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Home Studio Acoustic Treatment - Part 1

DIY Acoustics – The Home Studio

It all began 6 months ago.

I decided it was time to move house, office and studio, all in one hit. No one will ever know why I made this decision. In fact, after some serious rehab, I came to understand that people, normal people, do not make these kinds of decisions without thinking things through. But then if I was normal, I would be an accountant or football player instead of being a topless male car washer dude in my spare time. So, after another night at the BDMA (bad decision makers anonymous), I decided to bite the bullet, tense my buttocks and get on with it.

6 months later and I live in a lovely rural pad with birds n’ shit chirping away and where people say hello, instead of blading your ass for your mobile like in the big city. What does all this dithering have to do with this tutorial? Jack. It’s a way of bonding. So, let’s bond a touch……not too much, just a touch.

Ok, so house almost complete and the only thing left is to build the office/home studio. When I say ‘build’, I actually mean ‘convert an existing bedroom into studio but tell people you are building a studio because it sounds a lot cooler than saying I’m working from a bedroom’. When converting a bedroom into a studio, certain criteria have to be met and the most important of these is ‘make sure people sleeping in bedroom have found alternative accommodation’. Get this right and you’re on your way.

Why?

I am often quite amazed at how little regard home studio owners give to the environment they work in. Surely, as a producer/engineer/artiste, you want to be able to hear both clearly and accurately? Otherwise your mixes will never sound right and you will struggle for ages to cross that line whereby your mixes will sound true and good on all systems. I cannot stress how important it is to have a properly treated listening environment.

I often come across people in this industry that do not think twice about dropping a couple of gees on a synth/workstation and yet will not spend a penny towards optimising the listening environment that they record and mix in. So, I got to thinking. Ok, these people won’t spend a penny beyond the ‘egg carton solution’, so why not write a DIY tutorial on home/studio acoustics and keep it below £1000.

Yes people! You read correct. Treat your room with proper acoustical material and keep it all under a grand. To add weight to this tutorial, I chose the hard option. I decided to personally go through this tutorial hands-on, designing, building and applying the damn acoustics myself and I was only able to achieve this with the help of the Acoustic Guru Max Hodges (more later). Needless to say, my wife left me at this point. I also lost a lot of friends due to lack of socialising. I am very alone now.

As with all DIY projects, one needs an able and helpful friend, preferably one with good acoustic treatment knowledge, a sense of humour and be very strong so I don’t have to carry the damn Rockwool myself. Enter the one known as Max Hodges, also known as Max the Magnificent, Max the Marvel and Miraculous Max. Max Hodges is an expert when it comes to studio builds, both in terms of design and project management. Max’s specialities include Acoustics and Sound Proofing, or Sound Treatment, full consultancy services, studio wiring and installs, and technology training. He is also a big bastard so very useful to have when debts need collecting

I would like to take this opportunity in thanking Max for all his help and guidance during this project. I am hoping that by thanking him in public I can forego the dinner I owe him for all the help he has provided.

The Room

Before we go headlong into this project and well before we start on materials required blah blah, we need to look at the room’s dimensions and shape. In the UK most 30’s houses have bay windows on the ground floor, and to add to this ‘shape issue’, the ceilings are usually ‘coved’. This means that you have a non square or rectangular room and that there is coving where the ceiling meets the walls. The pictures that accompany this tutorial clearly show these characteristics.

I have included ’before’ and ‘after’ photos to show the state of the room prior to plastering etc. I have done this so as to raise a modicum of compassion in you so you can understand to NEVER EVER be at home when building work is done.

Before

Before

Bill the Plasterer

If you look at the first picture, you can see the coving on the top corner where the ceiling meets the walls. This can be a real headache when it comes to trying to put in corner traps etc as you need to shape the foam or Rockwool to accommodate the shape of the coving. The second picture shows the state of the bay area. A bay is pretty much what it says; a bay shaped like a semi circle with windows encircling the bay and facing outwards of the room.

The third picture shows Bill the Plasterer. The scratches on the walls behind him are the result of his reaction after I told him what I was going to pay him. This has, of course, no damn bearing on this tutorial.

The shape of the room is the most crucial aspect of any acoustic treatment project. An irregular shaped room would be a nightmare to tame, but equally important is the fact that the room must be equally balanced to provide a true stereo image. There is no point in sitting against a wall with your speakers head height and hoping to get a natural stereo field if the room is not shaped and balanced correctly.

