Archive for the ‘DIY’ Category

It’s been about a week since I’ve posted, but there is a reason for this. I took a trip up to Queensland last week to visit my friend, the very talented and future famous Sam Luff. I’d been planning this trip for a while and we decided we would take the opportunity to record, produce and release his first proper EP. His music page can be found here: I highly recommend you give his music a listen, especially if you’re into acoustic singer/songwriter style stuff, hes really very talented.

The recording session was a brilliant bit of fun, and he had a great setup to use, combined with some mics I brought up, we had all we needed.

The Booth: first we did some DIY acoustics treatment using some karate mats and a mattress that looked like acoustic foam. We first set it up on the floor for the sitting down instruments (ie. guitar, guitar amp) than moved it up to a table for vox. The room sound was kind of dead already, but this did a great job of catching all the direct reflections.
The Acoustic guitar: a simple spaced pair setup. Took some fiddling to get the mics in a good in phase position but we finally got there. Used my matched pair of Peluso CEMC6s, brilliant mics, they sound absolutely brilliant.

The electric guitar: For the guitar amp I put an SM57 right in the center then a CEMC6 back and too the right a bit, this mic was later panned to the right, this gave the guitar a brilliant image and position in the mix.

Voxs/Acoustic Lead: Both the acoustic lead and vox parts were recorded with my AKG perception 820. Great mic and relatively cheap for what it is. Vocals and guitars came out clear as day, and nice and dead.

And finally, double bass: This was also just done with the AKG, great smooth low frequencies.

All in all we finished up with some great dry tracks, there was a little bit of MIDI use for a backgrounded kick drum and a glockenspiel.

Stay tuned for the mix report!

Build a Triffusor

Materials (per triffusor):

  • 2x equilaterally triangular pieces of MDF wood
  • 2x rectangular pieces of MDF wood (width same as trianglar side)
  • 1x rectangular piece of MDF wood slightly shorter and thinner than other pieces
  • Acoustic foam rectangle the size of the 2 larger pieces of MDF wood
  • 5 long thin pieces of any kind of wood to be placed on one side for diffusion
  • A decent number of screws and some PVA glue (and some contact glue, though PVA will work)
  • Saw(s) and miter box (if cutting any of the wood yourself)
  • (Optional) beading for the edges


Attached larger pieces of MDF wood to two sides of one of the triangle. PVA glued, and then screwed them together.  Attached other triangle to other end of the rectangular MDF wood in the same way.

Used contact glue to attach acoustic foam to one side of the triangular prism.

Put smaller wood rectangle where third side of triangle would go and push it in so that it sits further back than the other sides.

Place long thin strips of wood against the side with the deeper wall and glue

Acoustic Properties:

–       Reflective side: The reflective side is smooth wood, allowing the sound to bounce off easily, creating direct reflections.

–       Absorptive side: The side with the acoustic foam is designed to absorb sound. When the sound hits the acoustic foam it enters any tiny gaps in the foam and bounces around inside it so many times that barely any of the sound manages to get reflected, most of it dies within the foam.

–       Diffusive side: The side with the further back wood and strips of thin wood running up and down it is designed to diffuse any sound that hits it. Either before or after the sound hits the back panel, much of it will reflect off the strips causing it to be reflecting off to the sides, known as being ‘diffused’, often used to stop early reflections from causing phase cancelation without killing the reflections all together and risking deadening the room too much.

Personal Uses:

  1. In parts of my room there are cupboards and dressers that would cause unusual reflections, reflective side could be placed in front of these to give more direct reflections.
  2. Diffusive or absorptive side could be placed at the back of my room where the first direct reflections would occur to send them in different directions of absorb them to reduce possible comb filtering in the listening position.
  3. Absorptive side could be placed facing out of the corners and be used as a bass trap.

Evaluation: Overall, each of the triffusor’s sides has the acoustic properties they were designed to have, and the triffusor itself is very sturdy and solid. If building more, the only thing I would do differently is take more time perfecting some of the measurements in attempt to get that really neat and tidy, professional look.

The backboard for the diffusive panels had some bend in it after being placed in too tight. The diffusive panels needed holding screws to hold it in place till the glue dried and keep the bend in the backboard down, and some of the panels started bending too so I had to use some tech screws to hold them too.

Turns out one of the easiest ways to cut acoustic foam in a straight, relatively smooth line is to mark out the cut with a pen, use a piece of wood as a guide and cute with a bread knife.

The point of building a triffusor was to have adjustable room acoustics, absorption, diffusion or reflection, depending on what I need, at the moment I’m wondering whether absorption in the corners as bass traps or diffusion in the speakers first reflection points is best. Since I’ll have some left over foam I’m thinking maybe put that in the corners to absorb bass and diffuse the early reflections, either than or put it along the back wall and absorb early reflections, then absorptive side of triffusors in the corners and absorb that too (my room isn’t particularly acoustically awesome)

Bought and cut panels for diffusive side today. Note to self: if a board has to fit between 2 others, get 1mm more cut off than you will need in theory, just to be safe. Bought some acoustic foam too, that stuff is great and really not that expensive for a large amount.

So I’ve never really had much experience experimenting with acoustics, and decided to ask my recording and sound reinforcement lecturer what I might be able to do for one of my projects for the class that would allow me to learn more. He suggested that maybe I should build a trifussor. For those of you who don’t know (which is probably most) a trifussor is a triangular prism with a diffusive surface on one side, a reflective surface on another and an absorptive side on the last. I have no carpentry experience as well as no acoustical experience but decided to give it a go anyway. So I picked up some medium density fiber wood from my local hardware saw, asked my dad to find me his drop saw and together we started cutting, gluing and screwing the wood together into the shape of a triangular prism. So far so good, and all thats left to do is attach the diffusive panels and the absorption material and I will have my very own pair of DIY trifussors.