This five-part series of articles will take a real world look at the why’s, where’s, when’s, and how’s of creating a professional-grade home recording studio. The articles will be written as things happen, and I’m sure there will be enlightening anecdotes, technical twists, and surprising turns (for you and me) as I attempt to actualize a vision that is shared by many recording enthusiasts. On the way we will meet and delve into the brains of some true icons in the industry, deal with building contractors and equipment suppliers, and plot and implement a game plan.
Part 3: The truth about isolation booths
We find ourselves immersed in the building of the isolation booth, after a slight delay caused by unforeseen delays.
The room is coming along well. Two dedicated 20-amp circuits have been installed for audio power. Lines have been run for lighting. The ceiling has been insulated and the outer walls are ready to be prepped for paint and wall treatments. Now that the main part of the room is taking shape, it is time to look at the ISO booth design and construction.
I had just ordered industrial felt to “float” the inner framing of the booth when I spoke to Nick Collerian at Acoustics First. He told me about a newer way to float the frame using Vib-X, a vibration-isolating pad made of DuPont Neoprene. Vib-X pads have a ribbed design, can be cut easily, don’t degrade over time, and are especially good at rejecting low frequency transmissions. I quickly called and cancelled my order for the felt.
Along with the pads, I got some Vib-X washers to isolate the bolts securing the wall footers.
It should be noted that an ISO booth is a room within a room. The outside of the structure is of typical design, while the inner structure is meant to “float” separate from the outer structure (and the entire building) by means of insulators, like the Vib-X pads and washers, as well as physical space.
The whole process of building the booth has been a bit nerve-racking for me. The room needs to float and be isolated, but air must flow through it. In addition, cables, wiring for lights, and electrical outlets must be strung through, and a door has to be installed. All of these holes in the structure can ruin the room’s isolation qualities if not treated properly.
Building the room
First the outer wall was constructed. At the same time, consideration for anything that had to be fed through the walls was mapped out and fabricated. This meant that all wiring and boxes had to be extended long enough to get through the two walls, and a provision for a run above the booth had to be put in to ensure ease of adding anything to the room at a later date.
Once the outer walls were finished, the Vib-X was installed on the footers and headers of the inner wall. The inner wall itself is situated so it doesn’t touch the outer wall of the booth. I found a 28-inch door and metal frame for an entrance and am now working on a design to place the door in an optimum position for both sound and space. A glass window is being ordered to give the ISO room door a view to the studio to make it less claustrophobic.
The inner walls, the ones you see as you stand in the finished room, consist of a layer of 1/2” sheetrock, Block Aid vinyl barrier, and 5/8” green rock.
The airflow issue wasn’t as bad as I expected due to the fact that a soffit was already put in next to where the booth is being built. I must admit, the original purpose of the soffit was for bass trapping. The soffit will be my “exhaust duct” and will be boxed in hard fiberglass insulation.
The inside of the box will have two 90-degree hard fiberglass barriers so that any extraneous sound will be minimized as it tries to pass around the corners. A low noise fan will be placed on the far end to evacuate air outside the studio properly and a vent will be situated on the near end where the duct will connect to the booth.
On the intake side, air being pulled into the booth will come in around two feet from the floor on the outer wall, run down the stud wall to a “T,” then pass down the adjacent stud wall and exit a few inches above the inner wall floor. As in the soffited area, by going thru 90-degree bends, the sound from these holes in the system will be greatly reduced. The floor of the booth must also float off the room’s original flooring. Wood blocks with Vibe-X “feet” and two-inch plywood with high-compression vinyl sandwiched in make the floating floor. Insulation will be packed in between the floating floor and the original flooring, and the edges of this floating floor will also be isolated from the inner walls of the booth.
Diligence in the construction process is very important. It can’t be stressed enough that the weakest link lowers the isolation properties of the entire booth.
As I said at the beginning of this series, I knew this would be a learning experience for me and that there would be twists and turns for us during this journey. At Sigma, I had a team of people who tackled different issues. I oversaw and lent my opinions but didn’t get into the nitty gritty. Plus money was never an issue there. If a wall had to be torn down or if we needed triple-isolating filters put into lighting schemes, it was just done. In my situation in the home studio, time and money are big issues, and a balance between goals and gold have to be met.
We’ve now encountered some of those expected – but unforeseen – twists. Late shipments, construction crews who are juggling different projects, money shortfalls, and things behind the walls have made the job more difficult and time consuming. I didn’t follow my own rule to triple any projected completion time and then be happy when it took a little less.
I had hoped to have the booth completed by now, but that didn’t happen. Hopefully by next month, great pictures of a finished booth will be in the mix.
Part 4: Nearing completion
95% of the studio is complete, enough to book mixing sessions and cut vocals. It took many man-hours and finagling to get to this stage. All that’s left are the finishing touches. Anything that could go wrong did. I was way behind schedule, with a lot of clients gently pressuring me to get it together. But now we can finally look at the final stages of the control room and iso booth construction.
After all the walls were sanded and primered, acoustic fabric was applied to all vertical surfaces. Sound Channels from Acoustics first is a dimensional fabric that combines excellent acoustic properties with a Class A fire/smoke retardant rating.
Sound Channels looks like carpet but is lightweight and easy to apply. At first we followed the installation instructions that said to “double cut” the material – that is lay the sections atop one another before slitting. This procedure is oftentimes used in putting up wallpaper, which is really what the process of installing Sound Channels is. But I think the instructions might have been for a different type of fabric. This had ridges, so we took a flat metal bar and cut along an indented furrow line of each section we fabricated.
