fiberglass wool for acoustic panels

[rajesh srinivas]

hi everyone.

I have with me few bags of Fiber Glass wool for ht room treatment as per pics below.

Kindly let me know whether i can use the fiber glass as Acoustic sound Absorbers to Minimize Sound Reflections,

2. Also have namada (Jute fiber sheets) padding with me and also which is easily available at my place as rolls,can it be used for corner bass traps.

thanks
r.s

 

[keith_correa]

Are you sure that "Namda" is jute fibre? In Mumbai, wool felt is usually called "Namda". But the pic does not look like wool felt. Wool felt exhibits good sound absorption. Not sure about jute.

See if you can get resin bonded rockwool or fiberglass slabs. Works well.

 

[sound_cycle]

can it be used for corner bass traps

how low do you need to to get ?


from Bass Traps 101 - Your Guide to Corner Bass Trap Placement

Use the quarter wavelength rule to determine the best gap size for a given frequency:

Optimal Gap (feet) = Wavelength = (1125 / Frequency)

OR

Optimal Gap (meters) = Wavelength = (343 / Frequency)


Example 1: for a 200 Hz sound wave, the wavelength is 1125/200 = 5.6 feet. A quarter of that is 1.4 feet (0.43 meters).

Example 2: for a 60 Hz sound wave, the wavelength is 1125/60 = 18.8 feet. A quarter of that is 4.7 feet (1.43 meters).

and you would need to do something like this

see also http://audioundone.com/do-it-yourself-bass-traps

with the four inches type thickness that wifes and livestening rooms permit, there is no much bass absorbtion that is going to happen.

You should be thinking DRC if you want to/ need to really do something about your bass

edit : or may be you are thinking of broad band absorption ?

ciao
gr

 

[rajesh srinivas]

Are you sure that "Namda" is jute fibre? In Mumbai, wool felt is usually called "Namda". But the pic does not look like wool felt. Wool felt exhibits good sound absorption. Not sure about jute.

See if you can get resin bonded rockwool or fiberglass slabs. Works well.

hi keith

namda what i have is a made from 100% jute with wool felt,they were earlier used as a internal base for sofa sets and also as a base for typewriter machine,i will post a closer picture tomorrow.

It is also used as a damping material i have used them in my earlier boxes with good results.

my query is can i use the same for corner bass traps,since it is non toxic,not harmful and available at a cheaper rate...

i know Rockwool and still better glasswool (fiberglass) sheets are the best,but what i have is loose glass wool (not slab),they use is it as a cooling material behind glass panes in building complexes to control the sunlight heat from entering inside.

i had collected few bags of them when one building was getting renovated.
my question is so can i use them to control the sound reflection????.

 

[rajesh srinivas]

hi
thanks for providing all the details..

how low do you need to to get ?

1. may be 40 hz

2. The website you have given is a good learning for anyone who wants to tame the low freq,earlier i had gone through this site..

The formula to calculate the distance between the wall the absorptive material is a good way to go.

so if i choose my low freq as 40hz then the distance of gap should be 7feet...thats too much....

3.

You should be thinking DRC if you want to/ need to really do something about your bass

i am not in favour of DRC,since the original sound will be altered....and we wont get the full audio experience...

4.

edit : or may be you are thinking of broad band absorption ?

BBA is a good way but we have to consider the cost....

t.s

 

[sound_cycle]

1. may be 40 hz

How did you arrive at this number

Do you have a room mode at 40 Hz ?

Or maybe you heard some track that booms that low ? My speakers don't go that low. I measure only noise from other sources at < 45 Hz.

so if i choose my low freq as 40hz then the distance of gap should be 7feet...thats too much....

That's the physics of it.

i am not in favour of DRC,since the original sound will be altered....and we wont get the full audio experience...

Lol. Why ? How ?

Have you actually ever heard DRC in action. You are welcome to come over if you have not.

BBA is a good way but we have to consider the cost....

It is inexpensive. But it will do anything worthwhile only in the say 400Hz range or higher.

Use a room calculator, I like this one amroc - the room mode calculator

If you can BBBS a usb mic measure your room

If you currently do not have any treatment in your room you are likely than not, not listening to stereo sound. Your problems are likely not bass/ room modes alone but other uglier things as well easier to solve things too, placement, early reflections. If you have not already positioned your speakers with mm precision and toed them in right, you are probably way ahead of the script. If you have, thats good next step is acoustic string and a RFZ. BTW you know you can lessen the impact of roomboom by altering your listening/ speaker positions right ?

