Setting up a low pass filter in OBS Studio

OBS Studio has built-in support for audio filters so you really just need to download some audio plugins and configure them in OBS. There's a (much more complex) version of this for OBS Classic at https://pastebin.com/rxks9Bvs



1) download Reaper VST plugins

Download the appropriate version's installer from https://www.reaper.fm/reaplugs/ and run it.

2) set up the filter in OBS

Open OBS. Click the gear icon next to your mic in Audio Mixer -> Filters -> Add -> VST 2.x Plug-in. Select reafir-standalone from the list. If you don't see any options in the dropdown menu, it might be an issue with 32- and 64-bit versions of different things, I don't know how that breaks down exactly but maybe try the different OBS Studio version? If you did find the reaeq-standalone option, click Open Plug-in Interface. Put some audio on in the source and you should see the signal in the editor in yellow. To check that the filter works, select Mode: Gate and try dragging the Gate floor slider, which should make the signal stronger or weaker, leaving the original as a shadow.

3) configure the low pass filter

Configure the parameters like this: https://www.dropbox.com/s/xuufub8l06fklzs/reafir.png

The CRT hum is roughly 15 kHz so put the gate somewhere around 14.x kHz. One of the points should be at 0 dB (I didn't see a way to set it exactly and dragging it with mouse might put it at -0.02 dB or something) and the other one at the bottom. If you cross them over the line flips so it doesn't really matter which circle you drag first and at which level, just make sure the end result is as in the reference image (red line low on the left and high on the right, signal unmodified on the left and disappearing on the right).