Pls validate my Idea - Acoustic Foam behind canvas painting

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aurobindosaha

aurobindosaha

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Kolkata, India
Hi

I am planning to set sound absorbing foam on back wall, which is about 12 feet from my speakers front panel.

I dislike the look of acoustic foam. I have planned to print 2x3 feet canvas of some landscape photographs on canvas prints that I captured during travel. In fact if I put three such canvas prints it will cover 6x9 feet of my back wall. But it may not be continuous cover, there may be some gaps between each picture. I will frame this canvas prints on top of the acoustic foams, and off course no glass or cellophane on top. The frame of these pictures will be made of hard paper cardboards.
fdd95314d26467b6a3917d6f0b12a94d.jpg


In stead of canvas prints, i can go for a very large Madhubani painting or Rajasthani painting. Canvas photo prints may have oil varnish which may prevent easy sound absorption. I think the best bet is something like katha stichting art ... stories narated by sewing threads and stichting art work.

Please let me know what you think if this will help.

For reference here's my room.
https://youtu.be/oQPgipf-xus

Thanks
Auro





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Imo these will not help for 2 reasons. First the sound absorbing foam will not absorb lower midrange and bass frequencies. So essentially they will create an imbalanced sound spectrum where the higher frequencies are mitigated and others are untouched in effect making them more pronounced. more importantly unless the fabric is acoustically transparent (I heard one way to experiment is blow through the fabric and your breath should be felt without diminishing on the other side), even the foam will do nothing. I can guarantee canvas is not acoustically transparent. not sure of the other options.
However you can consider these
GIK Acoustics ArtPanel
But they will cost a bit.
cheers,
Sid
 
I will second Sidvee ie dont put any absorbers..if you feel there is an issue put a Diffuser ( egg crate ) and you can of course put a thin painting over that. problem with absorbers is that you do not control what they absorb (unless done by a specialist) and i usually find they start absorbing harmonics too and makes the sound lifeless in some form or the other
 
Hi,

Thank you for your suggestions. Idea of diffuser, instead of absorber sounds interesting. But the problem is how to hide the egg crates that I put on wall. I understand canvas is not a good idea, photo paper ... I am not sure.. what other options should I think of to hide the egg creates?

Thanks
Auro

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Auro,

Do you really need to use room treatments? Unless you have a proper idea of what you need to do, I would not recommend it. As Sid has pointed out, you may end up killing some frequencies. Anything you do will result in some change in sound but don't assume that a change is better.

From whatever I have seen of your room - it should sound pretty good. Invite an experienced room treatment expert first before doing anything.

Regards.
 
Hi,
Thank you all for your response.

Nikhil you have a very valid point here. I am not sure what difference will diffusers or absorbers is going to bring, hence wanted to experience that. Siva mentioned - move the sofa 2 feet away from back wall, or/and put an acoustic foam in back wall. But he mentioned to enjoy the music more than getting picky about room treatments.

My floor carpet is arriving this week. Let me experience with that only. For now I will probably shelve the idea of back wall acoustic foam.

Thanks a ton for your advices.

Thanks
Auro

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I thought it was a great idea. Having around 2-4 inch of rockwool and covering it with a print of an accoustically transparent tissue printed from your local printo with your favourite poster.
 
I'm not so sure with music but in HT, some absorption behind the speakers and probably behind your seating position works great for dialogue intelligibility. While i agree with the folks here that you aren't sure of what you'll get overall but one thing is for sure that voice frequencies will benefit from not having reverberations. This is a very subtle thing, one won't notice it until after putting absorption - without absorption, you are most often straining to understand the movie dialogues but after it is much more comprehensible.
 
Auro,

Download these test tones from here:
Sine Sweep - Full Spectrum (20 Hz - 20 kHz)

Run both the log sweep and linear sweep files. And as the website says. "When checking by ear, the sound should evolve smoothly from the lowest frequency to the highest. No strong frequency dips or peaks should be present."

Another very easy way to determine the sound in your room is to play some pure male vocals. Our ears are very "dialed in" to vocals so you will hear straightaway if there is something wrong. If you don't hear anything too bad then chances are your system should be fine for 90% of the music you will be listening to.

The carpet will clean up sound in the HF range. Highly recommended and you will find listening more relaxed in long listening sessions.

The most difficult sound to tame is if you have problems with LF. Typically you will hear some reverberations or rumbles in the 80Hz - 120Hz range. This will vary according to the speaker room interactions. Many initially like the sound of "bass" rumble but as you get more into sound quality you will realize that this eats into the clarity of the mids. A nice fix for this if you would like to try is to block the bass reflex ports using a rolled up hand towels. Try and see if you like the sound with this. However keep in mind that bass issues are very difficult to tame if you have a room issue.

