Thursday, March 21, 2013

DIY QRD Diffusers for Home Studios: My Home Studio Renovation Project Pt. 1

The Centerpiece of my man cave, just above my beer fridge is my DIY QRD Diffuser.

Related to Elements: Crate Digging, DJ, Producer

You've seen these before, those "Skyline" or "Cityscape" diffusers gracing the walls of high end production studios.  Technically known as QRD Diffusers, besides looking really cool (well, they look better than empty egg crates) you may have wondered what they are actually intended for.  There's all kinds of scientific explanations with audio-nerdaphyle jargin out there.  If you really want to know what's going on with the sound waves when they hit these things, feel free to peruse this website's breakdown...  As you can see they even have a program that when room values are plugged into it you can really get into custom sizes.  I truly believe these things work as advertised but finding a professionally built one online at a reasonable price is never gonna happen.  Besides you don't need an engineering degree, or special software, as long as you have the tools and time you can just adjust your tool belts for your winter waistline and build one yourself! 

I'm not even gonna try to reinvent the wheel with this blog post.  I don't need to since these plans are already out there online and credit should be placed where credit is due.  Here are the plans I followed for the one I built and it is well written, simple to follow, and best of all IT REALLY WORKS! 

I can however, enhance these plans with a little how-to tips I learned along the way, perhaps this blog post might dispel some of your self-doubt if you are afraid to tackle this fairly simple DIY.

Tools Needed:

  • Plans
  • Pencil
  • Black Permanent Marker
  • Carpenters Square
  • Chop Saw or Mitre Saw (the sharper the blade the better, I wouldn't even attempt with hand saws, that would take forever so, a powered saw is a must)
  • Strong Wood Glue (I recommend Elmers' Wood Glue Max since it's strong, paintable and stainable)
  • Thin Plywood (1/8" thick) to mount it on (approx 18" X 18") (a 24 X 24 piece will leave plenty of extra)
  • 6 or 7 8 foot long (2X2) pieces (the primary wood)
  • Course Drywall Screws to hang it. (at least 2" long)
  • Heavy Duty Construction adhesive (like wood glue only stronger)
  • Optional Stain or Paint and appropriate brushes and drop cloth

Make sure you really eye up your wood before you buy it.  Inspect it well, choose super straight (not bent or warped) pieces or you will never get the pieces to stand up right.  If you make perfect cuts with no mistakes you can get away with buying 6 eight foot pieces of 2X2 but I would buy 7 if I were you, there is little room for error with only 6 pieces.  As far as wood types go, you can buy cheap old pine but I wanted something heavier, more solid and when stained I wanted the wood grain to really pop, so I chose solid oak.  At around 20 dollars per each piece this was not cheap so if you are on a tighter budget pine is much cheaper.

Stain or Paint First

One thing I did differently than those plans recommended was I stained the pieces before I cut them.  It is much easier to stain (or paint) several 8 foot long 2X2s vs. cutting them and handling them all one by one.  Not to mention gravity would work against you and you'd have dark spots or paint clots where all the joints of each individual piece of wood touched if you did the staining after the assembly.  It took 3 coats of stain on each side of the wood, so as you can imagine doing it any other way would take way too long.  

Stain First, cut later!  Angle the wood on a 45 so you can do 2 sides at a time.

Find a cool safe place to stain the long pieces.  I recommend water based stain since it doesn't stink up the whole house and is a cinch to clean up!  To kill 2 birds with one stone I cut a V notch into the top of a leftover piece of wood which held the pieces in a 45 degree angle so I could stain 2 sides at a time for each piece.   Three coats gave it the high gloss look I wanted, stain less coats for lower gloss looks.  Stain, then wait till those sides dry, rotate 180 degrees, then stain that side, wait, rotate again, stain again until you are satisfied that it looks good.

Use Jigs for Easy Identical Sized Cuts

Don't measure every piece, make perfectly sized jigs
The plans call for 4 different lengths of various sized pieces and I know for sure if I measured every single one and then cut them I would have 50 different lengths.  So using cheap scrap wood I measured exactly each size, labeled it with the sharpie, and nailed a flat leftover piece of wood with an overhang to the end of it.  By doing that I can place the long piece, put my jig right on top of the piece I am cutting and it will butt up against the end tightly.  Holding the jig in place you can lower the blade right up against the jig edge and as long as you hold it tight and don't cut your jig you will get a perfect cut.  It goes without saying that your chop saw should be locked in at 90 degrees before cutting.  The sharper the blade, the cleaner the cut will be.

Butt the blade against the jig then cut perfect lengths.

Store the cut pieces in a container after they are cut and prep for edge staining

After cutting all the pieces you need, clean them all off with a rag or shop vac and prepare to stain the best cut edge facing you.  The best cut side of each piece should be up if you want to see no blade marks or nicks.

