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Fast and Easy Mic EQ - Make Your Mic Sound Better with Shelf Filters!

Audio is subjective, that’s the first thing to always keep in mind when talking about what “sounds good.” While we believe that the ModMic products all sound AMAZING right out of the box, there may be a wide variety of reasons you’ll want to adjust the way your microphone sounds.

In this article we’ll be talking about changing the tone of a microphone. If you’re interested in filtering out background noise and adjusting the overall volume we’ve got this amazing tutorial on EQ APO and RNNoise.

To keep things simple we’re going to use shelf filters to adjust the bass and treble of the microphone. Due to the complexity of the human voice it is often easier and faster to adjust the lows and highs than mess with the mids, as the most important thing to keep in mind is that increasing one area is, in effect, decreasing another. If you increased the entire spectrum 5% it would be no different than increasing the volume 5%. As a result you have to pick if you want more bass, more mids, or more treble. You can’t have it all.

The Programs

You can use almost any audio program to adjust the EQ of a mic. However, that doesn’t mean necessarily using a 16+ band EQ program. While those minute adjustments may give you maximum control, the reality is a simple shelf filter can probably achieve what you want with far less headache. This is why to start we’re going to focus on the shelf filtering instead of more advanced concepts like EQ matching.

In particular we’re going to be showing screenshots from two common programs: EQ APO and Voicemeeter.

We use EQ APO for our RNNoise tutorial, therefore we'll focus on that in order to keep everything in one place. However, since Voicemeeter has a graphic EQ with shelf filters, we’ll point out what they look like as well. This will let you find similar functions in basically any common EQ VST or stand-alone program.

Both programs adjust audio in real-time, so feel free to record yourself at different levels and see if the changes you make are in the right direction.


Adjusting Bass, AKA: Low Shelf Filter

Adding bass can be a great way to add a feeling of depth to your voice, giving you that radio personality sound, but go too far and you’ll sound muddy and muffled.

For EQ APO the first step is to add a Low Shelf Filter This is found by clicking the green plus sign -> Parametric Filters -> Low Shelf Filter.

When added you’ll see 3 dials with various options near them. We’ll define these items below:

1: The dropdown menu lets you select corner or center frequency. This is basically where on the audio spectrum your adjustment is going to be located. For bass, a good starting point is a corner frequency of 200hz. The lower the number the less impact it will have on your voice overall, while going higher will begin to impact the mid-range as well. I’d keep this value  between 150hz and 300hz for adjusting the bass, but feel free to play around with it.


2: Gain affects the magnitude of the change. Don’t go overboard, 6-7dB is probably near the maximum you’ll want to adjust in any EQ adjustment. This value can also be negative!

Remember, bringing down the bass is, in effect, boosting your mids and highs, giving a more crisp sound if you feel the mic is “muddy” or “muffled.”

3: Slope is how sharp the change is. A shelf filter is a gradual change, which is what makes it easier to use than a banded EQ program. A high slope will be very abrupt, while a low slope may impact a too wide a range of frequencies. A slope of between 9 and 14 is usually about right for most applications.

The resulting frequency response curve of the settings in the image will look something like this.


 

In Voicemeeter you can access the graphical EQ by right clicking the EQ button in Master Selection. 


Here you’ll see multiple frequency selections. Just like in EQ APO you’ll pick one near the number you want and set it to that frequency. In this case, again, 200hz. Additionally, just like EQ APO you’ll see a gain indicator, and just like there we’ll set it to 6-7 at most. 

Finally and the big difference in that second to last icon. That’s the “Low Shelf Filter” symbol. It’s basically universal, so even if you’re not using either of these programs that’s the guy you’re looking for! Click that symbol to set a low shelf filter.

And that’s it really. Adjust the gain, location, and curve sharpness until you get the sound you want. 

Remember: You can use a negative gain value to improve a “muffled” sound!

Adjusting Treble, AKA: High Shelf Filter 

A high shelf filter can add treble to your signal, giving you a more crisp and clear sound. Go too far here and you’ll end up sounding compressed, like talking to someone on a telephone.

Just like in the low shelf filter we add this in EQ APO by going to the the green plus sign -> Parametric Filters -> High Shelf Filter.

1: We once again see the same frequency selection, and just like the low shelf filter, we’re going to set this to corner and this time to a much higher number. We suggest starting with a value of 3,000hz. This gives you a nice gradual increase from the upper mid-range. Typical reasonable ranges for this kind of filter would be from ~2,000hz all the way up to 5,000hz.

2: Be a little more gentle with gain than you would with low frequency. As we’ve already stated, the human ear is very sensitive, and it’s more sensitive to picking out changes to high frequency than low. I’d suggest adjusting this between 3-6dB. Remember, you can also make this a negative value to decrease sharpness in your voice, making you sound more “soft.”

3: Just like with the gain, we want to be more gentle with our increase in treble. We suggest a slope value between 7-12 for your initial testing. 9 is a good place to start. A rapid increase in slope can cause an unnatural quality in your voice, however, the lower this number the more it will also impact the midrange.

The resulting frequency response graph should look something like this.


 


Just like the low shelf filter, in VoiceMeeter the only difference is the icon is reversed, as seen here. Otherwise the same principals apply, adjust the gain and location of the curve with the dials.

What if you use both?

You can actually add both high and low shelf filters together to create V shaped sounds or even increase one while decreasing the other. Just keep in mind that your changes are relative, giving a V shape to your voice by increasing both high and low is effectively decreasing the mid range, which is where most of your voice is. So while it is fun to play with and you may produce a sound you like if you’re very gentle with the numbers, we don’t suggest it in most cases.

You can also create an inverted V signature by decreasing both the highs and lows, accentuating the mids. We stated at the start of the article, adjusting your mid-range is likely to produce a very unnatural vocal sound, but part of the joy of audio is experimentation, so feel free to test it! Just remember if you are decreasing gain across a wide spectrum you may need to increase the overall volume.

An inverted V using both high and low filters set to negative gain.

The most important thing to remember is that audio is subjective and to keep changes as small as possible. Over-tuning your microphone is likely to just make it sound worse, so try to use smaller values whenever possible.

Questions? Stuck? Drop by our Discord and hit up our community or staff for assistance.


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