In the case of my room, I was faced with a bay area with windows running across the length of the bay, and a built-in wardrobe on one side wall. This basically meant that I had to sit in the bay area and try to balance both sides of the room on either side of the bay. This all sounds good as bay areas often provide natural bass trapping, and hell, one cupboard? Let’s get those doors off! This sounded so easy…but it’s not just cupboard doors that need to come off. Shelves, rails and wood, basically anything that impedes the sound travel or could resonate. The goal of this ‘butchering’ was to attain a central position for me to sit in with equal space on either side of me so that the sound would be stereo balanced. If I left more space on one side, the sound would be imbalanced. We are not just trying to achieve a well treated acoustical environment but a balanced one as well. This is a mistake that so many home studio owners make. They cram themselves in one corner or side of the room and then wonder why there is bias to either channel in their mixes.

Once Max had had a good look and measured all the room’s dimensions, he came up with this diagram:

Ok, so a little explanation as to what is going on up there. This is an aerial plan, ie, bird’s eye view looking down on my ethnic ass.I am sitting right in front of the bay area and the ‘butchered’ cupboard is on my right (left as you look at the pic). Behind me is a wall with a door to it’s right. This wall is actually a chimney flue, where a fireplace once stood in grand and opulent fashion. This wall extends forward and this has caused that particular area to have a number of corners where the ‘flue’ meets the back wall of the room. On the right of the above picture you can see that Max has labeled the materials and their respective dimensions.

The Materials and What They Do

I am not going to go into what acoustic treatment is, how a room behaves, nodes, low end, blah blah. There are countless resources on the net that cover all manner of theory and application.
Nope, this tutorial is simply a DIY project for those that want to improve their home studio environment. I will, however, list the materials and state what their use is for. All foam materials came from RPG. These guys make top quality foam. Of course, there are many others and some are quite cheap, particularly the US manufacturers. But I like RPG stuff, top quality and design.

RPG material:

  • 4 Sheets of Melamine Blue Foam
  • 2 Boxes of Melamine Procorner
  • 2 Corner Blocks (300 x 300 x 300)

These will be used for the acoustic absorption and diffusion tasks. These are highlighted as dark and light grey in the diagram.

We also bought:

  • 10 Tubes of Silicone Sealant to use for ‘gluing’ the foam onto the ceiling etc.
  • 2 x 2 ply boards (use preferably 6-9 mm in thickness), and 2 vented MDF boards.
  • 1 Can of Flooring Adhesive Spray.
  • 3 packs of chicken wire.
  • 4 pack of Hedex Extra Strength

Now the nasty stuff:

Rockwool :

45kg/M^3. These come in packs of 1 metre x 600cm x 10cm, and 2 in a pack. We bought 12 packs.

The general consensus is to use the standard 60kg/M^3, but we needed the double layer packs and decided to use the 45kg/M^3. You can use either, depending on your requirements.
The Rockwool will be used for all the Bass Traps, the Super Chunk corner traps and for further absorption and Limp Mass panels for the facing wall of the room.

Panels:

Materials required for building each panel, and there are 8 panels to build.

  • 2 x 2400 x 19 x 100 (typically 98) planed softwood battens
  • 2 x 2400 primed white MDF battens
  • 4 Triangular corner brackets
  • 4 Right angle corner brackets
  • 16 12mm wood screws, of size to match brackets
  • 3600 x 600 of Chicken wire.
  • 100+ Heavy Duty Staples.
  • 600 x 50 x 19 batten
  • 4000 x 1000 wrapping material. Beige raw cotton is what I used.
  • Garden Gloves
  • Wood Glue
  • Plant sprayer loaded with 10:1 water- PVA mix with 1 drop of washing up liquid.

This is used to cover a film of PVA to all the Rockwool, both for health reasons and for fixing in place. We use the PVA solution to bond the external fibres. Rockwool is nasty, fibre glass infested, airborne material that breaks and frays easily. The PVA keeps stray strands in place. BTW, if you touch Rockwool with bare skin, then expect to be itching for a few years. If you accidentally touch the damn thing then immediately wash your skin with cold water and refrain from any sexual activities until the itching has gone away. Trust me on this. I couldn’t wear boxer shorts for a week. That is, of course, another story for another day.

These panels are made to house the Rockwool for the bass traps, broadband absorption panels and limp mass panel.

Tools required:

  • Electric Drill with Pilot hole bit, and Tank Cutter Bit (hole cutter)
  • Electric Screwdriver
  • MitreSaw
  • Heavy Duty Staple Gun
  • Jigsaw
  • Corner clamps if building single handed
  • Workbench

The Procedure – Let it Begin

To successfully design, build and integrate acoustic treatment, you need to PLAN. The diagram is the blueprint for how things should look, but it doesn’t always work out that way, as the more reference testing you do the more adjustments are needed. For this project the blueprint is actually quite simple. Building the bastards is another story entirely. But let’s kick off with what is actually being made.

