Is this something only hearing system perceives or does semi anechoic measurements show it as well? Its very unintuitive, as the pattern is made of acoustic interference it should measure (anechoic) so that there is not much highs past the beaming. On the other hand in room response is usually closer to power response than any single axial anechoic measurement so hearing perhaps registers it, but its not direct sound anymore. Is the clarity (or what have you) same at all listening heights?
edit.
missed the link, which shows simulation so I assume you also mean anechoic. What would be nice here was to compare ~point source and line array in the same place but as I don't have one I cannot do it.
Don't discourage imagination, instead feed it, its quite powerful although comes to wrong conclusions without enough/correct data. I trust you say the sound stays about the same within reasonable height (ignoring the extremes, floor and ceiling) because why would you lie. I have no intentions to lie or misguide either, I'm just outputting what seems logical for the information I have came across so far and its for learning thats all. Here is how I would use imagination here based on the new information and realization: Assume array is made of full range point sources. One of these full range sources is at same height with ear (or mic) observing and arrives first, sound from the drivers above and below arrive then and so on. Its independent on what height we are observing at the situation is pretty much the same. Path length relation of a source that is at ear height to Nth source above and/or below in the array is about the same, so pattern is roughly the same at any height as long as we are not observing at extremes of the array.
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While I agree with fluid, and I'd say a conventional speaker at ear height has similar effect on the opposite wall as an array would have, I can also add that anybody serious about his/her music enjoyment better break up that wall symmetry, either by diffusing the energy (e.g. a random filled bookshelf) or by absorbing it.
Personally, I wouldn't place the source lower to avoid this from happening. If you're that against treating the room properly, just choose a CBT speaker, as it spreads the energy in even more directions than a straight array, making it act less intrusive in an untreated room. Keeping the top end of a CBT from combing is even harder than with a straight array though, despite the shading. The CBT advertisement said different, I know, but that was a simulation, based on lots of very small point sources. So a construction/project like fluid linked to, acting as a CBT could be a part of the solution, as it still needs a fitting bottom end.
Nothing here is helping the OP much, can we move on? @vineethkumar01 do you realize how easy it can be to make your own absorbing panels? Lots of inspiration can be found in the projects here and elsewhere. There's also examples of diffusion panels if needed.
Personally, I wouldn't place the source lower to avoid this from happening. If you're that against treating the room properly, just choose a CBT speaker, as it spreads the energy in even more directions than a straight array, making it act less intrusive in an untreated room. Keeping the top end of a CBT from combing is even harder than with a straight array though, despite the shading. The CBT advertisement said different, I know, but that was a simulation, based on lots of very small point sources. So a construction/project like fluid linked to, acting as a CBT could be a part of the solution, as it still needs a fitting bottom end.
Nothing here is helping the OP much, can we move on? @vineethkumar01 do you realize how easy it can be to make your own absorbing panels? Lots of inspiration can be found in the projects here and elsewhere. There's also examples of diffusion panels if needed.
Absorption panels can be covered with decorative or artistic fabric. When done with good aesthetic sense, no one would guess that they serve an engineering purpose rather than a decorative purpose.
Hi @wesayso
Thanks for the links on DIY acoustic panels. Currently, I am trying to choose infill material for the same. 🙂
These are the kind of material options that I have for 40kg/m3 density:
1)
https://www.auralexchange.com/product/nankarrow-geofill-premium-fireproof-acoustic-infill-boards/
absorption coefficients for the above material taken from the above website:
2)
https://www.auralexchange.com/product/roxul-rockwool-safe-n-silent-pro-acoustic-insulation-boards/
I was considering the Rockwool 350 variant from above.
I am still confused about whether I need 4inch thick panels or 6-inch thick panels (and that is a mighty stretch in terms of WAF 😀)
I went to the following site to get an idea about the coverage required in my room and got the below results:
https://www.acoustimac.com/room-calculator/
I am considering getting 4 numbers of 6ft x 2ft gobo-type panels, which have wheels so that they can move if required. Since I will be living in this or another rented accommodation for the foreseeable future, I may have to adjust with non-wall mounted panels if possible. I am not considering buying more such big panels at the moment since a bit more furniture might come into the living room eventually, and a bigger & thicker rug. Diffusor is out of consideration for the moment..
