Sound Proofing Advice

[haygeebaby]

Greetings all - this is my first post - I've been lurking around and reading and absorbing all the great information and advice on the SNA forum. I want to get some ideas and advice on improving my room acoustics.

My listening room is about 4m long x 3m wide x 2.8m high. On one side of the 3m long wall is a window - the other side is the door to the room. The other 4m long wall is bare. All walls are double brick and plastered. There is carpet and a nice rug over the carpet as well.

A 42" plasma is mounted on the 4m long wall in the middle and I sit pretty much in the center of the room on a leather lazy boy - with the 5.1 speakers in the obvious layouts. I run both a HT setup and a stereo setup in the same area.

After reading some posts I decided to place an un-used bed matress on the rear bare wall, and placed a thick blanket over the plasma directly in front of the listening position. The imaging and clarity improved a great deal.

Rather than using the blanket and matress - I've decided to invest in some purpose built and eye pleasing alternatives. I'm thinking of purchasing the Soft Sound Pyramid Studio Foam for the back wall, and Soft Sound Anechoic Hanging Baffles to cover the front facing wall - from http://www.soundproofcow.com/

Can anyone comment on the use of these two products ? Or recommend similar or better products - preferably obtainable in Australia.

Thanks in advance.
Will post some pics as soon as I figure out how to.

Regards

Ken

[Keith_W]

Hi Ken, welcome to SNA! I bought my acoustic foam from studiocel, which is a Melbourne based company. They coat the foam with an attractive looking flock, so it doesn't look too out of place at home.

However, a quick google search reveals quite a few more suppliers. I was surprised to learn that Clark Rubber sells acoustic foam, and if it's typical Clark Rubber prices it will be very cheap.

You have to be aware that foam will selectively absorb some frequencies more than others. For example - unless you have really thick and dense foam, it will do nothing for bass frequencies. Therefore, overtreating your room with foam replaces one type of coloration for another.

I'm not saying don't do it - by all means do it. Short of changing my speakers, adding foam has made the biggest difference to my sound. But as always, final tuning has to be done by ear and according to your preferences, unless you are handy with room measurement software. Good luck!

[haygeebaby]

Thanks for the info Keith. Some of those sites look promising and not that expensive. I'll email a few and see what advice they can provide. Hope to pull the trigger on getting this stuff soon.

I just checked out the pics of your system - sweet bit of kit mate.

Hope to get some pics of my room upgrade for everyone soon. Doing a complete overhall for 2010.

Happy year new to everyone.

Kind Regards

Ken

[Craigandkim]

I want to get some ideas and advice on improving my room acoustics.
Can anyone comment on the use of these two products ? Or recommend similar or better products - preferably obtainable in Australia.

Hello Ken,

as you have probably already gathered there is a lot to be said about room acoustics and how to tackle the problems associated with speaker/room interaction and accurate frequency reproduction.

Some advice which will save you money; make your own passive absorbers.

There is an abundance of info contained within this folder already. Kye has posted a very valuable and easy to follow post on making perforated panel absorbers, I've thrown in a couple of photos of my broadband corner traps and there countless of other offerings as well as the raw material needed and where to get it.

We have all made references to highly regarded material, in particular Floyd Toole and F Alton Everest (Sound Reproduction: loudspeakers and rooms & Master Handbook of Acoustics respectively) there are great www sites by respected authors ie http://www.realtraps.com/info.htm by Ethan Winer.

You'll get great satisfaction out of making something yourself for less than the price of commercial products which work just as well if not better.

Cheers

[dr_strange_hifi]

You can also use egg cartons but again you might be back at square one in the eye pleasing department.

[Elill]

Forget foam or just about any other product sold in Australia like this, they're all rubbish. Unless its 48kg/m^3 its not going to work properly.

Get the WHITE HD batts in 48kg from Acoustica and cover in a acoustically transferent cloth - you want it at leave 100mm deep for a rear wall, preferrably 150mm

http://www.acoustica.com.au/hdbatts.html

I'll also second Toole's book - it is a bible, a must read.

BTW - absorbers like that suggested will only work if you're at least 3ft+ from them (its a sound air partical velocity v pressure issue)

[haygeebaby]

This is the type of info I need - thanks guys.
Problem is - I'm not really into DIY - bad with my hands.

What about Fonic Tiles for the rear wall ? Anyone use them before ? Any comments on them ?
http://www.fonic.com/gallery.htm

30 minutes to 2010 - happy new year all.

Regards

Ken

[Elill]

The fonic products are foam and unless they're 48kg^m3 or higher in density they're not going to perform as you need them too....I know, I know, they sell them.....people buy them....dont say you weren't warned.

