BY BObby Owsinski
Welcome to my new column dedicated to exploring the ins and outs of surround sound recording and mixing. Just about everything in our business is based on equal portions of art and craft, but before you get to the art, you must perfect the craft. What I’ll try to do is give you the basics that will enable you to get on with the art (and the fun) of surround recording and mixing as soon as possible.
Although several of the subjects have already been discussed in past articles, many of you have either just recently joined us, or some of the previously discussed info needs to be updated, so we’ll go over some of these topics once more just to make sure that everyone’s got the basics. I’ll try to give you the info in as concise a format as possible, but the approach will always be from a �hands-on� perspective. We�ve gotten pretty good at surround production during the time that this magazine has been published, but some of the techniques have changed due to better purpose-built equipment, the demands of the marketplace, and experience. Some of the upcoming columns will cover speaker placement, calibration, real-world bass management, different surround formats, encoding, and lots more.
So let’s get started. The first thing to discuss is what kind of surround system to select, specifically what type of surround speaker to choose.
There are two types of monitors to consider when setting up your surround system: direct radiators or dipoles.
The direct radiator is a loudspeaker where the principal output is directed at the listening area. Universally used for the front channels in a multichannel sound system and widely used for the surround channels, direct radiators are often found to be better for localization, but poorer for reverberation and ambience than a dipole radiator.
A dipole radiator is a loudspeaker having a figure-8 directional pattern and often used for reproducing the surround channels by placing the listening area in the null of the figure-8 pattern. Dipoles are often found to be better at reproducing enveloping sounds such as reverberation and ambience, but poorer at localizing than a direct radiator. Dipoles can also better simulate a theater loudspeaker array when used in a home theater environment.
So which type of monitor should you choose? Should you use five identical direct radiators? Should the surrounds be dipoles? Perhaps all of the above to cover all situations?
Of course, the type of program you’re working on will determine the answers to these questions. For instance, if your typical program mostly contains source information from the screen channels, like classical music or ambient program tied to picture, then dipole surrounds should be considered. If the program is primarily pop music, then direct radiators are probably in order. It should be noted, however, that the majority of home theater systems use dipoles at the moment, so the engineer might want to check his work against that type of system at some point just to be safe.
I do see a trend away from dipoles though. It seems that when the home theater was used mostly for movie playback (in the beginning of the home theater craze), then dipoles made a lot of sense and most hardware manufacturers developed speakers based on trying to capture that theater environment. Now that more music is available on DVD with aggressive source material in the surrounds, manufacturers have recognized the need for direct radiators. Also, I�ve not seen dipoles used in any studio surround setup in at least a year, with the exception of some M&K �Tripoles� (which combine the attributes of both dipoles and direct radiators).
Back on the subject of direct radiators for a moment. It’s important to use five identical direct radiators. Using two smaller speakers of the same manufacturer, or different models altogether, will work, but you run the risk of getting fooled when your disc is made and you listen at home (a theme that will continually come up in this column). If you know that all you’ll ever be putting in the surrounds is ambience, then maybe they’ll work. But as soon as you begin to put direct source material with some bass
content back there, then you run the risk of either over-EQ�ing or mis-balancing because the speakers are too small, underpowered, or mismatched.
So, to sum up:
1. Choose the type of surround speakers based upon the type of program material that you’ll be working on.
2. If in doubt, be safe and choose direct radiators.
3. If you choose direct radiators, five identical speakers are best.
Why didn�t I mention the subwoofer? Because the subwoofer is important enough to deserve an entire column (or two) of its own. We’ll get to it soon enough.
Next issue: The Truth About Placement
You can find more on this topic and a lot more on my new DVD How To Set Up Your Surround Studio, available soon from Surround Professional magazine.