Rockwool vs sand as filler for bass traps

[Bluu]

Wow, rockwool/glasswool is completely out of question. I have a baby and a dog at home and I cannot imagine that this stuff can be good for them.

Sunil - While I agree that a DIY effort will be more economical, I have neither the wherewithal nor the time to diligently fabricate a trap. I'm still hopeful that furniture and other household embellishments will help fix the issue.

Nick - Your foolishness is welcome in any thread! :lol:

Sid - Thanks for the inputs. The link you posted is the exact one I looked at which led to this thread.

As far as I can see, using sand seems much safer. However, the results are not predictable because I don't think anyone here has used sand before. Secondly, sand can be a pain to clean in case of spillage and the trap will also be very heavy.

So, I'm going back to Shivam's recommendations of breaking large surfaces. I will try to source inexpensive corner pieces to break the corners of the room.

 

[captrajesh]

I know that sand is excellent in damping resonating surfaces but am skeptical of it being capable of gobbling up bass overhang.

Sound energy is a wave form i.e. has frequency & amplitude. The boom is on account of the low frequency waves getting reflected off the room corners & forming a separate wave form which would travel back & forth, which we perceive as boom. The only way to reduce (not eliminate, you can't) is to reduce the amplitude progressively. The cheapest way to do this would be (IMHO) to hang thick fabric diagonally behind the speakers as sound wave's amplitude would weaken considerably if it is to propogate through different mediums. I recollect experiencing this at one me our FM's place when the boom disappeared instantly when he hung a turkey towel besides his right speaker which was positioned bang in front of a room corner.

 

[Bluu]

Thanks Capt sir.

I have another question about this. My speakers are toed-in quite a bit to get the imaging correct. Could that be causing any of this boominess? The rear-firing ports are pointing at the wall corners as a result of the toe-in.

I'm going to put a stack of newspapers on the left wall corner tonight to see if its any better.

 

[pdhanwada]

Thanks Capt sir.

I have another question about this. My speakers are toed-in quite a bit to get the imaging correct. Could that be causing any of this boominess? The rear-firing ports are pointing at the wall corners as a result of the toe-in.

I'm going to put a stack of newspapers on the left wall corner tonight to see if its any better.

Bass frequencies below 125 HZ are omni directional meaning they are spherical waves. I dont think toeing of the speakers has effect on boominess.

Thanks
pandu

 

[captrajesh]

My speakers are toed-in quite a bit to get the imaging correct. Could that be causing any of this boominess? The rear-firing ports are pointing at the wall corners as a result of the toe-in.

The toe in is not going to influence the quantum of bass overhang.

Bass frequencies below 125 HZ are omni directional meaning they are spherical waves.

AFAIK, all waves are spherical and propagate akin to the waves created by throwing a stone in the stationary pool of water. We cannot perceive the direction because the wavelength is too big for our ears to sense the direction.

 

[Bluu]

Are there safer substitutes to glasswool? Sand seems to not be the answer here. What are my other options? Will a corner piece comprising of a wooden frame, filled with an agent (to be decided) and covered with an Auralex (6x3) panel solve all these issues?

Aren't there any simpler things that can be stuffed into a frame in place of glasswool? Something like foam/the soft thing in cushions/pillows? Sorry if this is completely wrong

 

[pdhanwada]

Are there safer substitutes to glasswool? Sand seems to not be the answer here. What are my other options? Will a corner piece comprising of a wooden frame, filled with an agent (to be decided) and covered with an Auralex (6x3) panel solve all these issues?

Aren't there any simpler things that can be stuffed into a frame in place of glasswool? Something like foam/the soft thing in cushions/pillows? Sorry if this is completely wrong

Bluu,

I was in the same situation when did DIY bass traps. Tried to research for material which can be used for bass traps other than rock wool and glasswool. I went thru All the AVS forum threads and gearslutz.com forum threads. Did not find any.

May be SIDvee can put his insight into this.

Unfortunately unlike in US we dont have any commercially available bass traps available. We are forced to DIY.

Santosh was talking about stacking triangular anutone boards in the corner. I would think it would be significantly costly.

I remember Himadri using rockwool for triangular corner bass traps. You can check with him about his experiances.


As Sidvee said in his earlier post, putting it together is a problem. Once you close the cabinets, I guess you should fine. Thats what I see now in my theater.

One other precaution you can take is cover the mouth with a plasticsheet then bass traps become non porus to the inhabitants.

Thanks
Pandu

 

[t.antony]

...
I'm going to put a stack of newspapers on the left wall corner tonight to see if its any better.

I had few experiments with a 3 feet tall newspaper bundle in the room corner and experienced some encouraging results around the 120Hz region. I wanted to keep it there permanently but wify had other ideas. I am keeping a shoe rack at that spot now.

I recollect some experiences where my powdered-clay filled speaker stands did act as low freq bass traps when placed at certain locations in the rooms. Powdered clay is denser and heavier than sand, IMO the sand column could also do a good job in converting the low frequency energy into heat.

