Tag Archives: audio recording

Introduction to Microphones

You can buy a microphone for $2 and you can buy a microphone for thousands of dollars. That’s a pretty big spread of dollars for microphones!

Fortunately these days you can get good mics at fairly inexpensive prices. If possible, find a good music store and get them to record something with the mic before you buy it. Some stores will even allow you to take it home, especially if they know you’re likely to buy several mics. Over time you can keep upgrading your mics.

I suggest that you start with two dynamic microphones. Later I’ll explain what a dynamic mic is, for now dynamic mics are relatively cheap and a good dynamic mic can sound pretty darn good.

Put them as close together as you can, directly in front of the ensemble you want to record. I suggest you have them at an angle to each other, somewhere between 100 and 135 degrees.

2 microphones at the correct angle for recording
How to angle 2 microphones

Generally the easiest way to do this is to have one mic over the other. This is called using a stereo pair and is a very common technique for professional recording.

Most of the time people recording a choir or ensemble will have two mics, but they will both be facing the group and will be between 4 and 10 feet apart. There is a very good acoustical reason that is not the best way to record- the distance between the mics will cause certain frequencies not to be recorded properly. If the mics are close together the frequencies that are lost are too high to hear. If you have a large group you can put them 25 or more feet apart and the frequencies being lost will be below the bass register.

Put the mics as close to the ensemble as you can, although they need to be far enough away that the entire ensemble will be heard. The angle of the mics will help give you better coverage. 12 feet is a good starting place, although it will vary with your group. Record some loud parts and some soft parts, listen, and adjust until you like the result.

Now, for those curious about how mics actually work, here are a few details. There are two main characteristics of mics- the way they turn sound into a signal to be recorded, and the pattern they use in deciding which sounds to emphasize.

There are two primary ways that mics turn sound into an electric signal. Dynamic mics (usually less expensive) use the same principal that makes a loudspeaker work but turn it backwards. Sound moves a small diaphragm back and forth, and an induction coil generates a small current.

Dynamic Microphone
Dynamic Microphone

Condenser mics have two very thin plates, with an electric charge between them. Sound changes the capacitance between the two plates. Condenser mics need a charge to start out with, which can be provided a number of ways. If you have a mic that needs +48 volts of “phantom power”, it is a condenser mic.

Condenser Microphone
Condenser Microphone

There are many variations and even other ways that sound can be turned into an electric signal. If you’re curious, grab one of the books on the subject and you will find a most fascinating area of science and engineering!

The housing of the mic which goes around the part that actually converts the sound is used to make sure that the mic picks sound up from the correct direction. If you are trying to record everything that happens in a room, you want a very different mic than if you are trying to pick up one instrument that is 100 feet away. Modern mic technology is very good at controlling which sounds are picked up and which sounds are not. It’s up to us to understand what the mic does so that we can make sure our recordings get the sounds we want instead of the person coughing in the third row.

Omnidirectional microphones pick up everything from every direction equally. They aren’t used a lot for recording since usually that’s not what we want to do. I used an omnidirectional mic once with a 8 member singing group. They surrounded the mic and all sang directly towards it. There were some minor fluctuations since the singers had different volume levels, if we had had more time we would have experimented with placing certain singers a little closer and certain singers a little farther away.

Unidirectional mics give stronger signals in one direction. You may have seen mics referred to as “cardiod”, they pick up sounds in front of the mic better than sounds to the sides.

There are also hyper-cardiod mics which have a stronger cardiod pattern, and even and shotgun mics which are designed to pick up a small area that may be at a distance from the mic.

There are also bidirectional microphones, which pick up sound from both front and rear but exclude sound from the sides. They are less useful in recording music.

The history and practice of building mics is a huge subject- many books have been written about microphones. But you don’t need to understand everything about microphone technology to get a good recording of your choir. Find a couple of decent dynamic mics, place them carefully, and use our RipEditBurn Plus to create a great recording.

Next- Cables And Connectors

by Tom Jeffries, Chief Blazing Officer at Blaze Audio

Tom is a former professional musician who has been running companies that develop audio software for 34 years. He studied with Charlie Schlueter as principal trumpet Minnesota Orchestra for four years. Charlie Schlueter went on to do 25 years as principal trumpet with the Boston Symphony Orchestraā€ˇ. Tom also played principal trumpet for the St. Paul Chamber Orchestra and principal trumpet for the San Jose Orchestra.