Listening room snake oil?

[klettermann]

Listening room design and materials was one of the topics discussed during a recent visit to a fancy audio salon (more details on that HERE). One new thing I learned about was the importance of the proper floor covering fiber choice, as most listening spaces are carpeted. To my surprise I was told that pure wool is the only viable choice. Nylons, polyesters, polyolefin, cotton, sisal etc are apparently unsuited for listening spaces as their absorption or something adds colorations and too damping (or not damping enough?). Apparently though it's OK to put wool carpets over other kinds. There was no explanation offered for why wool is acoustically magical. Chemically wool is a form of nylon (polyamide) and I'd expect them to be quite similar, but no. I can't imagine where this stuff comes from. This goes way beyond cable elevators and $700 audio ethernet switches. Snake oil is plumbing new depths. God save us.

 

[anotherhobby]

Dude, I just got this vintage hand woven cashmere rug that sounds amazing!

 

[Bjorn]

All carpeting is very band limited, meaning it will alter the spectral content and is thus not a good way to treat a listening room.

 

[fatoldgit]

All carpeting is very band limited, meaning it will alter the spectral content and is thus not a good way to treat a listening room.

For me, this is an interesting topic but one I havent done any research on

My 8m x 5m listening room has a concrete floor and rather than use carpet I used carpet tiles which are probably around 2mm - 3mm thick and obviously have no loom as a traditional carpet would.

It has occurred to me whether I should get some real carpet.

Any thoughts on carpet tiles V real carpet?

Thanks

Peter

 

[Justdafactsmaam]

Listening room design and materials was one of the topics discussed during a recent visit to a fancy audio salon (more details on that HERE). One new thing I learned about was the importance of the proper floor covering fiber choice, as most listening spaces are carpeted. To my surprise I was told that pure wool is the only viable choice. Nylons, polyesters, polyolefin, cotton, sisal etc are apparently unsuited for listening spaces as their absorption or something adds colorations and too damping (or not damping enough?). Apparently though it's OK to put wool carpets over other kinds. There was no explanation offered for why wool is acoustically magical. Chemically wool is a form of nylon (polyamide) and I'd expect them to be quite similar, but no. I can't imagine where this stuff comes from. This goes way beyond cable elevators and $700 audio ethernet switches. Snake oil is plumbing new depths. God save us.

Half truths. Thick wool carpets are *better* absorbers but other rugs and carpets still work to a degree . None of them offer full bandwidth absorption down to the Schroeder frequencies.

 

[Berwhale]

There was no explanation offered for why wool is acoustically magical.

Perhaps it's just wool gathering? I'll get my coat...

 

[Keith_W]

Ewe, sounds like they yakked a lot of nonsense. Fur gods sake, what a pile of fluff. I hope you told them to shag off?

 

[Bjorn]

For me, this is an interesting topic but one I havent done any research on

My 8m x 5m listening room has a concrete floor and rather than use carpet I used carpet tiles which are probably around 2mm - 3mm thick and obviously have no loom as a traditional carpet would.

It has occurred to me whether I should get some real carpet.

Any thoughts on carpet tiles V real carpet?

Thanks

Peter

Using carpet on the floor should be avoided as previously indicated due to very bandlimited nature. Besides, we don't want to absorp such a large surface. Carpeting a floor will lead to a very unlinear result and with over dampening the highs. It can't really be corrected either.

Use a wooden floor instead and treat specular reflections surgically and with high effect down to 250 Hz area. And use a speaker that either avoids or minimizes floor reflections. A small thick woolen carpet between listening position and ears can be an ok compromise.

 

[krabapple]

Toole: in one of his big rooms he used "dense thick clipped-pile carpet on 1-inch (25 mm) felt underlay" along with a 'large wall hung Danish Rya rug over an air space". "Both were efficient broadband absorbers...[that]...resulted in a mid-frequency RT of about 0.5s"

Sound Reproduction, 3rd ed., chapter 7.

