All Types Of Audio Compressors

Various Compressors

Compressors are indispensable tools for Mixing and Mastering. You've probably heard that audio engineers in professional studios have a favorite compressor. Although their basic function is to compress the audio signal and make it louder, they can actually do more than that. They can change the envelope of the audio or add different harmonics and add a new character.

Some compressors can be really fast and tough, while others can be incredibly smooth. While some of them have parameters that you can control everything on, some of them may only have 2 potentiometers.

Welcome to our article where we explain the different uses depending on the music style and compare them to better see the differences between them!

• To learn the working principles of the compressor, check out the ''What Is An Audio Compressor?'' article.

1. FET Compressors

UNIVERSAL AUDIO 1176

Field Effect Transistor (FET) compressors use transistors for compression and are famous for very fast attack and release times. This is what gives them their characteristic feature. These compressors tend to have rich and lush distortion.

They are fast, clean, and reliable; They can be used on almost any element in mixing and mastering projects. Generally, FET compressors do not have a threshold knob. In these cases, the audio signal is compressed according to the input level; The higher the input, the greater the compression.

2. VCA Compressors

API 2500

Voltage-controlled amplifier (VCA) compressors have multiple parameters (threshold, ratio, knee, attack, release, etc.) and fast response time, making them a good choice for compressing audio such as rhythmic instruments and percussion, as well as fast transients and peaks. VCA compressors use a control signal to determine whether the gain reduction is applied to the signal.

If you do not apply high compression in VCA compressors, it does not add too many harmonics or distortion in the audio and generally produces the tone and timbre as if it were the original.

3. OPTO Compressors

TELETRONIX LA-2A

Opto compressors or optical compressors use a light source to know how much compression to do and a resistor connected to that source. The stronger the input signal, the brighter the light source glows, and the greater the gain reduction.

Although light is really fast, the turn-on and turn-off time of the lamp inside Optical compressors is not as fast as the light itself, so the reaction of Optical compressors is slower than Fet or VCA compressors. Since their attack and release times are slow, this type of compressor can generally be preferred as bus compressors.

4. VARIABLE MU Compressors

FAIRCHILD 660

Variable Mu, Vari-Mu, or Tube compressors. These compressors are the oldest type of compressors and they use tubes for gain reduction. The level of the input signal determines the amount of compression applied.

Additionally, these tubes are famous for adding warmth, color, and harmonics to the sound. It is indispensable for those looking for vintage tones. In general, it has slow attack and release times.

• Opto Compressors do not use tubes for gain reduction, they use a resistor to detect the tube light.

5. PWM Compressors

CRANE SONG STC-8

PWM or Pulse Width Modulation compressors use high-frequency pulse signals with "on" and "off" values to apply gain reduction. It divides and mutes the signal into certain parts, and reduces the average amplitude of the signal according to the width of the "on" and "off" values.

PWM compressors provide extremely transparent compression. It has really fast attack and release times. That's why it is widely used by Mastering engineers.

6. DIODE BRIDGE Compressors

RUPERT NEVE DESIGN 5254

Diode bridge compressors, as the name suggests, apply gain reduction using a diode bridge or ring. It generally requires a low-level signal and that's why there is an attenuation stage before gain reduction is applied. This may cause noise in the output signal. Well Matching diodes are very important to keep distortion to a minimum. Unmatched diodes may introduce undesirable compression characteristics when compression is applied.

• Non-linear compression gives the compressor its character via harmonic distortion.