Room help please.

Hi Everyone I am trying to replace the acoustic foam in a small voiceover/mix room. Currently there is about 2" thick foam on all the walls starting 3' from the floor (where there isnt a window/door). The foam is about 10 years old and was painted, and now most of the paint is gone due to dry rot and its dusty mess. So that needs to go. With that foam the room was very dry, something I am unsure is suitable for our needs. This is for a college radio station, so a balance of low cost and somewhat decent results is what we are aiming for. Looking good is also a requirement. We use two dynamic mics to record voiceovers, and the room was soundproof enough for our needs with the old foam. If getting rid of it is going to make a difference, that also needs to be factored in, but i think the studio was built with soundproofing in mind with doubled windows and doors. I was thinking of getting some 2" wedge acoustic foam and lining the wall next the the ceiling with it, or putting it in diamonds at various places in the room. What I am aiming to get is decent sounding voiceovers and true representation out of the monitors. I have attached a drawing of the room. It has an 8' drop ceiling with the standard whiteish (fiberglass?) tiles. the windows are 40"x39" and start about 3' off the ground, leaving 21" of wall above them. the door (frame) is 41"x86", leaving 10" of wall above it. From the floor there is commercial grade carpet going 3' up the walls. Thanks for any help or comments.

Aloha and welcome to the forum, milesdf I've attached for drawing for easier reference :wink: Is there any chance you could attach some pics of the room also? Most of the designs for acoustic treatments you'll find here will be for using some type of insulation material to absorb the low-mids - high freqs instead of foam based products. Here's a good reference for some basic principles about acoustics, absorbers and construction - SAE Website: http://www.saecollege.de/reference_material/index.html (be sure to click on the acoustics, absorbers, construction tabs at left, and tabs that appear at the top of the pages) Wall units plans - http://www.johnlsayers.com/HR/index1.htm Here are some links regarding vocal booths that might prove helpful: Vocal Booth Acoustic Treatment - http://www.johnlsayers.com/phpBB2/viewt ... booth+jpeg Venting a Vocal Booth - http://www.johnlsayers.com/phpBB2/viewt ... booth+jpeg Vocal Booths - http://www.johnlsayers.com/phpBB2/viewt ... ?p=443#443 Building a Vocal Booth - http://www.johnlsayers.com/phpBB2/viewt ... booth+jpeg Iso Booth Ideas - http://www.johnlsayers.com/phpBB2/viewt ... booth+jpeg

Quote: http://www.johnlsayers.com/phpBB2/viewt ... ?p=443#443 A vocal booth need to be quite dead with no apparent roomsound if you want a tight vocal sound. When I say dead I mean right across the frequency spectrum which requires various absorbers aimed at different frequency ranges. Have you been to the SAE site? check out absorbers. http://www.saecollege.de/reference_material/index.html cheers, john

Quote: http://www.johnlsayers.com/phpBB2/viewt ... booth+jpeg Mode-wise, a 5 x 6 x 7 (inside) booth looks very good. It will also fit into an 8 foot ceilinged area if necessary, and is big enough for 3 (very) friendly vocalists or 1-2 with a guitar, so that's what I'm going to start with. Once I finish (don't stop breathing while you wait, I have 'way too many projects still open) you could change dimensions to suit, just do NOT make any two dimensions the same, or more than one dimension in even # of feet. Steve

Hope these help, Aloha 8)

thanks for the links, it does seem like alot of this is focused on building and soundproofing though, i would just like to re-emphasize that i dont have the resources to build much of anything in there, and it is sound proof enough, so I would just like to get vocals sounding nice and be able to listen to the monitors without much room influence. from what i am reading, its not very nessecary to put absorbtion on the wall in front of the vocal, only behind them so the sound ends up bouncing on the reflective wall but then is absorbed on the other one before it gets back to the mic. the issue here is that there is a window on the other wall were the absortion would go. I have also read that there are issues with standard foam because it doesnt absorb enough low frequencies, so more broadband devices have to be used. I guess i can see this because the tone from the old foam wasnt too good, almost "in a box" as described by some of the posters. good info already. maybe i will have to turn the desk in that room so i can get a good wall behind the vocal. edit: i will try to get some pics tommorrow.

milesdf wrote:

thanks for the links, it does seem like alot of this is focused on building and soundproofing though, i would just like to re-emphasize that i dont have the resources to build much of anything in there, and it is sound proof enough, so I would just like to get vocals sounding nice and be able to listen to the monitors without much room influence..

Kendale gave you the short answer to the vocals here:

Most of the designs for acoustic treatments you'll find here will be for using some type of insulation material to absorb the low-mids - high freqs instead of foam based products.

As far as "listen to the monitors without much room influence.." goes, the reference material Kendale referenced gives you a good start on it. Andre

hmm thanks for the clarification, I see your point about foam not absorbing in those ranges. how much low frequency absorbtion do you think I need? its not like we are singing, just normal level talking. i also am liking the idea of using insulation in a pretty enclosed box, as this would probablly last forever, solving the issues we had with the foam. are such units commercially availible, as we are part of a school and woodworking is going to be a little difficult.

