Pvc pipe diffuser

[DaggerToe]

This was fun! About a 3 hr build...
It probably won't do much...
But it looks cool...

PVC and Super glue....It's surprisingly sturdy

Used skyline calculations and room node calculator
from these sites

Calculate a Two-Dimensional Primitive Root Diffuser
http://www.mh-audio.nl/ASG.asp
http://www.mh-audio.nl/ACalculators.asp

It's still in progress....Next I'm going to bath it in a vat of acoustic gold snake oil....
dfegad

Should I cap the holes?
and with what?
this was built for my recording room....it's not a mixing room...

maybe clear caps...with LED's in the bottom...I don't know....

[Jens Eklund]

Unless you seal the top of the tubes, it will not scatter much for normal incident angles (spatial or temporal). What it does for other angles might be interesting!

[DaggerToe]

good point....

what do you hypothesize an open tube against a reflective wall does?

What If I stuffed the pipes with insulation?

Or maybe cut dowels to fit inside and placed them at calculated depths.....

thanks for responding.....

[tINY]

I like the idea of caps with LED's. Slip on PVC caps should work...




-tINY

[DaggerToe]

Oh Ya!

[Jens Eklund]

Originally Posted by DaggerToe

Oh Ya!

Now all you have to do is seal the gaps between the pipes (otherwise there will be a lot of absorption going on), make eight more of them and finally measure the performance:

http://www.rpginc.com/research/rimages/3DGoniometer.jpg
RPG Diffusor Systems

[12ax7]

Originally Posted by Jens Eklund

Now all you have to do is seal the gaps between the pipes (otherwise there will be a lot of absorption going on)
[...]

Hmmm...

...Is that ALWAYS a bad thing?

.

[Jens Eklund]

Originally Posted by 12ax7

Hmmm...

...Is that ALWAYS a bad thing?

.

Not necessarily but if it’s diffusion your after, yes.

[Glenn Kuras]

Wow.........................I like the polys () on each side! And the arm gives it that "modern" feel.

[12ax7]

Originally Posted by Jens Eklund

Not necessarily but if it’s diffusion your after, yes.

I understand, but I guess what I mean is: Wouldn't there be a use for a device that diffused what it did not absorb?

(Like in a room that was smaller than one would like?)

.

[Jens Eklund]

Originally Posted by 12ax7

I understand, but I guess what I mean is: Wouldn't there be a use for a device that diffused what it did not absorb?

(Like in a room that was smaller than one would like?)

.

Yes, but the problem is that you don’t know what range is absorbed and by how much, and secondly; what is needed in your particular situation?

Oh, and don’t get me wrong now, I encourage experimentation!

[12ax7]

Originally Posted by Jens Eklund

Yes, but the problem is that you don’t know what range is absorbed and by how much, and secondly; what is needed in your particular situation?

Oh, and don’t get me wrong now, I encourage experimentation!

Ah, yes.

...The old "Predictability Monster", eh?

(This seems to keep coming up over and over on this sub-forum.)

Experimentation and trial-and-error methods are devilishly expensive and time-consuming in the field of studio acoustics, it would seem.

.

[SAC]

But experimentation should also be done with an awareness of the variables to be addressed.

The effectiveness of diffusion, properly done, is dependent upon reflection and re-radiation of energy.

Diffusors Already exhibit a much higher degree of absorption due to edge diffraction than is optimally desired. Thus, designs that dramatically increase this, especially using what are in effect tuned resonators that are also EQing the reflected energy within the desired range of reflected energy is not a 'design goal'.

[12ax7]

.

Ever noticed how acousticians are damn bloody irritating when they start making sense?

.

[SAC]

Perhaps that is why some are so @%#$ crazy - they have actually spent a fair amount of time focused on an awareness of the issues in some cases the equivalent of Zeno's heap and trying to derive solutions to them!

Oh, and lest anyone get the wrong idea, few actually enjoy telling others that their ideas are flawed. And even those that do would enjoy it much more if they were able to shout "hallelujah" at novel solutions that succeed!

[DaggerToe]

SAC is definitely Nutts!

I love and hate that guy...

