You are here

DIY acoustic treatment.

Customising, building or repairing your own gear? Need help with acoustic treatment or soundproofing? Ask away…

Re: DIY acoustic treatment.

Postby thefruitfarmer » Tue Dec 14, 2004 9:09 pm




“I don't have any 1.25" thickness RW6 data but Bob Gold's absorption data sheet
bobgolds.com
shows 2" RW6 flat to the wall as dropping off a cliff between 250 Hz and 125 Hz... so I reckon 1.25" flat on the wall don't do much at all on your LF resonances.”


These 30mm panels were never intended to treat the LF……and like you say they don't.

Incidently, Rockwool are selling something rather similar…… Rockwool (click on the “reverberation” link for the pdf)…

“OTOH 2" RW6 with a 12" gap aint too shabby for LF.... so I would surmise that air gap can significantly improve LF performance in this material.”

The 100mm traps across 6 tri-corners, 2 wall/ceiling corners and 2 wall/wall corners has a gap of 13” at the maximum point. These eat up the bass.


“Also, as described previously in this thread, if you could get a full ceiling treatment system of some kind, that would really help. In a room this small, that is the first thing I would have done... getting a small room to work at high SPL aint trivial. I am given to understand from Paul [who's ears I probably trust more than my own] that Mark did it, but twern't easily done.”

Interesting that, the more I think about it the less of a PITA a ceiling job seems to be and it would have the advantage of keeping more floor space too. The ceiling could come down a little (only a 6” gap between ceiling and top of window though) and this would also have the advantage of making the room not a 8’6” cube. I would expect that less bass trapping would therefore be necessary after installing a lowered ceiling. However, there would be less room for the bass traps so the whole plan could backfire if the amount of trapping required exceeded the now reduced space to put it in.

I would n’t like to predict the results, despite liking the idea with its potential to create a more ergonomic room…..

…….and that rockwool is nasty and itchy stuff to work with so I think I’ll stay with what I have for now.
User avatar
thefruitfarmer
Frequent Poster
Posts: 638
Joined: Wed Sep 01, 2004 12:00 am
Location: Kent UK

Re: DIY acoustic treatment.

Postby Studio Support Gnome » Tue Dec 14, 2004 11:05 pm

Foz wrote:Replying to various points from various folks:

1) Rockwool and fiberglass are both utterly inert materials [basically sand] - getting all worked up and pretending they are harzardous materilas is a waste of time... more fun to worry about Aluminium cookware IMO. The stuff is very scratchy, and long sleeves are definately reccomended... full hazmat suits are not a benefit to the process [unless you think they are sexy]. Paying attention to this advice may save you some discomfort, but it may also waste an absurd amount of time and trouble... use you common sense. If these materials were not safe, all construction sites would be hazardous waste zones, and all modern buildings would need to be unihabitable.

Avoided contact is a good idea but don't start pretendeing you are dealing with plutonium. Having working in the boat building trade I have more than a passing acquaintance mineral fiber [I have been covered head to toe in its dust from ginding hulls moer times than I can count]. The stuff will cover you in tiny cuts (it is like glass) and these take a couple days to heal and leave your skin and throat feeling raw and prickily. All in all it a great idea to keep it off your skin, but it aint that big a deal.. not near as bad as getting wet concrete all over yourself [now that will stuff will tear you up and leave you miserable] just because a material is abrasive doe snot mean it is hazardous.. don't confuse the two concepts. Also, once set in place the material will not bother you.. you could put a stack of 703 in the corner of your bnedroom and it would never cause irritation ['cept maybe your spouse' bitching].

2) Backing boards, fabric covers, sticky sprays, elaborate fittings and fixtures are all meaningless from an acoustic stand point... if not required to meet your aesthetics (or tin foil hat hazardoius material fantasies) then skip these parts as much as possible.. they just waste time and money.

Good Luck!


Foz.

The irritation and tissue damage that can be caused by inhaling the small fibres, is not to be taken lightly.

Advising some otherwise is [irresponsible]. ***Edited for argumentative tone***

The stuff is not of itself carcinogenic or toxic, BUT the damage it can cause to soft tissue in the lungs can increase the likelihood of all sorts of unpleasant and often fatal illnesses. They can also trigger asthma attacks and other respiratory trauma.

I suggest you check your health and life insurance policies very carefully.... because self inflicted harm may not be covered, and it's possible that they may refuse to pay on that basis.

