DIY Room Accoustics for Home-Theatre

[sash]

Hi audiohead,

Interesting post.

Incidentally, I have personally designed and implemented the acoustic treatment in my room. I have use Medium density Fibre wool on the walls and part of the ceiling.....

Care has been taken to have a mix of absorptive and reflective surfaces..... diffusers on the 1st reflection points on the wall and behind the listener.

No corner bass traps used.

I love Bass and I know its VERY VERY diffficult to tame bass and get it right. Most audiophiles cop out and set up systems which are bass shy..... a pity...

I have Very large Floor standing speakers ( each with 3 nos 8 inch woofers ! ) and a rather small room ( 14.5 ft length x 10.5 feet width x 9 feet height). Amplification is 400 Watts per channel into these speakers using mono blocks. The sound level reproduced are pretty high, if the mood calls for it.

It may seem like an impossible task, but Fibre wool ( 3 inch thick with a 3 inch air gap before the wall ) has done wonders !

You are welcome for a listen, since you too are in Mumbai...

@IndianEars would you be able to post some pictures? Both of the speakers and of the traps/wall treatments. Would love to take a look.

 

[IndianEars]

Thanks for your interest sash.

I had posted pics eons ago.

Will dig out and see what i can do.

I am not good a posting pics ( never seem to show up... )

Worst case I will put in my Drop Box and post links..... probably over he weekend.

 

[Arunshenoy]

Hi Shelley,
Really impressed by your Research and DIY skills. I am also planning to build my HT. My room dimension is 18X15X10. I am planning to put 25mm wood wool in the frame leaving 12mm space between the wall and cover the frame with grey colour Carpet cloth which is used for speaker boxes and also in cinema hall walls.
Anybody Please advice me. Thank you in advance.

 

[audiohead]

Hi audiohead,

Interesting post.

Incidentally, I have personally designed and implemented the acoustic treatment in my room. I have use Medium density Fibre wool on the walls and part of the ceiling.....

Care has been taken to have a mix of absorptive and reflective surfaces..... diffusers on the 1st reflection points on the wall and behind the listener.

No corner bass traps used.

I love Bass and I know its VERY VERY diffficult to tame bass and get it right. Most audiophiles cop out and set up systems which are bass shy..... a pity...

I have Very large Floor standing speakers ( each with 3 nos 8 inch woofers ! ) and a rather small room ( 14.5 ft length x 10.5 feet width x 9 feet height). Amplification is 400 Watts per channel into these speakers using mono blocks. The sound level reproduced are pretty high, if the mood calls for it.

It may seem like an impossible task, but Fibre wool ( 3 inch thick with a 3 inch air gap before the wall ) has done wonders !

You are welcome for a listen, since you too are in Mumbai...

Hi, can you give more specifications about the density of the fiber wool, what material did u use to make the traps ply / wood or something else.
Also please share what prime number did u make the diffuser for also if its a standard built or built to trigger particular frequencies.
Also if you could share the pics of the traps, diffusers and absorbers you built would be great too.

I was also wondering if you used 3 inch thick glass wool for bass traps or broadband absorbers.

Please share all the info.

Thanks

 

[sdurani]

I am planning to put 25mm wood wool in the frame leaving 12mm space between the wall...
Anybody Please advice me.

25mm of absorption is so thin that it will only absorb the high frequencies and sound the same as turning down the treble knob on your receiver.

If you are going to absorb, then you should make the absorbers broadband (absorb equally at all frequencies down to about 200Hz). This way, the panels won't act like a tone control.

To get broadband absorption, the panels need to be at least 150mm thick. Or, if you want to save some money, make them 100mm thick and mount them with a 100mm air gap between the wall.

 

[audiohead]

25mm of absorption is so thin that it will only absorb the high frequencies and sound the same as turning down the treble knob on your receiver.

If you are going to absorb, then you should make the absorbers broadband (absorb equally at all frequencies down to about 200Hz). This way, the panels won't act like a tone control.

