Amplifying your sound - Amplifiers and Mixers

In the first post of this series, we talked about health and safety. Now that we know the necessary precautions we have to take, we can talk about the main devices we are dealing with: amplifiers and mixers.

1. What is an amplifier?

Amplifiers are not unique to music. In fact, they can be found in most, if not all, electronic equipment. Their basic function is to increase the magnitude of a signal, which is itself defined as a current that varies through time. Microphones, electric instruments and digital devices feed signals to audio amplifiers and mixers, which then amplify them to make them come out of speakers with the volume and characteristics that we want. 

The main difference between an amplifier and a mixer is the number of signals that each of them can handle. The amplifier is designed for only one, while the mixer can process multiple signals at the same time. Due to this, amplifiers tend to have a built-in speaker, while mixers don't.

2. Basic elements of an amplifier.

• Gain: The ability that your amplifier has to increase the amplitude of a signal by adding energy from its power supply to it.

• Volume/Fader: It determines the gradual increase or decrease in the level of an audio signal. It allows you to control how loud a track/instrument sounds.

• EQ: It is the balance between the volumes of different frequency bands within an audio signal. These frequencies are bass, middle, and treble (high).

In addition, you will find in both devices a power supply, which they need to amplify the signal, the same input plugs, including XLR and TS/TRS connectors, and LED indicators to show whether the signal strength is at a safe level (green), slightly high (amber) or high enough to potentially cause damage (red).

Amplifiers and mixers come in different colours and weights. The type and location of their sliders and knobs also varies. Amplifiers can usually be set on poles, while mixers don't.

3. Which one to choose?

When deciding what to get for your PA system, consider:

• The amount of signals you need to amplify. Count instruments, microphones if you sing or want to address the audience between songs, and backing tracks.
• Your type of instrument. For example, a keyboard is usually better amplified by a mixer, because it can handle the low and high frequencies more precisely.
• Your music genre. Some of them favour tonal coloration and distortion, while others don't.
• The size and acoustics of the venues you are most likely to play at.
• The means you have to transport the amplifying device, along with your instrument and other devices (microphones, speakers, etc.), to venues.

If you have doubts or questions, it is worth to check whether music stores in your area offer demos.

Bear in mind that a PA system can have both mixers and amplifiers. As an example, the Millicent Stephenson Trio has the singer's microphone, the saxophone and the keyboard connected to a mixer, whilst the bass is connected to a separate amplifier. There are two reasons for having it this way. The first is that the low frequencies of the bass can overpower the mixer's system and drown other signals. The second, that amplifiers designed for electric guitars and basses don't usually seek to reproduce the signal as accurately as possible, but rather, they add tonal coloration and distortion to the sound. Due to this, and given the limitations of the context, the bass will have more character and freedom if it is not added to the mixer. 

 
We hope that this article clarified some of your doubts about amplifiers and mixers. Please, share it with anyone who could also benefit from this information.