Help with LEDE for our room extension

[Moondog55]

For those who don't know, Live End Dead End

When we add the extra 1.5 Meters to the lounge it will give me an opportunity to improve ( slightly ) the listening environment and perhaps build in the Front and Left Right speakers for the home theatre.

I can't do much with the existing plan or walls, the North wall contains a large window which will remain.

West wall is/will be the new one, the East wall is going to be doubled anyway and if I can afford it will be done with GreenGlue.

I have 2 full sheets of 18mm MDF which I can use on the West wall, but double studding is out due to lack of money.
Open to comments and sensible suggestions

[tricky4000]

Hi MoonDog,
So what exactly would you like suggestions on?
I'd like to help and talk about what you're doing.
Tricks

[Moondog55]

Hey tricks
I was beginning to think this was dead.

We are moving a wall soon and I want to make this a semi permanent and wife acceptable room.

At the moment the dead end is old wool blankets and polyester doonas hung on the wall behind daggy 1970s woven curtains and Cecile is adamant that they will not be returning.

I would like a fractal surface on the side walls but I have no idea of how to build one.

The new wall needs to accommodate the stereo and the TV/home theater plus my 1200 vinyl and the CD/DVD/Blueray disks.

I am thinking of using the roof cavity for a new sub-woofer system as Cecile has decided the 200 liter box in the corner is taking up a little too much room, but that is still to be determined.
I'd like to utilise the ceiling if I can, either by sloping a separate panel or by putting up a block covered panel

[Master Splinter]

If you require a high SAF (spouse approval factor) your chances of doing a decent anechoic wall are going to be minimal, unless said spouse doesn't mind something that looks like it came from a medieval torture chamber. (see pics)

You might be able to sneak in a combination of drilled wooden sheet with sound absorbing material behind it (http://www.soundservice.co.uk/acoustic_wood_panels.htm).

If you want to go ahead with the diy torture chamber look.....errr diffuser, there's a good thread here (http://www.gearslutz.com/board/bass-traps-acoustic-panels-foam-etc/369164-diy-diffusors-max.html).

And a sub in the roof....sounds like it will have lots of funny resonances...could I convince you to try a sub built into a coffee table instead????

[Moondog55]

Done the coffee table sub thing.
Was thinking of a simple infinite baffle in the roof cavity using a dozen cheap woofers I have in the shed,

[jago]

probably not cheap Alyos (http://www.acoustica.com.au/alyos.html) but have a look at there other products ... I'm looking to use acousticflex f8 between my floors but thats a different matter.

[Moondog55]

Love them, can't afford them but I'd like to.
Those Cheops pyramids would be better if they used a mixture of pyramid size and heights on the one panel so i would not need to buy different panels

[tricky4000]

If you want to do it on an idea that slightly resembles a budget MoonDog, try buying a few sheets of 19mm MDF. Cut strips along the long edge of the sheet at various widths; 50mm, 75mm, 85mm, 30mm, 20mm, etc. Cut the strips the height of your floor to your ceiling and put them against eachother until your cover the whole back wall (opposite to your front of house speakers). GIve them a paint. Sub is always better on the ground. I don't recommend overhead sub. Besides, you'll pick up all sorts of resonant frequencies in your roof cavity. Not good. Not to mention cracking ceiling plaster. Subs need a good solid base to sit on. A sloping ceiling is a big advantage. If you can do that, do it! Maybe Cecile will like the idea of thick pleated ceiling to floor curtains on either side of your theatre room. Don't forget some carpet below your feet and a really powerful amp and powerful speakers. With all that deadening, you'll need a monster amp and speaker system.
Moondog, its hard to do this kind of thing on the cheap.

[Belair_Boy]

G'day All.
I am interested in this thread as I have a home theater in the new house and have the opportunity to add some acoustic bells and whistles.

I have seen a cheep/free "Cheops pyramid" alternative using the base of egg cartons stuck to a wall. I am not sure how effective they would be but must be better than a blank wall. Maybe an option to consider as it it cheep and easy to try and if it doesn't work it can all be recycled.

