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Instructable by Jim Robert ( Death By Protools )

Gobos are really useful things especially if you're working in a sub-par recording environment (ie. your living room). So what exactly is a Gobo?

Baffle - A physical object that absorbs or otherwise reduces the volume of sound which passes through it, or is reflected by it.

Gobo - see Baffle.

In other words, It absorbs or blocks sound. Those are the 2 main ways this effect can be achieved:

1. Absorbing the sound (converting it to heat via friction) - this is what foam, cloth, and other porous materials do.
2. Reflecting the sound (bouncing it back where it came from) - this is what concrete, and other non-porous materials do.

Here's a youtube video of the finished product:

 
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Step 1: Gather your materials

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Recipie for 2 Gobos:
note: Each step covers what to do for one gobo. You need to do the instructions from step 3 - 12 twice to complete both gobos.

Ingredients:

  • 16 feet of 2x12 lumber
  • 12 feet of 2x4 lumber
  • 2 - 2' x 2' pieces of 1/4" plywood
  • 2 - handles (I used cabinet handles)
  • Box of 2" wood screws
  • Fiberglass insulation
  • A cover for the absorptive side of the gobo

note: I used pegboard for my absorptive side. I evens out the frequency response a bit, if you're not sure what that means, my advice is to use pegboard. If you want your gobo to absorb lots of high frequencies the you can staple canvas around the open side of the gobo instead.

Step 2: Gather your Tools

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Tools you'll need:
  • Circular Saw
  • Drill (with a 3/32" bit; A screwdriver bit would also be useful)
  • Measuring Tape
  • Screwdrivers
  • Pencils
  • T - Square
  • Boxcutter

Step 3: Cut your pieces

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I labeled the dimensions of each piece as I cut it:

  • (2x) 2x2 1/4" plywood
  • (2x) 2x2 pegboard
  • (4x) 2' long 2x12
  • (4x) 1' 9" long 2x12
  • (4x) 2' long 2x4
  • (4x) 8" long 2x4

Step 4: Mark your 2x12's for drilling

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Mark the 2' long 2x12's, 2.5" from each end. These marks show you where to drill later on.

Step 5: Set up a box prototype

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Set up the 4 sides of the box on a flat surface and tape them together. The 2' long sides are shown on the left and right in the picture, and the 1'9" sides are shown on the top and bottom in the picture below.

Step 6: Drill and screw!

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Drill at the places you marked, and try to make sure that the you get the bit centered by the width of the 1'9" pieces. You should end up with 8 holes (2 on each corner). Put a screw in each hole.

The four pieces should make a perfect square with 90 degree corners. Use the T - Square to check this is the case as you go.

Step 7: Add the reflective side

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Put the 2' x 2' piece of plywood over it (it should line up with the edges of the box you've built so far). I didn't need to drill holes before putting in these screws, but if you're worried about it, or using really fat/long screws, it may be a good idea.

Step 8: Remove tape

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Pull off the tape we put on in Step 5

Step 9: Attach the handle

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You want to center the handle so that it'll fit nice later on. The end goal is to have it fit between the feet of the gobo above it so that they can be stacked easily.

In this picture, the long 2x4's on either side of the center row (the one with the handle and the shorter 2x4's) represent the positions of the feet of another gobo. Don't attach these long pieces, they're just to help you understand.

Before you attach the handle mark where the holes need to be drilled by putting the handle on it's side. Drill from top to bottom through the marks you just made. Then it's a piece of cake to attach the handle using the screws that come with it (all the handles at Loews came with screws)

Step 10: Cut the Fiberglass

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Cut the fiberglass insulation into 22" segments. If you used 15" wide RC-13 like me, you'll need six segments per gobo.

Cut 2 of the 6 segments in half (as pictured).



Step 11: Put the fiberglass in the gobo

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Put the fiberglass segments in the gobo facing out (each layer facing out, though it doesn't matter a whole lot which way the individual pieces are facing).

Step 12: Attach the absorptive side's cover

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Attach your cover. I used pegboard because of it's flatter frequency response. You can use canvas if you'd like to tame those higher frequencies, or if you just want to block sound with minimal absorption just put plywood on this side as well.