Sound Channels adheres to the wall with Chapco 305, a specific adhesive that is made for interior wall carpet installation. This stuff is so good that we could skip the installation suggestion of putting temporary staples at the top of the fabric strips to hold them while the adhesive dries. Prepping is very important: sealing the drywall with primer before applying the adhesive paid itself back in dividends. This D.I.Y. job by an inexperienced installer took about 24 hours – I had to cut and adhere some 40 linear feet of the fabric. I should note that my room has many angles, uneven areas, and doors and windows to go around. Not to mention the booth has a bowed wall.
Once the fabric was installed and cured, we hung the bass traps and absorbers that Nick at Acoustics First recommended based on a dimensional drawing of the space. On the front wall there are two half-round cylindrical broadband absorbers by Geometrix. These are made with 1-inch thick curved acoustical glass fiber with wooden supports.
Between the bass traps are two rectangular Sonora absorbers. On the ceiling over the engineering console there’s a Sonora panel made specifically to hang horizontally.
Once these sound controllers went up, we noticed a marked difference in the treated room versus the room right next to it (my bedroom). The room is by no means “dead,” nor was it ever meant to be. The treated room has a much more pleasant, controlled feel to it than the painted drywall with it’s edgy “slap.” Of course, this was determined by shouting and clapping our hands. When all is finished, full range music will be the gauge for the room’s acoustical success.
Floors and workstation
The next step was laying a floor for the studio. Half-inch plywood had already been glued and screwed into the floor. The next step was to lay flooring. I choose 3/4” Bruce hardwood oak. It’s durable, looks great, and fits nicely with the warm vibe I was looking for in the space. The oak was laid both in the control room and isolation booth. Trim was cut and painted for the floor and ceiling and now it was finally time to deal with the airflow and cable runs to the iso booth.
The booth… Wait, I’m still uncertain and afraid. I think I’ll build a workstation first.
Fortunately for me, we had a room at Sigma that had a Protools rig set up in an Argosy workstation, so I knew of the company and the quality of their materials. I ordered the VR 70 Argosy workstation with flat top rack sections for near field monitors. The console came neatly packed in about 13 boxes. It takes at least two people to assemble these babies, as some pieces are large and unwieldy, so my dad came over to lend a hand. It took us only three and a half hours of moderately-paced work to put the console together. The instructions were clear and concise and the fit and finish of the workstation was impeccable.
Okay… okay… the booth
The make-or-break day had come.
I had to commit to cutting holes for airflow and wiring in the booth, and close the outer (visible) ceiling. I decided we should put a two-inch cant in the ceiling so it and the floor were not parallel. Just like the control room, the booth shouldn’t be dead, just controlled and pleasant. On the one large wall in the room, we took two pieces of leftover 1 1/4” round and mounted it vertically at the centerline of the wall. Then we took a piece of masonite (pegboard without holes) that was a little wider than the width of the wall. I am bad at math so we cut it with trial and error.
Once we found the right size to make a nice curve, centered at the now half-round “keel,” we screwed the masonite to the walls in two horizontal sections. Before the second section was in, we stuffed some fiberglass between the wall and masonite to hinder any sympathetic vibrations that sound waves might induce in the arced panel. We did the same thing for the top panel and then used duct tape to hold the two panels together before we put the Sound Channel fabric over it. Once all the fabric was installed in the booth, we put quarter-round up in the corners and top and bottom to further reinforce and hold the curve line.
Our next issue was getting wires from the workstation to the booth. I did not want to build a run through the floor, so I had decided early on to run plastic pipe up the wall, behind the console, then across the ceiling and into the sofit that was being used as a conduit for a room-to-room vertical fan.
After the pipe was painted and hung, we used a string that was set inside as a “fish” to pull six 22-gauge communications cables into the booth. Once inside the booth, we used Wiremold piping and Wiremold boxes to surface mount two boxes: one for microphone connections and one for headphones. We pulled three lines in each box. Two lines were connected to off-the-shelf switch plates with XLR connectors surface-mounted to them. The other line in each box was tucked in and is available for a future application. We made the same terminations on the other end of the wire and then connected them to my Digidesign 192 converter.
After the lines were checked, we mounted a room-to-room variable-speed fan to suck air out of the booth. This was mounted over the steps in the stairwell by attaching it to the sofit’s outside wall. Inside the sofit, we made two vertical half-inch-thick plywood plates and mounted them to segment the sofit into three equal zones. A large hole was cut in each. Now air being pulled out of the box had to run through three 90-degree bends, significantly lowering any noise that could seep through the opening.
Early on in the construction of the booth, we anticipated the need to have air flowing into the booth, but acoustically, you don’t want a straight hole through the walls. So we made eight-inch cuts in the outside wall, between two studs, and framed it with 2x4s. The same thing was done on the inside wall, offset from the other hole, so air and any sound it carried had to pass thru three 90 degree bends before it entered the room.
This part of the work was the final major hurdle. The doors have been sealed temporarily with weather strip, and we’ll look at the door and the proper way to seal it on the next installment. At least that’s the plan.
It’s been a real whirlwind of activity filled with surprises – both good and bad. My first session for recording was booked and it didn’t look like the studio would be 100% complete by downbeat. Stay tuned next month for an honest evaluation and any changes that need to be implemented.
Michael Tarsia is a two time Grammy recognized Engineer, with over two dozen Gold and Platinum album credits. He is also a Director and Instructor for the Sigma Soundz Recording Arts Program. Learn more at www.miketarsia.com, email firstname.lastname@example.org, or call 215-837-1002.
Acoustics First Corporation offers a full range of acoustical materials, including sound absorbers, barriers, diffusers, and specialty products used in studios for recording, broadcast, and multi-media production. Learn more at www.acousticsfirst.com.