Styrofoam 2D diffusor

[Nordenstam]

Must admit that I've spent some time just sitting there staring at the diffusers. It sounds a bit muffled. Much clearer when turning the other way around, facing the speakers! :P Seriously: Sounds better than it ever did before! Which may not say much in itself but I haven't found anything like it around my part of the world. If only it was possible to take a picture of the sound! It would look so crisp as to almost be unreal in a computer graphics way.

The entire rear wall is 1 feet deep rockwool, with the exception being less where there's diffusers and more in the corners. No fancy bass trapping, yet! The wood panels are simply placed in front of the absorbers to send some more sound back into the room. Have had the diffusers for half a year. The big new thing came during three weeks of downtime around christmas. Moved everything; gear, absorbers, diffusers, sweetspot, speaker and sub placement.. So it's not a before/after diffusion, it's a before/after better application of the diffusers. There's also another 8 diffuser units in the rear part of the room, on the sides and in the ceiling.

Room is 6x3.9x2.8 meters (20x13x9 feet). Roundtrip speakers->rear wall->sweetspot is 8.5 meters, more than 20 milliseconds. Still got some tweaking to do. Going to add more reflectors to the absorbing panels. As much as possible without messing with the sound. ETC's and stuff. Angling the reflectors open up exciting possibilities. Will have a try at the Haas kick. Have an idea how to make several reflections raytrace into the sweetspot approximately at the same time, giving a boost in level at around 25ms. Going to be nice project in its own right!

It aint bad is it as though. One visitor made this legendary comment: "so this is what good sound is!" Modern LEDE: live end diffuse end. Not killing the front totally. It's the quick reflections points that are dead, not the entire front part of the room. It's more fun to listen to music, EQ and compression have never been easier to dial in right, issues in the tracks jumps out at me and says HELLO - FIX ME!, people visiting don't feel so strange as in a very dead room and it's more fun to listen to music. It's great!

[terry j]

well done, congrats.

The hardest part is still ahead of you...making them look great and as if they are an interior decorating choice.

I mean the entire treatment as a package.

Once you have done that, you might impress Kari Bremnes enough that she will use your studio...then after her will follow royksop! (does that name mean anything?? I tried to answer you in that thread but lost my response...so bugger it!)

[Nordenstam]

Originally Posted by terry j

The hardest part is still ahead of you...making them look great and as if they are an interior decorating choice.

Sigh.. You're right! It's going to be tougher.

Originally Posted by terry j

royksop! (does that name mean anything??

Røyk=smoke, sopp=mushroom. It's the local term for puffball mushroom. (google it if you haven't seen one of those, it's an organic smoke bomb!)

[PaulP]

Originally Posted by Lupo

Røyk=smoke, sopp=mushroom. It's the local term for puffball mushroom. (google it if you haven't seen one of those, it's an organic smoke bomb!)

You eat those things ? ! We see them all the time around my parts. The kids
love to poke them but I'm always worried about getting spores in our lungs
(not a great place for mushrooms to grow).

Paul P

[Northward]

I don't want to ruin the party but... In my book Styrofoam isn't dense enough to give the diffusors good performances.

[Nordenstam]

Hi Thomas!

RPG use the same material and they manage to measure quite well. ?

[Nordenstam]

Originally Posted by PaulP

You eat those things ? ! We see them all the time around my parts. The kids
love to poke them but I'm always worried about getting spores in our lungs
(not a great place for mushrooms to grow).

Do remember they was a lot of fun when we was kids. Smoke grenades!

[casual-p]

Originally Posted by Northward

I don't want to ruin the party but... In my book Styrofoam isn't dense enough to give the diffusors good performances.

I was thinking this. I wonder if spraying the surface with a reflective coating (maybe a few coats of clear gloss??) would do the trick and further improve the performance of the diffuser??

[Northward]

Originally Posted by Lupo

Hi Thomas!

RPG use the same material and they manage to measure quite well. ?

I know... I respect RPG, but in this case all I can say is "no comment".

AFAIC, you need more density. The impedance change has to be greater for some important freqs to be reflected and thus diffused properly.

The wood we use for skylines has a density of .32

[Tomer1]

Fiberglass molding might result in a solid but lightwight solution.
Not really an option for the home DIYer though.

[PaulP]

Originally Posted by Tomer1

Fiberglass molding might result in a solid but lightwight solution.
Not really an option for the home DIYer though.

The BBC tried this but found it was too difficult to release the product from
the mould.

They also considered other methods like injection moulding but the price of
the moulds was very high,and using plaster in a soft type of mould like those
used to make garden ornaments.

How about coating a styrofoam diffusor with polyester resin ?

You're not supposed to have styrofoam insulation that is not behind gypsum
board so I wonder about diffusors made from the same material.

Paul P

[Nordenstam]

Originally Posted by Northward

I know... I respect RPG, but in this case all I can say is "no comment".

AFAIC, you need more density. The impedance change has to be greater for some important freqs to be reflected and thus diffused properly.

The wood we use for skylines has a density of .32

I'm not enough into this to calculate these impedances. If there is a quick guide available somewhere, or even a wiki link to the general idea, please post a hint!