Insurance companies have used thinner excuses to renege on payment expectations ...
*** edited out pointless and argumentative bits ***

To quote Linus "Oh I love mankind alright, it's people I can't stand ! "
Max


***OI!, Max, Bloody well behave yourself and stop winding up the residents! You're making a fair and important point which, for the record, I completely agree with, but you're not making it like the polite, friendly and considerate chap I know you are. I know it's important and we share some very strong feelings on health and safety matters but you still need to make the point properly or you undermine it's validity.
Now be a good boy or Santa won't be bringing you a nice new PC to replace all those dodgy old Macs ;) :bouncy: 0VU :) ***
User avatar
Studio Support Gnome
Frequent Poster (Level2)
Posts: 2921
Joined: Tue Jul 22, 2003 12:00 am
Location: UK
Mostly Retired from Audio.... If I already know you I'll help,  if not....    Ask Hugh Robjohns, unless that is you're in need of 80's shred guitar... that, I'm still interested in having fun with...

Re: DIY acoustic treatment.

Postby thefruitfarmer » Wed Dec 15, 2004 11:54 am

c'mon OVU....... :roll:

What Max wrote (I read the "raw" version and it is n't that bad IMO) does n't need removing unless someone actually complains about it.

For the record I reckon Foz is right when he says we are not dealing with plutonium here. I made the panels and traps without a space suit, mask or gloves and I feel fine. The risks are not clearly established and I don't feel we need to panic quite yet. However, people used to inhale asbestos dust and work with it daily until the link with cancer was established in the 70's.

Thing is, I have done the work without taking precautions and at this point in the game I don't appreciate people hyping up the potential risk. If I was doing this again I would use a mask, gloves and hazmat suit. The fibres are itchy and burrow into the skin, stay on your clothes and get in your lungs. Although no sinister risk has been established I reckon it's worth using the safety clothing anyway to avoid the itching and extra individual washing of your regular clothes - especially if you are working with the stuff on a regular basis.

I am still waiting for Foz to reply with an alternative plan for an 8'6" cube room. So far he has posted the suggestion that I set the 30mm panels away from the wall (which is not really practical) and I reckon three panels on the wall absorbs as much as two panels set away from the wall, whilst taking up less space. I don't really know if the theory supports this assertion but I would like to find out. I would also like to know if ceiling treatment would be practical and whether the resulting reduced space in the room would be sufficient for adequate bass trapping.

I started this thread so anyone wishing to make their own DIY treatment would have a template they could use as a basis for their own treatment. I have taken a "suck it and see" approach and taken ideas from what people have used with success rather than calculating in theory what should work and then building to that specification. I don't reckon that theory can always be translated into the real world with complete accuracy either - as soon as you put a person and furniture in the room you affect the acoustics.

The system I have allowed me to install several panels and easily move them around and add more once I had listened to the room and decided on a second tweak. Treatment to the ceiling or stacking triangles of Rockwool in the corners would be somewhat more permanent and consequently more difficult to adjust. The fitting method I used means I don't have to count on my theoretical calculations making an accurate prediction (my physics and maths is okay but not up to graduate or professional level) for the real world.

At the moment there seems to be a great deal of people quoting figures and pretty graphs at each other and trying to decide whether data is valid or whether we have reached the boundary of physics . This is all very interesting in a way (I am following the infamous real traps thread as it goes) but this is not much use to people who want to treat their room without getting the calculator out.

I just want people with a working, practical or theoretical knowledge of acoustics to apply it to the real world situations, like my box room. This would helpful to those of us lacking that particular education when we want to make our own acoustic treatment without heading for disaster or expensive mistakes.

:angel:
User avatar
thefruitfarmer
Frequent Poster
Posts: 638
Joined: Wed Sep 01, 2004 12:00 am
Location: Kent UK

Re: DIY acoustic treatment.

Postby Paul Woodlock » Wed Dec 15, 2004 7:25 pm

thefruitfarmer wrote:......

I am still waiting for Foz to reply with an alternative plan for an 8'6" cube room. So far he has posted the suggestion that I set the 30mm panels away from the wall (which is not really practical) and I reckon three panels on the wall absorbs as much as two panels set away from the wall, whilst taking up less space. I don't really know if the theory supports this assertion but I would like to find out. I would also like to know if ceiling treatment would be practical and whether the resulting reduced space in the room would be sufficient for adequate bass trapping.

Greetings Grower and Harvester of Fruit :)

You could do worse than have a look at Mark Edmonds Studio Build Diary http://forum.studiotips.com/viewtopic.php?t=456

It sound absolutely great in there.




I started this thread so anyone wishing to make their own DIY treatment would have a template they could use as a basis for their own treatment. I have taken a "suck it and see" approach and taken ideas from what people have used with success rather than calculating in theory what should work and then building to that specification. I don't reckon that theory can always be translated into the real world with complete accuracy either - as soon as you put a person and furniture in the room you affect the acoustics.

