The best audio filters for OBS

Audio filters are designed to enhance audio inputs in OBS. When you are working with audio filters it’s important to remember that audio device filters can be used in a chain. This is because the order in which you use each filter will affect the sound that you get in the end.

Here is a list of default OBS audio filters

• Audio Device Filters
  • Compressor – The compressor can be used to make any audio source sound more full. Compressors allow you to limit audio peaking beyond 0dB by making loud noises quieter when they peak. The main compressor adjustment is called Ratio and the higher the ratio the more compression will be used to reduce the loudness of audio when peaking. The Compressor includes a Threshold setting you can use to set the audio level at which the compressor should start working. The Attack and Release settings allow you to adjust how quickly the compressor effect will ramp in and out when the Threshold is reached. An Output Gain can be used to increase the overall volume after the compression effect.
    • Sidechain Compression (aka Ducking) – Sidechain compression can be used to automatically adjust the volume of an audio source to make room in the audio mix for another audio source such as a microphone input. For example, you can apply a sidechain compressor to a background music track to automatically reduce volume when you are speaking through a microphone.
  • Expander – An expander can be used to remove unwanted background noise by setting a low-level threshold for audio that you want to be removed. The expander works similar to a compressor but on low-level noise. Therefore, the expander has similar features such as a Threshold, Attack, and Release.
  • Gain – Gain can be used to increase the volume of a source. If possible, the gain should be adjusted before it is captured into OBS to avoid unwanted noise.
  • Invert Polarity – Only used to help with phase cancellation issues which is an audio phenomenon that reduces the audio’s overall strength.
  • Limiter – Limiters are a specialized type of compressor that is designed to be used at the end of an audio processing chain. Limiters are used to limit audio from peaking above 0dB.
  • Noise Gate – The noise gate is a simplified version of the expander. You can set a level of noise on your audio input that you want to be automatically muted.
  • Noise Suppression – This filter is effective at removing low-level noise from computer fans and other electronic devices. When the filter is set to 0 it is off. You can adjust the noise suppression to remove background noise but keep in mind that the filter will affect the overall sound of the source as well.
  • VST Plugins – Support for VST 1 and 2 plugins is available in the core installation of OBS.

Most audio experts will recommend that you start with the following audio chain order. 

1. Noise suppression
2. Gate
3. EQ
4. Compression

Audio Gain Structure

Before you start enhancing your audio with any chain of audio filters, you should always start by optimizing the gain of the audio system first.  This can be done with any hardware audio mixer or directly in the operating system by using the Windows, Mac or Linux audio settings. 

When you are adjusting the incoming audio gain, speak loudly and watch the audiometer. You want to adjust the gain so that the loudest audio is a few levels below the max level. This will ensure that the audio coming into OBS is clean and undistorted.

Using a Noise Suppressor

When you are adding audio filters, it’s highly recommended to use headphones so that you can clearly hear the adjustments you are making. Start with a Noise Suppression or Expander to remove any unwanted noise from the background of your audio. You do not want to use too much noise suppression or you will distort the audio. Use just enough to remove any background hum or noise that may be coming into OBS. OBS offers two default noise suppression options which are Speex (low CPU usage, low quality) and RNNoise *good quality, more CPU usage). 

Next, you can add an Audio Gate to automatically mute the microphone when you are not speaking. A well-configured audio gate is designed to naturally mute background audio in between breaths and sentences as you speak. A poorly designed audio gate may overreact to make your voice sound unnatural and choppy. The most important level to adjust is the Gate level. This is the level at which audio will be muted when you are not speaking. Here you are looking for a noticeable audio level that captures the sound of breathing but not so high that it would capture actual speech. It’s recommended to use one of the free VST2 plugins for OBS from Reaper.fm for optimum performance. The ReaGate plugin can be installed on any Windows computer and added to OBS using the VST 2 plugin filter option.

Using a Noise Gate

There are a few tricks you can apply to a Noise Gate to make it sound more natural. If you have a deep voice you can use a High Pass Filter around 80 Hz to make the audio gate sound more natural. If you are using the default OBS Noise Gate there is no option for using a high pass filter. If you find the noise gate makes your voice sound unnatural you will want to adjust the Attack and Release settings to tune how quickly the filter affects your voice. It’s a good idea to record a few tests as you adjust the noise gate. Try listening with your headphones and focus on the beginning and end of words to make sure the gate is not turning on or off too quickly. 

