Custom made diffusors?

[bwo]

I'm trying to find out who can build high quality good looking diffusors that diffuse well down to the Schroeder frequency without breaking the bank. The standard RPG Diffractal or QRD are pretty much too shallow and though I'm sure RPG can make custome ones, they seem to be a company that charges much.

Living in Norway, and considering freight cost, that also need to be taking into consideration. It may seem obviuos that the best thing would be to get diffusors built here, but Norway is a high cost country and even with shipping and tax I believe it would be cheaper to order from abroad.

I'm thinking either diffusion down to 500 Hz and scattering lower or diffusion down to 250 Hz area. Depending on prices. Yeah, I know that requires depth. And I understand it's not going to be directly cheap.

[Jens Eklund]

Unless the room is very big, there’s usually no need for diffusion below about 400-500 Hz.

[bwo]

Originally Posted by Jens Eklund

Unless the room is very big, there’s usually no need for diffusion below about 400-500 Hz.

To even find a diffusor that works effectively down to 400-500 Hz is difficult. I've haven't seen any. And as you know, there are several ways to show a measurement.

I like RPGs Diffractal, but it will not yield the result I'm after.
http://www.rpginc.com/products/diffr...cal%20Data.pdf

[kasmira]

GIK Acoustics. Acoustic Panels and Bass Traps.

"The Q7d is a 7 root well diffusor design that begins scattering at approx 350Hz and offers effective and even diffusion up through 3 kHz. The Q7d offers additional scattering up to the upper limit of approximately 7 kHz"

Quite a bit more reasonably priced than the RPG diffusors if I remember correctly.

Not sure how much shipping will cost to Norway though. And they don't have a chart showing exactly how much it works at 350hz. If Glenn comes in this thread: do you guys have data of this posted and I just missed it? Or can you give us a small bit of insight into how much diffusion we're talking in the lower frequencies?

bwo, it might be easier to play around with a diffusion calculator and really get to know exactly how big of a diffusor and how deep of wells you want. Look around on threads to find a descriptive enough thread with images on how to build them. Find a local carpenter to build one for you. I really doubt it would cost more than buying a pre-made diffusor and having it shipped. Even though GIKs is very reasonably priced for its size, if you get a woodworker to build you one, he could probably get better prices on wood than you could and they would look a lot better than most DIY ones, and I couldn't imagine it costing any more than GIKs diffusor.

[Jens Eklund]

Originally Posted by bwo

To even find a diffusor that works effectively down to 400-500 Hz is difficult. I've haven't seen any.

Remember that the highest possible normalized diffusion coefficient possible for a phase grating diffuser is about 0,6 and if that high, the bandwidth will probably be very limited. Polys can exhibit higher diffusion coefficients but then temporal diffusion will be limited or non-existing if only single or two period(s). I personally think that diffusion coefficients above about 0,3 - 0,4 is very good and if over a large bandwidth; excellent.

[Jens Eklund]

Originally Posted by kasmira

"The Q7d is a 7 root well diffusor design that begins scattering at approx 350Hz and offers effective and even diffusion up through 3 kHz. The Q7d offers additional scattering up to the upper limit of approximately 7 kHz"

Quite a bit more reasonably priced than the RPG diffusors if I remember correctly.

Not sure how much shipping will cost to Norway though. And they don't have a chart showing exactly how much it works at 350hz. If Glenn comes in this thread: do you guys have data of this posted and I just missed it? Or can you give us a small bit of insight into how much diffusion we're talking in the lower frequencies?

Perhaps this might interest you:

http://www.gearslutz.com/board/6014298-post14.html

Please note that the normal total panel width when talking about diffusion coefficients is 3,6 meters, not 2,4 meters as in some of the examples in the above post.

[kasmira]

Originally Posted by Jens Eklund

Perhaps this might interest you:

http://www.gearslutz.com/board/6014298-post14.html

Please note that the normal total panel width when talking about diffusion coefficients is 3,6 meters, not 2,4 meters as in some of the examples in the above post.

Wow, beautiful post. May I ask the thread that was posted in? I'd like to read discussion on that if there was any.

I really need to make a Gearslutz bookmark folder on my browser for these important documents, calculators, builds, studies, etc.

Thanks!!

PS: On the last picture posted, titled Freeform, you noted "positive and negative panel" - What does this mean?

[Jens Eklund]

Originally Posted by kasmira

Wow, beautiful post. May I ask the thread that was posted in? I'd like to read discussion on that if there was any.

Look in the upper right of your screen

Originally Posted by kasmira

PS: On the last picture posted, titled Freeform, you noted "positive and negative panel" - What does this mean?

The “Freeform” was the working name of my diffuser model now called the “Optiffuser” which comes in pairs of positive and negatives panels.

[Mctwins]

Hi
Wing diffusor starts from 300Hz, why DIY, just buy it.
Thanks

[Jens Eklund]

Originally Posted by Mctwins

Hi
Wing diffusor starts from 300Hz, why DIY, just buy it.
Thanks

Where can I find data on these? Meassurements or BEM predictions.

[kasmira]

Originally Posted by Jens Eklund

Look in the upper right of your screen

The “Freeform” was the working name of my diffuser model now called the “Optiffuser” which comes in pairs of positive and negatives panels.

Sorry, I wasn't clear on my post. I wasn't asking what freeform meant, but instead, what positive and negative panels were? I assume its a pair of diffusors that are mirrored? (edit; wow, just noticed I've ALWAYS been spelling diffuser* wrong)

Oh and wow - I always figured there was a way to get to the original thread in linked posts, but never saw that small link up top. Thanks again, Jens!

