Tech Tuesdays is our weekly geek-out, with a new geeky topic every Tuesdays.

This week, I’ll try to keep it short and simple.  Polar patterns are just a fancy way of saying pickup – patterns.  They’re the directions in which different mics (and sometimes the same mic in different modes) pick up sounds.  As you can see above, there’s lots of math and theory behind the patterns out there, but in music production, you tend to just deal with a few patterns and move around to see what works. 

Cardioid

If you’ve only got a few mics and they aren’t break-your-bank expensive, then chances are you’ve got cardioid mics.  They’re the ones that kind of act like a flashlight.  Cardioid mics tend to pick up sounds in front of them, and reject most of the sound behind them.  Try to picture a shape like a semicircle coming out of the front of your mic. 

Keep in mind that polar patterns look different at different frequencies – bass is harder to keep directional than treble frequencies. This means that if you’re trying to place mics to pick up one source and reject another, the mic will have a “tighter” pattern with higher frequencies. 

Due to their ability to reject sound from behind, mics with this pattern are favored in live performance and multiple-microphone setups.  Probably the place where rejection is most vital is in vocal mics on stages.  Sitting just beneath and behind the mic is usually a ridiculously loud stage monitor, so being able to block out sound from the speaker helps keep feedback at bay.  

Examples: SM58, SM57, AT2020, Shure KSM27, and a million others. 

Super/Hyper Cardioid 

The super and hyper cardioid patterns are designed to be able to focus in on sound coming, rejecting most of the surrounding noise.  It’s like taking a flashlight and focusing the beam so it shines farther but not as wide.  You’ll also see that these kinds of mics have a small area of pickup behind them.  This is a side effect of their design, and is usually worked around by angling the mics so that their sides point at what you’re trying to avoid.  

If you encounter mics with this kind of pattern, it’s often very specific instrument mics or small-capsule (pencil) condensers.  

A good example is the Shure Beta 52 Kick Drum Mic.  It’s got a very focused pick up pattern in order to reject the many other sounds happening around it (i.e. the snare, toms and cymbals in the rest of the drum kit).  Other times I’ve used super or hyper cardioid mics on drum toms or as choir overheads.  

Other times you’ll see these more focused patterns used in smaller pencil condenser mics for higher frequency sources.  

One other place you’ll find them is on set for video/film shoots.  The mics you see encased in plastic, fur-covered capsules on the end of tall boom poles often have super or hyper cardioid pickup patterns.  This allows the mic holder to focus in on what the actors are saying, without the mic having to be so close that you can see it on camera.  

One last note: Super and Hyper cardioid aren’t technically the same thing, but you’ll hear the terms interchanged a lot.  Just keep in mind that hyper tends to be the tighter pickup pattern, with a stronger pickup behind the mic.  There’s a lot of debate/math that goes into the difference between the two, though I’m not sure how useful the distinction is.  I prefer just listening and deciding if it’s working for me or not.

Examples: Shure Beta 52, Shure Beta 98, e609 Silver, Sennheiser MKH416

Omni

Some people start discussions of polar patterns with omnis because they’re like a point of reference for describing the other patterns.  I think its important to note, however, that if you’re just starting out in music production, it might be a while before you encounter an omni mic.  

That’s not say they’re rare, or aren’t out there, but most mics under $100 have some sort of directionality to their patterns (i.e. they pick up better in some directions than others).  Omnis, on the other hand pick-up sound in all directions “equally” and are often used in situations where multiple sources are being recorded with a single or pair of microphones.  

I think the reason most smaller-budget mics aren’t omnis is because they can get tricky to use.  Most people just getting started don’t want tricky, they want point-and-record simplicity.  Unfortunately, because omnis pick up in all directions, you have the potential to pick up bleed from other instruments, delayed reflections off of walls, and other sounds you’re not trying to focus on.  

These problems are actually different techniques to be used in recording, but they tend to rely on good acoustic conditions and isolation.  If you’re in a fantastic studio, then moving omnis around a room can get you incredibly natural sounds.  But in your bedroom recording a guitar amp, you’ll have a hard time competing with the noise from your window, your roomates cooking in the kitchen, and even your own computer’s infernal fan.  

Lastly, if you’ve got a mic that’s an omni, chances are it can switch to several other patterns.  There aren’t a ton of mics out there that are omni-only (though they exist).

Examples (Omni-only): Neumann KM183, Electro Voice RE50

Examples (Switchable Omnis): AKG C414, Shure KSM44

Figure 8/Bi-Directional

The Last pattern I’m going to cover in our roundup are figure-8 mics.  As you can guess, these mics have a polar pattern that picks up in front of and behind the mic, while rejecting the most on the sides.  It seems like a rather strange pattern for music recording, but it has some amazing uses.

This is another pattern you tend not to see in cheaper mics because most designs rely on dual capsules to create the figure 8 pattern.  These mics are also almost always able to switch patterns to omni, cardioid, and sometimes super or hyper cardioid.  The exceptions to this are ribbon mics, which are figure-8 by design and aren’t generally switchable.

Often times you’ll see figure 8 mics used in conjuntion with other mics to create combination patterns like the blumlein and mid-side setups.  Hopefully I’ll have a chance to delve into those another time.  

Used by themselves, figure 8′s are spectacular at recording multiple sources like two harmonizing vocalists.  Having both singers stand facing each other with the mic between them is an interesting way of capturing their sound, while maintaining that live-harmonizing feel.  Keeping singers in the same space also tends to make it easier for them to sing together.  

Examples (Ribbon): Royer 121, Royer 122, AKG C414, Shure KSM44