No DIY? Hmm.....given Electronic Enterprises at Gordon a call - he used to sell fibreglass based panels. OR hire an apholsterer to make some 100mm frames, fill them with the Acoustica product and cover in GOM fabric from Acoustic Vision in Melbourne - or call Gordon at Acoustic vision and ask for panels

[flemo]

Hi Ken,

Earlier this year I built my own acoustic panels and bass traps, during which I learned some things. The biggest lessons were less is more, and it's tricky treating a room for the mid range to high frequencies.

Is your room primarily HT or music?

What areas of your room have you identified as causing problems or requiring improvements, or what are you trying to achieve?

Have you optimised the placement of your speakers, and matching of speaker cables?

Is your hi-fi furniture made from glass and steel, or timber etc?

What components are you using in your system and are they matched?

IMO before you spend a cent on room treatments make sure you cover all the bases with your system and ensure you have optimised it to its full potential.

From my experience, be careful what you read on the net about acoustic treatments, not everybody needs them as many would make you believe, and some may only require very little (less is more).

Cheers, flemo.

[kajak12]

Hi Ken,

Earlier this year I built my own acoustic panels and bass traps, during which I learned some things. The biggest lessons were less is more, and it's tricky treating a room for the mid range to high frequencies.

Is your room primarily HT or music?

What areas of your room have you identified as causing problems or requiring improvements, or what are you trying to achieve?

Have you optimised the placement of your speakers, and matching of speaker cables?

Is your hi-fi furniture made from glass and steel, or timber etc?

What components are you using in your system and are they matched?

IMO before you spend a cent on room treatments make sure you cover all the bases with your system and ensure you have optimised it to its full potential.

From my experience, be careful what you read on the net about acoustic treatments, not everybody needs them as many would make you believe, and some may only require very little (less is more).

Cheers, flemo.

well said flemo,great advice

[Elill]

Hi Ken,

Earlier this year I built my own acoustic panels and bass traps, during which I learned some things. The biggest lessons were less is more, and it's tricky treating a room for the mid range to high frequencies.

Is your room primarily HT or music?

What areas of your room have you identified as causing problems or requiring improvements, or what are you trying to achieve?

Have you optimised the placement of your speakers, and matching of speaker cables?

Is your hi-fi furniture made from glass and steel, or timber etc?

What components are you using in your system and are they matched?

IMO before you spend a cent on room treatments make sure you cover all the bases with your system and ensure you have optimised it to its full potential.

From my experience, be careful what you read on the net about acoustic treatments, not everybody needs them as many would make you believe, and some may only require very little (less is more).

Cheers, flemo.

I'd have to disagree with this entirely. I'd have an OK system in a good room, rather than the other way round. Just get Sound Reproduction, educate yourself and then decide. 10,000 subs aren't going to fix a natural mode in your room.

Less is rarely more in the case of treatments, if you're going to do it correctly you need a lot of thick dense absorbers and appropriate diffusers - depending on the nature of the room.

A room shouldn't be treated for "high frequencies" or just low or whatever. It should enhance the sound across the entire spectrum, otherwise you're effectively turning up or down certain parts of a recording and it wont be reproduced as the engineer/recorder intends it to be.

[Craigandkim]

Forget foam or just about any other product sold in Australia like this, they're all rubbish. Unless its 48kg/m^3 its not going to work properly.

BTW - absorbers like that suggested will only work if you're at least 3ft+ from them (its a sound air partical velocity v pressure issue)

Hey Elill,

thats a pretty big statement considering there are many other versatile products which will do "the job" that are not 48Kg/m density.

Another thing to consider is what "job" are we actually trying to address for haygeebaby- first reflection off the rear wall or overall bass absorption? Couple of different approaches here- diffusion or absorption.

Also; flemo has some valid points: find the optimum placement of your speakers first before any treatments- frequency responses as you well may know, are determined by the interaction of the speakers placement and the room boundaries. Different placement will evoke different responses.

You've obviously used and worked with this stuff, whats the price of the Acoustica 100mm sheets and whats it like to work with?

Could you clarify your second statement here, what do you mean (absorbers like those suggested and only work if you're 3ft + away)??

Regards

[Elill]

thats a pretty big statement considering there are many other versatile products which will do "the job" that are not 48Kg/m density.

Density is important in terms of how the product absorbs sound across the spectrum. Because these bass traps are resistive in their design (not membrane), different densities will absorb or reflect sound accordingly. 48kg or 3pcf is the universally accepted “norm” as its coefficients have been found to perform best for the typical treatment options i.e. corner traps or reflection points – as “broadband bass traps”. Some studies have shown increasing density works better. Thickness is key however 4” or 100mm minimum. Oh and too dense and it’ll start reflecting high frequencies (not a bad thing in certain circumstances, but beyond my skill to determine).
Check out BOB GOLDS for specific material data.

first reflection off the rear wall or overall bass absorption? Couple of different approaches here- diffusion or absorption.