All the pieces ready for the final coat of stain with the best edges up
Now the fun part... (not really)  Staining the ends of 144 pieces, for me 3 more times.  The trick is to put on some kind of music cause this is really boring without something playing.  Have a dry rag handy to wipe the excess drips that run down the sides that are already stained.  Stain is runny, so seriously, have a dry rag nearby if you don't want black stain runs down each piece.  Paint isn't as bad but the same dripping will occur with paint if you aren't perfect (which you are not).

Once you are done staining and it has dried, line up 12 of the pieces (any size length) side by side and measure the length of all these 12 pieces tightly placed in a row.  It should be right around 18" since the original pieces are not true 2X2s.   Keep in mind it won't be exactly 18" because the stain or paint made each piece a little thicker.  You can cut the backer of your diffuser to this to the exact width of the 12 pieces or you can make it a bigger square to make it easier to hang as I did.  I cut my 1/8" piece of plywood the exact same size as the piece of drywall that it was to cover so it was much easier to hang in that location and it covered the drywall completely therefore making it look like the diffuser was glued right to the drywall with no backer at all.  This is up to you whether or not you want it invisible looking or something with an obvious edge, you could even frame that edge if it bothered you with small pieces of trim.  

Once you cut your backer square piece to approx 18X18" or larger, print out your diffuser layout for easy assembly of the pieces.

Before you start gluing any pieces, paint your backer piece the desired color of paint and make sure it is bone dry.  Then find the center of the backer with the old draw an "X" trick.  I found the center of my backer plywood piece drawing an "X" using a straight edge and penciling from corner to corner.  I then drew 2 center lines on the the elevation layout to split it into quarters... this.

Split diagram into 4 equal quarters and start crossing off as you glue.
I drew the same quadrants on the backer plywood piece using the carpenter square so the center intersection was exactly dead center of the "X".  Draw these lines darker than the X, if you follow these straight lines closely you will not gradually go off course even without drawing a full grid.  Starting in the upper left of the lower right quadrant, glue the pieces one by one where they belong and cross off each piece you glue as to not loose your spot.  Make sure you spread the glue on the entire surface of the bottom of each piece, and have a dry rag handy to wipe off any excess glue that pushes out when you press the pieces down.  Keep gluing and keep crossing off each number on the layout as you proceed.  It is VERY important that you stay exactly on the edge of the line on this first row because all other pieces in the quadrant butt up against that row.  If you get the first row wrong, it will get harder each row and eventually you will be way off.  Take your time gluing and be a perfectionist with the first row and then it will start to go very quickly.  Repeat for the remaining 3 quadrants keeping the first row perfect with each one.  Gradually as you glue each piece the diffuser will start to come together.  Since I used heavy oak, I glued the sides of every few pieces that touched each other for extra sticking power.  It may have been unnecessary, but I didn't want any of the pieces falling on my beer fridge so I played it safe with every few pieces getting a little extra side glue.  

Now the hard part...Wait at LEAST 24 hours before moving it, leave it alone on a flat surface so the plywood doesn't bend and it dries perfectly flat.

Glue and Screw the backer securely to the wall and make sure you hit studs!

For this next part you will want the help of a strong friend.  Mark the wall and draw a perfectly level line where you want the piece to live.  Find the wooden or metal wall studs by knocking the drywall listening for them or use a stud finder.  If there are no studs where you want it, then you should reconsider moving it to where studs are, or at least get some heavy duty drywall anchors that grab the back of the drywall.  I wouldn't trust them though, because this thing is VERY heavy so try to find a spot with 2 studs one on each side.  If you use construction adhesive along with screws don't plan on taking this with you when you move, it will never come off with that stuff.  I used construction adhesive and screws, so I guess if the next person who buys my home doesn't like records they are gonna have to learn to live with it.

Once this is securely in it's new home, drive the screws just beneath the surface of the backer wood and caulk or putty the screw holes to hide them.  Once that filler dries paint it the same color as the wall and it will look like it's "floating" on the wall.

Now, sit back, bust out a cold brew, drop a needle on your favorite record and you'll notice how much sweeter the music sounds.  I swear by it, this truly does work.  I could tell immediately that slap-back bass echos no longer plagued my space.  After I coughed up all that money for wood and glue, I was quite satisfied with the results.  In the end it became a nice looking functional unique sculpture piece for literally hundreds of dollars less than what I could have bought online.

Fully diffused.

Stay tuned!  Part 2, which is some more in-depth DIY man-cave plans is coming soon.

Also check out the Youtube Video Walk through of my finished Studio for a 360 degree view.

For DIY Records Shelves Plans see our most popular DIY Simple Record Shelves Blog Post

For before, during, and after pics of the studio and further information check out the thread post at and by all means, please join us


  1. This thing works. I want one in my studio now!

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  2. Thank you for this post. I am almost done building one that's 36"x36"... Can't wait to put it up behind the sweet spot in my mixing studio!!! Again, thank you for listing everything :)

    1. Thanks for the feedback! I'd love to see a picture of it when it is finished!

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