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Compression! VCA, FET, ECT!

Compression types explained

Shadow Hills CompressorToday is the day to talk about the confusing and epic staple of music production – compressors!
At the Continuum Music Studio and the Music and Recording Arts Academy we have a variety of hardware as well as digital compressors available. We believe in options and having the “right tool for the job.” This is why we have a small Home Depot growing ūüôā
Knowing why you choose a compressor is as vital of the question how to use one. The why can be broken down into 3 points:

1. Tone

2. Character 

3. Purpose

The how can be broken down into 3 categories:

1. Feel

2. Time

3. Balance 

Now. As you can see this is not your run of the mill explanation of compression. We are taking an “intuitive and universal approach” in our explanation to start, in a moment… The gory details!
Softube 1176
Every box or plug in has a vibe and that vibe will be great on some sources and overbearing on others.

Step 1

Getting to know the vibe of your tools – so use them, daily!

Step 2

Understanding the basics of how these boxes operate to achieve the desired results.
So, let’s break down each type of compressor! Get excited here are some great quotes from reliable literature and links to great sources for further growth:


“VCA¬†stands for Voltage Controlled Amplifier. Technically most comp circuits could be described as VCAs in a sense, but in practical usage it means an IC chip that contains transistors that follow your incoming signal level (voltage) to determine how much negative gain to apply. VCAs are typically associated with fast, clean compression with precise controls over attack and release. Symetrix, dbx, Boss CS-3, Maxon CP9Pro+, and Alesis 3630 are examples of VCA comps. Most cheaper rack comps are VCA controlled. The THAT Corporation, originally a division of dbx, produces most of the VCA chips you’ll encounter.”


DBX 165


“Optical¬†comps contain a light source that gets brighter as your signal gets louder, and a light-sensitive resistor that reacts to the brightness of the light by decreasing its resistance. The resistor works in either a feedback loop or a voltage divider to change the level of your signal. In some older designs these were separate components, but in 99% of modern designs the light and the resistor are encased in one small black cylinder. Optos are generally described as very smooth, slow-releasing, and “organic”. They can be very neutral/invisible, or very squashy/”effecty”, depending on how the circuit is designed. Optical examples include Demeter, Diamond, EHX Black Finger, Retrospec, and Joemeek.¬†ELOPis just a trademark of the brand Manley, for their opto comp design.”


Avalon Compressor


“Tube¬†compressors, almost always, are really¬†optical¬†comps with a simple 12AX7 tube gain stage added on the end. However Vari-Mu (short for Variable Mu, also a Manley trademark) designs use a vacuum tube in place of a transistor, where the variable voltage input changes a tube’s bias instead of a transistor’s gain. It has a somewhat different action, generally claimed to be even smoother and more “creamy” or “organic.”


Manley Vari Mu


“FET¬†stands for Field Effect Transistor, and they are essentially a subset of VCAs, with their own particular qualities. FETs are often used as a solid-state emulation of tubes, but the main reason a comp will be advertised as FET-based is so you’ll associate it with the famous and coveted UREI 1176. So it’s mostly about the marketing, but you can expect more “color” in a FET effect than from a clean VCA. Aside from the 1176, the other examples of FET comps are mostly expensive rack units by brands like Vintech, Daking, Purple, and Chandler. The MXR M87 pedal is marketed as a FET comp, but it sounds just like any regular VCA unit.”




“Feed-forward¬†means the control circuit will receive (“hear”) your signal before the signal goes through the amplifier stage; this is the more modern approach.¬†Feed-back¬†means the controller receives the signal¬†after¬†the amplifier stage, and this is more associated with older designs. “How they sound” is a very subtle shade of distinction, you’d have to try both to have a feel for it. Most of the previously-named circuit designs can be built to feed forward or back.”


Well there you go! Plenty of intuitive info to practice on the daily and detailed technical info so you sound like you know more than you do! Lol, we do this all time time! Lol, just kidding… well kinda. Lol
Go compress the balls out of some stuff for God sakes!

Descriptors provided by:

Additional Reading:–audio-953

As Always,

Stay Passionate Music Producers and Never Stop Making Art!

Written by: Kriss Walas

A Licensed Continuum Music Studio Blog Creative Work

© Copyright 2015 Kriss Walas and Continuum Music Studio. All Rights Reserved

Kriss Walas
Kriss Walas
Kriss Walas is a constantly expanding musician, composer, music producer, mixing engineer, mastering engineer, writer, DJ, artist manager, CEO, record label owner, Reiki practitioner, meditation enthusiast, avid learner, and spiritual activist. Now, at age 31 Kriss has committed himself to living through heart and only spending his time on endeavors he is passionate about. It is for this reason he is proud to be working with the amazingly passionate and talented artists, partners, and educators who are affiliated with The Continuum Music Studio and The Music and Recording Arts Academy.