Also; flemo has some valid points: find the optimum placement of your speakers first before any treatments.

Agree – speaker placement is crucial, although in some cases (like mine) the room will largely determine where they go as it is small…..wider the better in my opinion. Placement of subs is even more important.
Diffusers need to be big and have a significant distance to work - unless its something like an RPG BAD Panel...even then they need a good distance from the listener to be effective.

You've obviously used and worked with this stuff, whats the price of the Acoustica 100mm sheets and whats it like to work with?

The Acoustica stuff is cheap relative to say the CSR/Fibreglass alternative which is called Ultratel – that is about $350 a bag (3 50mm thick panels, I think you get about 3sqm a bag). I can’t recall the exact price, but it’s very affordable.

Could you clarify your second statement here, what do you mean (absorbers like those suggested and only work if you're 3ft + away)??

Sure, resistive trap performance is maximised when the sound air particle speed is maximized (not pressure) which is a 1/4 of the wavelength's distance out from a wall. So at 100Hz the wavelength is about 3.4m so one-quarter equals 85cm.

[Craigandkim]

Hi Elill,

yes, I'm quite familiar with Bobs chart, thanks.

What I was trying to point out to you is that material's do not have to be 48Kg/m to be effective as absorbers in the lower end frequencies (with reference to bass traps).
Density plays a role (ie: for rigidity) but as you point out thickness is a more important attribute in a given material.

Please refer to a cross section from Bobs chart and have a look at the highlighted area's. At the same thickness, the materials all have approximately the same coefficients in the lower end- however the density varies greatly.

Its the individual material co-efficient properties not a specific density and as you correctly point out the thickness will add more benefit especially when combined with placement at the 1/4 frequency wavelength providing the most efficient energy dispersion.

I just wanted to ensure that haygeebaby didn't get the impression from your first post that if it wasn't 48kg/m3 it was useless as a bass trap.

Regards

[Elill]

I just wanted to ensure that haygeebaby didn't get the impression from your first post that if it wasn't 48kg/m3 it was useless as a bass trap.

For DIY options, anything other than 48kg IMHO isn't a good idea as you're not really constructing a broadband trap, rather targeting a specific frequency, which could do more damage to your room then good. That said Toole is a little vague on the topic - I think Ethan Winer has some lab data on it though.

[Craigandkim]

Hey Ken,

if you're not a position to DIY maybe someone can help you perhaps? It is very easy with minimal tools required and lots of step by step instructions off the various www sites.

Have you priced the Fonic or Studiocel stuff yet and compared to DIY?

I have some StudioCel products I managed to get off ebay for about 1/3 the retail price (You can see the red flocked corner ceiling traps in the photo), this was before I found the many helpful threads in the forums like SNA.

I think probably the most pertinent point is to try and understand what you are trying to achieve by using the various products (bass traps, first reflection panels, diffusers etc). For example a corner broadband bass trap is very unlikely to effect the high frequencies purely because of its positioning and the directionality of the smaller wavelengths.

Anyway get a photo of your room and compare it with suggested layouts for acoustic treatments and see how ya go.

Hope we have helped and not confused,

Regards

[flemo]

For DIY options, anything other than 48kg IMHO isn't a good idea as you're not really constructing a broadband trap, rather targeting a specific frequency, which could do more damage to your room then good. That said Toole is a little vague on the topic - I think Ethan Winer has some lab data on it though.

Hi Elill,

What room treatments have you installed, and what problems did you identify to warrant the treatments? And more importantly, did they work?

Cheers, flemo.

[Elill]

Hi Elill,

What room treatments have you installed, and what problems did you identify to warrant the treatments? And more importantly, did they work?

Cheers, flemo.

My current room is nonexistent – read in construction. I had treatments in our last room (and house) which were designed to help a variety of issues. This room will also be treated. PM me if you want my build thread....I dont like flogging other forums.

A couple of things; Firstly, there are sections of a recordings (movie soundtracks) at around 20db. If the ambient noise of a room is > 20db (from either equipment or some external noise) you’re not going to hear that section of the track…that is a little over simplified but its more or less how it works. So soundproofing is paramount.

Secondly, each room will have natural acoustic properties, such as reverberation for example, depending on size, construction of boundaries, fittings, furnishings etc. These “room effects” cloud the reproduction of audio in a manner not intended by the recording engineer (because they didn’t record it in your room). The aim of treatments is to remove these clouds. It doesn’t matter how good your system is, if the room is non-conducive to reproducing a particular sound the only way to fix it is to fix the room, not the equipment.

