Im interested to know how foam eggshape panels acually work & why are they not so effective in small project studios?

I have small areas of flutter echo post Bass trapping can i place diffusion to control this?

What are the most critical areas of my tracking room i need to worry about




Edited by manleyelop (08/11/11 08:52 AM)

The foam panels actually absorb rather than diffuse - the egg crate shape just gives more surface area. The reason they're not often recommended around here is because rigid fibreglass is much more cost effective and will probably last longer as foam will deteriorate and crumble after 15-20 years.

James.

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JRP Music - Audio Mastering and Restoration.
http://www.jrpmusic.net

Hi manleyelop!

To add to James’ sensible reply, let me also add that diffusors in general can be counter-productive in a small project studio because although the ‘break up’ the reflections you have to be a couple of metres away from them, otherwise you’re likely to hear several strong reflections rather than the diffuse field you really want.

Diffusion is great in larger studios though


Martin

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YewTreeMagic

I bought the Foam panels quite a while ago so im stuck with them unfortunatly but have treated the room with Bass traps which has much improved tracking..Just wondered if i could combine the two really..

So am i best not using the foam diffusers in a small room at all?

Absorbers not diffusers!

You can use foam with the rockwool traps. Some people put the foam on top of the rock wool traps. Some on here don't rate the foam stuff at all unless it is RPG, so try the room with and without it and see what works best for you.

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http://soundcloud.com/richie-royale
http://www.mixcrate.com/richieroyale

Oh do u mean there absorbers not diffusers

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http://soundcloud.com/richie-royale
http://www.mixcrate.com/richieroyale

Ha.. i guess that means Yes

Thanks For the Help

Edited by manleyelop (08/11/11 02:41 PM)

Quote Martin Walker:

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Hi manleyelop!

To add to James’ sensible reply, let me also add that diffusors in general can be counter-productive in a small project studio because although the ‘break up’ the reflections you have to be a couple of metres away from them, otherwise you’re likely to hear several strong reflections rather than the diffuse field you really want.

Diffusion is great in larger studios though


Martin

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that rather depends on the diffusor....

a Binary Amplitude Diffusor , for example, behaves quite differently in that scenario from a deep quadratic slot design, and a skyline type design is different again.


small tracking rooms can fairly practically make use of both skyline and binary amplitude types

We did an article on Diffusion a while back, intrduces some of the basic concepts etc. have alook it might help -

http://www.gikacoustics.com/uk_education_diffusion.html

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David Shevyn General Manager GIK Acoustics Europe
www.gikacoustics.co.uk

Thanks

Quote Martin Walker:

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Hi manleyelop!
diffusors in general can be counter-productive in a small project studio because although the ‘break up’ the reflections you have to be a couple of metres away from them, otherwise you’re likely to hear several strong reflections rather than the diffuse field you really want.

Diffusion is great in larger studios though
Martin

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Martin, your response addresses a potential problem I could have.

I'm planning to convert a 3.7m x 3.7m x 2.4m bedroom into a studio primarily for mixing and some 1-track at a time recording of vocals or individual instruments. Initially I'm thinking that the listening position will be centered about 1.4m off the front wall leaving it about 2.3m off the back wall. In addition to other trapping, I am considering a 1.2m x 1.2m weighted vinyl bass trap with a DIY skyline diffusor made using wood blocks over the top centered on the back wall behind the listening position. With the trap and the tallest block each being about 0.15m tall, the listener would be about 2m from the top of the diffuser. Would that be enough distance for the diffusor to work? Also, would a combo diffusor/trap work (i.e. diffuse higher frequencies and dampen lower frequencies}?

Thanks.

Bill

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Slow but sloppy.

The words foam and diffusors should never be used together. This nomenclature is marketing speak by some acoustic products manufacturers to hook those that are not informed. Open celled acoustic foams are relatively inexpensive and easy to install. Search for one that has absorption performance parameters that are smooth in their rate of absorption over the frequency ranges you need.

Regards,
Mike

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www.acousticfields.com low frequency absorption solutions. Listen to the music without hearing the room!

i hope i get the answer that how do diffusion panels work.thanks for answer it.

From our own article on diffusion, I hope this helps for the basics -

Diffusion is a very misunderstood concept in the audio field. What exactly is diffusion? According to Webster, there are several definitions which relate to various fields. Let’s take a look at the generic definition and one more audio related.

Diffusion: The movement of a substance from an area of high concentration to an area of low concentration.

Diffusion: In audio, the scattering of sound waves, reducing the sense of localization.