Hope you find this useful. Keep in mind that what I have mentioned is keeping in mind that your system is in a hall/living room space. What you read online for dedicated listening rooms is a different ball game altogether.

Regards.
 
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Hi Auro,

A broad rule of thumb I've found is that an absorber will give you a more focused soundstage while a diffuser (behind the speakers) will deepen the stage going further back from the speakers and make it bigger. I had a wall to wall bookshelf that worked wonders earlier. In your room some open bookshelves with books should work wonders for breaking up that flat wall. Maybe two standing shelves one each behind the speakers and a couple or one shelf of books above the TV. In the absence of proper absorption (for frequencies), diffusion works far better (you won't make it worse). You get a lot of these fancy designed book wall racks also on urban ladder etc. A few of these to treat the wall behind the listening position too. Both should work together to add up for you.

Regards
 
Last edited:
Nikhil said:
Auro,

Download these test tones from here:
Sine Sweep - Full Spectrum (20 Hz - 20 kHz)

Run both the log sweep and linear sweep files. And as the website says. "When checking by ear, the sound should evolve smoothly from the lowest frequency to the highest. No strong frequency dips or peaks should be present."

Another very easy way to determine the sound in your room is to play some pure male vocals. Our ears are very "dialed in" to vocals so you will hear straightaway if there is something wrong. If you don't hear anything too bad then chances are your system should be fine for 90% of the music you will be listening to.

The carpet will clean up sound in the HF range. Highly recommended and you will find listening more relaxed in long listening sessions.

The most difficult sound to tame is if you have problems with LF. Typically you will hear some reverberations or rumbles in the 80Hz - 120Hz range. This will vary according to the speaker room interactions. Many initially like the sound of "bass" rumble but as you get more into sound quality you will realize that this eats into the clarity of the mids. A nice fix for this if you would like to try is to block the bass reflex ports using a rolled up hand towels. Try and see if you like the sound with this. However keep in mind that bass issues are very difficult to tame if you have a room issue.

Hope you find this useful. Keep in mind that what I have mentioned is keeping in mind that your system is in a hall/living room space. What you read online for dedicated listening rooms is a different ball game altogether.

Regards.
Click to expand...

Some time ago, i did exactly this in my HT when i bought a new receiver (Pioneer 930). I could isolate the problem frequency in my room immediately. I think it was in the range of 40+ HZ or something. The room would rumble uncontrollably and boom. If i placed the sub in another position, the freq would shift. So i did the next best thing. I used the receiver's subwoofer's eq to reduce the emphasis in that freq range - the boom disappeared. I may miss some action in that freq range but at least it won't give me a headache
 
Without disrespect to anyone, just putting random objects, including household objects as acoustic treatments will have some impact but will be totally unscientific and equivalent to a guesstimate or a shot in the dark. If your ears like it - great, but when one can spend lakhs on equipment, by listening to them with the same ears, why not spend half or 1 of those on the most important component of all - the room - regardless of whether it is dedicated or a common room. Spend some time to measure the room, recognize where the issues are and try to specifically address those areas by proper acoustic treatment panels etc, that have validated laboratory measurements. This will pay far more dividends in sound quality, resolution, imaging, soundstaging, tonality etc than spending on equipment. Typical Indian construction with all its hard reflective surfaces is very detrimental to good sound, first that has to be tackled even before considering multi-lakh equipment - which is akin to putting the cart before the horse. Anyways I am not an expert by any means but just my thoughts, perhaps I am wrong.
Cheers,
Sid
 
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Hi,

This is turning out to be an interesting thread. Lots of knowledge gain for me. Thank you for sharing your expertise.

I have got 5x7 ft shaggy carpet today AVIRA HOME BEIGE SHAGGY CARPET-5x7 Feet https://www.amazon.in/dp/B015CW0Q22/ref=cm_sw_r_cp_apa_1ypbybH7BWSRZ , placed it 1 ft away from speakers, and it ran till my sofa.
a7baff64e57e077b09f7c8a5d3f6c211.jpg


I listened to male vocal, guiter, drums and I find the sound now has little less brightness, drums sounds are more strong, cymbals brightness is reduced and little more warm. I liked it. Listened for about 2 hours, and the sound is more comforting now to my ears. I had to turn the volume about 10% more, to hear the details in low frequencies which was clearer without the carpet. For the first time my neighbors complained :)

Anyway, I guess for now I will stay with the comfort listening that the introduction of the carpet has brought. I may not be able to turn the volume to 40% though, 30% volume on 75 watt 89 db sensitivity of AP amp in my 14 by 22 ft room is good enough.

Thanks
Auro

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