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Live/Tracking Room DIY Diffusion/Scattering Acoustic Treatment & Material Options

Discussion in 'Room Acoustics / Isolation / Treatment' started by ChrisH, May 11, 2015.

  1. ChrisH

    ChrisH Active Member

    In my opinion (i think most will agree) that after the original source (instrument, amp, ect..) the room that the instrument is being tracked in is the first stage of EQ.

    Given that idea I believe you want a general multi-purpose tracking room to have a tight bottom end and bright highs. I'm aware that this is subjective and a matter of taste, application and of course room dimensions.

    1. If you have too much high frequency absorption, the instruments you track in that room will most likely sound lifeless in the high's, due to the lack of good high frequency reflections.
    2. If you don't have enough low end absorption, the room will probably be "boomy" and "boxy".

    I think it's really easy to overdo high frequency absorption, which leads me to trying to come up with different ways to make thick absorption panels reflective/scattering in the highs yet still absorbing the lower frequency.
    I've noticed allot of thick absorption panels in higher end studio's have very thin 1/16 inch wood panels with holes drilled in them.

    My question is..
    What are different simple ways of going about making absorption panels/walls/ ceilings that scatter highs and absorb the lower frequency's?
  2. pcrecord

    pcrecord Don't you want the best recording like I do ? Well-Known Member

    I'm far from an expert but the first thing to understand is that frequency response of acoustic panels depends on the tickness and type of material.
    Before you start anything, you need to know what are the room's defects if any. the best way to do so is actually record in it and analyse the results.
    If recordings of vocal, acoustics and other instruments with different mics and placement all give too much 200hz.. that should be your main focus.
    Once the 200hz is taking care of, record again.. and so on.. long but you'll get the sound you want.

    Going on with calculations and theory is good.. but some go at it with closed eyes and creates problems instead of fixing some.. take your time !
    ChrisH likes this.
  3. Kurt Foster

    Kurt Foster Distinguished Member




    Bass trap - Wikipedia, the free encyclopedia
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  4. audiokid

    audiokid Staff

    it blows my mind that for over a decade this site has had some of the industries leading acousticians and not one of them posted information that we can refer people to here. rotf
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  5. ChrisH

    ChrisH Active Member

    I getcha, was just thinkin in the means of different materials for basic scattering of highs? I have not seen that on here, maybe I'm blind?
  6. DonnyThompson

    DonnyThompson Distinguished Member

    By "type of material" I believe that PC is referring to density, which is important. For example, 3" of Roxul has much more absorbent quality, and can also absorb a wider frequency range, than the same 3 inches of regular household insulation, or even typical auralex can.

    Roxul Safe and Sound, Owens Corning 703, 705, etc. are but a few of the common materials used in DIY acoustic treatment. They are light, and can be framed for attachment to boundaries, and can also be easily covered with fabric for nicer looking aesthetics.

    And, don't discount using an air gap in-between the back of the material and the boundary you are adhering it to. This can increase the absorption efficiency of the material.

    But, you have to know what issues you are treating for first.

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  7. kmetal

    kmetal Kyle P. Gushue Well-Known Member

    Those panels are 'helmholtz resonators'. Tuned broadband bass traps. Just like slats, the pegboard is the same concept. The relationships between board surface, and absorbabtive (holes with insulation behind), along with the depth of the air gap behind it, determine what frequencies it attacks. The more board surface (smaller holes /spaces) absorbs more bass and reflects more highs. So if your room is boomy in the mudrange, build a mid bass trap that attacks that area.

    I've been fascinated with polys and curved surfaces, so I'd put them in if I was making a place right now. If I was gonna go with a nice RPG or DIY diffusive/reflective type thing this is the room to put it in. Maybe a nice stone facade on one wall for giggles.

    Tracking rooms are a comletely different animal, and I don't belive there is a solid science on diffusion in general, and certainly not in 'how to make an amazing room'. Calculators are unsure for large racking areas where RT60 is a concern, and you need a smooth decay/intelligibility. Also an area where true diffusion has an effect. @audiokid There is no easy way to quantify 'good' like there is 'flat', and there's no easy way to calculate flat. So really I think it's a question of having the ability to use high level acoustic modeling, if your gonna pre design a signature into a room, and even then, acousticians know it's an art science, not an exact one. So I think we don't see easy answers to these diffusion, tracking room questions cuz they're t aren't any, and each one is custom. I think doing that would be like us remixing each persons song ourselves, in the mix critique section. I think it comes down to a combination of money, and lack of an solid 1+1 answer

    Unless your building it for a specific purpose, like vocals, where there is an expected frequency range you need to complement, then you just need some broadband treatments. A few corner traps, some ceiling absorption, and some wall panels. I usually don't like to have 2 untreated surfaces facing each other, in the couple tracking rooms I set up.

