Choosing a Polar Pattern (Part 1)

  Now that I covered different microphones and their basic elements in my last blogs the only other thing to understand when using a microphone is their pickup patterns. A pickup pattern, also called polar patterns, is the direction that the diaphragm (see Microphone ‘Magic’ for an explanation) inside the microphone is focused on. It is in these pickup patterns that the diaphragm picks up vibrations from sound. In general, there are three categories for pickup patterns: unidirectional (cardioid), bidirectinal (figure-8), and omnidirectional (boundary) configurations.

  The unidirectional pattern is the most popular pickup pattern for microphones. As you can guess by the beginning of the term, ‘uni’-consisting of one, the configuration of a unidirectional pickup pattern is focused on one direction- the front of the microphone. This pattern is also referred to as the cardioid pattern, because as you can see in the diagram, the pattern looks like a heart.

  With sound vibrations being isolated to only one area, the unidirectional pickup pattern is great for live sound engineering when you want to control the source of an input. The microphone will block out any ambient noise, like from a guitar close to a singer, and focus on just the vocals coming from the singer.




*Check out Part 2 for info on bidirectinal (figure-8), and omnidirectional (boundary) configurations.

Microphone 'Magic'

  The microphone is probably the most important element in the recording chain, it shapes the initial sound of the instrument or voice that you are recording or reproducing through a live PA. Many talk into a microphone like it’s ‘magic’, but there are key elements to every microphone that make it work and understanding theses basic elements are a must for any audio entrepreneur.

  Microphones are transducers (a device that converts one form of energy into another) that take acoustical energy (sound waves/vibrations) and convert it into electrical energy (the audio signal). The main element inside a microphone that is used in converting the energy is called the diaphragm. Different types of microphones (which I will talk about in a later blog) have different patterns for picking up sound waves, but they all have a diaphragm. The diaphragm is a thin piece of material (such as paper, plastic, silk, or aluminum) that vibrates when it is struck by sound waves. For example, below is a typical hand-held mic, called a dynamic mic, with a paper diaphragm that picks up the sound waves.

  Carefully attached to the diaphragm is a copper coil wrapped around a magnet. This magnet and coil produce a magnetic field inside that microphone used to convert the sound waves into an electric audio signal. When the diaphragm receives vibrations the coil moves back and forth, over the magnet, creating an electromagnetic induction. This induction is the audio signal that is then sent to a sound board for mixing, EQ, and gain/volume control of the signal.

  If you think about it, a microphone works the same as a speaker, but backwards. The microphone converts the sound waves into an electric audio signal and after it is sent through a sound board,  the signal is boosted by way of an amplifier and then sent to a speaker that converts the electric audio signal back into sound waves. Here is an example of a speaker diaphragm which looks a lot like the inside of a mic, but beefed up a lot more and reversed.

  Now the next time you go to an event with a PA system you will have a better understanding of the 'magic' of the microphone. Feel free to explain it to your nieghbor sitting next to you.

*Don't forget to let me know what you think by leaving a comment below.

Analog and Digital Consoles

In our culture today technology is changing all the time and you have to stay on top of the ‘digital’ age to know what’s going on. When it comes to the sound industry there is a struggle between what is better, a digital board or an analog board. Since my blog title is Understanding the Basics, I don’t intend on giving an in-depth lecture on everything an analog and digital board can do. Instead, I just want to lay out some of the basic features in order that you can gain an understanding of both.

First lets get an understanding of what analog is. When a person speaks into a microphone the air vibrations of their voice hits a transducer in the microphone which turns the vibrations, or audio signal, into an electrical signal called analog. Whether you use a digital or analog board this process is the same (because there are no digital microphones). Once this analog signal goes into the board it will pass through a pre-amp, which amplifies the signal so that it can be manipulated for processing, recording, live sound, or whatever else you want to do with it. It is in this manipulating process where the difference takes place. Lets first take a look at the analog features.

In an analog console the signal is processed in different layers, one at a time. The signal usually flows through a gain (volume knob), then EQ, then it might go through a dynamic processor unit then to the fader. With an analog system, you have all the knobs in front of you and you see the signal flow that the analog signal is going to take. If the signal is to be reduced in volume then you use the gain or fader, if it needs equalization then use the EQ knobs, if it needs to be compressed then send it to the dynamic processor rack, and so on until the signal is sent to speakers for live sound, or recorded.

With a digital console the signal is sent to an ADC (Analog Digital Converter) that changes the signal from analog to a digital signal. Digitizing the signal turns it into a bunch of “0’s” and “1’s”, an algorithm of sound. Once this is done the console becomes a computer like machine with a central processor that can effect the sound simply by changing the number values in
the algorithm of the digital signal. Unlike analog consoles, most digital consoles have internal dynamic processor and effects/EQ that can be applied to certain signals. The great thing about a digital console (having the central processor) it that once you have the mix you want the digital console can save those settings so that you can apply them latter.

There is much more to understand about analog and digital consoles, but hopefully this gives a little basic insight to some of their differing features. Please be sure to share any of your comments below.