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AUDIO FORUMS >> Member's Systems Picture Gallery >> DIY Diffuser Idea
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Message started by JMeader on 01/17/22 at 18:43:52

Title: DIY Diffuser Idea
Post by JMeader on 01/17/22 at 18:43:52

Left field on this one What about taking different sizes of PVC pipe, cutting them in half and mounting on say plywood to act as a diffuser.

Why
1 lighter than a would build
2. easy to paint
2. hopefully cheaper????

Thoughts

Title: Re: DIY Diffuser Idea
Post by GroovySauce on 01/18/22 at 13:45:50

Welcome to the forums!

I did a quick search and there is a company that makes something that sort of resembles what you described.

A few considerations.

There are different theories on diffusion. Some would say that what you described is a diffuser, others would say it's a sound redirection device or a sound scattering device. If it acoustically benefits your room, that's up for you to decide. I've tried a few different described as diffusers. The best ones I've tried are quadratic residue type based on prime numbers.

Every surface music hits changes the way the music sounds when it reaches your ear. Music bouncing off a glass, drywall or wood all sound different. Wood has a pleasant sound to me, plastic doesn't.

What frequency range are you going to be hitting with your proposed design? with 3" PVC I'm guessing it will be 4,000hz+ ideally 150-4,000 would be the main focus to start.

Here is the best part. The cost of making 2 24x48" devices like you described seem inexpensive and easy to do. Give it a go and see how it sounds to you. If you observe an improvement Whoo Hooo! If not it sounds like a fun experiment.

I got a kick out of your position in the build queue with the date in your signature :D

Title: Re: DIY Diffuser Idea
Post by JMeader on 01/18/22 at 16:20:10

Your response corresponds to what I have found and read. The math based design consistently gives better results based on reviews.

I was looking for a more economical version that could be easily replicated. Oh well will give it a try, as you say cost is nominal.

My system is in front of a large window and I have a large 75 inch TV in-between my La Scala's about 2 feet behind. We also have heavy drapes covering the entire wall behind the speakers, so a major absorber. The room has 10 ft high walls and the the ceiling is barrel shaped with another 4 ft to the peak. In addition one side is open to a dinning room. This combination has significant impacts on the room's sound. My listening position is about 12 ft away and near the back wall.

With the La Scala's about 6 ft apart and a very modest toe in gives the best sound stage and depth. Sound stage is wide but depth is shallow. The goal of room treatments is to enhance depth.

At this time I am seriously considering changing my order to just a Torie Jr due to the volume of my room. The good news I have the time , the bad news i have plenty of time

Title: Re: DIY Diffuser Idea
Post by DirtDawg on 03/11/22 at 18:25:29

Hey, Groovy,

That pic you posted resembles the fractal based geometry diffusion panels I intend to build soon for my room, except that the "long lands" will be differing depths and the surface of each will be textured along its length with smaller and varying "break-ups" to extend the upper range of the diffusion characteristics.

We have recently moved residence, so my wood shop still looks like a Goodwill overflow donation site, but I am making headway on that front. A little each day, but no where near cutting and routing wood yet, sadly.

Progress has slowed some due me falling and breaking my arm in three places, but maybe there's a plan there I just don't understand, yet.

Title: Re: DIY Diffuser Idea
Post by DirtDawg on 03/11/22 at 18:30:11

JM,
I was also wondering about, instead of using paint on the plastic tubing, maybe something like Rhinoshield for the finish. It's kind of rubbery, but I doubt it's soft enough to turn your diffusers into absorbers.

Title: Re: DIY Diffuser Idea
Post by JMeader on 03/11/22 at 21:51:58

a light coat should work,

Have you started a project yet

we are about to remodel our kitchen so kind of busy on my end

:)

Title: Re: DIY Diffuser Idea
Post by GroovySauce on 03/12/22 at 00:24:37

DirtDawg, If your room doesn’t have adequate absorption, it will behoove you to work on absorption first.

If you are planning on making some diffusers I would suggest going with a QRD. You can use the calculator at this website http://www.digitalaudiorock.com/cgi-bin/qrd.cgi to figure the dimensions to use for the diffuser.

