Audio System Components Explained

Posted on Apr 19, 2025 in Electronics

Sound Basics

Sound: the sensation produced in the ear by sound waves. The human ear distinguishes 3 qualities: loudness, pitch, and timbre.

Audio Sources

Audio sources generate sound signals. These include analog tuners (AM, FM) and digital tuners (DAB).

Source Features

  • Distortion: Harmonic distortion (THD) is the most important. It is measured in percentage (%). The lower the value, the better the sound quality.
  • Signal-to-Noise Ratio: Measured in dB. The higher this value, the less noise is introduced into the signal, and the better the source.
  • Power: Most sound sources have an integrated amplifier that can reach 15-20W RMS.
  • Pre-outputs (RCA): These are signal outputs for high audio quality. The output level is expressed in Volts. This is the most important value; a signal of 4V in the manufacturer’s specifications is a good pre-output, but you may find up to 9V.

Speakers and Types

Speakers transform electrical signals into acoustic signals.

Speaker Parts

  • Ventilation
  • Magnet
  • Chassis
  • Suspension
  • Membrane
  • Central dome
  • Coil
  • Spider

Speaker Types

  • Full-Range Speakers

    Cone and double cone: reproduce all audio ranges.

  • Elliptic Speakers

    Have the behavior of two different diameters.

  • Coaxial Speakers

    Multiple speakers in one unit, available in 2, 3, and 4 ways.

  • Component Speakers

    • Tweeter: Reproduces treble frequencies up to 20,000Hz.
    • Woofer: Reproduces mid and low frequencies (300Hz – 3000Hz).
    • Subwoofer: Reproduces low frequencies between 18Hz and 1500Hz.

Speaker Parameters

  • Nominal Impedance: Often works with 4Ω.
  • Sensitivity: A way to measure performance when the speaker converts electrical power into acoustic output.
  • Frequency Response: Information provided by the manufacturer that lets us know the frequency range the speaker can reproduce.
  • Power Rating (RMS): The power the speaker can handle for a long period of time without being damaged.
  • Maximum Power: The power it can withstand for a short period of time.

Audio Amplifiers

Amplifiers provide greater power and sound quality. They connect to the low-level or RCA outputs of the source to amplify the signal.

Amplifier Qualities

  • Regulated Power Supply: A stabilizing element to prevent internal components from being damaged.
  • Output Power: The power it is capable of delivering according to the connected speaker impedance.
  • Stability: Refers to the load the amplifier is capable of supporting.
  • Damping Factor: The capacity of the amplifier to respond quickly to the signal it receives.
  • Signal-to-Noise Ratio and Distortion.
  • Gain.

Amplifier Types

  • Single channel or monophonic.
  • Stereo (Two-channel).
  • 4 channel.

Audio Filters

Their function is to prevent frequencies outside a desired range from reaching the speaker.

Filter Features

  • Band Pass: Refers to the frequencies that will reach the speaker without attenuation.
  • Band Attenuated: Frequencies reach the speaker with minimal attenuation.
  • Cut-off Frequency: The frequency where there is a fall of about 3dB.
  • Filter Slope: The ability of the filter to achieve faster attenuation or gain as a function of frequency.

Types of Audio Filters

  • Passive Filters

    Composed essentially of coils and capacitors. Installed between the amplifier and speakers. Do not need external power.

  • Active Filters

    Composed of electronic elements. Installed between the sound source and the amplifier. They are separately energized and often require dedicated amplifier channels for each frequency range they divide.

Specific Filter Types

  • Low-Pass Filter: Passes low frequencies to the amplifier or loudspeaker.
  • High-Pass Filter: Passes high frequencies to the amplifier or speaker.
  • Band-Pass Filter: Passes frequencies between two values to the speaker or amplifier.

Audio Equalizers

An equalizer is a device whose purpose is to attenuate or accentuate different frequencies or bands, adapting the sound to the listener’s ear.

Audio System Connections

  • Power Cable

    Feeds the power amplifier. It must support high current flow, so its gauge must be considerable. It should be a good insulator, soft, flexible, and withstand temperature variations.

  • Low-Level Audio Cables

    Carry the signal from audio sources to power amplifiers, designed to avoid interference and noise.

  • High-Level Speaker Wiring

    Carries the amplified signal from the amplifier to the speakers.