Setting up a Recording Studio in Your Home. Part 1 — Introduction, and Echo Reduction.
In this series of articles, I shall attempt to get you started at setting up a sound recording studio in your home. The techniques herein work especially well for recording flute music, but should apply to other instruments as well.
I’m your sound man in this series of articles, and have no suggestions regarding anything but the soundtrack of your next video production.
Having spent eight years in the production of the five albums described on my website, I am in a position to help you avoid pitfalls and achieve good results. If I could do this without a Ph.D. in Acoustics, you can too.
For starters, you can consult the body of practical advice already on the Web:
First stop on your Web research should be Eric T. Smith’s Practical Guidelines For Building A Sound Studio. Mr. Smith’s Guidelines are written for those who wish to build a studio instead of merely adapting an existing room for use as a sound studio. Though my suggestions herein are aimed at the latter, Smith’s Guidelines describe walls and floors of an idea studio, from the inside out, and thus provide an insight into the intimate life of sound waves.
Mr. Smith works for Auralex (R), a company that sells acoustic foam. I used and recommend Auralex’s products, as well as those of their competitors, Markertek (R), and Silent Source.
Acoustic foam is expensive, and this touches off the most important concept I want to emphasize herein: finesse.
While setting up your studio, you could waste gobs of money if you are not willing to compromise. Instead, you could use mitigating techniques to get a good recorded sound on a low budget. A mitigating technique is just a fancy phrase for band-aid.
In Medicine, there is a technique called titration, which translates to our domain as “Spend the least possible additional money on improvements, until the recorded sound is acceptable to your ears”.
The key is knowing what to listen for. My best answer is “a natural sound”. When you start, your recordings may sound like they were made in a box, instead of in a more suitable venue. This is common. But, how to fix?
Echoes are Bad
The first demon to exorcise is echoes. Reverberation, often confused with echoes, can be a problem too, but echoes are our number one enemy, unless you really like that “pipe culvert” sound.
Fortunately, it is easy to diagnose this problem. You need to get your studio’s impulse response. A single, loud hand-clap will do. Listen for echoes. Specifically, if the echoes come back to your ear in a “pulse train”, the room will need some form of echo-reduction treatment. In words, what I mean by pulse train could be descirbed as “CLAP Clap Clap clap clap, etc.”, wherein the clap’s echoes trail off in volume with time. If you can make out individual clap sounds in the echo, the room needs treatment.
Effective room treatment to reduce echoes requires understanding their cause: parallel room surfaces. Parallel walls, or flat (level) ceilings above hard floors, bounce the sound back and forth like a caffeinated ping-pong ball in a cement vault.
If the parallel surfaces are sufficiently close, you may even perceive a musical pitch in those echo pulses. This is very, very bad.
Anything that makes those sound waves behave less like that ping-pong ball can help. If you can find an alternate room where the walls are not parallel, or the ceiling is angled (not level), moving to that room can help. If you are already in your least-parallel-surfaced room, you can place absorbent material on troublesome parallel surfaces. Note that you need not cover every square inch of hard surface in the room — but instead, just the parallel surfaces. And, even on the pairs of such parallel surfaces, you may get by with just covering one of those surfaces — until the echoes are tamed. Record something and listen for sufficient improvement. But for now, just listen for hand-clap echoes, and ignore any other “sound blemishes”.
Baffling Predicament
Adding baffles (panels) that are not parallel to any other surface can also help. Makeshift baffles can be made of just about any material. If you are lucky, just opening or closing a closet door can often foil the “conspiracy” of the parallel walls.
For reducing echoes, any absorbent material will do. You can try egg cartons, acoustic foam, or just soft cloth fabric — so long as the fabric does not lie flat on the surface. It should be loose. Better still — folded or pleated, like a drapery. I’ve not tried the following, but I’d bet crumpled newspapers might even work, if aesthetics are not your concern.
As a cost-reduction measure, some types of treatment can be applied in patches with good results, instead of over an entire wall. Patches, especially of thick treatment material such as foam, or egg cartons, are effective because they disperse the sound’s wavefronts and reflect them back into the room “confused”.
Flat or hard ceilings can be treated by tacking an old sheet to the ceiling using a sparse, irregular tacking pattern. Looks funny, but works.
Don’t Ruin Your Walls
While we are on the topic of appearance, you might want to be careful about how you attach treatment materials to wall and ceiling surfaces. I used tiny brads to attach foam patches to sheetrocked walls, thinking that the tiny holes would not be noticeable after removing the foam material. Wrong.
Other issues I plan to discuss in future posts include: standing waves & nulls, reverberation, microphone choice & placement, equalization, electronic reverb, acoustical and electrical isolation, and performer’s “geographic discipline”.
For your amusement and amazement, consider Orfield Labs’ no-compromise anechoic chamber design, described in this article, and this video. Their design may be slightly beyond your budget.
Quiz
Here is a thought-exercise that should serve as a quiz to measure your grasp of the concepts in this post:
It is an Urban Legend that a duck’s quack doesn’t echo. Of course it can echo. But, why might the echoes not be perceived as echoes?
Article link: http://www.syllaria.com/StudioArticlePart1.htm
Next: Setting up a Recording Studio in Your Home. Part 2 — Reverb, and Soundproofing.
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