Walls & Ceiling-Diffusion or Absorbtion?

giles117 · Post by **giles117** » Sun Sep 14, 2003 6:41 am

Just having fun Ethan.

Yeah everyone wants an easy fix to lifes physic problems.

blackdrum · Post by **blackdrum** » Mon Sep 15, 2003 3:59 am

ok. great info! thanks!

so here's what Ive decided for the control room:

-john's slot resonators for sides & front of room
(do i "splay" the front room resonator to face up to the ceiling? or off to the sides?)

-OC Fiberglass Insulation on the back wall
(do i make a frame out of 1x1s? wrap in burlap?)

-Vinyl floor. (all i can afford, will this be ok? better than carpet?)

-Absorbtion on the celing (cover it all? or just in certain places?)

Im not going to 'tune' the 'LIVE' room until i finish the control room.

Im getting burned out quickly.

This seemed like a great & exciting idea, but its A LOT of work!!

knightfly · Post by **knightfly** » Mon Sep 15, 2003 4:27 pm

The fiberglas can be wrapped in cloth (fireproof, preferably) which can be glued to the outer perimeter in back, like wrapping only the visible portion of a christmas present and gluing the paper on the rear edge. If you want, you can make the panels portable by mounting them like this

http://johnlsayers.com/phpBB2/viewtopic ... ight=mount

Vinyl floor is fine, carpet sucks. (literally, for high frequencies) - you generally want more EVEN absorption, in order to keep the room neutral sounding.

Cover the entire ceiling if you can - minimum over the mix position. See drawing.

Hope that helped... Steve

blackdrum · Post by **blackdrum** » Wed Oct 01, 2003 9:14 am

hi
we went way over budget, so i was wondering if it would be ok to leave just painted plywood for the floor in the 'live' room (studio) instead of putting down tile???

also, in the SAE diagram which was recommended to me here:
http://www.saecollege.de/reference_mate ... ge%202.gif

i am a little confused as to which panels are which. can anyone tell me where i need john's slot panels and where i need other panels?

thanks

PS-the final dimensions of the rooms are:

control room = 8ft 4 inches X 13ft 10 inches (7ft 11 inches ceiling)

'live' room (studio) = 18ft 6 inches X 8ft 11inches (8ft 8inches ceiling) (on floating floor)

a little different than I said in the earlier post.

knightfly · Post by **knightfly** » Wed Oct 01, 2003 6:50 pm

Acoustically, the plywood won't be a problem. However, in order to get paint that is durable enough for floor use you may end up spending as much as it would cost for sheet vinyl, which would last a lot longer than paint.

"can anyone tell me where i need john's slot panels and where i need other panels? "

Not sure which ones you're unclear on - they all seem to be labeled as near as I can tell... Steve

blackdrum · Post by **blackdrum** » Thu Oct 02, 2003 8:07 am

the ones i am unclear on are the ones in the back of the control room labelled "Cloth Front"

Thanks!

knightfly · Post by **knightfly** » Thu Oct 02, 2003 12:37 pm

Guess that part is a little vague if you're not familiar with all of John's sites - go here -

http://www.johnlsayers.com/HR/index1.htm

and scroll down to "THE REAR WALL ABSORBER" - If you build to the floor plan you posted, you would just enlarge the dimensions of the absorbers and build the V-shaped part as two absorbers... Steve

midigod · Post by **midigod** » Thu Nov 27, 2003 6:00 am

I have two questions regarding diffusion:

1. Knightfly, you said "In rooms that are small enough NOT to have a minimum ROUND TRIP path from mix position to rear wall of at least 22-25 feet, it's not recommended to use diffusion on rear walls but use absorption instead." My room will be right on that cusp, measuring about 22 feet from mix to wall to mix. Would it be a good idea to have some diffusion and some absorption, or should I go only with absorption?

2. Of all the differing types of diffusion, I'm finding it hard to determine which type would be best. I've read posts in this forum that say that radiused wall sections aren't really diffusion, but this product:
http://www.soundcontrolroom.com/saturn.htm
claims to be a diffusor, and uses radiuses to accomplish it. Other than Helmholtz types, which I can understand being more useful in the low frequencies, can anyone tell me the practical difference between the Skyline, Saturn, Well, and Radius types? In other words, if I'm picking out diffusors, how do I know which type to use?

Thank you very much for your time!

-Craig

knightfly · Post by **knightfly** » Thu Nov 27, 2003 6:44 am

1. At that distance, it would be borderline. I would play it safe and build the back wall absorptive, then if you wanted to "play around", try a DIY diffusor or two and see if it makes things better or worse.

2. "radiused wall sections aren't really diffusion" - Alton Everest would disagree with that, as would I. If you send a sound wave into a convex surface, only a minute portion of it will come back the same direction. Granted, that's not RANDOM diffusion, partly because you can easily predict mathmatically where the rays will reflect to, but they're so scattered that it would be difficult to tell the difference once you're 10 feet from the diffusor.

A Helmholz is an absorber, not a diffusor - although, the slots might cause a tiny bit of diffusion.

The Saturn and Radius types (Polycylindrical) could be similar if you were to mount some small radius poly's 90 degrees to others, so the diffusion was hemispeherical. However, $50 apiece makes me reach for my power tools...

The skyline and QRD types do similar things, but again in order to get hemispherical (both axis) diffusion, you need to mount some of the QRD types in opposite axes (some vertical, some horizontal) - From a DIY standpoint, the QRD's would be easier to make (assuming you actually follow the formulae instead of just gluing random blocks to a sheet of plywood and painting/staining it)

In this type as well, I see the prices they want for a $3 piece of injection molded plastic and immediately quit thinking about it in non-DIY terms.

Before I spent much time and effort on building anything, I'd put some large bookshelves at the rear of the room and randomly fill them with books, bric-a-brac, etc, anything that doesn't RATTLE, and see if you like the effect. The real deal will do more, but it should give you an idea whether it's worth pursuing... Steve

midigod · Post by **midigod** » Thu Nov 27, 2003 7:12 am

Steve-

Thank you so much for your response. I agree about the price of molded plastic. I also agree about the radius diffusion - it has struck me in exactly the same way. That maybe it's not true diffusion, but in the practical application, it'll be exactly the same thing.

I'll use absorption for the rear wall, and save the radiuses for the live room.

-Craig

knightfly · Post by **knightfly** » Thu Nov 27, 2003 7:52 am

Everest's Master Handbook of Acoustics shows enough info/pix for a reasonably experienced DIY'er to build poly's - BTW, have you watched America's Funniest Videos recently? Guess what they have on their walls - If you're into overpowering effects, think what that wall would look like with alternating colors - or, as they've done, accent lighting for shadow effects... Steve