Please let me know if the above ideas would be of any use..
@hifijim decorative kind of fabric, I am definitely trying to get. At least some fabric that gels together with the colour schemes of the sofa and other things.. Otherwise, these things (including myself) will be kicked out of the living room pretty soon. 😀
Thanks for the links on DIY acoustic panels. Currently, I am trying to choose infill material for the same. 🙂
These are the kind of material options that I have for 40kg/m3 density:
1)
https://www.auralexchange.com/product/nankarrow-geofill-premium-fireproof-acoustic-infill-boards/
absorption coefficients for the above material taken from the above website:
2)
https://www.auralexchange.com/product/roxul-rockwool-safe-n-silent-pro-acoustic-insulation-boards/
I was considering the Rockwool 350 variant from above.
I am still confused about whether I need 4inch thick panels or 6-inch thick panels (and that is a mighty stretch in terms of WAF 😀)
I went to the following site to get an idea about the coverage required in my room and got the below results:
https://www.acoustimac.com/room-calculator/
I am considering getting 4 numbers of 6ft x 2ft gobo-type panels, which have wheels so that they can move if required. Since I will be living in this or another rented accommodation for the foreseeable future, I may have to adjust with non-wall mounted panels if possible. I am not considering buying more such big panels at the moment since a bit more furniture might come into the living room eventually, and a bigger & thicker rug. Diffusor is out of consideration for the moment..
Please let me know if the above ideas would be of any use..
@hifijim decorative kind of fabric, I am definitely trying to get. At least some fabric that gels together with the colour schemes of the sofa and other things.. Otherwise, these things (including myself) will be kicked out of the living room pretty soon. 😀
What works fine is absorption sheets/blankets made of schredded jeans etc. Has a pretty high absorption rate and is not a health risk.
In the Netherlands: https://www.akoestiekwinkel.nl/ecoc...AVa2QdZRH5w6CSrB_lXKcZt7H4-32Hc8aAjR2EALw_wcB
In the Netherlands: https://www.akoestiekwinkel.nl/ecoc...AVa2QdZRH5w6CSrB_lXKcZt7H4-32Hc8aAjR2EALw_wcB
Thanks for the suggestion.. 🙂
Somehow I have many concerns regarding health issues due to rock wool/fibreglass/other mineral wool.
This is why I am looking for alternate materials. One option for me is the polyester fibre based filling I have linked in my previous post.
Unfortunately, it doesn't look like I can get similar material as you had suggested locally. Maybe I will try to search around a bit more..
4" thickness with a slight air gap between panel and wall should get you acceptable results...
What you see in my room is a 2" thickness poster/panel behind the listener (filled with fluffy fiberglass with a layer of wool felt on top of each side) and the panels behind both curtains are 3" thickness fluffy fiberglass, again covered with wool felt on both sides, with an air gap of at least an inch behind them. That was quite effective to get me a room on another level.
What you see in my room is a 2" thickness poster/panel behind the listener (filled with fluffy fiberglass with a layer of wool felt on top of each side) and the panels behind both curtains are 3" thickness fluffy fiberglass, again covered with wool felt on both sides, with an air gap of at least an inch behind them. That was quite effective to get me a room on another level.
What can be also very good is wool. Be it very well cleaned, so just the "bare" fibres.
Would this be an option? https://www.archiexpo.com/prod/knauf/product-50767-1554869.html
It's what I have as isolation between my ceiling and upper level floor as insulation. Ecose is the binding component, it does make it a more ECO friendly product to handle. It is soft to the touch and not irritating or itchy.
I used the (real) wool felt on both sides of the fluffy fiberglass in my panels to keep that nasty stuff encapsulated. Plus the two differing materials put together work better than each of them by itself. The wool layer is thin (about 5 to 7 mm), I could have made a panel using the wool only, as I bought a huge roll of it.