The Bass Trap panels will adorn every corner and will be connected at an angle to cover as much surface area as possible and with air gaps left behind for better trapping qualities. The broadband absorbers will also be built as panels and symmetrically placed away from all the walls (maintaining an air gap) and in between the bass traps. They will also face each other on opposing walls. The Super Chunks will be placed from floor to ceiling in the two main corners directly adjacent to the monitoring positions. The Foam will be placed on the ceiling, both suspended and fixed, at the surround area of the bay area and the corners where the ceiling meets the bay edge. The layout will be symmetrical for the purposes of maintaining balance and not triggering any bias.

Building The Damn Panels

Step 1

Take the two 2400 x 19 x 100 lengths of timber and mark up at 1800/600 (from either end)

Set the Mitre Saw to Cut at 45 degrees through the timber and, at right angles across the timber...Cut the timbers, so you have 2 pieces of 1800 in length, and two of 600. This is done so that the battens meet perfectly at the corners and edges, so that they are flush and look funky.

Mitre Saw Placed on Workbench 1800 length batten being cut at 45 degrees
2 x 1800 and 2 x 600 length battens Lining up 2 battens for further cutting
After lining up the battens, screw 2 screws right through the two battens so as to keep them aligned and rigid. Then start to drill the holes in to create an empty groove. Space between the holes is subjective and down to you. On the longer 1800 battens, we cut 6 holes. The holes are created so we can then saw them to create an empty groove.
Max is sawing the battens between the holes to create the grooves

The panels with the grooves cut out.

You should now have 2 x 1800 battens with grooves in them and 2 x 600 battens with grooves in them. Now, let’s join these together to form the frame of the bass trap. It is clear, well I hope it is, that the 2 1800 battens will form the length of the frame and the 2 600 battens will form the width. Now let’s join the battens and create the frame.

Let me explain what Max is doing here. He is placing the battens into the corner clamps and tightening them in.

Here, you can see the corner clamps being fixed in. 
Once the corner clamps are fitted, the battens are then glued to each other and kept tightly in place by the clamps. The triangular corner brackets are then screwed in (top of frame in pic), and inside the corners right angle brackets are used to fix the battens firmly together and in place. Now you need to fix 2 x 600 battens in-between and on one of the 1800 sides. This ensures that the frame is kept rigid and does not collapse. More importantly, they are there to hold the barbed wire and Rockwool.

Ok, so you now have a frame. Leave the frame to dry and then psyche yourself up for the next stage; the dreaded ‘Chicken Wire Finger Splitting Swearing’ event. The trick with using chicken wire is patience. Whatever you do, do not rush and stretch the chicken wire. If you do then the Rockwool that will sit in the frame will have no grip and solid frame to hold it in and in time it will begin to sag. Oh, and it looks like shit too.

Count your fingers before you start to stretch the chicken wire, and when done, count your fingers again to make sure you didn't leave any behind in the frame.

If you know someone you don't particularly like, get them to do the chicken wire bit.

Saves on hitmen too. 

Carefully unroll the chicken wire until it is even across the entire length and width of the frame. Starting at one end, carefully use the staple gun and staple the chicken wire to the frame. Make sure to staple the side where the dividing battens are. This is the back of the frame, where the Rockwool will rest. 
Go all around the frame and slowly 'stretch' the chicken wire until it's taught, and then carefully staple it to the frame. Once finished, trim off the excess chicken wire, using wire clippers, until no wires are protruding. 

And NOW

A completed frame. You need to do this as many times as needed for your room. We made 4 of these frames.

And now let’s look at completing the bass trap.

AAAARRRRGGGGHHHHH! Rockwool.  Spray the Rockwool as advised earlier. Spray both sides and all the edges, then spray some more using the PVA solution. 
As you can see we have used a double layer of Rockwool, trimmed to fit the frame. Because the Rockwool is 1 metre long and you will need 2 of these per frame, you will find that because the frames are 1.8 metres in length, you will need to trim 20 cm off the length of one of the Rockwool slabs.  Use a knife or trowel to fit the Rockwool into the frame until it is nice and compact. Now start to attach the chicken wire, exactly as before. This ensures that the Rockwool is kept in place and does not sag. 

Leave to dry and then………cue Thunderbirds are go soundtrack!

Completed Bass Trap framework and Rockwool.

Cover Trap with fabric and staple to secure. Looks good and protects you and environment from the Rockwool.

In part 2 we look at sorting out the acoustic foam and finishing off the home studio build!