Human speech fundamentals can get down into the 130 Hz range, so I would aim to absorb down to 100 Hz. For this, corner absorption rather than flush wall mounting is necessary. Two inch thick mineral wool panels across the corners of the room will be effective down 100 Hz (not much after that), which will cover al but the lowest modes of vibration in your room. If you need to monitor music in that room, I would use 4" panels acrosss the corners as they are effective down to about 60 Hz.

...as this would probablly last forever, solving the issues we had with the foam.

Modern high quality foam will last a very long time.

David French wrote:

Human speech fundamentals can get down into the 130 Hz range, so I would aim to absorb down to 100 Hz. For this, corner absorption rather than flush wall mounting is necessary. Two inch thick mineral wool panels across the corners of the room will be effective down 100 Hz (not much after that), which will cover al but the lowest modes of vibration in your room. If you need to monitor music in that room, I would use 4" panels acrosss the corners as they are effective down to about 60 Hz.

...as this would probablly last forever, solving the issues we had with the foam.

Modern high quality foam will last a very long time.

thanks for the advice! corner panels are going to be very difficult to achieve in this room though, I am thinking. how wide do you think they have to be? do they have to have the wooden slats on the front? I think our issue with the foam stemmed from the paint that was on it, not the foam itself. after ten years the paint has started to dryrot. will 4" corner panels alone be sufficient in these rooms, or will I also need more absorbtion on the walls?

The performance spec I gave you for rigid mineral wool is for the standard 2' x 4' panel size. When placed across the corner at 45 degrees, the edges come out approximately 17" from each corner along the surface of the wall. No wooden slats should be used. The design is quite simple; all you need is a panel of Owens Corning 703 or equivalent wrapped in fabric for looks and fiber control and some method of mounting the panel. For your room, for the purposes of recording speech, I would guess that one 4" thick panel placed vertically at 45 degrees across each wall-meets-wall corner would take care of the low end. I would also use additional absorption, either 2" 703 with an airspace of 4" foam, flush mounted on the walls in the center of each surface.

hmm. you will notice in the drawing that one corner cannot recieve such treatment due to the door being right there. is there any way to account for this? how about these panels in the corners from the walls to cieling? would this make any difference? The pages on building these contraptions seem to be very good, they look pretty easy to make and I think i can borrow the neccessary tools. im going to get pictures now, if i can find some batteries for my camera.

Don't worry about the door issue. You will have similar performance in the low end if you put two in one corner; however, you will get better high end performance if you distribute the panels evenly. Floor to ceiling is the standard idea, so if you'd like to do that and it's convenient, go for it.

round 2 on posting pictures, resized this time. edit: hmm i cant post comments, well here they are: 1. from door looking into the left corner. 2. from door looking into the right corner. 3. corner next to door. 4. very old studio gear, will be upgraded soon. 5. corner behind door, flaky paint foam is visible. 6. nasty nasty foam, from behind harrassed by hands looking for the lightswitch over ten years.

David French wrote:

Don't worry about the door issue. You will have similar performance in the low end if you put two in one corner; however, you will get better high end performance if you distribute the panels evenly. Floor to ceiling is the standard idea, so if you'd like to do that and it's convenient, go for it.

thanks for the reply. I was talking about putting corner panels horizontally instead of vertically, such as the corner between the wall and ceiling, instead of wall and wall. So what I am thinking is two 4" corner panels and 2-3 2" wall panels, all 2'x4'. What kind of results will this get me? from what i am reading and hearing, it will probablly be much better in the low end but the foam will have done a better job in the high end.

Don't use horizontal wall-meets-ceiling placement. The ceiling tiles will do the job in this dimension. I would try to work in four vertical panels if you can. Comparing the room with foam to the room with fiberglass, yes, the foam room is more effective in the high end.. the really high end. There's probably nary an 18kHz reflection in that room. Too bad there's nary an 18 Khz sound coming from anyone's mouth. The big problem with foam on the walls like that without any other treatment is that is just soaks up the highs and leaves the low end problems sounding even more conspicuous.

David French wrote:

Don't use horizontal wall-meets-ceiling placement. The ceiling tiles will do the job in this dimension. I would try to work in four vertical panels if you can. Comparing the room with foam to the room with fiberglass, yes, the foam room is more effective in the high end.. the really high end. There's probably nary an 18kHz reflection in that room. Too bad there's nary an 18 Khz sound coming from anyone's mouth. The big problem with foam on the walls like that without any other treatment is that is just soaks up the highs and leaves the low end problems sounding even more conspicuous.

by vertical panels do you mean on the walls or in the corners, like I should bridge a corner with two panels instead of just one?

I mean in the wall-meets-wall corners, placed vertically, and at 45 degrees across the corner.

that is going to be really really hard in this room and have it still be functional. is thier any way to get the same absorbancy in less space? we could probablly make the panels 5' long. i think in order to keep functionality we will not be able to eliminate too much of the corners, 1.5' out from the wall on each side is probablly the maximum we can do, and of course the one corner behind the door cannot be used. is there any way to still meet the original goal? i am sorry to have to say it, but this room doesnt have to be perfect, just be good enough for college radio work. thanks for your help.