Using an EQ

Next, you can work on an EQ. An EQ can make a voice or other audio source easier to hear and understandable for listeners. Unfortunately, there is no default EQ for OBS and you will need to use a VST 2 plugin to gain this functionality. Using an EQ takes some getting used to but you can apply some best practices to get started. If you are creating an EQ for the human voice, you can use basic high-pass and low-pass filters to remove unwanted noise and enhance the vocals. Male voices and female voices differ in the frequencies they generally exhibit. Male voices range from 80 to 500 Hz. Female voices range from 175 to 1180 Hz. Most EQ interfaces will show a graphical display that starts at 20 Hz and goes up to 20 kHz. Since the human voice generally starts at 80 Hz, there is no reason to include audio from frequencies below this area. Between 80 and 120 Hz is the lower bass sound of the voice and it is very important for intelligibility. In between 200 and 300 Hz is the boom of a voice which gives it its fullness. Between 300 – 1000 Hz you will hear the reflections of the room. Finally, between two and three kHz you can usually add clarity to your voice. Regular telephone calls generally max out at 3 kHz. Between five and 15 kHz is what is called sibilance which provides minimal nuances in the human voice. Anything above 15 kHz is not needed for most audio capture systems. In fact, you can trim out some unwanted high-pitched sounds by removing these higher frequency EQ bands.

Using a Compressor

The final stage for most audio chains is the Compressor. OBS does offer a built-in compressor you can use with any audio source. The compressor will help “level out” your audio throughout an entire period of time when you may speak louder or softer at various times. The main compressor adjustment you want to start with is the Ratio. The Ratio adjusts the entire compression that is added to your audio. Adjusting the Ratio is easy to listen for, because the effect makes your voice sound more and more like a radio host. Once you have the ratio you like, you will need to set the Threshold. The Threshold is the level at which your compression ratio will start to kick in. To set the Threshold speak loudly and determine where you would like the compressor to limit your audio from peaking at the top end of your loudest moments. 

The default OBS Compressor offers a very interesting feature called Sidechain/Ducking. Once you have configured a professional audio chain, you may want to apply the Sidechain/Ducking feature to other audio sources you have in your audio mix. Sidechain/Ducking will take the audio levels from your microphone and automatically lower the audio from other sources when it is active. This is a great way to automatically mix together your audio sources when you want the audience to be able to better hear your voice over other audio sources playing the background. 

Sidechain Ducking in OBS

You can apply a Sidechain to any audio source with the Compressor filter. The Sidechain/Ducking dropdown menu is the last option in the default OBS Compressor filter. This is where you can select the audio source you would like OBS to use to effectively reduce the audio. When you create this filter, name it specifically for “Sidechain/Ducking” so that you can remember the purpose of this filter is different from a normal compressor because it takes its direction from the selected Sidechain audio source. When you create this filter, you will be able to adjust how much the audio “Ducks” when your selected microphone is active. Therefore, you can set the Threshold, Attack, and Release just like a regular compressor. 

Key Takeaways:

1. Audio is always one of the most important portions of video production.
2. OBS offers default audio filters that can be used to enhance your audio production
3. OBS also supports VST plugins which provide additional enhanced audio adjustment capabilities with higher quality graphical interfaces.

Additional chapters from the OBS Superuser Guidebook

• Chapter 1 - An Update on the Updates here
• Chapter 2 - How to Customize OBS here
• Chapter 3 - How to Optimize OBS here
• Chapter 4 - How to use the core features of OBS here
• Chapter 5 - How to use video filters in OBS here
• Chapter 6 - How to use audio filters in OBS here
• Chapter 7 - The Top 10 OBS Plugins here
• Chapter 8 - The Multiple RTMP Streaming Plugin here
• Chapter 9 - The Automatic Scene Switching Plugin here
• Chapter 10 - How to record multiple sources in OBS here
• Chapter 11 - How to dock sources with live video in OBS here
• Chapter 13 - How to use NDI in OBS here
• Chapter 14 - How to route Audio in and out of OBS here
• Chapter 15 - How to use Virtual Audio cables with OBS here
• Chapter 16 - How to use VST Audio Plugins for OBS here
• Bonus Chapter - How to fix audio sync issues in OBS here
• Chapter 16 - How to use use hotkeys with filters here

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• Learn how to install the NDI plugin for OBS (and why you should) here
• Learn more about the latest OBS user interface (UPDATED for 2019) here
• Make your audio in OBS sound great with these VST 2 plugins here
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• Learn how to add a webcam and set up a picture in picture scene inside OBS here
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