I am thinking about making few diwan style sand pillows made out of empty cement sacks

 

[Bluu]

If glasswool is the only solution then I will need to get the work done outside my home and ensure that the cabinets are sealed.

Newspaper stack might work but will look fugly. If it does work, cant I just use a shredder to shred it and then use it as a stuffing agent?

 

[sidvee]

Bluu,

I was in the same situation when did DIY bass traps. Tried to research for material which can be used for bass traps other than rock wool and glasswool. I went thru All the AVS forum threads and gearslutz.com forum threads. Did not find any.

May be SIDvee can put his insight into this.

I am afraid Pandu is quite right Bluu. The best method is rock or glass wool. Another options is Owens Corning 703/704 (not too sure about the models, some are denser and thicker) rigid pink fiberglass, but I am not sure they are available here. Secondly you have to remember that whatever you use should have broad band absorption, meaning if it absorbs some frequencies and reflects others, then you will have peaks in other frequencies. Hence the best approach, at-least IMO, is graph a basic measurement of your room response (all you need are test signals - downloadable) and a db meter (iphone app. also should work) from your listening position - this will give you good picture of your room curve. Then as you add treatments (whatever they may-be, newspapers, rock wool or sand), repeat the test and you can see the peaks getting tamed - you can add more or less treatments and hear what works for you. Of-course the db meter may not be very accurate, but still IMO it is better than doing it by ear. Evidently the goal would be to get a fairly flat response from approx. about 40 hz (depending upon your speakers) to 15,000 khz with +-2 or 3 db variation and smooth response as opposed to sudden rises and drops.
Cheers,
Sid

 

[Bluu]

I'm downloading a dB meter for my Android phone. Will run some tests and post the results for the experts to comment on.

 

[pdhanwada]

If choosing between rockwool vs glasswool

I would pick rockwool because of two reasons

1. it is cheap
2. Based the study done safetey of rockwool > glasswool

The Comparative Safety of Rockwool, Fiberglass, and Organic Fibers (a review) - Gearslutz.com

Thanks
pandu

 

[Bluu]

I will try to find some dealers for rockwool in Bangalore and see. Just so I don't get cheated, how much does it cost?

 

[pdhanwada]

I will try to find some dealers for rockwool in Bangalore and see. Just so I don't get cheated, how much does it cost?

It is not very expensive.

First try to find out the quantity required in cu ft. Based on that you can check with your dealers.

I used the 96 kg/cu m material.

The labour costs for cabinet, plywood for the cabinets were more expensive than the rockwool itself.

I guess Rockwool by itself costed me less than Rs 7000. Again it depends on how much you need.

Thanks
pandu

 

[Thad E Ginathom]

One other precaution you can take is cover the mouth with a plasticsheet ...

Another detail to add to my mental picture of Bluu listening to music!

But, returning to sanity

How much can be done with furniture? Would a soft chair be any good, compared, say to the three-foot stack of newspaper?

 

[pdhanwada]

Another detail to add to my mental picture of Bluu listening to music!

But, returning to sanity

How much can be done with furniture? Would a soft chair be any good, compared, say to the three-foot stack of newspaper?

I meant the mouth of the cabinet not the listner's mouth.

 

[santhosh]

Missed this thread somehow. Very informative *rates 5 star*

I will try to find some dealers for rockwool in Bangalore and see. Just so I don't get cheated, how much does it cost?

Hi Ayush,
This thread has some info on vendors dealing in acoustic materials:
http://www.hifivision.com/av-enhanc...oustic-tiles-materials-vendors-directory.html

 

[Bluu]

Another detail to add to my mental picture of Bluu listening to music!

But, returning to sanity

How much can be done with furniture? Would a soft chair be any good, compared, say to the three-foot stack of newspaper?

LOL!

I did not find time yesterday to try this but the plan is to put some furniture against the bare wall on the left side and some newspapers and cushions against the left corner.

----------

I noticed something yesterday which I thought I should bring up. Have you guys heard of a concept called "sympathetic detonation"? Basically refers to a military idea which says that if there are two explosives placed near one another and one is detonated, there is a good chance that the second one will also go off. Hence, sympathetic detonation.

The reason I brought this up is because I realized that I have an old sub-woofer belonging to my Cambridge Soundworks speaker set lying in the left corner of the room (behind the left speaker). Could this be causing/accentuating the boom? Maybe the sub is passively contributing?

Obviously, I will try to remove and see if it makes any difference but I want to know if something like that is even possible.

 

[malvai]

LOL!

Could this be causing/accentuating the boom? Maybe the sub is passively contributing?

Obviously, I will try to remove and see if it makes any difference but I want to know if something like that is even possible.

I am not sure if it is causing the boom, but it would surely muddy up your LF. try it out. the sound will clear up considerably.