Tips for Choosing Speakers and an Amplifier

Professional audio engineers have to be able to trust the sound coming from their speakers. When you mix your audio, you need audio monitors that can handle the full range of audio intensities and frequencies. Ideally, your monitors will have a flat frequency response from 20 Hz to 20,000 Hz (or 20 kHz). This means that they neither attenuate nor amplify any frequencies. Flat frequency response is important for critical listening because the speakers themselves are not “coloring” the sound.

In addition to the speaker quality itself, additional factors affect your audio monitoring environment:

Frequency Response and Dynamic Range

Speaker quality varies greatly depending on their purpose as well as their price. For example, speakers in a portable stereo or television are designed to play audio that has already been mastered by a mixing engineer. Mastered audio such as audio CD, radio, television, and movie sound has a compressed dynamic range (meaning levels are fairly consistent and loud).

Speakers and amplifiers that are designed for mastered audio often intentionally emphasize certain frequencies, as is done with the bass enhancement feature found on many systems. This may make an audio CD sound better, but it is not recommended for mixing production sound because you get a false impression of the audio signal. For example, if your speakers overemphasize frequencies around 2 kHz, you may compensate during mixing by reducing the intensity of audio around 2 kHz. If you then play your mix on a different set of speakers with a flat frequency response, the frequencies around 2 kHz will sound too muffled.

Figure. Illustrations showing flat and not flat frequency response.

Self-Powered Versus Passive Speakers

Speakers powered by an external amplifier are called passive speakers. When you use separate amplifiers and passive speakers, a number of factors affect the overall frequency response and quality of your audio. Instead of using a separate amplifier and speakers, a simpler option is to use self-powered speakers (speakers with built-in amplifiers). These have become increasingly popular, especially for studio monitoring and video editing.

Self-powered speakers deliver more consistent performance because both components are designed to work together and are housed in a single enclosure. For video editing systems, self-powered speakers are a good, easy-to-use solution. Self-powered speakers accept line level inputs, so it’s fairly easy to connect them to your audio interface.

Amplifiers and Signal Levels for Unpowered Speakers

Unpowered speakers require signals with higher voltage than consumer and professional equipment can provide directly. These levels are known as speaker level audio signals, while audio devices such as tape recorders and audio mixers usually provide line level signals. An audio amplifier boosts line level signals to speaker levels to properly drive speakers. Wide-gauge speaker cables that can handle the higher electrical strength of speaker levels are used to connect the amplifier to speakers.