experiments in acoustics

Movable isolators are used to baffle instruments such as drum kits during multitrack recording sessions. Without them, bleed can be a major problem for recording most musicians. Below, I’ve compiled a theoretical to-do list for building such an isolator on a budget, as a DIY project. As of this post, a lengthy explanation of what to get and why to get it is at hand. The step by step instructions are to come.

What to get and why to get it.

A. Decide what you want to do.

1. For general purpose isolators in studios, 4’ high absorbers block out most lateral bleed from drums and amps at the frequencies that really matter.

2. To absorb anything effectively, a barrier that surrounds the subject to be isolated needs to be made so that no gaps (small enough to fit a paper through) are open between the four corners. To achieve this, I suggest making the sides of the isolators fit together with soft, durable materials, then lock with something like a well placed gate latch. Its time consuming but without such locking, it might not work half as well.

3. If the barrier isn’t going to be permanently in one location, weight and mobility will be an issue, so wheels should be designed into the end product. Wheels open a new can of worms with the issue of ground clearance leaving space for sound leakage between the floor and the bottom of the barrier. This is easily solved by cutting sheets of fiberglass and/or plywood that fit into this space after the barriers are moved into place.

4. 4 separate isolators will be needed to make an adequate barrier in a square shape around the subject unless the subject is put in a corner (then you’d only need two). Each one should be exactly the same and should be wide enough to encapsulate a drummer and all his drums, since that will likely be the largest space you’ll need to isolate during a normal session.

B. Get materials. (more…)