I use it inside my speakers too, which works better than fiberglass by itself, plus it's there to keep the nasty fiberglass fibers from entering the drivers.
I guess if the numbers for that option "1) Geofill" are right, it performs broadband and isn't that far behind the Rockwool and achieves even better absorption at lower frequencies.
It's what I have as isolation between my ceiling and upper level floor as insulation. Ecose is the binding component, it does make it a more ECO friendly product to handle. It is soft to the touch and not irritating or itchy.
I used the (real) wool felt on both sides of the fluffy fiberglass in my panels to keep that nasty stuff encapsulated. Plus the two differing materials put together work better than each of them by itself. The wool layer is thin (about 5 to 7 mm), I could have made a panel using the wool only, as I bought a huge roll of it.
I use it inside my speakers too, which works better than fiberglass by itself, plus it's there to keep the nasty fiberglass fibers from entering the drivers.
I guess if the numbers for that option "1) Geofill" are right, it performs broadband and isn't that far behind the Rockwool and achieves even better absorption at lower frequencies.
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I don't discourage imagination, (otherwise nothing would move forward) just to combine it with a verification method that works.
Density is only a rough approximation for Gas Flow Resistivity but something that resembles Owens Corning 701 would be reasonable that is 24Kg and has a GFR of about 8300 MKS Rayl. Higher density tends to stop the broadband effect and put more of a slope to the absorption.
Movable panels are great and it is better to have them off the wall, porous absorbers work best 1/4 WL away from the wall for the lowest frequency but that can become impractical. An air gap works like adding thickness and is advisable.
You can play around with the porous absorber calculator to see the effect of thickness density and air gaps.
http://www.acousticmodelling.com/8layers/porous.php
My panels are 150mm or 200mm thick sized to fit the width of the roll of insulation. They both free stand quite nicely with an MDF frame and are covered with fabric on both sides. The dark grey panels are 200mm and straddle the room corners and the light grey panels are 150mm spaced away from the wall. I don't find them visually intrusive.
I have another printed panel that is not as thick as it is wall mounted.
Frames are quite basic
There is no need to be concerned, it is quite easy to be scared by rumours but there has been a lot of research into the effects of mineral fibres and the glass wool type are extremely easy to make completely safe with no issue. You would have to be quite reckless to cause an issue.
Having said that if the correct polyester types are available they work just as well for acoustics just cost more and aren't always as easy to find.
Any inorganic dusts that are inhaled can deposit into your lungs may cause problems in the long term. The most well studied is silica (from coal mine workers) and asbestos (from construction workers)
Unfortunately some of effects that are deemed safe today are not known until LONG after exposure eg. cigarette smoking, diesel particulate matter, UV-B.
From MDF to wood chip dust I can't imagine breathing the stuff in would be GOOD for you. So I would use a masks and eyewear protection suitable for the job. I would love to see the data for mineral fibers or recycled glass wool.
Recycled glass I love to use in speaker cabinets but it gives me a crazy itch, which I need to shower afterwards. I'm already have eczema and generally quite sensitive skin. YMMV, and see an independent medical opinion for your own use case.
Unfortunately some of effects that are deemed safe today are not known until LONG after exposure eg. cigarette smoking, diesel particulate matter, UV-B.
From MDF to wood chip dust I can't imagine breathing the stuff in would be GOOD for you. So I would use a masks and eyewear protection suitable for the job. I would love to see the data for mineral fibers or recycled glass wool.
Recycled glass I love to use in speaker cabinets but it gives me a crazy itch, which I need to shower afterwards. I'm already have eczema and generally quite sensitive skin. YMMV, and see an independent medical opinion for your own use case.
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These two are rightly a whole different ball game. I can understand the concern during manufacture where the greatest risk of inhalation occurs.
A cheap ported MDF speaker might throw some dust out, does the average person put on a hazmat suit to go into their attic/loft where there is most likely a considerable amount of uncovered fibreglass or equivalent?
Peanuts or shellfish can be deadly to those allergic to them so everyone needs to consider their own tolerance for any risk and act accordingly.