One additional option is to skip the fiberglass and use Plexiglas instead of plywood for both sides. This makes a see through gobo, which is useful when you have several gobos and you want to stack them without breaking the musician's eye contact.

note: there is no insulation in the picture. This is just because I'm dumb and took the picture at the wrong time ;). Don't take the fiberglass back out of the box.

Step 13: Attach the feet

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The feet are necessary to make the gobo's stackable. Again, I didn't need to drill before putting in these screws. However I did need to put the screw in, take it out halfway, and put it in again (to get a tighter fit).

Whatever you do, just make sure you put the screws in far enough that they're somewhat inset into the 2x4. You don't want the screw sticking out, or else it'll be wobbly and also scratch wood and tile floors.

Keep in mind that these need to be all the way to the edges, because the handle and alignment 2x4's need to fit in between them.

Step 14: Attach the alignment 2x4's

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Sorry to use the same picture twice, but this one is the best shot to illustrate the point. You want to attach these alignment 2x4's so that they're in line with the handle with space for the feet of the next gobo, which would be on top of it.

Step 15: Admire your handiwork!

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Good job, now you have 2 gobo's which are stackable. Now you can make as many as you want and build a giant wall of gobos!
jim5150jvc2 years ago
are those 2x12s you used, or 1x12s? in the photos, they look thinner than the 2x4s
Damn it, man. Awesome idea and beautiful execution. You've done a great job helping me out with this. Thanks a lot!
popproject7 years ago
excellent idea and execution. i wonder if there might be a way to make the gobo lighter using a different material instead of wood. i.e. plastic storage bucket, cardboard etc...
You could, but keep in mind that different materials have different absorptive and reflective qualities. Some might argue that the more dense materials are preferred. Even the type of insulation used makes a pretty radical difference. Using layers of different types can assist in a more linear attenuation across the frequency spectrum. Personally, extremely dense insulation in the center, with a thin layer of lighter insulation, covered with a canvas is preferred. The 2x12 construction used in this 'ible seems a bit of overkill to me, personally... my recommendation would be 1/2" or 3/4" plywood for the top, the sides, the bottom, and the reflective side. If canvas is used with a non-rigid insulation, it may need to be braced up, to keep it from pushing out on the canvas too much. Just my 2 cents... as a professional audio engineer. ;o)
Justinger7 years ago
Very nice instructable. Due to the nature of the insulation, I wonder if a version that is collapsible for storage would be possible? The portability alone is great though.
I would imagine you could rip the 2x12 boards in half to 2x6s and then put hinges inside so you can make them flatter but larger. there might be some problem with repeated or prolonged use squashing the insulation though.
Zak Justinger7 years ago
Justinger, I'd think a zig-zag of strips of soft fibrous material (like used for some pinboards, or maybe even acoustic ceilings) could work and could indeed fold up like a screen. By not opening the zig-zak, but leaving the angles acute, damping will be better. Not tried this though.
carpespasm7 years ago
These look like they would be very useful in setting up a home/garage recording studio. I might make some of these some time in 4ft units. Do you think the batting would stand up on it's own in that legnth or would it need some pegs run through it to keep it from "slouching" in the box over time?
JustAboutRealJAR (author)  carpespasm7 years ago
it'll work just fine... I have a pair of 4' x 8' gobos, that I built with the same size lumber. The only change you should make is to use thicker pieces of insulation so they don't slide, maybe R-19 or R-30
frugal7 years ago
Aren't those 1x12, not 2x12?
JustAboutRealJAR (author)  frugal7 years ago
no they're 2x12. The reason the measurements only account for them being 1.5" is that 2x12's get milled down to be a little smaller, and end up being closer to 1.5 x 11.5
gmoon7 years ago
Very nice, good job.

(The term Gobo is also used for light baffles. I.E., creating background patterns in photographs, "masking out" light, etc...)
Although I would never probably use a gobo, this instructable is very well illustrated!

=)
Simple and effective, I like it