Will big green screen suffice as 'poor man' sound treatment?

Discussion in 'Recording Gear and Equipment [BG]' started by Ukiah Bass, Jan 11, 2018.


  1. Ukiah Bass

    Ukiah Bass

    May 10, 2006
    Odd question for you cats who've built home studios...

    My home office is also my music studio. Essentially about 12 x 12 but with some odd angle walls / ceilings / staircase that break up the standard cube. I'm adding a new dimension by building a green screen along two walls. Should be enough space for 3 musicians and related video production.

    The room has a slight amount of echo. Not much, but it's there if you listen closely. Wood laminate floor, some bookshelves to break up the wall space. I was thinking of adding minor acoustic treatment but with the big green screen suspended in front of a staircase that was contributing to the slight echo, I'm wondering if that might be unnecessary. The perpendicular side of the green screen is a foot out from the wall so there's airspace behind the partition. The green screen is a thin muslin material.

    Can any of you comment on how a big green screen might cut noise in a very small recording environment?

    This is a concept of how it will look. My ceiling is 8 feet so the screen will go from ceiling to floor.

    1442853762882.jpg
     
  2. Very cool setup you have planned.
    I see you are sloping up from floor to walls and doing a gradual "corner" between walls, which all would seem to help out the cause. I guess, unless you have some acoustic modeling software, it might be hard to say for sure.
    Kind of spitballing on this, but could the two GS walls be at an angle that is not 90 degrees?
     
  3. ddnidd1

    ddnidd1 Supporting Member

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  4. Ukiah Bass

    Ukiah Bass

    May 10, 2006

    I chose 90 degrees to maximize floor space. It's gonna be tough enough to get enough separation between the green screen and talent for lighting the screen AND provide adequate space for talent, then main front side lighting and cameras. I'll suspend all the lighting from the ceiling to maximize floor space but this is the challenge of a small-room video studio.

    As for the "floor curves," I'll lay a big green screen across the floor. The two sides of the screen will be laying on top of the floor section -- about a foot of extra screen. Should work.
     
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  5. Stumbo

    Stumbo Guest

    Feb 11, 2008
    Hardwood floors=echo.

    Rugs and wall treatments usually do the trick.
     
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  6. ddnidd1

    ddnidd1 Supporting Member

    With a small room you will also experience very pronounced (low frequency) room modes, which are extremely difficult to treat in a small room.
     
    JRA likes this.
  7. silky smoove

    silky smoove Supporting Member

    May 19, 2004
    Seattle, WA
    Your biggest problem will be low frequency content. That holds doubly true in a small room. Now compound that by a room that's got really tough dimensions acoustically (even if they're broken up to some degree) and you've got a serious problem with low end control. Don't despair! Most people have these kinds of problems.

    First-off, a green screen does not have enough mass to do anything to low frequency content. If it has ANY effect on frequencies lower than 500hz I would be positively shocked. Maybe even 800hz. Don't count on it doing anything for the room other than reducing decay times in the midrange and high frequencies.

    As for treatments that won't interfere with your video production: Can you hang wall treatments behind the green screen? Using 4" of OC703 with a 4" air gap behind the panel is a very effective treatment for upper bass and lower midrange frequencies that will only protrude about 8" off the wall. Can you stand to lose that much floor space as your green screen moves forward a bit? If you can congregate your treatments into corners they'll be even more effective.
     
  8. Ukiah Bass

    Ukiah Bass

    May 10, 2006
    I'm reading the Acoustic Fields background and watching the vids. As usual, I've dived into a project without knowing full parameters!! Actually, on the first video planned for next month, we'll do a "mimed" production because we've already finalized audio. That takes the pressure off. But I'm looking past that one and there is no reason why treatments can't be installed behind the green screen. Sounds like a rug is step #1, or at least a few throw rugs to take a baby step. Thanks @silky smoove -- your comments about specific frequencies and the green screen is what I'm looking for.

    Just out of curiosity, what advice would anyone have for placing cabs? It's my experience that most groups in small rooms face them all toward the middle of the room. Typically ends up being a sonic mush. For purposes of acoustic recording, is it better to place them facing different directions? All the same direction? My intention is to take as many signals direct to minimize use of mics and use IEMs for monitoring. People watching the final video will have no idea it was shot in a tiny space. But I'll sure be sweating through unseen issues to get it to a good sonic and visual place!

    16 feet, 4 inches of green screen ceiling track will be installed tomorrow. The 16' x 9' green screen, 60 grommets and 60 track rollers are all assembled and ready to go. A pair of LED light panels with soft boxes are ready for testing against the screen. Those will be suspended from the ceiling a few feet out from the screen once I determine the optimal positions. Other light panels will be purchased and go up once I prove screen lighting is do-able. I may not have foreseen all the acoustic issues but I'm in firm control of cash flow!
     
  9. silky smoove

    silky smoove Supporting Member

    May 19, 2004
    Seattle, WA
    The closer to walls, and even moresoe to corners the more additional bottom end you'll be adding to the mix. Your low end will be more omnidirectional than your high end. If you're using room mics to capture the live mix I would try and center your low end generating equipment and spread out your pieces that have less low end content. If you can keep the more directional frequencies headed in different directions it would probably be wise, but you won't really know until you have them in the room to hear what they're bouncing off of as reflections are often just as, if not more destructive than the source of the sound. Try to get as much done via close mic'ing (or DI) as possible to fill out the room mic sound as needed.
     