[Mctwins]

Jens...
Hmm..If you are interested about data and BEM why don't you just buy a couple of pcs and run the test for yourself.
Thanks

[Jens Eklund]

Originally Posted by Mctwins

Jens...
Hmm..If you are interested about data and BEM why don't you just buy a couple of pcs and run the test for yourself.
Thanks

So anyone that wants so know about the performance of a product should accept to produce the testing by themselves ...

[Jens Eklund]

Originally Posted by kasmira

... what positive and negative panels were? I assume its a pair of diffusors that are mirrored?

Yes.

Originally Posted by kasmira

(edit; wow, just noticed I've ALWAYS been spelling diffuser* wrong)

http://www.gearslutz.com/board/7030013-post24.html

[Mctwins]

Originally Posted by Jens Eklund

Unless the room is very big, there’s usually no need for diffusion below about 400-500 Hz.

There is no need for a big room if diffusor is being used. Wing and Golden Horns diffusors are designed to work in small rooms.
Thanks

[Jens Eklund]

Originally Posted by Mctwins

There is no need for a big room if diffusor is being used.

You are free to believe whatever you want ...

[Mctwins]

Originally Posted by Jens Eklund

You are free to believe whatever you want ...

Believe, I don't have to believe. My own room is proof enough and it isin't big.

Thanks

[Jens Eklund]

Originally Posted by Mctwins

Believe, I don't have to believe. My own room is proof enough and it isin't big.

What have you proven with your room (and your room is not really small, now is it)?

[Mctwins]

Originally Posted by bwo

I'm trying to find out who can build high quality good looking diffusors that diffuse well down to the Schroeder frequency without breaking the bank. The standard RPG Diffractal or QRD are pretty much too shallow and though I'm sure RPG can make custome ones, they seem to be a company that charges much.

Living in Norway, and considering freight cost, that also need to be taking into consideration. It may seem obviuos that the best thing would be to get diffusors built here, but Norway is a high cost country and even with shipping and tax I believe it would be cheaper to order from abroad.

I'm thinking either diffusion down to 500 Hz and scattering lower or diffusion down to 250 Hz area. Depending on prices. Yeah, I know that requires depth. And I understand it's not going to be directly cheap.

What do you do if your Schroeder freq is around 125Hz?
What do you mean and what are you talking about?

[Mctwins]

Originally Posted by Jens Eklund

What have you proven with your room (and your room is not really small, now is it)?

When you say big do you mean a warehouse?

[Jens Eklund]

> about 100 m³ is big to me. < about 40-50 m³ is small in my book.

[Mctwins]

Originally Posted by Jens Eklund

> about 100 m³ is big to me. < about 40-50 m³ is small in my book.

Ok, I understand. But if you are in between do you define it as medium?

[Mctwins]

Jens..I forgott, what book?

[Jens Eklund]

Originally Posted by Mctwins

Ok, I understand. But if you are in between do you define it as medium?

Sure, why not.

[Jens Eklund]

Originally Posted by Mctwins

Jens..I forgott, what book?

In my book - Idiom Definition - UsingEnglish.com

[Mctwins]

Originally Posted by Jens Eklund

Sure, why not.

Ok...So does it mean under 40-50m3 you don't need to use diffusor?

[Mctwins]

Originally Posted by Jens Eklund

In my book - Idiom Definition - UsingEnglish.com

I understand, I was just joking.

[bwo]

Oh boy. This thread is being destroyed.
Let me make myself clear; I'm not interested in diffusors from Svanå (SMT). And I don't want hear about their philosophy, which I by the way totally disagree with. But that's not to be discussed here.

An option could be to use QRDude and get a carpenter to build them. But I would feel safer having someone who's well acquainted with building diffusors and has measured the end result.

Thanks Jens for the information. What's your opionion on diffusion above 5k like the Diffractal is performing. Is it still an advantage considering that it will remove flutter-echo at those high frequencies?
And do you know how deep a Diffractal would have to be to get good diffusion down to 400-500 Hz?

Also, what exactly is the difference between diffusion and scattering?

[boggy]

back on topic....

Originally Posted by bwo

I'm trying to find out who can build high quality good looking diffusors that diffuse well down to the Schroeder frequency without breaking the bank..........
I'm thinking either diffusion down to 500 Hz and scattering lower or diffusion down to 250 Hz area. Depending on prices. Yeah, I know that requires depth. And I understand it's not going to be directly cheap.

Down limit for lowest working frequency for diffuser in the small room is distance between listener and diffuser, which needs to be three (or four, if you like to be sure) wavelength of lowest working frequency. So in small rooms usually this limitation is about 1kHz, if we include in calculation that we need also wideband absorber behind diffuser. So Schroeder frequency isn't that good direct reference for lowest working frequency of diffusers in room.

Originally Posted by bwo

To even find a diffusor that works effectively down to 400-500 Hz is difficult. I've haven't seen any.......

If you like to see diffusers which have lowest working frequency below 500Hz, here are some examples (click on image for more info):

[Jens Eklund]

Originally Posted by bwo

Oh boy. This thread is being destroyed.
Let me make myself clear; I'm not interested in diffusors from Svanå (SMT). And I don't want hear about their philosophy, which I by the way totally disagree with. But that's not to be discussed here.

An option could be to use QRDude and get a carpenter to build them. But I would feel safer having someone who's well acquainted with building diffusors and has measured the end result.

Thanks Jens for the information. What's your opionion on diffusion above 5k like the Diffractal is performing. Is it still an advantage considering that it will remove flutter-echo at those high frequencies?
And do you know how deep a Diffractal would have to be to get good diffusion down to 400-500 Hz?

Also, what exactly is the difference between diffusion and scattering?

Scattering vs. diffusion:
http://www.gearslutz.com/board/7153789-post15.html

As far as the rest goes, I’ll send you a PM later ... I don’t think I want to continue in this thread.