Google can help you out there, I read enough to have my own concerns alleviated before I bought a lot of fibreglass, the Knauf ECO stuff available locally is very different to the horribly itchy stuff of old.
The Knauf ECO stuff is exactly the one I use now for lining cabinets. Far more affordable and better damping than polyester fibrefill or Dacron. Still a little itchy, so I couldn't imagine using any of that older stuff.
As for the MDF or wood chip dust, I meant whilst cutting sheets, routing holes and doing round-overs and being covered head to toe in that fine MDF dust. And thinking that it's totally inert. Wearing a mask is a must, IMHO.
Once it's cut, I have zero concerns regarding a ported MDF cabinet or MDF /chipboard based furniture.
Exactly so why be concerned about fibreglass when it is properly contained in a frame covered with fabric?
On a completely unrelated note, I saw this sound system over at the line array thread.
A driver matrix with beam-shaping capabilities.. 😀 (Similar to what we do in multi-antenna wireless systems these days)
https://holoplot.com/systems/
This is the kind of sound system I have been thinking about for some time now.. 😀
I predict that the next thing would be the sound system domain equivalent of intelligent/reconfigurable reflecting surfaces (IRS) that we have been researching heavily in the past few years in wireless.. 😀
IRS systems enable controlling/manipulating the wireless signals at different places in between the transmitter and receiver. A sound domain IRS equivalent, when placed at (probably) the reflection points of sound in rooms, can manipulate (at least the mid-to-high frequencies) the reflected sound to the liking of the listener/combat some of the problems caused by rooms, I guess.. 😀
Maybe we will start with 3D printable versions of configurable acoustic metamaterials.. Anyway, interesting things to think about 😀
A driver matrix with beam-shaping capabilities.. 😀 (Similar to what we do in multi-antenna wireless systems these days)
https://holoplot.com/systems/
This is the kind of sound system I have been thinking about for some time now.. 😀
I predict that the next thing would be the sound system domain equivalent of intelligent/reconfigurable reflecting surfaces (IRS) that we have been researching heavily in the past few years in wireless.. 😀
IRS systems enable controlling/manipulating the wireless signals at different places in between the transmitter and receiver. A sound domain IRS equivalent, when placed at (probably) the reflection points of sound in rooms, can manipulate (at least the mid-to-high frequencies) the reflected sound to the liking of the listener/combat some of the problems caused by rooms, I guess.. 😀
Maybe we will start with 3D printable versions of configurable acoustic metamaterials.. Anyway, interesting things to think about 😀
I found an interesting comparison between different types of measurements of the same speaker (nearfield+farfield merged, ground plane vs Klippel NFS) done by different individuals and published by FM stoneeh over at ASR. Please find the attached document for the same. I, for one, really appreciate his efforts.. 🙂
From what I understood from the attached document, what was more interesting to me is that FM stoneeh mentions about some improved formula for nearfield+farfield merging, and he has an article about it here:
Now I really wish I knew some German language at least enough to understand what the new method in the above video is.. 😀
From what I understood from the attached document, what was more interesting to me is that FM stoneeh mentions about some improved formula for nearfield+farfield merging, and he has an article about it here:
Now I really wish I knew some German language at least enough to understand what the new method in the above video is.. 😀
That whole thread over at ASR is very informative
https://www.audiosciencereview.com/...ents-spinoramas-with-rew-and-vituixcad.21860/
Perhaps not for beginners, but people with an intermediate level of measurement expertise can really benefit from reading that thread start to finish, twice...
j.
https://www.audiosciencereview.com/...ents-spinoramas-with-rew-and-vituixcad.21860/
Perhaps not for beginners, but people with an intermediate level of measurement expertise can really benefit from reading that thread start to finish, twice...
j.
While I think the measurement approach at ASR is easy enough to do for a small two way - all of this becomes a lot harder for large 3-ways with complicated geometry.
Sure it could be improved, but it’s sound advice.
He who would learn to fly one day must first learn to stand and walk and run and climb and dance; one cannot fly into flying.
Nietzsche
He who would learn to fly one day must first learn to stand and walk and run and climb and dance; one cannot fly into flying.
Nietzsche