This audio thing sadly will not work without measuring it. It is an objective unforgiving beast, what you listen/ want to listen is very important, but you cannot ear it out.

If you have mic and a PC source, try out any of the trial DRC around. It will blow your mind if done right.

It is very easy to do it right.

And it is measurable, reproducible etyadi.

Finally you cannot or should not attempt a clutch change in your car with only a hammer. It is a versatile tool and I do not mean any offence to hammer owners. You would ideally use all required appropriate tools. you would need to use placement and low cunning, treatment and DRC. Any one of them alone is not likely to get your car running.

ciao
gr

 

[keith_correa]

With DRC you are not altering the original sound but you are preventing the original sound from being altered.

Would like to see clearer and close up pictures of that jute felt. Not because I will be able to answer your questions but because I'm just interested

 

[rajesh srinivas]

With DRC you are not altering the original sound but you are preventing the original sound from being altered.

Would like to see clearer and close up pictures of that jute felt. Not because I will be able to answer your questions but because I'm just interested

(DRC) or simply compression reduces the volume of loud sounds or amplifies quiet sounds by narrowing or compressing an audio signal's dynamic range.

But why would you require to do it,when the audio which is recorded by studio master in audio format like dts hd master or dolby true hd simply needs to be heard in its true or original form to get the real feeling of an home theatre experience????

i prefer to my audio listening to be original (studio recorded quality) without any changes...

i am enclosing some more pics of namda (jute wool) which can be used as diffusers or corner bass traps..

request hifi members to share there thoughts regarding its usability..

thanks
r.s

 

[rajesh srinivas]

hi sound

Do you have a room mode at 40 Hz ?

i havent done my room measurement yet just presumed it to be so...

Have you actually ever heard DRC in action. You are welcome to come over if you have not.

DRC is used basically to see that nothing gets louder while you are listening,it acts more like a compressor where an audio signal gets adjusted to individual likings///

With regard to hd movies the audio which we are suppose to listen as recorded by the studio master in its true/original form and to feel the real HT experience will be changed,for which i am against.I like to listen audio or video in its original form....

If you currently do not have any treatment in your room you are likely than not, not listening to stereo sound. Your problems are likely not bass/ room modes alone but other uglier things as well easier to solve things too, placement, early reflections. If you have not already positioned your speakers with mm precision and toed them in right, you are probably way ahead of the script. If you have, thats good next step is acoustic string and a RFZ. BTW you know you can lessen the impact of roomboom by altering your listening/ speaker positions right

I havent yet dont my room treatment,hence this thread for knowing if i can use
my available resources like loose glass wool,namda(jute felt) for my room acoustics.

i will post a separate thread showing the sketch of my ht room will need then a detailed
answer,steps,procedure,choice of materials etc. right from the scratch like you mentioned correction in bass and room modes,early reflections,exact speaker placements (lcr and surround) etc..to build a true HT..

r.s

 

[keith_correa]

Please read this about DRC.

Yeah, I like to listen to music in it's original form too. Unfortunately my room gets in the way.

 

[rajesh srinivas]

Please read this about DRC.

Yeah, I like to listen to music in it's original form too. Unfortunately my room gets in the way.

hi,
Best way to get the room's acoustics right is by
ARC Room treatments (installing absorption panels, diffusers, traps, etc.), if properly installed solves your purpose,then comes the digital correction though if required....

The draw back of DRC is it solves the problem at one location,one spot,,one person seated only..i.e.they set up the adjustment for that one place in the room,Not a good situation..

In your link its drawback is clearily given in the heading "CHALLENGES'..

Anyway its individuals choice to choose between ARC OR DRC and the way they like to listen.....

Have you seen the new pics any suggestions..i am thinking of using the loose glass wool as it will be more absorbent then the rigid fiberglass...
but not sure about namda (jute) whether it will act as a good basstrap..

t.s

 

[keith_correa]

All the best to you.

 

[koushik]

Rajesh, I second you. Acoustic treatment is hard to beat. It is when you have no option or way to implement them, then compromise with DRC.

Also, your observation about a single position correction is also very true in case of DRC.

 

[koushik]

Moreover, digital has no option to reduce amplitude of a signal. The only way it can reduce volume is by cutting bits, so you lose bits and hence the output is not bit perfect.

 

[sound_cycle]

Rajesh, I second you. Acoustic treatment is hard to beat. It is when you have no option or way to implement them, then compromise with DRC.


Moreover, digital has no option to reduce amplitude of a signal. The only way it can reduce volume is by cutting bits, so you lose bits and hence the output is not bit perfect.