The system I have allowed me to install several panels and easily move them around and add more once I had listened to the room and decided on a second tweak. Treatment to the ceiling or stacking triangles of Rockwool in the corners would be somewhat more permanent and consequently more difficult to adjust. The fitting method I used means I don't have to count on my theoretical calculations making an accurate prediction (my physics and maths is okay but not up to graduate or professional level) for the real world.

At the moment there seems to be a great deal of people quoting figures and pretty graphs at each other and trying to decide whether data is valid or whether we have reached the boundary of physics . This is all very interesting in a way (I am following the infamous real traps thread as it goes) but this is not much use to people who want to treat their room without getting the calculator out.

I just want people with a working, practical or theoretical knowledge of acoustics to apply it to the real world situations, like my box room. This would helpful to those of us lacking that particular education when we want to make our own acoustic treatment without heading for disaster or expensive mistakes.

:angel:

I disgagree the StudioTips 4 Devices Test Data isn't valid for real world use. You don't need a calculator. The data shows a valid comparison of two commercial devices and 2 DIY designs. Of course their are OTHER factors, than sheer acoustic absorption performance, when choosing a method, but absoprtion performance is important none the less.

Regarding practical applications. Corner wedge DIY broadband absorption, along with absoprtive panels on the walls/ceiling to diminish early reflections has bee shown to work in practise many times.

I would also like to know if ceiling treatment would be practical and whether the resulting reduced space in the room would be sufficient for adequate bass trapping.


Ceiling treatment ( assuming enough available height ) is great!

In fact in my studio build I don't have much height at all, so I am taking this approach......


From the listening position I am building a false ceiling that slopes downwards towards the front wall. No one can stand up in this area anyway, due to it being full of furniture ( DAW Workstaion to be exact ;) ), so the reduced height doesn't matter. This false ceiling will be full of rockwool. It will serve TWO purposes. The thicker rockwool above the false ceiling where the front wall meets the ceiling will be broadband standing wave trapping, and as the sloping ceiling gets higher towards the listening position, the rockwool here will serve as an early reflection absorber 'panel'


So to answer your above question, I would say that the ceiling treatment can be a part of the 'standing wave trapping treatment', and not something that leaves less room for trapping ( as I think? you were asking/indicating. I hesitate to use the word 'bass trapping' as standing waves can affect lo-mid performance as well. :)


Also it's a shame you can't put the Early reflection absorbing panels away from the wall a bit. Is space too tight to even put the 30mm panels so there's a 30mm airgap behind them. You'll lower the freqeuncy of efective absoprtion, plus incrasing absorption performance overall.

Bear in mind that when sound reflects off a wall, the velocity of the air particles is zero at the wall. So that absorption right at the walls surface for reflections is ineffective.

Just some thoughts :)


Paul
Paul Woodlock
Regular
Posts: 183
Joined: Tue Nov 23, 2004 1:00 am

Re: DIY acoustic treatment. *DELETED*

Postby Ethan Winer » Wed Dec 15, 2004 8:42 pm

***Content moved to new thread on standing waves here 0VU :)***
User avatar
Ethan Winer
Regular
Posts: 207
Joined: Tue Nov 19, 2002 1:00 am
Location: New Milford, CT USA

Re: DIY acoustic treatment.

Postby Paul Woodlock » Wed Dec 15, 2004 8:56 pm

***Content moved to new thread on standing waves here 0VU :)***
Paul Woodlock
Regular
Posts: 183
Joined: Tue Nov 23, 2004 1:00 am

Re: DIY acoustic treatment.

Postby Ethan Winer » Wed Dec 15, 2004 10:41 pm

***Content moved to new thread on standing waves here 0VU :)***
User avatar
Ethan Winer
Regular
Posts: 207
Joined: Tue Nov 19, 2002 1:00 am
Location: New Milford, CT USA

Re: DIY acoustic treatment.

Postby Guest » Wed Dec 15, 2004 10:53 pm

***Content moved to new thread on standing waves here 0VU :)***
Guest

Re: DIY acoustic treatment.

Postby Ethan Winer » Wed Dec 15, 2004 11:00 pm

***Content moved to new thread on standing waves here 0VU :)***
User avatar
Ethan Winer
Regular
Posts: 207
Joined: Tue Nov 19, 2002 1:00 am
Location: New Milford, CT USA

Re: DIY acoustic treatment.