I have 6 prime 7 2.25x10.75” the mathematical frequency range is 360-3013 Hz. People say that in practice they will do an octave below the lowest frequency. I’m not sure about an octave above the high frequency.

So with mine I’m looking at a range of 180-3013 (6026?) Hz.

When using QRD, you need to make sure you give enough space between the listening position and the diffuser.

Take the lowest frequency the diffuser will diffuse and put it into this http://mcsquared.com/wavelength.htm calculator. Mine at 180hz I get 6’ 4” minimum distance between the diffuser and listening position.

Here is a video https://www.youtube.com/watch?v=MRvue5ZCiyc on how to assemble a QRD—once you have cut the pieces.

Adding absorption was the most impactful thing I’ve ever done to all my listening rooms. My current room is the only one I’ve added diffusion to. Diffusion took it to another level. My understanding after spending hours, months researching, absorption is the foundation and diffusion only makes sense once you have addressed absorption.

Title: Re: DIY Diffuser Idea
Post by DirtDawg on 03/12/22 at 05:52:27

Thanks, Groovy,

I had not seen that particular Youtube vid. Looks like a nice kit.
The reason I was looking into the fractal based diffusion techniques was mainly because I've been "playing with" re-iterated non-integer geometry since the first time I heard of it. With my first computer, finally I have a machine to continue the iterations for me. I am a bit of an artist, "in my dreams."

Problem I have run into is that most of the work I find on this study, that I can access, is either intended for archetects trying to minmize ULF pollution from HVAC systems in giant buildings OR the DOD won't let me read classified documents. Apparently our navy uses this geometry to enhance submarine stealth and they're not sharing. Yet.

Anyway, I have not done more than a couple of months of reading and I find myself trying to re-invent the wheel sometimes. So, no wood lost to experiment, yet.
Our January, "ice and snow" move to a new home was off to a great start, but now, a cast from elbow to wrist slows me down quite a bit. Just typing one handed is like trying to seduce a "mean girl with a whip" or something. Let alone setting up my wood shop again.

I appreciate the advice and the links, but you are right about absorption having a massive effect. I moved one of these Ikea mattresses that my daughter bought when she moved out for a while, meant for the "Tiny Home" ilk I think, which is a big foam thing that folds into a table, just behind my speakers in my hard surface listening area and I was amazed at just that amount of absorption in the room.

Already addressed the tile floor with a jute pad and cool rug, but four more surfaces to go. I say four because behind my sweet spot is a wide open "dead sounding" space full of padded furniture with book shelves and my home theater set up. Not much to worry about from that area, except when the "drinking age, living in dad's house" kids are bouncing around in there. ;D

I have goofed some with that QRD calculator that you linked and from what sweep measurements I have taken in my room, I can probably use prime 7 diffusers like you did. I have a massive 6dB+ peak from .8K to 1.3k to deal with early on.

Thanks, again. I have lots to do!

Title: Re: DIY Diffuser Idea
Post by piezoman on 03/20/22 at 21:04:36

Hey Nigel, are those diffusers your work? That's really impressive!

Brad

Title: Re: DIY Diffuser Idea
Post by GroovySauce on 03/21/22 at 11:54:05

Brad,

I bought them from a guy on ebay. https://www.ebay.com/itm/174595019471?hash=item28a6ac92cf:g:YfcAAOSwMuNf~2SB

I asked for a custom depth of 12 or 16 inches. Due to the way he makes them, he would need to retool to make anything deeper than 10.75" that's what I went with.

He does sell them as functional not beautiful. Looking closely there are flaws and imperfections. Sitting 12+ feet away from them they look fantastic.

Once I get settled in my new place I'll order more.

Title: Re: DIY Diffuser Idea
Post by jec3504 on 06/20/22 at 00:33:15

Groovysauce,

Quote:

The best ones I've tried are quadratic residue type based on prime numbers.

Want to use this on my front wall Nigel. Couple questions, My speaker and listening position are 6' and 14' away from front wall.

Front wall, any thought and mixing Vertical and horizontal? Should I have to worry about my open baffles distance when using the quadratic residue diffuser calculator?

Thanks Joseph

Title: Re: DIY Diffuser Idea
Post by jec3504 on 06/21/22 at 23:28:15

Never mind above question moved speakers into new position. See question in room treatment thread....please lol

Joseph