Know the types of compressors and how they work.

Know the types of compressors and how they work.

Did you know that there are different types of audio compressor? Get to know each one of them and learn how they work


These use an optical isolator circuit formed by a lamp or LED and a photocell. The light source shines more or less depending on the input level. The photoelectric cell reads the varying brightness of the light source and changes gain accordingly. Optical compressor response time is slower than other types, with a smooth attack that can be almost unnoticeable. A good example of this type of compressor is the “Shadow Hills Mastering Compressor“.

Know the types of compressors and how they work


Probably the most common type of compressor is the VCA (Voltage Controlled Amplifier). These are super versatile. A VCA compressor uses an integrated circuit (IC) to give precise control over gain reduction. These generally don’t “color” the sound much, and have very little distortion making them one of the most popular types of compressors on the market. Example: Vertigo VSC-2 Quad Discrete.

Know the types of compressors and how they work


These use transistors to vary the gain. FET compressors use transistors to more reliably emulate tubes. They tend to have a unique, fast, clean sound. There aren’t really that many of them, due to the extra circuit required. Example: Universal Audio 1176.

Know the types of compressors and how they work


Most tube compressors are based on one of the circuits above, with one or two tubes in the signal path, for a warmer sound, or colorful as we call it. Example: Manley – STEREO VARIABLE MU

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A multiband compressor is exactly what it sounds like, a compressor that works differently in different frequency ranges. This allows more or less compression to be done on the low frequencies than on the highs or vice versa. The advantage is that the Atack, Release and Ratio for example can be adjusted completely differently, reducing or increasing the amount of compression in each frequency range. They work by splitting the input across multiple filters. Each signal is then passed through its own compressor then recombined (mixed) at the end. In this case, we have at least 2 compressors working at the same time. These, mostly found in DAWs in the form of plug-ins, are uncommon in Hardware, the famous analog world. Example: TUBE-TECH SMC 2B

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Q: What are the types of audio compressors?
A: There are several types of audio compressors, each with unique characteristics:

  1. Optical Compressors:
  • Optical compressors utilize a light source (such as a lamp or LED) and a photoelectric cell (or photocell). The input level determines how much the light source shines, which in turn controls gain reduction. These compressors have a smooth attack and are known for their subtle, transparent compression. Example: Shadow Hills Mastering Compressor.
  1. VCA Compressors:
  • Voltage Controlled Amplifier (VCA) compressors are among the most common. They use integrated circuits (ICs) to precisely control gain reduction. VCAs are versatile and generally transparent, making them popular for a wide range of applications. Example: Vertigo VSC-2 Quad Discrete.
  1. FET Compressors:
  • Field Effect Transistor (FET) compressors use transistors to vary gain. They are known for their fast response and can emulate the warmth of tube compressors while maintaining a clean sound. Example: Universal Audio 1176.
  1. Valve (Tube) Compressors:
  • Tube compressors incorporate vacuum tubes in the signal path, adding warmth and color to the audio. They are favored for their rich harmonic distortion and musical characteristics. Example: Manley Stereo Variable Mu.
  1. Multi-Band Compressors:
  • Multi-Band compressors divide the audio signal into multiple frequency bands, allowing independent compression of each band. This enables different compression settings for lows, mids, and highs, enhancing control over dynamic range across the spectrum. Example: TUBE-TECH SMC 2B.

Q: How do these types of compressors work?
A: Each type of compressor operates differently based on its circuitry and components:

  • Optical compressors use light and photoelectric cells.
  • VCA compressors utilize integrated circuits for precise gain control.
  • FET compressors rely on transistors for gain variation.
  • Valve compressors employ vacuum tubes for warmth and color.
  • Multi-Band compressors split the signal into frequency bands for independent compression.

Q: Where are these compressors commonly found?
A: Optical, VCA, and FET compressors are commonly used in both hardware and software forms, while valve compressors are primarily found in analog hardware. Multi-Band compressors are predominantly available as software plugins in digital audio workstations (DAWs).

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