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How to Build a Quiet Studio Environment

There is a lot of knowledge about how to build a home recording studio. Underneath most of this is an implicit assumption that a recording studio is something you build to keep sounds from going in or out of a room. After all, the recording enterprise is an inherently noisy enterprise. Or is it? In the past, when most home studios were designed for recording a "band", you know, a 4-5 member group that has a drummer with a full kit of cans, a couple guitarists with big-haired amps. A Bass player with his or her stack, and the keyboard player with their amps.
Wait a minute! Is this how everyone works today? Of course some of us do, and have active bands that gig and record. But what about everyone else? How many of us are essentially a one person operation, using a computer, keyboards and samplers, and a mixing board? How many of us are only using a computer? Don't be shy now. My bet is most of you. The rules for what a recording studio should or can be have changed as a result of the wonders of modern technology. If you are a part of this revolution, this article is for you.
The number one consideration of a home-based project studio is not soundproofing, but the making of a quiet room. I find it kind of funny that some people will spend thousands to treat their room yet never quiet the stuff inside the room itself! You walk in and hear a noise coming from computer fans, whines coming from hard drives, zip drives, SCSI drives for samplers, fans in samplers, fans in amps. This is no way to work on music or produce audio. What one finds is that this racket masks other problems in the studio, like 60 Hz hum at the console outs, poorly set up gain on mics, synths and other instruments. It's rather ironic. People who have a noisy studio create their stuff, mix and master it and never really notice that the entire production is imbued with noise problems. When the piece is done, they still don't notice it because, yep, they listen to it in their noise-infected studio. So let us post rule number one. Ready? Here it is.
To create music you must be able to hear your sounds. Doh! OK, I can see you dudes rolling your eyes. Some of you have bought the hype that you need $2,000 studio monitors to do this. Yes. Studio monitors are important, but even if you have the best monitors in the world you are still going to have major problems if you cannot clearly and totally hear what is coming out of them! So let us be clear. The number one enemy to good sound is the noise in your room, coming from the very devices you make music with. The louder your room is, the louder you have to monitor your music, the faster your ears will fatigue in a session and the greater the likelihood you may damage your hearing after years of constant, relentless exposure to high sound pressure levels. On the other hand, with low ambient noise in a room, you can find a lower comfortable volume level at which to work. This saves the ears a lot of wear and tear and you can work longer, and do those major projects that require successive all night sessions.

How to quiet your music creation room

Lets take a brief look at how professional studios do this to get a clue. Pro studios are multi-room operations. At minimum, there are 3 rooms. The "studio" where the performers play and are singing, playing instruments and drums, etc. The "control room" where the mixing board and patch bays and quiet outboard gear resides. Finally is the "machine room" where, you guessed it, all the noisy stuff goes. The problem for the home studio is that, usually, one room has to fulfill all these functions.
If you were able to quiet the room significantly, you could have a control room and studio room be the same room. You can record sensitive vocals and acoustic instruments with those sources gone, just don't swivel that chair too much. So, the goal has to be to develop some kind of machine area where all the noisy equipment can go. As usual, there are expensive ways to go about this, with sound isolation racks, buying only the quietest hard drives and fans. A better solution is to use the room's closet to store the noisy machines. The best solution is the simplest, and the cheapest. Cut a small hole in the wall and run some long cables into the next room.

Sound Isolation enclosures

There are companies making these now. They are expensive and may not totally eliminate the noise, but they will significantly reduce it to the point where you can work more comfortably. One of our members, Houston H, at studio-central forums has designed his own isolation enclosure. Really nice job. Here's a link to some pics and a discussion of the process. There's a cool tip there about using under the PCs in the enclosure. Check it out.

The Closet Approach

The closet approach is probably more problematic than the other approaches because putting your gear in a closed tiny room will actually make it resonate louder unless you take great pains to totally insulate the closet so sounds cannot leak out. You can cut down on the internal resonance in the closet by adding generous layers of sound absorbing materials, and installing a heavy door with weather stripping. Sound travels through air so it is important to seal the door as much as possible. Cable access becomes a problem here. if you think you can run the cables under the door, you will have too much leakage and you will still hear noise. The solution here is to drill a hole from the wall to the closet so you can run your cables through there. Once you have the closet sealed and tight then another problem arises: Heat. In a sealed tiny room the computer will eventually become like a furnace. It will not be able to dissipate heat very well if it is 100 degrees in the closet. You may be shortening your computer's life and worse, may be creating a fire hazard. So you need ventilation, which is much easier said than done. Assuming you do not want to re-route air conditioning ducts for this, you will at minimum need to install two fans where the back of the closet goes into the next room. One fan exhausts the air out while the other brings cool air in.