To get broadband absorption, the panels need to be at least 150mm thick. Or, if you want to save some money, make them 100mm thick and mount them with a 100mm air gap between the wall.

I would agree to disagree!, broadband absorbers and bass traps are 2 completely different things with different functions and purpose.

While bass traps are used for absorbing low frequencies from 20hz - 120hz(With Membrane inside) , the broadband absorbers are used for absorbing high and mid range frequencies.

With a 50mm insulation you can make a broadband absorber and with 100mm insulation u can possibly achieve those 250hz above frequencies.

To absorb them 40hz - 120hz frequencies you would have to build a bass trap with a membrane inside and a vacuum box also leaving a cavity in between the bass trap and the wall of around 50mm depending on the room size and /or if its a tri trap or a regular bass trap.

And honestly there is no difference between 100mm or 150mm cause u definitely need the membrane inside the bass trap, 150mm insulation would do exactly what the 100mm insulation would and i speak here from experience.

Also im talking about at least 96kg/m3 density of glass wool only, not rock wool! (Preferably Owens Corning 705's)

Besides, these days there are a lot of new synthetic absorptive material that one can sandwich between the traps and absorbers but you still wont be able to achieve the results to equal up to a bass trap with a membrane.

The bad side of DIY traps and absorbers, one would never be able to test them NRC for the build. The tests itself cost about 30k per test, you can always Mode test your room before the installation and after to check the absorbed frequencies but then again how many here have the knowledge or the time for that matter.

People spend lacs in pro audio gear, but little did they know about room acoustics? You can buy that denon 300k amp for your home theater but if your room is not acoustically right then what good is it?

So i would suggest to find a professional in room acoustics who would charge you a bomb or find some one like these guys cueacoustics.in who manufacture ready to use acoustical products or go the DIY way and buy that expensive home theater system and save on the acoustics, the choice is yours.

Sound is perceived, its a perception of a human mind.

P.S. : I have no affiliation with the manufacturer i mentioned earlier, it was for info purpose only.

 

[sdurani]

I would agree to disagree!, broadband absorbers and bass traps are 2 completely different things with different functions and purpose.

Where did I ever mention "bass traps" in my post that you quoted?

 

[sdurani]

I have no affiliation with the manufacturer i mentioned earlier

Then why do you keep mentioning them in almost every post?

 

[audiohead]

My bad about the bass traps, no offense to you.

The only reason i mentioned that is cause of my experience with them and their stuff is really good, that was for everyone's info!

 

[Soundstage]

My bad about the bass traps, no offense to you.

The only reason i mentioned that is cause of my experience with them and their stuff is really good, that was for everyone's info!

Sir,

I do not know about the quality of the stuff sold by Cue Acoustics, but they seem to be pretty tardy when it comes to responding to prospective customers.

I spoke to them on the evening of 05 Dec for a quotation in connection with their bass traps and at their request promptly texted them my email id. 5 days have gone by and I am yet to hear from them. And yes, I also texted them a reminder on 08 Dec.

 

[audiohead]

Sir,

I do not know about the quality of the stuff sold by Cue Acoustics, but they seem to be pretty tardy when it comes to responding to prospective customers.

I spoke to them on the evening of 05 Dec for a quotation in connection with their bass traps and at their request promptly texted them my email id. 5 days have gone by and I am yet to hear from them. And yes, I also texted them a reminder on 08 Dec.

Sir,

I cant comment on that cause they were pretty prompt when i contacted them, though it took 7 business days for the shipment to reach me but they did mention that on the time of purchase.

Are you making a listening room or a home theater?

 

[Soundstage]

Sir,

I cant comment on that cause they were pretty prompt when i contacted them, though it took 7 business days for the shipment to reach me but they did mention that on the time of purchase.

Are you making a listening room or a home theater?

Sir,

Within minutes of me posting the above, I received a call from Mr. Amit, the representative of Cue Acoustics I had spoken to on 05 Dec. He apologised for not sending the promised quote as "one of his colleagues had passed away and he had been quite busy on that account".