Put one panel across each corner that you can. Also use 4" on the walls with as much airspace as you can. This will be ok. 1.5' out from each corner is juct about exactly how much you need to come out: sqrt(2) feet.

David French wrote:

Put one panel across each corner that you can. Also use 4" on the walls with as much airspace as you can. This will be ok. 1.5' out from each corner is juct about exactly how much you need to come out: sqrt(2) feet.

this is not taking into account the 4" of fiberglass though. can the edges of the fiberglass be cut so its frame would fit flush in the corner and be caulked? this would look pretty sweet as well.

Yes, bevel cut is fine.

one more thing, how is fiberglass generally cut? pair of scissors? thanks.

A serrated knife works well... also an electric carving knife or table saw if you have them.

great, it looks like this is going to happen. unfortunatley our advisor is probablly going to make us pay facilities to remove the old foam and adhesive, (which in my opinion is bullshit). it does look as able we will be able to build these panels discreetly and then call them purchased though. funny how it works when your involved with an organization, so much politics and bullshit you have to deal with. it appears now that this room is going to switch places with the office, which has pretty much the same dimensions, except it has a window next to the door as well. I think what we will end up doing is 2'x5' 4" thick panels in 2 or 3 of the corners. we will then try for some 2" thick 2x4 panels on the walls in various places. we also would like to make the main control room acoustically sound. I dont think I really have to make up schematics, its almost the same except that the side with the door is extended 4' and the door is on the extension on the right side. the desk is on the side of the door. the side next to the door is pretty much a window, unfortuatley. I am planning to put 2x5 sections of 2" thick panels in all four of the corners, on the window side they will have to be cut a little narrower. there will be a 4x6 2" panel on the wall behind the person talking into the mic. would it be benifical to use 4" foam on this panel? we are aiming for only medium volume vocals in this room, are corner absorbers neccesary? our mics are dynamic and very good at off axis rejection, so maybe only a panel in front of the mics (behind the speaking person) that can absorb down to 100 hertz?

Corner absorbers are necessary in virtually ANY room; volume is relatively unimportant, other than possibly exciting actual wall panels more (if they're not solid concrete) - first thing to consider in any room is positioning of the "instrument" (voices are instruments) - if the instrument is in a null at a particular frequency (in the case of voice, between roughly 100-3000 hZ) then that frequency won't be as loud in the recording. So the first step (assuming you get to start from scratch) is laying out the room so the normal mic position is NOT at any even multiple of any dimension (not 1/2, not 1/3, not 2/5, etc) - same with any monitor speakers, other than stereo needing to be symmetrical left to right) - once this is done and tested for best frequency/tonal balance, THEN you add treatments to FURTHER smooth out the response that couldn't be helped by positioning of both source and mic. Positioning of mic or source relative to any boundary will also color the sound by phase cancellations, so this needs to be kept in mind when deciding on layout as well. If you START by placing all the treatments you THINK you need, you won't be able to hear what the room DIMENSIONS are doing to your sound as well, so likely won't get as optimum a setup. If you're going to use foam, I'd recommend only using Auralex' PRO panels, not sure but possibly Illbruck now also makes denser panels (maker of Sonex); most other foams aren't as dense, so won't absorb to as low a frequency, leaving you with more of that "boxy" foam sound. As to only having absorbent behind the speaking person, keep in mind that even a directional mic is still a pressure device; if the capsule of the mic is in a null caused by distance between mic and ANY wall, it will still affect the level of that frequency; so you need to absorb ANY close surface you don't want causing phase cancellations(comb filtering)... Steve

thanks for the reply. I am not for or against foam, infact i like the fiberglass panel idea because it is cheaper, and I am having bad expiriences with the current foam. im not sure if mic placement can really be set, these mics are on positionable booms, and they are generally positioned to location of greatest comfort. starting from scratch on the room is pretty much immpossible, and there has to be room for a couple people and a desk, and the windows still have to be mostly unobstructed. so perfection is immposible. how close to getting decent results can i get?

I know life is full of compromises, but it's easier to come up with workable solutions if you understand what the tradeoffs are; that's the main reason I posted. In any setup, acoustics will often be butting heads with practicality, such as the mic booms you mentioned, usable space, pieces of gear being within reach for adjustment and viewing, etc - In this type of application, about the best you can do is to help make the people who will use the gear AWARE that moving the mic just an inch or two can make things better or worse. Like the old saying goes, first you learn WHAT the rules are, and WHY; then you'll know which rules you can break, and what will happen when you do. The RE-20's I saw in the pix are typically used by radio "voices" because they make everyone sound "bigger" with their nice round bottom end; this can be either minimised or exaggerated by juxtaposition. Moving the mic will change boundary response between mic and walls/ceiling, etc, repositioning the speaker's head can do the same, as can distance between mouth and mic; aside from smoothing out the room (trapping any and all usable corners, patches on walls, "clouds" for floor/ceiling flutter, etc, the main thing to keep in mind is that the more aware people are that positioning can/will affect things, the more likely they can use this to improve their results. For a room such as yours, that's about the best you can do; ideals are more something to keep in mind while you do what you MUST in order to do anything at all... Steve