Those 2 definitions may seem to be very different but they really aren’t. If we think of a series of sound waves bouncing off of a wall, they’re concentrated and moving in the same direction at the same time. The reflections off of the wall will come back to the listener at approximately the same time and from approximately the same direction. The ‘concentration’ is still in tact in the spatial and time domains.

Now, if we introduce a diffuser onto that flat surface and we generate the same sound waves, what happens? Most people would say that we are scattering the sound in other directions rather than in the directly reflected path. This is true, but is not the whole story. A good diffuser not only changes the reflections to propagate in different directions, but does so EVENLY in all directions. Just splitting a wave to go into 2 directions doesn’t do enough. We’ve effectively changed the concentration of the waves in a certain portion of the room. We’ve also effectively taken the intensity of the initial wavefront and split it among the various reflections so that each one is not only coming from a different direction, but each is also weaker and harder to distinguish but we’ve lost no energy in the process.

A proper diffuser also impacts the time domain. If we have the same wave and it gets reflected into multiple directions evenly, the length of the path the various waves must take to reach the listener also changes. In the world of sound, distance is time. For ease, we can say that 1 foot equals approximately 1ms of time. So, if we’ve changed the path into say 8 different paths (in reality, there are many paths but we’ll look at 8 just for ease of understanding), each one ideally with have a different path, which means that they’ll arrive at 8 different times. Again, we’re diluting the concentration of sound but this time in the time domain instead of spatially. In addition, these different path lengths cause differences in the number of reflections and the amount of air the wave passes through which will cause each reflection to have a different intensity (more dilution in yet another domain – intensity).

So, now we have 8 reflections that have been changed and are all different in 3 domains – time, direction, and intensity. This makes it much more difficult for our ears and brain to determine exactly where the sound is coming from. This fits perfectly the definition of a lack of localization. The net result of this is that we trick our brain into thinking the room is larger that what it is and yielding a more spacious sound.

There are a great may myths about ‘home brew’ ways to provide diffusion. Most do not work at all and many work poorly or only over a very narrow range of frequencies. Let’s take a look at one – a bookcase with books set at randomly varying depths.

First of all, books, if anything will be more absorptive than reflective at all but the highest frequencies. Second, random depths do not generate random reflections over a predictable and controllable area. The width, height, spacing, and pattern of the wells of a diffuser are carefully calculated to make sure they generate a smooth and even scattering of the waves over optimally a 180 degree angle. Third, without the careful calculated spacing, we can cause frequency related aberrations due to constructive and destructive wave interactions from various reflections. We’re in effect getting very little of the benefit of a diffuser while causing more issues in the frequency response.

Another myth is using CD/DVD cases or LPs in the same sort of random manner. In addition to the issues presented above, the cases themselves are so narrow that the frequencies that would be affected would be only in the highest ranges. Again, the width, depth, and pattern of the wells and peaks of a diffuser not only generate the proper diffuse pattern, but also determine the frequency range over which a diffuser is effective.

Frequently Asked Questions:

Q: Is it true that I have to sit far away from diffusion to make it work?
A: Well, yes and no actually. You need a certain amount of distance between the listening position and the diffuser to allow it to do its job. The closer you sit, the less chance the waves have to move farther from you and the less difference there is in the timing that they reach your ears. They’ll still have some effect but not as much.

Q: Is it true that you need to have a large room for diffusion to be effective?
A: Again, yes and no (seeing a pattern here? Every room is different). Normally, in a smaller space, one needs proportionately more absorption for bass control than in a larger room. This leaves less space for diffusion – not to mention the issues raised in the first question. However, diffusion can still be effective up high in the room to assist in killing slap echo and controlling the ‘zing’ in a room – especially a tracking room.

Q: What is the best place for diffusors?
A: This really depends on the situation and what you’re using the room for. Diffusion can be used up high in a room to kill slap echo, in the rear of the room along the side walls, in place of absorption on the ceiling, etc. The most common place to see diffusion in a studio environment is on the rear wall. However, many times, you’ll benefit more from absorption there to kill a strong bass null off the back wall.

Q: How would these help in a live tracking room?
A: In a live room, we want it to be as the name implies, relatively live. But, we still need to get it under control in terms of decay times. We also want to get that ‘big’ sound. Diffusion can help to eliminate echo and produce a nice large sound without killing too much of the liveliness. It does so by spreading the sound, causing it to move through more air and bounce off more surfaces which decreases the intensity of the sound. For decay time control, diffusion is normally used in conjunction with broadband absorption.

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David Shevyn General Manager GIK Acoustics Europe
www.gikacoustics.co.uk