If you’re an iZotope blog regular, you’ve probably read a lot of mastering tips and tricks for EQs, compressors, limiters, imagers, and every other processor around. But what about choosing an order for these things? While signal chain composition isn’t discussed much, it’s an integral step in mastering.
What is a mastering signal chain?
A mastering signal chain is a series of processing effects applied to a signal in a linear order. Each signal process alters the signal for the next process in the chain, and so on. If you don’t think through the signal chain, you’ll likely need to add extra processing to compensate and “fight” against the chain’s upstream processing. Why fight it when all you might need to do is change the order a little?
How do you choose a mastering signal chain?
The most common thing to do when you start working on a song is to set up and tweak EQ’s, compressors, and limiters until you’re happy with the result. But, a signal chain is context dependent. The processing you choose to use, and the order of your chain, should reflect the material you’re working with. We can easily fall into a routine where we wind up using the same things in the same order all the time, so it’s important to think about the type of signal we are feeding into the device or module. It also helps change your perspective on how to approach mastering a song.
The first step to create a well-defined signal chain is to listen to the track and make notes on what you’re hearing. Here are three questions to ask yourself:
What do you want to change?
What are the artists/producers notes?
Out of all the tools you have, what would be the best choice to achieve what you want?
Follow these steps and you’ll have a solid plan of action, and more importantly, a well-ordered mastering signal chain. Let’s dive into a few common mastering signal chain questions.
Do I EQ or compress first when mastering?
The answer depends on what you are trying to achieve. If the track has frequencies standing out that need to be cleaned, it’s better to EQ the signal first, before compression. Using corrective EQ here will feed a more balanced signal into the compressor, helping to avoid any potential unwanted pumping.
Compressing before corrective EQ can create unwanted pumping, and a master with fuzzy lows and mids. Trying to fix this by adding extra processing will not always work, so switch up your compressor and EQ placement to help mitigate this effect. This thought process can also be applied when using mid/side EQ and compression.
Should I use stereo imaging in a mastering signal chain?
Stereo imaging can be used to address potential problems, or to add that extra “3D” sound if the mix needs it. However, use stereo imaging with caution! You can easily create phase problems and unwanted balance changes. A common mistake is to widen the image too much, which causes the image to lack center, and lose punch.
Applying the same thought process as corrective EQ, addressing problems with the stereo image before doing anything else will help achieve the sound you are looking for faster. If you're using stereo imaging just to add some extra shine, it is probably a good idea to add it towards the end of the chain, with a sound that is more to your liking. Here is an example of how I used stereo imaging in a recent session.
Mastering signal chain example, from start to finish
The song I was given to master had quite a bit of low end, too little top end, and a few transients popping out. After listening to the track several times, I realized the signal below 100 Hz was pretty wide, resulting in a lack of punch. To fix this, I added Ozone’s Stereo Imager, and closed the stereo field below 100 Hz. This helped the low end feel focused and punchier.
When I had the stereo image where I wanted it, I added an EQ and notched out the frequencies that were overbearing.
The next processor was my compressor, just to take care of some of the transients. Since I dealt with the low end before hitting the compressor, I had a little more room to play around in, without the risk of pumping.
As a result of cleaning up the low end, the top end opened up on its own. However, I still thought it needed a little more top end, so I added a second EQ to do that.
My last processor was a limiter, with a setting of no more than 2 dB gain reduction just to bring the level up a little and make sure nothing peaked. Since I was happy with how the track was sounding, a transparent limiter was all I needed.
Once you have your chain, make sure to go back and tweak the parameters needed to attain the sound you are looking for. The result here is a well balanced mix with punch and clarity. Each processor did very little, but the specific combination and order helped achieve the sound I was looking for in a simple and efficient way.
Beyond basic processing tips and tricks
In mastering, a de-esser like the one found in RX is used to fix specific issues rather than achieve an aesthetic. It can be used to address sibilance, as well as percussion that needs taming. Because of this, it is often used early in the chain before compression to avoid unnecessary triggering of the compressor. Make sure you are not modifying instruments you don’t intend to!
Reverb is rarely used in mastering, but when used in the right context, it can open the stereo field in subtle and beautifully ways. The most common use is a general enhancement of the sound. Reverb is often placed at the end of the chain before your brick wall limiter. It’s should be very subtle, 5% goes a long way!
Tape emulation can be placed at any point in the chain, especially with how easy to modify the parameters can be. A good place to start is placing it at the end to simulate printing back to tape.
Take advantage of the endless EQs available, with many tones. A good trick is to use a clean EQ for surgical corrective work, and then add an EQ with more character to achieve that warmth or sparkle you are looking for.
Experiment and become a breaker of chains
Like I said earlier, no two signal chains are completely alike. It’s entirely dependent on the sound you want. Don’t limit yourself just to EQ’s and compressors, try tape emulators, exciters, multiple EQ’s and even reverb! Because of the variable nature of the material we work with, mastering software like Ozone is designed for you to build and break a signal chain, switch up the order, and experiment!
Here are two exercises to help you experiment with mastering signal chains:
Once you are close to a sound you like, switch the modules around again. What changes? Why? Do you like it more? If you do, why do you think that is?
Add a processor that you did not think would work and place it at different stages. Was your original assumption correct?
Exercises like these help teach you the sonic characteristics of each processing module.
Mastering all about subtle moves to achieve a specific sound. By now, you have realized how impactful the order of processors is to your results. There is no right or wrong answer as to what should go where. It is possible to achieve a similar result by approaching your chain from different angles, but it’s about what works for you and the tools you have. By thinking things through and experimenting with your chain, you can achieve better tonal balance with less processing and in less time.