The Put it in the Next Room Approach

This, for me, was the best way to go. I've had success at the Tweak Lab. Drill a 4 inch hole above the baseboard going into the adjoining room. Make sure there is space in the next room for your computer and a rack unit. Then make an inventory of the cables you are going to need to pull this off. If you have a fire wire or USB audio interface, its easier. Get a few USB hubs for stuff like the mouse and computer keyboard. Perhaps the hardest are cables for the video monitors. VGA extension cables are easy to use, but avoid the cheap ones as they may cause ghosting on the screen. Digital video extenders are available too, but if you carefully map things out before you drill you might find a way to get the stock 6 foot cables on most LCD monitors to make it into the next room into the back of the computers. Here's the list of things I had to buy to complete this project.

2 15' VGA cables (the thick kind with ballasts at each end)
2 6' SCSI cables for the samplers, using a zip drive as an intermediary.
1 12' serial cable extender for the cable that goes from the audio interface to it's PCI card in the computer
1 25' serial cable extender for the MIDI interface to the serial port on the computer.
1 20' USB extender with 2 ports
1 20' keyboard extension cable
2 20' stereo extension cables for my secondary soundcard (an SBlive)
1 Ebtech hum eliminator to kill 60hz hum from the sblive's long audio lines.
Amazingly, for me, this worked. If I open the door to the room, I can hear the computer whirring away out there. When I close the door, it is totally silent. There are a few things to observe here. First, get good quality vga cables. The cheap ones may cause ghosting on your monitors, or may blur the image. With SCSI, you have to be careful about long cable lengths. Put your sampler as close as you can to the wall the cable will exit if you can. I could not, so I enlisted the help of an old zip drive. Have the scsi signal buffered in the zip drive made a 12 foot run possible. I have had success with 25 foot scsi runs this way, but that is really pushing it. A 25 foot serial cable, surprisingly, is not a problem at all with my MIDI interface (a Unitor 8 and AMT8 combo) And believe me, I have LOTS of data going down this cable. My USB mouse and PS2 keyboard had no problems with long cables. The only serious problem was my sblive soundcard with it's 1/8inch stereo mini-jacks. I use it for system sounds and for monitoring and sometimes recording. Its a 30 foot unbalanced path. I was not surprised to hear a loud 60hz hum coming from it to my computer speakers that I use as surround nearfields. The Ebtech hum-eliminator totally cleared that up.

This was, without a doubt, the best upgrade I have made in my studio since I started using hard drives. I can once again hear and pinpoint troublesome noise at my mixer and take steps to get rid of it. When I am doing sound development work I don't have to crank the gain or wear headphones to hear subtle nuance. Thanks to the lower levels of monitoring I can compose and mix all night long without disturbing neighbors or roommates. Silence and music have a mutually beneficial, almost magical relationship. Silence is the perfect backdrop for bringing sound from the world of our minds to the real world.

What is SBIR?

SBIR (Speaker Boundary Interface Response) - This is a term to describe how the proximity of a speaker to a hard boundary (wall/ceiling/floor) will change the response, especially in the low end. This is something that not a lot of people understand nor consider when planning a room.

Sound radiates from a driver in different ways. Higher frequencies act like a ray and move in straight lines from a point. As you get lower in the spectrum, they begin to radiate more like a sphere. By the time you get below 500Hz or so, you're getting pretty spherical radiation. By the time you get to 125, it's purely spherical.

That said, imagine sound coming from a driver at say 100 Hz that is coming directly at you. There are other waves that are wrapping around the cabinet and bouncing off the front wall and then back at you. When 2 waves of the same frequency meet in this way (one direct, one having bounced off the front wall) there is an interface of the 2 waves (some describe this as interference).

Constructive interference occurs when the 2 waves happen to be in phase with each other. This yields a reinforcement of that frequency or a peak in response. Destructive interference occurs when the 2 waves are 180 degrees out of phase. This yields a partial cancellation of that frequency (the bounced wave has less amplitude) resulting in a dip or null at that frequency.

This can cause WILD variations in frequency response. However, one can sometimes use this to your advantage. If you play with speaker positioning in relation to the front wall (behind the speakers) and the side wall, you can 'tune' the response changes. This can be beneficial when attempting to smooth overall response.

Let's say that you have peak at your listening position at a given frequency. If you can find a place that images well and works with the video positioning that will create a slight dip due to SBIR, the net effect is a smoother response at your seat. It's kind of like using an EQ without having to put one in your system.

Generally, you're best off if the distance from speaker face to front wall, driver centers to side wall, and driver center to floor are 3 different dimensions in order to not reinforce any specific set of harmonics by having all the boundaries generate the same SBIR effect.

If you still have issues, you can treat the walls directly beside and/or behind the speakers with appropriate materials to further reduce the intensity of the reflected wave to it's imact when interacting with the direct wave is minimized. If you have issues say from 125Hz up but OK below that, then a thinner panel may be in order - say 2". If you have problems all the way down, then something thicker may be appropriate.

Also remember that there will be interactions between the sub and boundaries and also between the sub and mains and their boundary responses.