Serial and parallel compression represent two techniques you can use to maintain transparent, clean-sounding compression, enrich the color of your audio, or mix in aggressive compression with your uncompressed audio signal.
These two methods of compression use serial and parallel processing to add a unique form of energy or clarity that differs from regular processing—one compressor on one channel. We’ll go over when you should use serial and parallel compression, and how to set them up.
Compression Basics
The main function of compression is to quieten the loudest parts of an audio signal (downwards compression), and boost the softest parts (upwards compression). Compression doesn’t make an audio signal louder, it makes it quieter via gain reduction.
When the decibel (dB) level goes above the threshold value, compression begins. You can precisely control how your audio is compressed by learninghow to use all the parameters in compression plugins.
The distinct strengths and colors ofthe different types of compressorsare of particular relevance to serial and parallel compression. Choosing the right compressors for the job will unlock further tonal qualities and effects in your audio.
What Is Serial Compression, and How Do You Set It Up?
Serial compression is named as such for its use of serial processing. Serial processing can be defined as the use of two or more of the same type of effect in a series on one channel (e.g. two EQ plugins). Therefore, serial compression is as simple as using two or more compressors on one of your tracks, busses, or channels.
Generally, you will want to place your faster-acting compressor (in terms of attack and release times) first. Then, place the second, more subtle compressor somewhere below it in the effect chain.
When You Should Use Serial Compression
One of the main benefits of serial compression is that it can save one of your compressors from doing all the heavy lifting regarding gain reduction.
Say you’re aiming to apply -14 dB of gain reduction to an audio signal. If only one of your compressors is made to manage that hefty task, you can easily end up with an overly compressed sound with unwanted distortion and sonic artifacts. Introduce serial compression, and now you have two compressors that apply -7 dB of gain reduction. This will help maintain the natural sound of the original audio.
In addition to sharing the weight of gain reduction, serial compression can let you make the most of the unique strengths and tones of different compressor types. A frequently used serial compression combination is the use of a field effect transistor (FET) compressor followed by an optical compressor.
For example, an 1176 (FET) compressor or emulation is great for taming peaks and transients with its rapid attack time while also imparting a desirable color. Then, add in an optical compressor, like the LA-2A compressor or its emulations, with slower attack and release times for gentle and musical compression. In so doing, you get the best of both worlds regarding different styles of compression.
Just as compressors can add desirable character to your audio, distortion effects can do the same. Look intothe different types of audio distortionto see how else you can impart distinct colors to your audio.
What Is Parallel Compression, and How Do You Set It Up?
Parallel compression is named as such as it utilizes parallel processing. This form of processing refers to the procedure of processing an effect signal in parallel to the dry signal. In other words, both the wet and dry signals are processed and mixed together.
To set this up, you may either send the original audio to an available aux track with a compressor, or duplicate the original track (with a compressor on the duplicate). Typically, aggressive compression is the aim for the aux track or duplicate track compressor. Then, the aux or duplicate track is blended in with the original audio signal.
Another method is to use the mix dial found in most modern compressor plugins. This dial also lets you control the strength of the compressed signal in relation to the dry signal.
When You Should Use Parallel Compression
Parallel compression is a great way to add punch and excitement to your audio without losing its natural sound. Aggressive compression settings on your parallel compressor is the best way to reap the full benefits of this compression technique.
Bear in mind that the right compression parameters will depend on your audio and the effect you’re after. Get the balance right, and you can combine the sonic qualities of a heavily compressed signal with the natural tone of your original uncompressed audio.
The best kind of compressors to use for parallel compression are those that specialize in delivering high levels of gain reduction while maintaining a degree of clarity and desirable sonic coloration. This goes hand in hand with a rapid attack time. Once again, the Universal Audio 1176 (FET) compressor and its emulations are a great choice for parallel compression.
you may also use this technique to improve the definition of your audio. This is due to parallel compression applying upwards compression (boosts the softest parts of your audio). In fact, it does so almost unnoticeably as the human ear is drawn to differences in the loudest portions of audio rather than the quietest parts; and the loudest parts of the uncompressed signal remain untouched.
You may want to increase or decrease the strength and intensity of your parallel (or serial) compression for different parts of your mix. It can be useful to knowhow to use automation in your DAWto automate such changes easily.
Reap the Benefits of Serial and Parallel Compression
Once you’ve gotten to grips with the basics of compression, try and improve your audio by using compressors in series. Experiment with the tried and tested method of a fast-acting FET compressor first; then, use a slower, more musical optical compressor to enrich your audio.
Alternatively, place a compressor on a duplicate track or aux track, and blend it with the original audio for parallel compression. Apply aggressive compression, and you can add vitality and clarity to your creative works.
