Tuesday, August 10, 2010

How to Buy a Microphone

The Beginners Guide to Buying a Microphone

Of all the emails I get with questions about Native American flutes one of the most common is about what kind of microphone to use for the Native flute. Even if you're not recording a microphone can be used for amplifying your sound when you're playing live. Therefore knowing a little about mics and how you are going to use them will help you decide what kind of mic to purchase

There are two basic type of microphones. But before we get into them and look at how they are different, let's talk about how they are the same: The patterns in which they pick up sound. When I say pattern I'm talking about the shape that we use to represent the direction in which they will pick up a sound. There are a number of patterns but we'll look briefly at three: Cardioid, Bi-Directional or Figure Eight, and Omnidirectional. Some microphones will only use one of these patterns, but many have a switch that lets you choose which one you want to use.

The easiest to understand is Omnidirectional. Omni is Latin for all. So an Omnidirectional mic picks up sounds from all directions. No matter where the sound source is in relationship to the mic, it will be picked up equally.

Bi-Directional, or figure eight means that the mic will pick up sounds coming from both the front of the mic and the rear, but not the sides. This pattern when plotted on a graph looks like a figure 8, with the mic being in the middle of the two circles that make up the number 8.

A mic with a Cardioid pattern picks up sounds only from in front of it and just a little to the sides if the sound is near the mic. The pattern on a graph for this type of mic looks like a heart, or in truth more like a the outline of a plum. The mic is by the two upper lobes of heart.

If you're interested in seeing what these patterns look like on a graph you can find them here. You'll notice other patterns that we haven't covered here. But these are variations on these three basic types.

Native Flutes = Cardioid
For the most part, when talking about Native flutes, you'll want to use a mic with a cardioid pattern. You'll be playing in front of the mic and really don't want any other sounds to be picked up from the sides or back.

Different Types of Microphones
So now that we've looked at how mics are similar, let's look at how they are different. There are several different types of microphones but for the Native flute there are really only two that you'll need to worry about: Dynamic and Condenser. I'm not going to go into how these two types of microphones work, but rather talk about how they are used. If you want to know more about the circuitry involved there is a lot of information out there. You don't need to know this to use a mic. Let's look at dynamic mics first.

Dynamic Microphones
Dynamic mics are the types of microphones you see on a live stage. Singers use them on stage, as do instruments that need to be mic'd. They are, for the most part, inexpensive, can take a beating, and don't feedback as easily as Condenser mics. A decent, all purpose, dynamic mic can be purchased for $100 - $150. Dynamic microphones generally only come with a cardioid patter.

musical-echoesWhen playing a Native flute into a dynamic mic you want to get the flute's true sound hole, the one in front of the block, right up to the microphone. This is due to the fact that these mics don't pick up sounds that are not right next to them. (This is why they are harder to feed back)
Notice in the photo to the right how I'm trying to get the true sound hole as close to the mic as I can.

One of the reasons why these mics will not pick up sounds that are not close to them is because they are not as sensitive as condenser mics. This also applies to the range of frequencies they will, and will not pick up. As a general rule dynamic microphones will not pick up sounds that are very low in pitch e.g. low frequencies, or ones that are very high in pitch, e.g. high frequencies. Where they start to not pick up high and low frequencies will give each manufacture's model it's characteristic sound. (BTW a graph showing how a mic picks up certain frequencies is called a frequency response curve)

For the most part this lack of sensitivity really isn't a problem where Native flutes are concerned, due to these flutes limited range. Even if you take into consideration low bass flutes and super high flutes, which are well within the average dynamic microphone's frequency response curve.

I use a dynamic microphone when I perform live. How did I pick the mic I use? I didn't really. I just use the mic that came with my Fender Passport PA system. Why go out and buy another mic when the one that came with the PA works just fine? In fact I know that the mic's inability to reproduce really high frequencies works in my favor in that it acts like a filter on any high, breathy, windy or buzzy sounds coming from the flute. Noise that I would filter out anyway!

Condenser Microphones
Condenser microphones are more common for studio recording. Their electronics work in a different way than dynamic mics and are therefore more sensitive. This means that they will pick up sounds from farther away, that are quieter and very low or high in frequencies. Condenser microphones need to be powered, either by a battery in the mic capsule, or generally from the mic pre-amp. This external power is known as phantom power. Most mixing boards and digital I/Os have phantom power built into their pre-amps.

