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Removing Background Noise with Equalizer APO and Reaper's ReaFir

There is a new version of this tutorial using Real-time Noise Reduction here:

If you prefer manual noise reduction, detailed below, we suggest the easier to use Light Host and Reaper combination tutorial located here:

If you're experiencing background noise, odds are high it is either EMI, which comes across as a static hiss or a ground loop, which is a low hum in the background.

These problems come from your hardware setup, not the microphone, but fixing them is relatively easy and cheap. The easiest way is to buy a USB adapter like the one we sell.

However, there IS a free method, but it takes a little work and will slightly decrease the quality of the mic. How much? Here are some samples of the start and end of this process.

If you don't want to buy that USB you're going to need two programs, Equalizer APO and the Reaper VST plugin ReaFir.

Equalizer APO:

Reaper VST:

Make sure you download the correct version of the Reaper VST, 64 bit most likely.

Step 1: Install Equalizer APO (EQ APO)

When you install EQ APO you'll get a pop-up to select the devices you want to use. While you can select all the devices you normally use for audio (there's a lot EQ APO can do) the only one that matters for THIS tutorial is your microphone. 

As you can see in the image above, I have selected both our USB and a normal 3.5mm input, but you'll probably only want the 3.5mm input, as the USB should not require this tutorial.

Next, you'll need to reboot your machine.

Step 2: Install ReaPlugs by Reaper

Installing ReaPlugs should be as easy as running the installer. You may need to reboot after installing this as well. Just make sure to note where you've installed it, as that will be needed in the next step. The best practice is to leave it in the default directory, which is where other programs may look for it.

Step 3: Set up EQ APO

Start by running Configuration Editor in the EQ APO directory, but remove everything so you're looking at a blank slate. When you're done it will look like this:

Neat! Now we have to add only two items to the top. First, click the + sign in the top left and add Control -> Device and then click "Change" and select only the mic we want to edit.

Once you have that selected press "OK" and then click the plus sign under the Selected Device. Now add Plugins -> VST Plugins and then the load button. It's this guy:

Navigate to where you installed ReaPlugs and load the file "reafir_standalone." 

It should look like this when you're done:

Finally, press the button labeled "Open Panel." We're now ready for the final step.

Step 4: Configure ReaFir

This looks more complex than it is, so don't panic! Under "Mode" select "Subtract." It's highlighted below:

Then drag those two dots ALL the way to the bottom, so you end up with a flat line at the very bottom of the screen. It'll look like this:

At this point, you can click "OK" or "Apply" and actually go test your recording! ReaFir's subtract mode comes with a built-in noise suppression, so messing too much in this area isn't needed. However, if  your mic is too quiet simply add some mic gain on the right-hand slider marked "Output Gain." Test in increments of 5dB, keeping in mind the higher this goes the worse quality will get (but the louder your mic will be).

One thing to note: If you crank your volume WAY up you'll probably notice you traded a "hiss" for a very low "hum." For most people this is the end, the hum should not be easy to hear compared to the hiss and would only matter if you were doing real recordings.

Here's the final result:

In my tests, it is possible to remove that humming, but it will come at decreased quality, and worse, every machine will be different so I can't give you a set of magic numbers to use. However, I have included the final optional step for those who want to play around a bit with this.

Optional Step 5: Build a Sound Profile

If the initial treatment isn't enough there's one more step you can use to decrease the background noise further by automatically building a noise profile.


EQ APO cannot build a noise profile automatically. While other programs can (Such as OBS and Cantabile), EQ APO has a much lower footprint on your PC. This means to get the performance of EQ APO and the accuracy of an automatic noise profile we need to create the noise profile somewhere else and IMPORT it into EQ APO. It's not hard, but it is long enough to warrant its own post.

Go here if you want to learn how to build and import a noise profile from OBS to EQ APO.

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