Come over - what you heard on your previous visit was just pure crap. A hint of the real sound did not exist then. And it was not really stereo we were listening to that day.

As for DRC being a compromise you should read up the recent stuff.

I have no issue with anyone not wanting DRC. Or any opinion against. The "facts" posted are however incorrect

OP has got it very wrong. He can actually get a slightly bigger sweet spot with DRC. And It* would be easy even for someone who has actually not ever heard a good stereo image to set it up.

(edit: * measurements, DRC and a little RTFM)

My apologies for the directness/ bluntness. Absolutely no impoliteness is intended.

ciao
gr

 

[rajesh srinivas]

Moreover, digital has no option to reduce amplitude of a signal. The only way it can reduce volume is by cutting bits, so you lose bits and hence the output is not bit perfect.

hi koushik,

so true to what you say...

What ever i have written are facts about DRC,it does RC but with drawbacks,I am not against nor degrading sound_cycle efforts in implementing and
testing it..may be to his success.

But instead of that what i suggest is the ""REW""..more details link as below,

REW - Room EQ Wizard Room Acoustics Software

more here

REW Forum at Home Theater Forum and Systems - HomeTheaterShack.com

There is no better way to correct your HT room with a combination of REW and corresponding measured acoustic panels....should definitely get a flat frequency response throught the room.

r.s

 

[sound_cycle]

hi koushik,

so true to what you say...

]What ever i have written are facts about DRC

But instead of that what i suggest is the ""REW""..more details link as below,

r.s

Ummm thanks for the heads up.

Please read up and inform yourself.

REW was what I tried first - documented and described here in hfv as well., REW is great at many things. Not at DRC. and the plugin for fb2k is downright useless.

Thanks. And atvb with your efforts.

and if you want to to claim hope misunderstanding or misrepresentation and then repeating it make up fact, i politely disagree and call you out on that.

FTR out of this thread

 

[koushik]

REW was what I tried first - documented and described here in hfv as well., REW is great at many things. Not at DRC. and the plugin for fb2k is downright useless.

I think Rajesh is not mentioning about DRC, as he is not DRC believer. He is talking about the waterfall graph that REW produces and treating the room accordingly.

 

[rajesh srinivas]

I think Rajesh is not mentioning about DRC, as he is not DRC believer. He is talking about the waterfall graph that REW produces and treating the room accordingly.

Hi Koushik

Been busy few days so couldnt reply to your post.

My post is only related to HT,not stereo Listening....

Yes if i use REW if need arises it will be Only to know about the current frequency response in your room and apply corrections needed so that you can correct it by adding acoustic treatments..

More observations towards drawbacks of REW/DRC (with digital EQ) and advantages of room acoustics.

1. As i already mentioned earlier,Room treatment will solve the room modes for all the seats whereas EQ will solve it for a position provided you take measurement at many locations,though its an uphill task and also to adjust the EQ filter settings for different locations is very difficult.
2. whatever peaks/dips corrected by EQ, it will be added at some other location. There are also limitations how much boosting can be done by EQ. Many eq programs will limit to 6~8 db max as it can cause amp clipping. Room treatment does not limit yourself in this regard, however it can limit how much treatments can be added.
3. Digital correction can only solve/address to the frequency problems in the room but cannot solve "time domain issues", i.e issues with when different parts of the sound reach the ear, and these cannot be fixed except through acoustic treatment...

So i feel is to use DRC only for analysing things and acoustics for correcting them...

If you properly set and do your room acoustics correctly then that can be a permanent solution to feel/hear/listen or can even see the sound as intended in its true form.

Home Theatre is nothing but having a movie theatre at your home to view and listen to sound the same way as we do it in real theatre..

I firmly believe that movie Theatres only do there acoustics correction with wall treatments,never in digital way...so this will be the base for projecting any movies..

Same way HT should be designed and built so that there is no need to frequently tweak/adjust/tune your digital EQfilters to either cut or boost the frequencies according to your room modes for each and every movie...
more so it will be like a situation where your mind will always be focused towards corrections rather then to get immersed in the movie...

sorry for being very elaborative since i wanted to share my knowledge and experience with everyone to let them know the advantages and drawbacks between ARC VS DRC...

i can conclude this by saying ARC - permanent solution, DRC- never ending solutiion..

Few HIFI LINKS for the same issues..

http://www.hifivision.com/av-enhancers-room-acoustics/41862-acoustic-treatment-vs-digital-room-correction-equalizers.html


http://www.hifivision.com/speakers/60428-considering-room-anomalies-speaker-design.html


thanks
R.S