- Brandon Allshouse
2020 Studio Redesign: Building a mastering studio
2020 Studio Update!!
In 2020, Steel House Mastering underwent a massive room update with comprehensive custom made acoustic treatment. Lets go throw some of the changes that were made, the choices of treatment materials, placement, and what didnt work, that all comes together to equate a more accurate listening experience resulting in better quality masters on your music!
Prior to this, with the exception of some large corner bass traps and a large custom built cloud, the rest of the room was built using standard 4” thick 2x4ft rockwool absorbers. I have a post at https://www.steelhousemastering.com/post/diy-acoustic-treatment on how you can build some of these for yourself. For a lot of situations these are more than an acceptable form of broad band absorption, as well as an effective option to straddle in the room corners for bass trapping.
Wanting to hone in on some specific issues, I knew I had to go big or go home. Sound is energy, and the lower the frequency of the sound, the more space (mass) needed to stop or attenuate the sound.
My first goal was a plan of attack, a scaled diagram of what I roughly intended on doing and how it would fit in the room. Starting with graph paper with every block corresponding to 4” I drew what would soon become of the new iteration of Steel House Mastering. Pictured below you can see the room is small compared to other rooms, another reason more comprehensive treatment was needed.
The first step was ripping everything out of the current space, a necessary, but laborious task. From there it was time to rip up the carpet and replace this with hardwood flooring. While some may argue that carpet is good for studios because of taming high end specular reflections, these reflections are also normal in human hearing and how we perceive sound naturally. I’d also argue it's unnecessary if your ceiling is going to be non reflective in the case of a large overhead cloud.
After the long task of laying floors it was time to start building the new traps. The first thing I built were the new side absorption traps (these were actually built and tested in the past room design to determine effectiveness). These side traps are 8ft tall, 2ft deep, and 10” deep total. They are constructed of a wood 2x2 frame with 8” deep ½” thick MDF wave guides. Contrary to how the room blueprints were drawn, the wave guides face towards the monitors in theory, funneling sound into them. The panel was then loosely stuffed with R30 fiberglass to not impede air flow (ie, making it reflective), followed by 2” of rigid 703 insulation behind them against the wall. An interesting note to make is that while the left side of the room, an exterior wall, has 703 behind the traps, in later tests it showed that the right side of the room was less effective with 703 behind the traps (an interior wall with a closet behind them). It should be noted these wave guide traps are not my design in principle, and were heavily influenced by the acoustician John Brandt.
After the side trap construction it was off to construct the new “super traps” for the front corners of the room. The corners are 3ft wide, 8 ft tall, and 2ft deep. Bigger is better when bass trapping. Much like the side panels I employed a similar design using wave guides constructed of ½” MDF panels. Rigid 703 went against the wall, and the whole trap was again loosely stuffed with R30 insulation. Time for the front wall!
The next step was to rebuild a new ceiling cloud. Before I was using a 8ft by 4ft cloud, 6” deep of rockwool insulation. In order to tackle the floor bounce bass build up, I decided to go deeper this time with a 15” deep cloud, 8ft by 4ft. The wood frame, constructed of mostly 2x2s to keep the weight down, was then stuffed with 10” of R30 fiberglass and 2” of 703 against the back side facing the ceiling. A daunting task, but another I wanted to make was adding a grid diffuser to the face of the trap.
A grid diffuser works in theory by acting as a sort of funnel for sound. Off incidence sound gets bounced into it, reflected around inside, and any sound that gets reflected out of the bass trap then gets reflected again coming out. The past studio space had a 2D QRD (skyline diffuser) on the back wall, but seeing that was taken out in lieu of deeper back wall trapping, I wanted to be sure these new room wouldnt be too dead, while also increasing the effectiveness of the ceiling cloud trap. Constructed of 5mm plywood cut in 3” deep slats, 8ft long, and then grooves were cut every 3”. These were then assembled together like a giant spice or wine rack, creating a grid of roughly 3x3x3”. Other commercial products I’ve seen had a 3x3x3 grid which is why this was chosen. After attaching this to the ceiling cloud, the only way to ensure it was safe was to put cross beams up across the rafters in the ceiling and mount the cloud using 8” eye bolts and heavy duty carabiner clips. Ended up using some steel S hooks to move the cloud closer to the ceiling but left the carabiners in place for added safety. Despite the wood frame of the cloud being pretty light weight, all the insulation and the large grid diffuser added up to a serious chunk of weight.
Now that the front corners and ceiling were done I could focus on making the front wall completely absorptive. The idea behind this was to minimize Speaker Boundary Interference Response, or SBIR for short. This is the act of bass cancelling itself with the reflection from the front wall, generally creating a deep null in your bass response. The only real way to combat this is a technique called soffit mounting where you build a front wall baffle and your speakers are now part of the front wall itself. However given the Barefoot Monitors I use have side radiating woofers, this was not an option, nor is it a long term option as the next speaker upgrade I'm looking at making are incapable of being soffit mounted. The next best thing was to bass trap the front wall without taking up more room than I could afford.
I started with 2 wood frames roughly 3ft by 5ft. This would allow me to wall mount the computer monitor between the two traps. I opted for rockwool for this application as it was only 5” deep and I knew a denser insulation in this application would be more effective for the bass region I was targeting. While rigid 703 probably would have worked just fine as well, I had extra rockwool from the previous traps I was using and didnt have extra rigid without having to buy more.
The back left wall corner was next, and far more simple as it was the same dimensions as my front corner traps, minus the wave guides. I spoke to a few other engineers and after looking at other room designs noticed a lot of other rooms didn't wave guide the wall corners. It's possible I’ll go back and visit this and test whether it's more effective or not, but for now it's just rigid 703 against the wall and then stuffed with R30 fiberglass.
Lastly, back wall came next with a 10” total depth, 5ft wide, and 8ft tall. Rigid 703 was placed against the wall, and then the trap was filled floor to ceiling with R30 insulation. The back wall is a place you don't want to skimp on treatment and trap as much as you can afford to. Next to the back wall are 2 standard 2x4ft 4” thick rockwool traps. The reason I couldn't extend the back wall treatment wider was the door would have been impeded.
After the entire room was put together, it was time to put the monitors and gear back in and run some tests with Room EQ Wizard (REW) as a measurement program. This free program allows you to measure every aspect of room acoustics you would need from phase response, frequency response, and the time domain. I spent 2 days afterwards adjusting monitor positions and calibrating the room correction DSP I use via a minidsp unit in my monitor path.
All the hard work was worth it as this room translates beautifully to the outside world. The sound is tight and direct, bass is a lot clearer now than in my previous room. The room isn’t dead sounding due to the large grid diffuser, and the color and vibe is way more vibey and enjoyable than the darker color scheme I had before.
Hope you all enjoyed the process of constructing a mastering a studio. If you have questions, feel free to ask! If you would like to hear work I’ve mastered for others, please head over to the main page of Steel House Mastering. If you also need mastering, hit that contact button and lets chat!