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  10. Ukiah Bass

    Ukiah Bass

    May 10, 2006
    Lots of vids out there. My quick intro on this reveals most are speaking to treatment of a home mixing studio. Treatment of a small home recording studio (as in multiple live instruments and vocals with an emphasis on acoustic tracking) does not seem to be top of mind. Second in priority seems to be home theaters. Kind of disappointing but it is what it is. Just have to dig deeper.
     
  11. silky smoove

    silky smoove Supporting Member

    May 19, 2004
    Seattle, WA
    That's because mixing has a lot of established practices that yield consistently great results from room to room (i.e. put bass traps in the corners, broadband absorbers at the first reflection points, and a cloud above the listening position to practically guarantee a room that works well for most mixing scenarios). Tracking is a much more preference-driven affair. Do you want the tracking to be dead like in a booth? Do you want it to be lively like a large drum room? Do you want a live-end/dead-end setup? There won't be a video describing this effectively as it's wildly different from room-to-room, and application-to-application.

    As a general starting point I would try and place absorption such that you treat as much upper bass and lower midrange as possible and then stop there. You can do what I described above, or use more conventional corner straddling traps. Regardless you want most of your absorption focused on corners whenever possible, and remember that using treatment on each wall at a corner is just as effective as straddling the corner, albeit while requiring twice the treatment material but only taking up a portion of the floor space (it's all about trade-offs). Beyond that it will be down to personal preference and what type of sound you're trying to coax out of the room.
     
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  12. Ukiah Bass

    Ukiah Bass

    May 10, 2006

    Oh oh -- the studio room has seven corners, some literally nooks and crannies! I'll be an expert by the time this is over. And broke.
     
  13. silky smoove

    silky smoove Supporting Member

    May 19, 2004
    Seattle, WA
    A perfectly square room with a flat ceiling has 12 corners. Four vertical wall-wall corners, four horizontal wall-ceiling corners, and four wall-floor corners. All of them provide an equal benefit in terms of acoustic treatment. If the room is some shape other than an extruded rectangle (i.e. four 90-degree horizontal corners with a flat ceiling) then the number will be higher than 12. For instance, the same room but with a vaulted ceiling comprised of two slopes has 13 corners due to the inverted ridge.

    The important thing to remember from all of this is that it's not necessary, especially for a tracking room as opposed to a dedicated mixing room, to treat every possible location in the room. For tracking it might even be detrimental to do so. If I were in your shoes I would determine my budget for acoustic treatments and prioritize them within that budget in this order:
    1. Bass trapping in corners
    2. Bass trapping outside of corners
    3. Broadband absorption in problematic frequency ranges above the upper bass and lower midrange regions
    You might consider in purchasing some gobos to provide some isolation between sound sources, but that might also screw up the visual aesthetic of the video side of things. Don't waste money on diffusion products as your room isn't really big enough to make effective use of that type of treatment.
     
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  14. Pilgrim

    Pilgrim Supporting Member

    Any hard surface augments sound bounce. Any soft surface reduces it. If the green screen is a hard surface (which it appears to be) it will increase sound bounce and Echo. The option is to treat the other surfaces in the room so there are fewer hard surfaces for sound to bounce off of.
     
  15. silky smoove

    silky smoove Supporting Member

    May 19, 2004
    Seattle, WA
    Green screens are commonly not hard at all. They’re a bit like a fabric portrait backdrop. I can’t speak to the specific model that @Ukiah Bass is purchasing, but everyone I’ve used and the ones own by my film and photography buddies are all a relatively dense fabric material with a plastic’y treatment to the surface. I’ve also seen ones that are on a big roll and feel like heavy paper. Acoustically the screen will be nearly invisible, especially when compared to an untreated room.
     
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  16. Pilgrim

    Pilgrim Supporting Member

    OK, I was looking at it and it appears to be a curved cyclorama, which is usually hard. I know that green "sheets" hanging behind the talent are usually fabric, but that looked like a hard cyc to me. But my experience is TV studio oriented, unless its just a cheapo sheet of green material hanging behind someone.
     
  17. Ukiah Bass

    Ukiah Bass

    May 10, 2006
    Yahoo!!! Just hung the ceiling track and unfurled the green screen (which is a muslin fabric). Beginning initial lighting tests and placement. This is going to work! The audio treatment will follow.

    Green Screen Hanging.JPG
     
    Grumry likes this.
  18. silky smoove

    silky smoove Supporting Member

    May 19, 2004
    Seattle, WA
    I’m guessing the TV studio ones are more substantial like you’re describing than the ones that home users and small business professionals end up purchasing.
     
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  19. Pilgrim

    Pilgrim Supporting Member

    Right. The picture Ukiah Bass posted helps.

    Add soft materials elsewhere in the room and you'll be there.
     
  20. silky smoove

    silky smoove Supporting Member

    May 19, 2004
    Seattle, WA
    The picture definitely helps. @Ukiah Bass's post mentioned that it's made of muslin, which is PERFECT for acoustic treatments since it will freely pass air and therefore won't reflect low frequencies back into the room. So with that in mind the treatments can freely go behind the green screen without impacting the visual aesthetic of the video. Effective treatment (like I described in my posts above) with no visual impact? Win win!
     
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    Primary TB Assistant

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