These days, all gear is acceptably flat over the most important parts of the audio range. Distortion, aside from loudspeakers and microphones, is low enough to be inconsequential. And noise - a big problem with analog tape recorders - is now pretty much irrelevant with modern digital recording. Indeed, given the current high quality of even semi-pro audio gear, the real issue these days is your skill as a recording engineer and the quality of the rooms in which you record and make mixing decisions.
What's the point in buying a microphone preamp that is ruler flat from DC to microwaves when the acoustics in your control room create peaks and dips as large as 20 dB throughout the entire bass range? How important really are jitter artifacts 110 dB below the music when standing waves in your studio cause a huge hole at 80 Hz exactly where you placed a mike for the acoustic bass?
Clearly, frequency response errors of this magnitude are an enormous problem, yet most studios and control rooms suffer from this defect. Worse, many studio owners have no idea their rooms have such a skewed response! Without knowing what your music really sounds like, it is difficult to produce a quality product, and even more difficult to create mixes that sound the same outside your control room.
Ethan Winer, co-owner of Real Traps, a well known acoustic panel and design company, gives us the details on construction of absorptive panels to help tame that home or office studio.
Fortunately, more efficient bass trap designs are available that are much smaller. However, studios on a tight budget can apply rigid fiberglass in the room corners as shown in Figure 3a and lose only the small amount of space in the corners. Since bass builds up the most in the corners of a room, this is an ideal location for any bass trap.
Figure 3a shows the corner viewed from above, looking down from the ceiling. When the rigid fiberglass is mounted in a corner like this, the large air gap helps it absorb to fairly low frequencies. For this application 705-FRK is better than 703 because the goal is to absorb as effectively as possible at low frequencies. However, you can either absorb or deflect the higher frequencies by facing the paper backing one way or the other, to better control liveness in the room. Using 705 fiberglass that is two inches thick does a good job, but using four inches works even better. Note that two adjacent two-inch panels absorb the same as one piece four inches thick, so you can double them up if needed. However, if you are using the FRK type you should remove the paper from one of the pieces so only one outside surface has paper. Top
Besides the corners where two walls meet as in Figure 3a, it is equally effective to place fiberglass in the corners at the top of a wall where it joins the ceiling. With either type of corner, you can attach the fiberglass by screwing it to 1x2-inch wood strips that are glued or screwed to the wall as described previously. The 1x2 ends of these strips are shown as small black rectangles in Figure 3a above. One very nice feature of this simple trap design is that the air gap behind the fiberglass varies continuously, so at least some amount of fiberglass is spaced appropriately to cover a range of frequencies.
For a typical unfinished basement ceiling you can take advantage of the gap between the support beams and the floor above by placing rigid fiberglass between the beams. Short nails or screws can support the fiberglass, making it easy to slide each piece of fiberglass into place. Then cover the fiberglass with fabric as shown below in Figure 3b. You can optionally pack the entire cavity with fluffy fiberglass one foot thick and you'll probably get similar results.
Hopefully this will get you started on your way to making your mixing and recording space sounding as good as it can. Remember the gear doesn’t make the room - the room makes the gear! Want to learn more about the Recording Arts?
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Written By Rich Ott, Recording Arts Course Director and Instructor