AT-4050-in-shock-mountUnlike a dynamic mic, when playing into a condenser mic the sound source, in our case a Native flute, does not need to be right next to the microphone. In fact anything closer then 12" - 18" will over power the mic and cause distortion. It will also pick up noise from your lips and fingers moving. For Native flutes the best way to go is to have the mic in a shock-mount placed in front and above the flute at a 45˚ angle. It's very common to have the mic hanging upside down when recording this way.
The photo above shows my condenser microphone in it's shock-mount hanging upside down. This is a side view. The front of the mic is to the right.

I use an Audio Technica 4050 for 99% of my studio recording work. I asked several audio engineers what they would recommend for a good, reasonably priced, all purpose instrument mic and this was one of their recommendations. So far I've used it on all of my studio recordings except for a few tracks and have found it to be an excellent mic. When I bought it they cost about $750. They seem to have come down since then. But there are any number of good, reasonably priced mics out there if this is beyond what your budget will allow.

You might be asking yourself, "What mic did he use for the other 1% of his studio recording?" Well on a couple tunes that used a double flute I used a stereo mic, (which I'm not sure gave me the results I was looking for) and on a couple others I used a dynamic mic that was designed for drums! No one has ever mentioned that they can tell the difference and this doesn't surprise me. By the time you do some filtering, a touch of compression and add all the echo and reverb most people can't tell. But leads to another question...

How do you pick a mic for yourself?
So now that I've thrown all this information at you how do you wade through it all an pick a microphone for yourself? The truth is there are a few really easy ways to pick one. They aren't rules necessarily, they're more like guidelines...

1. Where will you use a mic the most?
In the studio or on the stage? If you're going to use it mostly in the studio then you might strongly consider a condenser mic. For anything else, stage, flute circles, family outings, public appearances, Madison Square Gardens..., then get a dynamic mic. It would be wise to not take a condenser mic onto a live stage. It can be done, but It's not worth all the extra hassles and it will pick up every little noise anyone even close to you makes. And that includes your noises as well...

2. What's your budget like?
If you don't have a lot of money you're better off with a good dynamic mic. That way you'll have money for a mic stand, cables and all the other gear the mic plugs into.

3. How quiet is your space?
If you plan to use a mic for only studio recording and your studio is your bedroom, how much unwanted noise is there? If you can't record yourself in a very quiet place then a condenser mic will pick up all sorts of unwanted noise. Computer fans, cars, planes, garbage trucks, neighbors yelling, dogs barking, phones ringing, your spouse / roommate flushing the toilet, the washing machine, birds, loud bees... Better to use a dynamic microphone that won't pick up all these noises. Unless of course you're doing some "Avant-garde, urban noise & flute recording".

I record my live instruments in a walk-in closet with acoustic foam covering the walls. I generally turn off all the phones (which, as my friends know, I rarely answer anyway), and even have my computer in an isolation box to damp down the fan noise. Trust me, when recording, not much is as anonying as unwanted noise that you can't get rid of.

Finally, the last thing to consider is that better equipment doesn't always make for a better recording. Why would I say that? Well what if you purchased some $5,000 microphone (yes, some cost that much) and when you record your flute you hear all this ugly stuff, like wind, buzz and air, in the recording that you don't like? Now you're just going to have to figure out a way to get rid of it. Maybe a less sensitive microphone wouldn't have picked up all that junk in the first place.

Keep in mind that the sound of the flute we hear in our head is not the same as the sound the mic hears. Our brains unconsciously and automatically filter out a lot of wind, air, buzz, fuzz, and other noises from the flute. A mic does not. It's kind of like hearing a recording of your voice. And you love how much your voice sounds... Right?

So if you aren't familiar with how sound works, and how to manipulate it through devices such as EQ, maybe you don't need that state-of-the-art microphone. Maybe an inexpensive dynamic mic is best for your needs and experience. You can always upgrade later.

...Plus, with a "cheaper" microphone, if your playing isn't all that great you can always blame the mic...

Happy Recording!

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