 

[Bjorn]

Toole: in one of his big rooms he used "dense thick clipped-pile carpet on 1-inch (25 mm) felt underlay" along with a 'large wall hung Danish Rya rug over an air space". "Both were efficient broadband absorbers...[that]...resulted in a mid-frequency RT of about 0.5s"

Sound Reproduction, 3rd ed., chapter 7.

That's not broadband absorption. Perhaps he was fooled by looking at the RT, a measurement that's invalid in small rooms. A common misunderstanding despite that it was proved otherwise decades ago.

 

[krabapple]

As Toole discusses the rationales for use of RT as a metric in both large and small, I think you've misunderstood what's in his book. You'll find it's covered in chapter 10.

 

[FrantzM]

That's not broadband absorption. Perhaps he was fooled by looking at the RT, a measurement that's invalid in small rooms. A common misunderstanding despite that it was proved otherwise decades ago.

Don't know enough to refute or approve but ... "Toole", "fooled" and "common misunderstanding" usually do not belong to the same paragraph. My money would be on Toole..


Peace.

 

[Axo1989]

Listening room design and materials was one of the topics discussed during a recent visit to a fancy audio salon (more details on that HERE). One new thing I learned about was the importance of the proper floor covering fiber choice, as most listening spaces are carpeted. To my surprise I was told that pure wool is the only viable choice. Nylons, polyesters, polyolefin, cotton, sisal etc are apparently unsuited for listening spaces as their absorption or something adds colorations and too damping (or not damping enough?). Apparently though it's OK to put wool carpets over other kinds. There was no explanation offered for why wool is acoustically magical. Chemically wool is a form of nylon (polyamide) and I'd expect them to be quite similar, but no. I can't imagine where this stuff comes from. This goes way beyond cable elevators and $700 audio ethernet switches. Snake oil is plumbing new depths. God save us.

Carpet schmarpet. Tatami over gappy timber planks is the only flooring for my listening rooms.

 

[Bjorn]

As Toole discusses the rationales for use of RT as a metric in both large and small, I think you've misunderstood what's in his book. You'll find it's covered in chapter 10.

Nah. Toole came around and understood that reverberation doesn't exist in a small room.

AES Journal Forum » Reflecting on Reflections

The AES Forum is where our members get to interact with each other in between conferences and section meetings.

secure.aes.org

But most importantly will a "dense thick clipped-pile carpet on 1-inch (25 mm) felt underlay" along with a 'large wall hung Danish Rya rug over an air space" effect the frequency response in a broad matter you think? Because that would be the nature if it's truly effective. Not "even" a 2" absorber is going to be very effective below 500-600 Hz, which we know well. And air space can't be much before you have an outflow of energy where the effect of build up energy is lost.

Perhaps we should listen to actual acousticians and who are experts in the area and look at valid measurements related to a small room. Ron Sauro of NWAA labs would be one to listen to.

NWAA Labs -- Complete High-speed Speaker and Material Testing

 

[Bjorn]

Don't know enough to refute or approve but ... "Toole", "fooled" and "common misunderstanding" usually do not belong to the same paragraph. My money would be on Toole..


Peace.

That's how human minds often works. We want to believe what we already believe.

But since Toole is the one you're confident in, let's look at some snippets from his article I linked to.

These rooms and those in which the recordings are reproduced are fundamentally different from live performance spaces, being smaller and acoustically far more absorbent—even large cinemas. When reverberation times measure around or below 0.5 s, one has to acknowledge that this is not reverberation in the original “diffuse field” sense; it is something else.

Understandably, these thoughts and practices have drifted into the domain of sound reproduction but we seem to have lost focus on what the numbers mean in the small, dead, rooms in which we live, listen, and work. We continue to talk about reverbertation times and invoke notions of critical distance, etc. The properties of acoustical materials are measured as if they were to be placed in diffuse sound fields: random incidence absorption coefficient for example. These are mismatched concepts and this is where problems arise.

While he's basically dabbling around in the article, and after all he's not an acoustician, he does clearly admit here that a true reverberation time and areas related to large rooms like for instance critical distance doesn't exist in small rooms and a mismatched concepts.