If the look of pyramids / egg cartons etc stuck to the wall has a low SAF, a screen in front of your dead end wall using a light speaker cloth type material on a frame will hide everything. Could also be fixed to Tricky's MDF creation to form a nice smooth looking wall. As it is dark behind the cloth you will just see the front of the material but as a WOW factor you could install some lights at the base of the pyramids, turning them on would reveal the secrets lying beneath. I saw a similar effect in an OMNI MAX theater where they backlit the screen to reveal the amazing sound system hidden behind.

I just had an idea, with the ICF building method I am using I always end up with a pile of polystyrene bits left over. A few hours with the hot wire cutter and I could have a mountain of pyramids to stick to the back wall. I guess the polystyrene would not be as good as the other exotic foam materials but as a baffle/diffuser they have to be better than nothing. Any thoughts?

[tricky4000]

Absorption of frequencies (usually over 500kHz) will begin happening on uneven surfaces, especially when the surfaces are porous. So what you're saying Belair is quite right. Egg cartons work well because there are many uneven (non resonating) surfaces. Add in a sloping ceiling and some unparallelled walls and you've got yourself a simple acoustic chamber.

[Belair_Boy]

Absorption of frequencies (usually over 500kHz) will begin happening on uneven surfaces,


Should that read 500 Hz, my hearing is not that good :U

[tricky4000]

haha
Yes, 500Hz.
Apologies.

[Moondog55]

The dead end is "Relatively" easy, just a matter of spending some money, but a really good "Live End" may be a much more difficult DIY.

I did once use those Presswood pallets as my live end but I cannot find any lately that would be worth painting.
I like the idea of the MDF strips, we could take the wall with us when we leave too and the added mass would help diminish sound in the rooms behind perhaps.

If I can find some decent Presswood pallets I'd be happy with 4 of those on the ceiling at the front.

Part of my lack of WAF at the moment are the 11 subwoofers on the lounge-room floor, 1 huge; 2 big and the others are 12 & 10s; which is why I am considering a roof cavity IB system.

[Belair_Boy]

Add in a sloping ceiling and some unparallelled walls and you've got yourself a simple acoustic chamber.

G'day Tricky
I am assuming the ceiling needs to slope from low at the front to high at the back or is it just a matter of having non parallel floor and ceiling?

Could the walls/ceiling be a series of short ramps rather than a plain surface, similar to a Fresnel lens. This way you could avoid loosing too much space in the room?

Does raising the floor in a series of steps, theater style, achieve the same effect?

How far do you go before the law of diminishing returns takes over?

Anyone's thoughts are appreciated:)

[tricky4000]

So long as the surfaces are not parallelled this will aid in the elimination of standing waves. The short ramps idea will work also. Remember with sound waves, its mostly about attenuation not complete eliimination. Attenuation is reduction. Reducing certain frequencies...you'll probably never lose them, but you can make them unheard. Ramping the floor is the most popular means as it also works to create a stadium like seating affect. You'll need a good solid base under your floor however because the hallowness underneath your seating could open up a can of bad-frequency worms. 11 sub woofers ey?? How many cinemas are you building MoonDog? haha

[Moondog55]

Hi BelairBoy
The room has far more influence than everything else combined.
Good rule of thumb we use at DIYAudio, One third power and source, one third speakers one third room when doing budgets.

That 1/3 room also includes speaker placement but usually the room dominates so a few hundred dollars on acoustic treatment gives real and quite large benefits.

The difference that simply hanging some heavy curtains in front of the rear wall is simply amazing.

But I really mean heavy, ours are hung 120mm from the wall (Well they were) on double curtain brackets and consist of Op-Shop wool blankets hot washed and tumble dried to felt them, cheap polyester doonas and a decorative mesh in front.
Book shelves filled with different depths of books make good diffusers too, CD/DVD racks dont