Pardon me for saying so, but the logical inference to be drawn from this rather uncanny coincidence is that either you are in close contact with Cue Acoustics, which is contrary to your repeated declarations of not being affiliated or associated with them in any manner,

or,

You happen to be Mr. Amit of Cue Acoustics yourself, which is even worse, as you are resorting to subterfuge in promoting Cue Acoustic products on this forum.

 

[audiohead]

Ok this is getting weirder, my intent was simple to help people out there who have been struggling with the same issues as i was. Let me make things clear, i came across this forum only about 3 weeks back and that was because i was looking online for acoustic solutions. I have spent about 6 months trying to look for acoustic panels for my production room, i tried all the international brands that had their sellers in India and was disappointed with the prices i was offered eg. i was given a ridiculous price of 39,500 INR for a primacoustic bass trap. I then realized that i wasnt gonna get it cheap and i couldnt afford what was being offered from the international brands.

I tried looking for people in India who made acoustic panels and was again given a price of 36,000 INR. I really didnt know what to do about this situation so i started looking online on DIY traps and panels, i found out about rockwool and starting inquiring about it from different manufacturers and sellers and realized that none of them were ready to entertain me as my order was one bag only and they wouldnt supply a single bag which was also way more than i was looking for. I then tried looking for foam manufacturers in India and faced the same problem though i was lucky in 1 instant and found one manufacturer who was ready to send me a 1 meter sheet of foam from Delhi which costed me 4,920 INR in total to be precise. The foam was the worst than it looked in the picture that was on their website, i couldnt stick it to the walls it kept falling for some reason even when i used industrial glue, the foam also started loosing color in about a 2 weeks time and looked ugly. I had to then take down the foam and start hunting again for panels.

I was back looking for rockwool once again tried to find as much info as possible, in this process i also came across a lot of scammers. I was scammed by some one in chennai who gave me 8 bass traps + 10 absorbers for 18000 INR, i knew the deal was too good to be true and something somewhere was a miss. I still went ahead with the deal and sent the money to that persons account and he did send me the stuff btw he didnt mention that i had to take care of the freight as well which turned out to be 2,200 INR and i had to bear it. So the traps that arrived were 2 inch thick but looked good,they were easy to hang cause the had the conventional ear hanger. In 3 months the cloth had become loose and things from inside were now starting to fall out, the rockwool was in powder form and i had to throw the panel.

After a number of disappointing incidents i came across these guys from cue on shopclues.com, i was sceptical at first but since shopclues was involved and had a 30 day return policy and i had no where else to go i went ahead and bought one panel and was really surprised when it arrived. It looked pretty, i then tried to contact these guys who were very helpful and sent someone over for a free room test and then its as follows.

I agree i should have not mentioned them so much but i was excited about the panels and so went ranting to everyone who had the same problem. I have been banned before from different forums for taking brand names hence i was careful to mention about the affiliation bit. I hope this is enough explanation.


***DIY Bass Traps***Just found this pdf for membrane traps***

 

[sdurani]

Another post and yet another mention of the same company. Borderline compulsive.

 

[audiohead]

Ok! im done! no more post related to acoustic panels whatsoever!!!!

 

[Santy]

I cant comment on that cause they were pretty prompt when i contacted them, though it took 7 business days for the shipment to reach me but they did mention that on the time of purchase.

After a number of disappointing incidents i came across these guys from cue on shopclues.com, i was sceptical at first but since shopclues was involved and had a 30 day return policy and i had no where else to go i went ahead and bought one panel and was really surprised when it arrived.

In the first post, you mentioned that you bought from CueAcoustics directly and that the shipment reached in 7 days but in the post that followed, you say that you ordered on shopclues.com. OK we understand they were different orders.

Sir, had you registered here as a dealer (in case you are not aware, there is a paid option) instead of camouflaging yourself as a consumer, members would have appreciated your knowledge and recommendations even if they were biased towards your brand. What you are doing now will only backfire on you. People here I believe are matured enough to smell advertising. Sorry if it was harsh but I believe there are better ways of promotion though they may not be as cheap.