Lyd & Akustikk | Small rooms and reverberation time

www.lydogakustikk.no

True broadband treatment gives an entirely different result, both in measurements and to our ears. Few have experience with it in small rooms.
Oh as a side note. Even in large acoustical rooms, it's common mistake to use very thick drapes. It leads to a very unlinear result and is something we who work in the field see often. Such rooms needs to be fixed with far more broadband treatment.

 

[OldHvyMec]

Oh as a side note. Even in large acoustical rooms, it's common mistake to use very thick drapes.

That's strange I've used heavy curtains in mid sized rectangle rooms with great success for over 30 years.
They weren't studios they were listening room designed for music. Strange that an acoustician that helped
many vendors sell speakers at shows recommend heavy, THICK, deeply pleated curtains. Toole was no where
in any of the conversations BTW.

Sales results were usually the metric. They weren't selling curtains either, the curtains sold the equipment.
So you may follow who you like the facts are simple. Carpets, curtains and passive materials WORK to a point
they are not and off on switch that either work or not.

I've had people tell me how Helmholtz resonators don't work, they certainly don't if you don't follow what makes them
work. Of course heavy carpet mitigates vibration as a whole and overall work VERY well for reverberation issues.
BASS is easy once you understand that SIZE is the first thing not the last and mechanically tuning the room is a pre
not post thought. Helmholtz offers everything DSP offers in spades with just a little passive treatment and placement.

DSP all you want after the room is set up. I'm not recording or mixing music, I'm reproducing it, that is a whole different
set of rules.

 

[FrantzM]

Earl Geddes, another person, who knows a few things about Music Reproduction in the Home, recommends thick heavy curtains too.. I don't think he's an acoustician, perhaps didn't know what he was talking about either ...

Peace.

 

[Bjorn]

That's strange I've used heavy curtains in mid sized rectangle rooms with great success for over 30 years.
They weren't studios they were listening room designed for music. Strange that an acoustician that helped
many vendors sell speakers at shows recommend heavy, THICK, deeply pleated curtains. Toole was no where
in any of the conversations BTW.

Sales results were usually the metric. They weren't selling curtains either, the curtains sold the equipment.
So you may follow who you like the facts are simple. Carpets, curtains and passive materials WORK to a point
they are not and off on switch that either work or not.

I've had people tell me how Helmholtz resonators don't work, they certainly don't if you don't follow what makes them
work. Of course heavy carpet mitigates vibration as a whole and overall work VERY well for reverberation issues.
BASS is easy once you understand that SIZE is the first thing not the last and mechanically tuning the room is a pre
not post thought. Helmholtz offers everything DSP offers in spades with just a little passive treatment and placement.

DSP all you want after the room is set up. I'm not recording or mixing music, I'm reproducing it, that is a whole different
set of rules.

It's related to references. Only absorping the highs and leaving out all the midrange and bass creates a serious unlinear result. I'm sorry to be blunt but this kind treatment of absolutely sucks compared to a well treated room. Well known by anymore who has experience in the field.

 

[Bjorn]

Earl Geddes, another person, who knows a few things about Music Reproduction in the Home, recommends thick heavy curtains too.. I don't think he's an acoustician, perhaps didn't know what he was talking about either ...

Peace.

You're just looking for something to back up your beliefs. Sad.

 

[Waxx]

Thick curtains and carpets can help for very reflective rooms (with flat hard surface walls and floors) to eliminate the reverb that those create. But that is only on the high frequencies, they won't fix bass or lower mid issues, that is just science. I also use a thick (felt) carpet on my old stone floor in my living room, and it does the job on those high frequencies, but i need dsp to fix my mid and bass issues...

But a real treated room is always better, and not a small ammount better. And dsp can fix a lot more than any carpet or curtain can. But it won't fix the reverb effect of the high frequencies. There, thick clothing (be it a curtain or a carpet or both) is a cheap way to get most fixed that works, and if you want it perfect, hire a qualified acoustician and keep a large ammount of money ready to fix it with an extensive rebuild of the inner side of your room. But not everybody can afford that, or has the room/space/family agreement to do that.