    Just tame the room down with well distributed broadband stuff, and you'll probably be fine. You can certlny get into movable panels, or 'live sections' of walls, and have curtains, so you can mess with the liveness. A room this size is probably going to be pretty tight and punchy. Get rid of any obtrusive booms, and slap echoes, and that's about it. Get you natural verb from an adjacent hall, and the 70s guys will smile. There ya go, anything else you need there's a pluggin for.

    Your probably gonna want to focus your wall absorbsion so it's at mic level or lower. You can raise the overheads a bit to catch some more life.

    If there ever was a good place for 2" foam it's on low ceilings in booths. Saves space and kills the crap your mics never want to hear.
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  8. ChrisH

    ChrisH Active Member

    Thank you, Kyle. Fantastic information and insight as always.

    Your statement I quoted above is pretty on track to what my OP was asking about.
    I want to build tuned resonator traps that instead of just having a flat holed front surface, it would have more of like a poly curved surface to do some minimal scattering from parallel surfaces. Does that make sense? Basically a Poly Diffuser that is also a tuned broadband trap or resonator, possible?
  9. Kurt Foster

    Kurt Foster Distinguished Member

    you might be able to do that with a slat wall. frame it out with 2 X4s, fill with rock wool, cover that with tar paper and then put up the slats. that calculator sheet i posted earlier has the formulas for figuring out the spacing of the slats.
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  10. ChrisH

    ChrisH Active Member

    I've been playing with that calculator sheet since your last post, pretty awesome. I appreciate the help Kurt!
  11. kmetal

    kmetal Kyle P. Gushue Well-Known Member

    So a polyfusinator? Lmao. Yeah man I've been toying with that idea for a while. The curved nature of the cavity makes it different than what a typical calculator figuring. But using the same type of thinking you would for a corner trap (where it's a variable depth cavity) I'm guessing, is probably just fine.

    If you do nice wide arcs (or whatever the technical term is) then you could bend the slats lengthwise. I'd prefer this over the oak barrel look, of vertical salts on a poly, but that's astchetics. Your also not limited to pegboards, or slats. I think the main consideration is the board surface to space ratio, not necessarily the shape of the cutout. Ante up studios, in I think OH, closed a few years ago, but it was a $3m project according to some article. Chimaira did a crushing album there. They have some cool architectural details in their rooms, but not necessarily, hard to fabricate, at least from the surface anyway. If you can find some pics of this place maybe it will spark some ideas. Forgot we were talking tracking rooms , you might like some of the things they built into blue jay studio, in Carlisle, MA.

    With bass trapping, I've always had a hard time trying to quantify, how much of an effect they will have. The center frequency is fairly straightforward. When it comes down to "how many db" in the traps range, it would knock down, in a given area. But since this is a tracking room, it's not quite so critical, as its job doesn't have a particular sweet spot in mind.

    Hopefully we can find out more about this type of thing, because after the basic RFZ, it seems to jump right into PHD territory lol.

    Fun topics Chris. It's cool when we're all along for the pre production!!!!
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  12. Brien Holcombe

    Brien Holcombe Well-Known Member

    If the goal is to retain the mids and highs in the environment after the inclusion of absorption is introduced I would suggest a flame retardant breathable cloth rather than something as potentiality flammable as 15 or 30 # felt.

    If the goal is to contain the air-borne particles of the fibrous insulation...same thing applies.
  13. Rod Gervais

    Rod Gervais Active Member

    Actually I would not necessarily agree with this commet..........

    While it's true that the lack of low end control can be very problematic - a lack of reflections is not the same thing.

    If you were to walk into the center of the main rooms in Studios "A" at Avatar NY or Sonalysts in CT and set up to record an acoustic guitar - what you would find is that you had no reflections whatsoever from anywhere in the room (except for what might occur from the floor) if you were to close mic the instrument - and began to pick up the rooms influence if you were to raise the mic into the room.

    A mic up in the coffin would be the extreme when it came to reflections.

    The lack of high frequency reflections would leave what I would consider a "clean" guitar sound...... you would be hearing the guitar - and just the guitar.....

    It is not as if putting that guitar inside of even a completely dead room would some how change the sound emanating from the body of the guitar itself........ it would simply mean that the room did not influence the overall sound.

