reduce this problem will leave me with other issues. This is almost certainly a mechanical problem that ideally I would like to be able to resolve with a mechanical solution. I don't know where except perhaps for the corners (where floor strength is likely to be highest) but which presents other issues.

Mechanically speaking there are two ways to change the natural frequency of a spring mass system. You can either change the spring coefficient by placing something underneath the speaker as suggested, or you can attach something heavy the speakers

 

[Siwel]

^I understand that no matter what I do, the nature of small room acoustics can't be subverted or ignored and that there will be cancellations and reinforcement of specific frequencies for any given set of relationships. I'm perfectly happy with system response and my subs are are already eq'd (using their DARO function). The mains are not treated (with eq) so there's that but the subs are handling the vast bulk of energy below 40Hz.

I have REW on this computer and used it for modeling (with mediocre success...maybe GIGO issues) but use Audio Tools for the rest of my screwing around. I will need to get familiar with REW again and that's certainly not a bad thing but like I said.....I'm 95% clear this is most related to the transfer from the floor. That's why I think physically isolating them is the answer over further eq-ing the system. I am looking for the most cost effective way to do that. I understand Floyd Toole has his Salons hanging upside down, suspended from the ceiling! That's a bridge too far for me.

 

[Vuki]

What I find odd is that those speakers vibrate at all. Looking at Stereophile's measurement one would say it's almost impossible. Or do you think it's floor that resonates?

 

[Siwel]

^I'm as confident as I can be that it's the floor, not the speakers. I tilted them onto a single spike (always a physical act of courage)while running tone to test the theory. I would have physically lifted them entirely off the floor if I could have but that ain't happening! Trying to reduce the effect of transfer/contact to the floor by putting all the weight on one spike while taking as much weight a I could off of that contact point reduced the vibes to virtual inaudibility. Drop the speaker back onto all four spikes and the harmonic buzz returns. It's to do with the way they interface to the floor and how the floor responds and the energy gets transferred back and forth. Or so I think.

Nonetheless, I want to thank everyone who is participating in this discussion and assure that I am hearing everybody's ideas. I will be reporting back on the efficacy of the cheap isolation devices I bought resulting from Kal's link and will entertain everybody else's notions.....including eq!.....with my simple biases intact but my mind open to your ideas.

 

[Siwel]

Such speakers will excite room modes even if you put them both in the middle of the room.

Here's how it looked with my left speaker before correction (when it shaled my entire listening sofa).................

I should have mentioned to you that the JLA subs come with their version of automated eq (DARO) and consequently they are equalized to the extend possible with 18 assignable (cut only) filters, more or less conforming with your advice. If I have chosen my sub locations carefully (I think I have) they will do for the bass they contribute what REW is aimed at insofar as the subs are concerned.

 

[QMuse]

I should have mentioned to you that the JLA subs come with their version of automated eq (DARO) and consequently they are equalized to the extend possible with 18 assignable (cut only) only filters, more or less conforming with your advice. If I have chosen my sub locations carefully (I think I have) they will do for the bass they contribute what REW is aimed at insofar as the subs are concerned.

If you haven't verified their linearity with your measurement it is impossible to say how well automated EQ did it's job. Btw, if your mains aren't high-passed they are still playing down to their bottom end, and doing so uncorrected.

 

[youngho]

Here's an example of the use of isolation with actual measurements: https://www.digido.com/installing-dynaudio-m5p-loudspeakers-on-custom-isolators-from-av-room/

 

[Siwel]

If you haven't verified their linearity with your measurement it is impossible to say how well automated EQ did it's job. Btw, if your mains aren't high-passed they are still playing down to their bottom end, and doing so uncorrected.

They're high passed, fully capable and dedicated electronic crossover, a JLA CR1. It's visible in my photo. At this juncture in my thinking this is not an exercise in correcting frequency response. The room is treated and otherwise performs well. I do have RTA and FFT capability so I'm not entirely in the dark here and I do take measurements albeit I haven't taken the time domain related measurements beyond the gated stuff a basic fft does. This is a broadband problem exhibiting itself (but only with tone, not heard directly as such with program) at more than just a few isolated frequencies. Actually, I'm not convinced I will be able to solve this by decoupling or "floating" the speakers with what amounts to springs. In fact, I'm not precisely sure how I will use what I just bought but it's a thought and worth a try because I doubt eq will solve this. I believe this is a structural issue involving the flexibility inherent to the floor. It's a flaw in an otherwise nice room.

 

[QMuse]

They're high passed, fully capable and dedicated electronic crossover, a JLA CR1. It's visible in my photo. At this juncture in my thinking this is not an exercise in correcting frequency response. The room is treated and otherwise performs well. I do have RTA and FFT capability so I'm not entirely in the dark here and I do take measurements albeit I haven't taken the time domain related measurements beyond the gated stuff a basic fft does. This is a broadband problem exhibiting itself (but only with tone, not heard directly as such with program) at more than just a few isolated frequencies. Actually, I'm not convinced I will be able to solve this by decoupling or "floating" the speakers with what amounts to springs. In fact, I'm not precisely sure how I will use what I just bought but it's a thought and worth a try because I doubt eq will solve this. I believe this is a structural issue involving the flexibility inherent to the floor. It's a flaw in an otherwise nice room.

You don't need time domain to check if you have issues with room modes - MMM RTA with pink noise will do. If you choose to do it here is a nice video that explains how it should be done. It's very easy and quick procedure.

 

[Kal Rubinson]

It's reasonable enough to experiment with (like Kal's recommendations) if I can devise the best way to use it. Now, what might that be?

I drilled 1/2" holes in the middle of each so that the spikes fit in. It's a little tricky drilling the rubber. Using them on carpet, you might want bigger ones for stability.

 

[Siwel]

They don't look like isolators as much as absorbers.
Basically a set of correctly specified steel springs will isolate.
Expensive housings with bits of lossy polymer will absorb.
I think the Townshend isolators are absurdly expensive for what they are but they work correctly in an objective sense.

The Townsends are very expensive but in addition, I can't find anyplace that they are for sale on this continent. Even if I was of a mind, I'd have to buy them on a dare. I thought the Gaia design wasn't based on polymers, that it was a tuned spring based system. To be honest, I know little about any of these dedicated devices except what I have read.

 

[Siwel]

I drilled 1/2" holes in the middle of each so that the spikes fit in. It's a little tricky drilling the rubber.

I was thinking the same, to give the spikes a place to go. I have a drill press so maybe that will help.

 

[Kal Rubinson]

I was thinking the same, to give the spikes a place to go. I have a drill press so maybe that will help.

Indeed. Since my retirement, I no longer have access to a machine shop.