Thanks for all your responses...

My recording room is a cube 10/9.5/9.5

Just trying to bring it back to life. I've bass trapped all the corners (rolls of insulation)

Sound Blankets cover the walls and ceiling....carpet on the floor.

The Biggest changes=
1. I built a can trap....that thing is like an acoustic black hole(55 gallon plastic trash can filled w/ insulation...It's an easy build and very cheap.)
2. Blankets...killed all the high end
3. 28" Parabolic safety mirror in the corner w/ insulation stuffed behind it. This worked wonders for bringing back the high end....

I can't really tell what my PVC diffuser is doing...oh well...It looks cool and makes the room feel better.

Stay tuned for more experimentation.....I'm trying think outside the box...LOL! pun intended!

[Jens Eklund]

Originally Posted by DaggerToe

Just trying to bring it back to life. I've bass trapped all the corners (rolls of insulation)

Sound Blankets cover the walls and ceiling....carpet on the floor.

A diffuser will not "add" anything. It will simply scatter (and absorb) the remains of energy in your room.

If you want to "bring it back to life", start with removing the (thin) absorbers that killed it in the first place!

[SAC]

What Jens said!



The simplest way to do this is to literally remove the absorption on the side and back walls and to run ETCs and to then very surgically treat only those 'spots' where incident reflections lie hat are excessive in gain.

Additionally, one may find that there are opportunities to redirect or diffuse some of this energy such that it is retained in the space without impinging upon the ISD.

But ultimately, you cannot restore what has effectively been 'eliminated'. Thus the need (and challenge) of managing the finite energy available.

Oh, and BTW, you can in large measure determine very closely what the 'diffusor' is doing in context of the ETC by evaluating the 'before' incident energy signature with the 'after' spatial, temporal and gain variables of the ETC.

[DaggerToe]

What if instead of removing the blankets....I add a bunch of cool looking diffusion over the top of them....I'm definitely going to add more parabolic
mirrors...Maybe some stalactites...LOL!

[SAC]

Now it sounds like we are moving into the Fraggle Cave from the Muppets.....

[12ax7]

Originally Posted by SAC

Now it sounds like we are moving into the Fraggle Cave from the Muppets.....

...Or maybe:

The Stalacpipe Organ at Luray Caverens

.

[takman]

hey dagger...regardless of whether it sounds good or not........it looks cool!

i like it.

good job.

[terry j]

did you work out how to plug the tubes yet?

I have experimented with using tubes (just mucking about, never got to the stage of listening etc)

Anyway, a quick method I found was the following. Take it as you see fit.

I filled the tubes to wthin a half inch or so of the top with the little foam balls you can buy that normally go into those bag chair thingymabobs. Bean bags???

Anyway, that fills the cavity without adding much weight at all.

(do this when it is horizontal!!!) To finally cap it, mix a batch of plaster of paris. The best way to do that is slowly add the correct amount to the water, and let it settle for about twenty minutes!! Yeah, did not make too much sense to me either when I read it. Do a search, you should find the correct data,

When you give it the final stir, you have about ten minutes?? Grab a cup of the mix, pour it into the last half inch of space you have left with the styrene balls.

It will fill, seal and go off rather quickly, and the balls have settled in the pipe...maybe shake it prior to the plaster.

Also cool, if you go to the paint store and just grab whatever coloured tint (get the one for water based paint) you can colour the plaster of paris to boot.

Hope that helps or gives ideas.

A quick follow up idea, if you are tidy about it you could conceivably pour some of the plaster into the little spaces left between the pipes that are causing concern re absorption.

[shawn19]

this is great, i have been thinking about building one of these myself. a couple of questions. first, why not use it as a well diffuser? in other words, why not turn it around, and have the other side toward the sound? i guess this is a well separator vs. no well separator debate.
also, great links, but it seems the 2d diffuser is calculated assuming a grid pattern like
. . . . .
. . . . .
. . . . .
. . . . .
not like
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. . . . .
. . . . .
. . . . .
i don't think it would be difficult to do it for the second case, but was wondering if you used other values because of the grid pattern.
Shawn