NoLias 1.0

Update:
NoLias have been updated to v1.0. You don’t have to do anything if you already are using the release candidate, nothing has changed except it has left the testing phase and is working as expected on all systems.
If you don’t use it; You should…
NoLias is now distributed with a convenient setup file on both Mac and Windows. Hope you like it!

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I created NoLias to quickly determine if there are any aliasing artifacts created by plugins in a mastering- (or mix-) chain. It doesn’t measure anything, it’s nothing fancy, but sometimes the no-frills solution does the job better than any other approach.

NoLias runs a customized sine sweep, if there’s aliasing created, you’ll hear frequencies above Nyquist in the sweep fold back into the audible spectrum (see the video for an example).

The plugin consists of an on/off switch, level control for the sine sweep, and a simple spectrum analyzer. The analyzer doesn’t have a function, I used it while forming the sine sweep and let it stay out of esthetical reasons. In “off” mode, NoLias passes the signal from the input to the output untouched. When turned on, it starts to play the sweep.

How to use:

1. Put it as the first plugin in your effect chain.
2. Turn on the sweep.
3. If you hear a clean sine sweep you can stop here. If you hear aliasing as the sweep gets closer to 20kHz, continue to step 4.
4. Start bypassing plugins. If it goes away when you bypass a plugin, you’ve found the culprit.

There are a few ways to get rid of aliasing.

1. Check if the plugin has built-in oversampling and turn that on.
2. Upsample the project (start by doubling the sample rate).
3. Skip the plugin or use a similar plugin

Right after posting the NoLias plugin, I got questions about why aliasing distortion is worse than other kinds of distortion. To answer that I tried to create a null test to isolate aliasing distortion, but that turned out to be far more complicated than expected so I had to let that idea go. Instead, I can recommend the video linked below which will show you why and how aliasing distortion appears (you probably get it halfway through, you don’t need to watch the part with the animal sounds)

https://youtu.be/thw32YvLrYo

So, now that you understand what aliasing in digital audio is, you can start to imagine why alias distortion is worse than any other distortion. Most other kinds of distortion, digital or analog, are harmonic in one way or another. Aliasing distortion is not, it will add “out of tune” distortion to your audio. It makes the audio sound foggy and mushy. That said, my synth Burt uses aliasing to create new and interesting sounds. It’s not always bad, it can be fun too, but not while mastering!

Download for Patreons:

https://www.patreon.com/posts/74683988