Postby Guest » Wed Dec 15, 2004 11:09 pm

***Content moved to new thread on standing waves here 0VU :)***
Guest

Re: DIY acoustic treatment.

Postby Ethan Winer » Wed Dec 15, 2004 11:11 pm

***Content moved to new thread on standing waves here 0VU :)***
User avatar
Ethan Winer
Regular
Posts: 207
Joined: Tue Nov 19, 2002 1:00 am
Location: New Milford, CT USA

Re: DIY acoustic treatment.

Postby Paul Woodlock » Wed Dec 15, 2004 11:49 pm

***Content moved to new thread on standing waves here 0VU :)***
Paul Woodlock
Regular
Posts: 183
Joined: Tue Nov 23, 2004 1:00 am

Re: DIY acoustic treatment.

Postby Guest » Thu Dec 16, 2004 12:58 am

***Content moved to new thread on standing waves here 0VU :)***
Guest

Re: DIY acoustic treatment.

Postby thefruitfarmer » Thu Dec 16, 2004 1:33 am

Paul Woodlock

"Greetings Grower and Harvester of Fruit :)

You could do worse than have a look at Mark Edmonds Studio Build Diary http://forum.studiotips.com/viewtopic.php?t=456

It sound absolutely great in there."

Thanks Paul - I will have a look.

"I disgagree (that) the StudioTips 4 Devices Test Data isn't valid for real world use. You don't need a calculator. The data shows a valid comparison of two commercial devices and 2 DIY designs. Of course their are OTHER factors, than sheer acoustic absorption performance, when choosing a method, but absoprtion performance is important none the less."

I will have a look here as well.

"Regarding practical applications. Corner wedge DIY broadband absorption, along with absoprtive panels on the walls/ceiling to diminish early reflections has bee shown to work in practise many times.

Ceiling treatment ( assuming enough available height ) is great!

In fact in my studio build I don't have much height at all, so I am taking this approach......

From the listening position I am building a false ceiling that slopes downwards towards the front wall. No one can stand up in this area anyway, due to it being full of furniture ( DAW Workstaion to be exact ;) ), so the reduced height doesn't matter. This false ceiling will be full of rockwool. It will serve TWO purposes. The thicker rockwool above the false ceiling where the front wall meets the ceiling will be broadband standing wave trapping, and as the sloping ceiling gets higher towards the listening position, the rockwool here will serve as an early reflection absorber 'panel'

So to answer your above question, I would say that the ceiling treatment can be a part of the 'standing wave trapping treatment', and not something that leaves less room for trapping ( as I think? you were asking/indicating. I hesitate to use the word 'bass trapping' as standing waves can affect lo-mid performance as well. :)

Also it's a shame you can't put the Early reflection absorbing panels away from the wall a bit. Is space too tight to even put the 30mm panels so there's a 30mm airgap behind them. You'll lower the freqeuncy of efective absoprtion, plus incrasing absorption performance overall.

Bear in mind that when sound reflects off a wall, the velocity of the air particles is zero at the wall. So that absorption right at the walls surface for reflections is ineffective.

Just some thoughts :)


Paul"


Thanks for your constructive and practical suggestions, they make a lot of sense.

Maybe I will consider moving the panels away from the walls a little. The room sounds good as it is though so it may not be necessary but I may get some test tones and establish if another tweak is needed. Now everything is in place it will probably be possible.

:)

As for the rest of you, with your argument about standing waves, you can feck off to another thread. It really is turning into an argument about semantics and theory. Why does n't one of you start a thread called "what is a standing wave?" and continue the discussion over there?

:madas:

Anyway...the term "standing wave" is misleading as the pressure wave still moves through the air. If it did not then we would hear no sound. The practical point is that the energy from waves at certain frequencies (determined by the dimensions of the room) combines with itself resulting in notes at these frequencies sounding too loud. An effective acoustic treatment needs to absorb enough sound energy to result in a room that has an even response across the frequencies. There are various ways of doing this, which is what I am interested in.

:)
User avatar
thefruitfarmer
Frequent Poster
Posts: 638
Joined: Wed Sep 01, 2004 12:00 am
Location: Kent UK

Re: DIY acoustic treatment.

Postby Paul Woodlock » Thu Dec 16, 2004 2:04 am

Greetings James

Anyway...the term "standing wave" is misleading as the pressure wave still moves through the air. If it did not then we would hear no sound.


Sorry, but with a standing wave the various points of pressure remain at the same location. With a travelling wave, such as that in air caused by a vibrating speaker cone, the points of pressure move.


:)


Paul
Paul Woodlock
Regular
Posts: 183
Joined: Tue Nov 23, 2004 1:00 am

PreviousNext