Understand the Channel EQ of your Stan Logic Pro X, how it works and when to use it. A subject that apparently means a lot to you when you see the number of requests I have received!
A quick recap!
Before we understand the Channel EQ, let’s review some basic principles.
Sound is composed of frequencies, i.e. acoustic vibrations transmitted through the air that are picked up by our ear. These captured data are interpreted by our hearing system.
The frequency is measured in Hertz (Hz) and our hearing system allows us to hear frequencies ranging from 20Hz, known as low frequency sounds, to 20000Hz, high frequency sounds.
There are frequencies below 20Hz called infrasound you can’t hear them, but you can feel them while frequencies above 20000Hz can’t be heard or felt. This does not prevent some animals from being susceptible to it.
In this article I will explain as simply as possible the Channel EQ of Pro X software.
What is your type of EQ?
Without going in, in the different types of equalization know that there are several:
- Graph: The frequencies are predetermined and it is only possible to adjust them
- Parametric: It allows you to choose a frequency band and adjust its gain.
- Semi Parametric: the user chooses the midrange frequencies but the bass and treble have preselected and fixed frequencies.
- Adaptive equalizer which allows multiple and successive variations of corrections, predetermined by algorithms.
Let’s take a closer look at our EQ!
Logic Pro X’s Channel EQ is an 8-band Parametric EQ. This means that there are 8 filters defined by the manufacturer. Each of these filters contains three settings that we will discover as we explore.
Band 1: High Pass Filter
At the top the on/off button to activate or deactivate band 1 (same for all other bands).
High-pass or low-cut filters that allow high frequencies to pass through and reduce the level of low frequencies near the cut-off frequency. This band is used to filter the low frequencies of the track on which the Channel EQ is inserted. In the image above 39.0 Hz is the cut-off frequency. 48 dB/oct. This is the slope of the cut-off frequency. 0.10 is Factor Q.
To understand what is happening with the Q Factor also called resonance, look at the images below.
On the left the Q Factor is 0.10 while on the right the Q Factor is 3.20. Take a good look at the bump it generates on the 62.0 Hz frequency. You know this principle about synthesizers, the famous cutoff and resonance pots!
A little tip….
It is not uncommon to use one of these types of filters on a track that apparently does not contain a lot of bass. For example on a Cymbal Crash. The purpose of this treatment is to clean the residual frequencies that still remain at the bottom of the spectrum. This brings sharpness to the sound and avoids a pasty effect within your composition. We often talk about removing the mud that can affect the quality of a mix.
Another advice, trust your ear don’t look at your screen constantly…
Band 2: Low-shelf filter
Low-shelf filter that adjusts the low frequency level and has a minimal impact on frequencies above the cut-off frequency. In this image the cut-off frequency is 79.0 Hz, the reduction value is -6.5 dB and the Q factor is 1.00.
This filter is used to reduce unwanted noise such as rumble.
Personally I use it to sculpt a sound and thus leave room or reinforce other elements of the composition.
Band 3 – 4 – 5 – 6: Bell filter
Bell filter with three controls per belt:
- The frequency that defines a center frequency.
- Gain defines the level in dB of the band.
- The Q factor that determines the width of the frequency band around the center frequency.
Its use consists in boosting or attenuating a targeted frequency, without altering the original sound too much and its bell shape allows to gradually affect the frequencies around the target frequency according to the Q factor. It can be used to soften certain frequencies or to solve problems related to frequencies between instruments.
If you are a fan of Apple technology, it is possible to control your Channel EQ via Logic Remote! Yes, imagine working on your equalization with your fingertips on your iPad!
Band 7: High-shelf filter
High-shelf filter that adjusts the high frequency level and has a minimal impact on frequencies below the cut-off frequency. In the image above we have the cutoff frequency set to 7500 Hz, the gain is +4.5 dB and the Q factor is 1.00.
It can be used to slightly attenuate a frequency from 7000 Hz or, more often than not, to lighten a piece of music by increasing the desired frequency by a few dB. Be careful not to generate too many trebles. This type of treatment requires careful consideration.
We also talk in some cases about giving air in a mix! The use of this type of filter on frequencies ranging from 8000 Hz to 12000 Hz is a significant ally, once again your ear will be the only judge. This being said, beware of voice sibilants that can emerge if they are not properly processed upstream.
Band 8: low-pass filter
Low-pass filter that allows low frequencies to pass through and reduces the level of high frequencies near the cut-off frequency. Here in this image, we have the cut-off frequency set at 14200 Hz with a slope of 24 dB attenuated per octave and a Q factor of 0.71.
This filter has a drastic effect. Most often, it is used to remove the high frequencies from an audio track. Very often used for a well-known effect of electro music: the famous door opening or closing!
Imagine yourself at the entrance of a Club, you only hear the low-pitched sounds of the music being played. As the door opens, the frequency spectrum is revealed to you! This is the famous door effect which is opened… we can do the same thing with the door which is closed…
Concerning the use of the Channel EQ:
- Use the Analyzer button to see an FFT (Fourier Transformed) analyzer appear that allows you to view the changes made to the frequency curve in real time, you can choose post or pre-analyzer if you want to do an analysis before or after processing.
- If the command key is held down, the selected frequency can be dragged horizontally
- If the command key is held down, the gain of the selected frequency can be vertically shifted.
- Hold down the option + command keys and you can horizontally slide the selected frequency and the Q factor
- Don’t forget with Logic Remote and the iPad it’s great….
In your compositions:
Sometimes it’s interesting to reserve space for the voices so they can come out, use the low-pass filter to cut through and get more space and margin. Then use a bell filter to compensate for the loss. As in the image below to be experimented according to the voice and musical style.
- Use a low-pass filter and a high-pass filter to filter all low spectrum noise and noise in the upper part.
- Cut first, boost only if necessary, sometimes replace the sound makes more sense.
- Be careful with clipping and distortion when using the Channel EQ
- Only use equalizers if you really need them, don’t be the one with 8 equalizers on a single console slice.
- Find the problematic frequencies by scanning the frequency range with a narrow Q setting, then simply cut them off.
- Does your kick catch on with some bass notes? Tune the kick or bass….
The final word
This is a brief overview for understand the Channel EQ. There are still more complex elements discussed regarding this module specific to Logic Pro. I plan another article to finalize your knowledge of the Channel EQ and if necessary for your mixes…