    There is a difference between adding to the sound emanating from the instument and altering the sound of the instrument itself.

    You can always add some ambiance to a recorded sound to emulate a more reflective room........ but without reflections what you have is the pure raw sound of the instrument itself. That doesn't suddenly magically dissapear.

    kmetal likes this.
  14. dvdhawk

    dvdhawk Well-Known Member

    With all due respect, you've just missed them because it didn't interest you. I've seen, and read, countless resources over the years that were posted here by acousticians and builders - because it interests me very much. Thanks to Rod, Andre, Brien, Max, Glenn (Gulfo), Wes, Eric, Etc.
  15. Rod Gervais

    Rod Gervais Active Member

    I believe you missed the sarcasm in his remark.........

    Unless I am mistaken his point was that it would have been more appropriate had the links been to the data on this site.

    He can correct me if I'm mistaken.

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  16. dvdhawk

    dvdhawk Well-Known Member

    It's certainly possible Rod. I could be filtering that through some comments Chris made recently about the Studio Construction and Acoustics sections of RO, in a thread that was eventually purged. I know he's been laboring through cleaning up old dead links and recently made more accommodations for uploading files here.

    In any case, the fact that we can ask experts like yourself for their advice is priceless. I don't expect any of you to give away the store. It is how you and many of these experts make a living.
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  17. pcrecord

    pcrecord Don't you want the best recording like I do ? Well-Known Member

    I find that opening a door with partial informations is worst than giving no information.

    As many years as I've been here, I never withhold any information that could help someone to better record or mix even if that's a part of my living. I guess participating in a forum is more than making money to me. It's supposed to be a sharing, you give I take, I give you take...

    Audio acoustics is something hard to learn and I wish we could build an article or guide or anything that could make sens for EVERYone ;)
  18. dvdhawk

    dvdhawk Well-Known Member

    Marco you've proven yourself to be a pillar of the community here and very generous with your time and helpful advice. I sincerely admire your efforts and commend you for that, but this 'give and take' doesn't affect your livelihood in the same way.

    You have a lot of experience and knowledge to share, but you make your living recording music and providing photographic services, so a better analogy would be if we all showed up at your door expecting you to record our album for free and shoot the cover photo for free while you're at it.

    I don't think anybody is withholding information, but by the same token people who have dedicated their lives to acquiring the expertise to write a book shouldn't be expected to give away the contents online anymore than you should be expected to give away the music you've created.

    These fellows have been extremely generous with their time sharing their knowledge and experiences over the years, and we're lucky to have the chance to learn from people waaaaay further up the ladder than we are. To me that is what a forum like this is about, reaching back and helping someone else behind you come up a rung or two.

    Audio acoustics is a very challenging subject.

    I'm happy to freely share the four main things I discovered trying to learn more about acoustics via the internet, which are:
    1) The web is full of self-proclaimed 'expert' acousticians, mis-guided theories, and .
    2) One size does NOT fit all.
    3) Beyond "get the F. Alton Everest Master Handbook of Acoustics" the 'experts' don't agree on a lot of things.
    4) Lots of the 'experts' DO have product to sell, so you always have to consider the source, their professional track-record, including their biases toward their own product.

    With great respect and appreciation to you and all who share their time and talents here,

    I apologize to ChrisH, if we've veered off-topic.
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  19. pcrecord

    pcrecord Don't you want the best recording like I do ? Well-Known Member

    To me it's very different to explain to you how to do something and do it for you. I'm not expecting anyone to travel here and acousticly tune my room for free. But, pointing me to the right tools with explaination I can grasp is something I wish for. Thinking that acoustic know how is more important than mic placement and mixing techniques is like establishing that they are better persons because they know something or that knowledge is more important than others.

    I totally respect anyone taking time to help and explain any small part of a process (in any subject). I read very helpfull acoustic posts here in the past, so I'm not condaming anybody. I agree with you dvdhawk, some experts gave great help and should get our gratitude. but I just wish one of them go a bit further and establish some tools with simple instructions to help at least small projects like so many of us need to start off.

    Maybe all the information we need is available online and we just need a educated eye to put it together here it a well layout article ;)
  20. audiokid

    audiokid Staff

    Acoustics (live or studio) and how this directly improved my business has always interested me. I attribute that to my long career but it still blows my mind that we have had so many threads and pro's here and not one of them is as useful as the links Kurt posted. Go figure. Or better yet, why?

    I understand the links and the importance of a lot more than just gear, just not why we have never had better in 16 years online.

    Glad to be of service for them though. 16 years and counting :)

    Back to the OP.

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