Audio Compression Part 2: Putting A Compressor To Work in Your Studio – Tuesday Voiceover Tech Tip

When we use a Compression effect on our audition, it’s important to ask whether that effect might be overwhelming the performance. Do we hear the processing rather than the performance? That’s a good indicator that we may be doing to much. With Compression, it’s easy to fall into that trap. 

In my voiceover recording classes, I talk about Compression as a “tool of high leverage”. That’s a nerdy way of saying “…when you start to lean on a long crowbar – it doesn’t take too much pressure to start breaking things.”

Last week I went over the controls found on most Compressor plugins that we’re likely to encounter. Before we start applying them, it’s worth asking our client if it’s even necessary at all. If another person will be processing your audio further in the workflow, using compression can seriously impact what they might be able to do later on. That has a way of frustrating clients. If we are delivering final work to a client project, best practice is to confirm that applying compression is OK with them.

Some clients will want to handle that themselves, while others may expect you do it. It’s also possible that your client may have no idea what you are talking about. But it’s important to have that conversation.

What do we want a compressor to do in the VO studio?

In my last post I talked about two key ideas:

• Compression is activated when your audio reaches a “Threshold” level – a triggering amount of volume. Until we hit the Threshold, nothing actually happens.
• Multiple passes through dynamics tools is generally a bad idea. Use Compression once.

Used judiciously, Compression can solve several problems for us:

• It can smooth out performances which might have a bit too much volume variance (a wide dynamic range).
• The “make up gain” can boost the loudness of our audio so it’s appropriate for the project.

• Constrain dynamics with a bit more subtlety than what we do with a Limiter.
• It can sometimes “heal” raw takes that Peak past -0 dB

One of the reasons we try to control the dynamics is to provide a better experience for the listener. If our volume is reasonably consistent, then they don’t have to keep adjusting the playback level when listening to your audiobook or podcast. The trick here is to tune that “Threshold” so that the quieter portions are not affected. If we set the Threshold too low, it will cause everything to be at a similar volume, which gets noticeable quickly and sounds quite artificial. At that point, the effect starts to speak more loudly than the words we are saying. I realize that’s a bit of a grey area. But if we’re noticing “how” something sounds rather than the content, that’s a good test that we’ve been a bit too aggressive. 

Dialing in your voiceover compressor settings

I’ll usually play with the Threshold first – that lets me dial in when the Compression starts to impact the raw audio. Depending upon the user interface of your specific effect, this can be a needle which starts to move, or a change in color of the level meter. I find that Apple’s AUDynamics Processor provides a very good interface to see this occurring. It changes from blue to red as you pass the Threshold point.

Once I’ve adjusted the Threshold, I’ll decide how aggressively I want the Compressor to compress. That’s the Ratio I talked about last week. A ratio in the 2:1 range is usually pretty transparent, which is what we’re aiming for. Going past 4:1 is often very audible. If you are using the AUDynamics Processor (shown above)it just shows a curve rather than giving a ratio, but again it’s a very intuitive interface in that a flatter curve means that less audio is getting through. That’s the equivalent of a high ratio.

After that, I’ll either use the Make Up Gain to bring everything up to the desired level, or use a separate gain adjustment (Amplify or Normalize) to tune in the delivery volume I need. 

Compressors I like for a reliable voiceover workflow

Apple AUDynamics Processor

On the MacOS side of things, there’s Apple’s native AUDynamics Processor. This comes with every Apple computer and might be the only effects which appear in your recording software. It’s actually a very useful tool with a few other tricks. But, it provides a very neutral, clean compression with a very intuitive user interface. As you play your audio through the Dynamics Processor, you’ll see how adjusting the Threshold point activates the compression. Then you can adjust the reduction curve for more or less of an effect. 

HoRNet Plugins Dynamics Control

The HoRNet Dynamics Control acts in a similar manner to Apple’s AUDynamics Processor, so those of you on Windows systems won’t miss out (there is a MacOS version as well). You have a graph-like interface to view the audio levels and can set the Threshold and curve in a similar manner. I’ve found this bundled free through some promotions in the past, but these days it seems to be available for a nominal fee.

Kotelnikov from TDR

Another amazingly useful (incredibly free!) plug-in from the folks at Tokyo Dawn Records (their NOVA EQ is on my “must-have” list). The Kotelnikov Compressor‘s user interface here is a bit more opaque – mimicking a hardware rack style compressor. But all the controls are easy to understand, and it shows how much compression is being added through a quick-reacting display. 

Waves Compressors

Waves makes a bunch of popular compressors, but most are designed to add “character” to the signal – which is not preferred for voiceover. If you stay away from the more “classic” settings, these can work well – Wave’s CL2A – Renaissance Compressor / R Vox Compressor

Melda Productions MCompressor

(big tip o’ the mouse to George Whittam who introduced this to me)
I have to say that I was not familiar with Melda Productions plug-ins until just recently. George spoke about this in a session I attended and it’s a solid choice with some good features. Nice and neutral sonically and a price that is hard to beat (that would be free). 

Good “Native” Compressors

Presonus Fat Channel

If you are a Studio One user, this factory-supplied Channel Strip contains a good simple compressor. It also appears in the Universal Control for the Revelator io24 and can be used as inbound processing for your recordings. I find myself wishing they would make this available outside of the Presonus ecosystem, as it has easy setup and a clear interface.

Adobe Audition

Adobe Audition supplies a versatile Dynamics processor which shows the audio in a graph similar to the MacOS Dynamics Processor. They also provide a “Single Band Compressor” which can be useful, though the user interface does not supply much information.

Audacity Compressor

Audacity supplies a very workable compressor with their proprietary Effects. Though they do provide a rough graphic which corresponds to the controls, it’s a bit cryptic. This native compressor also turns on the Make-up Gain by default, and boosts the Peak output to -0 dB. You can uncheck this option, which I find to be a better approach for voiceover workflows. In most cases, you want to control your delivery loudness.

Compression Resource Update: I’ve created a companion video demonstrating some of the settings in typical compressors – check it out @JustAskJimVO on YouTube.

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