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It's been a while since I have written any articles so I hope that this one will satisfy your curiosity.

In this article I will be discussing Filters. Almost every synthesizer has a filter. Filters are sometimes called a VCF (Voltage Controlled Filter) but this is more common on analogue equipment.

What a filter does is it takes the audio or sound it receives from the oscillators (See Synthesis Basics - Part 1) and starts cutting frequencies of the top, middle or bottom frequencies.

You get many kinds of filters but I will be discussing the High Pass, Band Pass and Low Pass Filters.

Go have a look at your synthesizer. If you don't have a synth to work with go and download a free one. I would suggest something like Synth1. Look at the filter section of your Synth.

You will notice there will be markings or settings that show LP, BP and HP. Now just for clarity LP = Low Pass Filter, BP = Band Pass Filter and HP = High Pass Filter.

THE LOW PASS FILTER
The Low Pass Filter like it's name implies lets all the Low frequencies pass through while cutting of the high frequencies.

THE BAND PASS FILTER
The Band Pass Filter cuts of all the high and low frequencies and lets the middle frequencies pass through.

THE HIGH PASS FILTER
The High Pass Filter cuts of all the low frequencies and allows all the high frequencies to pass through.

Now that we know a bit about the different kinds of filters lets talk about the most common settings a filter has. The two most common will be "FREQUENCY" and "RESONANCE". Frequency can also be called "CUTOFF" and Resonance is sometimes called "Q" as well.

FREQUENCY/CUTOFF
The frequency or cutoff control the where the filter starts cutting of the frequency of the incoming signal from the oscillators. When you adjust this control you will hear the sound change between bright and dull.

So if you are using a Low Pass Filter your filter will remove frequencies higher than the CUTOFF frequency.

And if you are using a High Pass Filter your filter will remove frequencies lower than the cut-off frequency.

RESONANCE/Q
Resonance is where the frequencies at the Cut-Off position are boosted (played louder). When resonance is introduced, the frequencies around the Cut-Off are boosted slightly.

To understand how these two relate to each other can be achieved by playing around with the filter on your synth and to listen carefully what it does. Try playing a few notes and change your Resonance and Frequency settings if you hear a sound almost like swishing feedback that is called a filter sweep.

Well that is all for now. I hope this article was usefull to you.

In the next article we will be discussing Envelopes.