“I enjoyed last week’s tip (see inSync 7/6/01) about the benefit of using omnidirectional microphones. I have a multipattern mic that can do omni. Is this the same as using a dedicated omni mic in studio recording?”
Again we went back to Nika Aldrich for this one.
Obviously yes in some ways, but not all. Traditional multipattern mics are actually composed of two capsules facing back to back. These capsules are identical in design, and sometimes even share a common backplate.
What you actually have, then, is an omnidirectional microphone composed of two cardioid capsules back to back. While this works very efficiently to “simulate” an omnidirectional mic, it is not completely omnidirectional. It has the same properties as cardioids in that it does not have a flat off-axis frequency response and it is prone to proximity effect – from both the front and the rear.
A “true” omni has no proximity effect, and the off axis sound is going to be flatter. Even though a “true” omni will have some high frequency rolloff at toward the sides and rear, it is much flatter than a cardioid.
So the difference for you is that your multipattern mic will function more like a figure-8 microphone at higher frequencies, and will have proximity effect from all directions instead of none at all. For some types of microphone techniques and situations where omnis are appropriate, the multipattern mic will work well for you. One example would be room mic’ing. In others it will not. These include the close mic’ing techniques often done with omnis on acoustic guitars.
As with wine and guitars, one can never have too many microphones! A good pair of “true” omnis should be a part of any good mic closet!