What is a filter?
Filter-type effects are a general term for effects that alter the sound quality by tweaking the frequencies of sounds that are converted into electrical signals.
You may be thinking, “What are you talking about?” But filters are a function that everyone uses and touches without even realizing it.
The reason for this is that filters are a type of filtering system that includes tone knobs on guitar amplifiers and low-cut switches on microphone preamplifiers.
The equalizer is also a filter effect, but in GarageBand, filter effects include AutoFilter, SpectralGate, the vocoder-based EVOC 20 Filterbank, EVOC 20 TrackOscillator, plus Fuzz-Wah, and more.
These effects significantly alter the frequency spectrum of a sound or mix, resulting in changes to the sound or mix.
Wah-wah, which changes the sound of a guitar by altering its frequency response, is also a type of filter.
Filters were originally part of the sound creation circuitry of analog synthesizers.
They are now used as effects to change the sound, and have become independent effects called “filter effects” that are attracting attention.
Filter-type effects can be used not only as cuts, but also as sound creation effects.
low pass filter
The most commonly used filter is the low-pass filter.
This low-pass filter is a method of filtering by gradually reducing the sound from the higher frequencies.
Since it is a low-pass, it means to let the low pass through. Please do not confuse this with low cut.
By the way, low-cut means to shave off the lows.
Low-pass filters vary from model to model and plug-in to plug-in, and each has its own unique tonal characteristics.
What determines the tone is the cutoff frequency, and the effectiveness of the filter depends on where the cutoff frequency is set and how many dB are shaved off.
The cutoff freq. will vary depending on the model, so the tone will also vary.
Cutoff Frequency
Cutoff freqency refers to the operation of a filter that softens or muffles the sound by lowering the frequency to a certain level and then cutting the frequency.
high pass filter
A high-pass filter works in the opposite way to the low-pass filter described earlier.
Since it is a high-pass, it means that high frequencies are passed through. Please do not mistake it for a high cut (shave off high frequencies).
As the cutoff freq. is increased from the bottom, the low frequencies are shaved off and the sound becomes lighter.
band pass filter
A bandpass filter is a filter that cuts off the overtones above and below, leaving only the overtones near the cutoff frequencies.
It is characterized by a bell curve-like shape.
How to use filters
Basically, the filter is used to create sounds by moving the cutoff frequencies and setting the resonance.
The most common way to use a filter is to synchronize it with a MIDI controller and add changes to the song by moving the knob around in your hand.
If you get bored with the atmosphere of a song, you can use a filter effect to create a different tone, allowing the listener to enjoy the change.
It might be a good idea to create the sound together with other automation (panning, volume, and other effects) without thinking too hard.