Seems, from my experience, that 2x2 inch blocks of .32 density would reflect to well below 500Hz. Given that none of my units are much wider than 2 feet, this is the practical limit of my concideration. Do you have any idea how it fares in this regard? Or perhaps a hint as to how to calculate the result? Density is exactly ten times less than the wood you use.

[Tomer1]

How about coating a styrofoam diffusor with polyester resin

How would you achive a uniform coat? I imagine having different thickness hense a device with varing density will effect the diffuser in an unknown way.

[CodyMFDubb]

Has anyone tried using styrofoam diffusers and wood diffusers in the same room???

And I don't mean to be the dumb guy in the thread, but what exactly are the differences between all these diffusers??

EPS? RPG? PRD? QRD? ... any others I'm leaving out?

Also, what works best for which applications??

I could google and search but I'd rather hear it from people who obviously already have plenty experience with these.

Any help clearing this up would be appreciated, because any way to save money in this industry I'm willing to put in the labor.

[Nordenstam]

Hi!

Welcome to the wonderful world of diffusers! =)


Quick reply:

Originally Posted by CodyMFDubb

EPS? RPG? PRD? QRD? ... any others I'm leaving out?

EPS = encapsulated post script. Or.. Wait! Wrong topic. EPS usally means expanded polystyrene foam. The coffee cup material. I, and most DIY'ers, are actually using extruded polystyrene foam. It's not made of seperate beads, like the coffeee cups, it's a single piece of plastic.

RPG = Role Playing Game. Usually. In this case though, it's the name of THE company in acoustics treatment: RPG Diffusor Systems, Inc. - they've made just about everything that is fun and innovative.

PRD = primitive root diffuser. Produces diffusers based on encryption math. The results looks random. It's the math behind the typical skylines and the C studio at Blackbird.

QRD = quadratic residue diffuser. Produces diffusers based on math that is.. Hmm... Don't know why they started out with quadratic residues hundreds of years ago! The diffuser equation have the important property that the resulting list of numbers have a flat frequency response. The same as noise. Noise is random, hence the flat frequency response is close to random as well. They're symmetrical and therefore produce recognizeable patterns.

RTFM = there is none. Unfortunately! The closest you'll get is this book: RPG Diffusor Systems But you'll find plenty of info if you start digging into the diffuser threads in this forum!

Originally Posted by CodyMFDubb

Also, what works best for which applications??

Big topic..

Originally Posted by CodyMFDubb

Any help clearing this up would be appreciated, because any way to save money in this industry I'm willing to put in the labor.

It helps a lot if you're the sort of person that gets a puzzled look when people say that time is money. If you LIKE to do this sort of work - go ahead!

[CodyMFDubb]

Originally Posted by Lupo

Hi!

Welcome to the wonderful world of diffusers! =)


Quick reply:



EPS = encapsulated post script. Or.. Wait! Wrong topic. EPS usally means expanded polystyrene foam. The coffee cup material. I, and most DIY'ers, are actually using extruded polystyrene foam. It's not made of seperate beads, like the coffeee cups, it's a single piece of plastic.

RPG = Role Playing Game. Usually. In this case though, it's the name of THE company in acoustics treatment: RPG Diffusor Systems, Inc. - they've made just about everything that is fun and innovative.

PRD = primitive root diffuser. Produces diffusers based on encryption math. The results looks random. It's the math behind the typical skylines and the C studio at Blackbird.

QRD = quadratic residue diffuser. Produces diffusers based on math that is.. Hmm... Don't know why they started out with quadratic residues hundreds of years ago! The diffuser equation have the important property that the resulting list of numbers have a flat frequency response. The same as noise. Noise is random, hence the flat frequency response is close to random as well. They're symmetrical and therefore produce recognizeable patterns.

RTFM = there is none. Unfortunately! The closest you'll get is this book: RPG Diffusor Systems But you'll find plenty of info if you start digging into the diffuser threads in this forum!



Big topic..



It helps a lot if you're the sort of person that gets a puzzled look when people say that time is money. If you LIKE to do this sort of work - go ahead!

Thanks, i appreciate clearing it up for me.

When I lived in Nashville and went to school, we got to visit Blackbird and studio C is amazing... but of course that entire place is amazing and they have phenomenal gear.

Plus I don't sleep much so i have plenty of spare time.

[NLP]

Originally Posted by Northward

I know... I respect RPG, but in this case all I can say is "no comment".

AFAIC, you need more density. The impedance change has to be greater for some important freqs to be reflected and thus diffused properly.

The wood we use for skylines has a density of .32

Which units?!
.32 kg/m3, lb per cubic...?!

[Nordenstam]

Think it's safe to say that it's .32 10^3kg/m^3. Or 320kg/m^3.

Wood Densities

[NLP]

OK THX.

[Northward]

Originally Posted by Lupo

Think it's safe to say that it's .32 10^3kg/m^3. Or 320kg/m^3.

Wood Densities

Yes. With ~15% moisture level (standard).

Re your other questions: the choice of a wood over the other is also a consideration not only of acoustic performance but also long term behaviour of the wood. In 20 years it must look perfect. So that rules out pine for ex.

It's a mix of theoritical performances & real-life performances of the panel, how practical it is for the woodcrafters to build with it, costs and how it will behave in the long term.

Can't spill the beans about the technical stuff, but if you ever drop for a coffee, I'll be happy to have a chat about it.