As suggested, if you want to know more get a copy of Sound Reproduction by Floyd Toole and then start asking questions for your specific circumstances. There are also other forums which are full of people who do this stuff all day every day who can provide advice (I still consider myself to have a very elementary knowledge of the subject and I’ve spent the last 3 years looking into it). But you need to have a good understanding of the issues first before you go asking questions. This is because certain people, including myself, will have a view on how something “should” sound, based on their individual personal preferences. So if someone is recommending you do something, like for example put 100mm absorbers at all of a rooms first reflection points, its important you know why and what effect this might have, you, like I, might not like it.

[flemo]

My current room is nonexistent – read in construction. I had treatments in our last room (and house) which were designed to help a variety of issues. This room will also be treated. PM me if you want my build thread....I dont like flogging other forums.

Okay then which room treatments did you install in your previous room, and what problems did you identify to warrant the treatments? And more importantly, did they work?

A couple of things; Firstly, there are sections of a recordings (movie soundtracks) at around 20db. If the ambient noise of a room is > 20db (from either equipment or some external noise) you’re not going to hear that section of the track…that is a little over simplified but its more or less how it works. So soundproofing is paramount.

The best sound systems I have ever heard do not use room treatments. Those systems would have been close to 100% optimised. Those rooms were pretty much like mine - average.

Secondly, each room will have natural acoustic properties, such as reverberation for example, depending on size, construction of boundaries, fittings, furnishings etc. These “room effects” cloud the reproduction of audio in a manner not intended by the recording engineer (because they didn’t record it in your room). The aim of treatments is to remove these clouds. It doesn’t matter how good your system is, if the room is non-conducive to reproducing a particular sound the only way to fix it is to fix the room, not the equipment.

Agreed, once the system has been optimised to it's maximum potential. When the system is in sync then room treatments if required may only need to be minimal. IMO using room treatments to correct a poorly installed system, or a bad one, is putting the horse before the cart.

As suggested, if you want to know more get a copy of Sound Reproduction by Floyd Toole and then start asking questions for your specific circumstances. There are also other forums which are full of people who do this stuff all day every day who can provide advice (I still consider myself to have a very elementary knowledge of the subject and I’ve spent the last 3 years looking into it). But you need to have a good understanding of the issues first before you go asking questions. This is because certain people, including myself, will have a view on how something “should” sound, based on their individual personal preferences. So if someone is recommending you do something, like for example put 100mm absorbers at all of a rooms first reflection points, its important you know why and what effect this might have, you, like I, might not like it.

Of course we all have a view on how things should sound, otherwise we'd all own the same system, and listen to the same music. With all the technical knowledge, tests, graphs and scientific studies, it still comes down do personal tastes and the system being used at that time.

[Elill]

I found my notes on the cost of the Acoustica HD White Batts.

48kg (50mm) is $19.95 sqm + GST
32kg (25mm) is $6.65 sqm + GST
then they do a ~20kg or something, cheaper again.

I had been thinking about 50mm of 48kg, and 25mm of the others. There is a quote in Sound Reproduction of a study that said that works very well.

All I need now is a template and a plan for the BAD Panels and I'm set

[Craigandkim]

I found my notes on the cost of the Acoustica HD White Batts.

48kg (50mm) is $19.95 sqm + GST
32kg (25mm) is $6.65 sqm + GST
then they do a ~20kg or something, cheaper again.

I had been thinking about 50mm of 48kg, and 25mm of the others. There is a quote in Sound Reproduction of a study that said that works very well.

All I need now is a template and a plan for the BAD Panels and I'm set

Elill,

can you remember who the distributor was?

They are good prices - I'd be interested in getting some 100mm thickness in a size 1200mm x 1800mm.

Regards

[mondie]

l am interested in some 48 kg batts too, if you guys find a supplier and need to buy a minimum quantity let me know and we can go in as a group

Cheers,
mondie

[Elill]

acoustica.com.au

[haygeebaby]

Thanks for all the comments boys. I have been busy preparing the room - patching cracks, painting the walls and ceiling, and stripping out the old carpet. The last 3 days have past quickly. New carpet arrives in about 30 minutes I hope.

Looks like I'll take everyones advice - do some DIY - and use some 48kg batts.

First thing is to kill the sound bouncing off the front and back walls.

Cheers - Pictures to follow soon.

[Craigandkim]

Hey guys,

just heard back from acoustic- 100mm 48kg/m is basically $40 p/m.
I am hopefully finding out the lower end NRC ratings on this stuff (not available on the www site) as well as freight charges (SYD-CBR).

Regards