Using Filters - Part 1

Introduction

This is fairly basic stuff and pretty obvious to most, but since the topic came up a couple of times in the IRC channel, I have made this basic tutorial with pictures to visualize the filtering process.

I have used the free effects from GVST. You can get them here: http://www.gvst.co.uk

Whatever is explained here also applies to the internal filters of Renoise.

First let me start with a short overview of the most useful filters. After that I will provide you with some tips on how to use them. All filters have in common that they don't introduce a hard cut. That means when I use a low pass filter at 2kHz, there is still some activity above that frequency. That activity can be accounted to a smooth transition that filter have, which is called the slope. If the technical stuff is interesting for you, you might check the following links.

• http://en.wikipedia.org/wiki/Low-pass_filter
• http://en.wikipedia.org/wiki/High-pass_filter
• http://en.wikipedia.org/wiki/Band-pass_filter

Have a look at the following pictures. The red parts in the spectrum view are removed by the filter. Moving the knob in the VST will relocate the red parts accordingly. The blue parts are passed through to the output.

The Low-Pass Filter

Just as the name says, a low-pass filter will remove high frequencies.

The High-Pass Filter

A high-pass filter is the opposite of the low-pass filter and removes low frequencies.

The Band-Pass Filter

A band-pass filter removes low and high frequencies. A band-pass filter can also be simulated by chaining low- and high-pass filters.

Tips

If you have a song with lots of instruments playing, there is a high chance your mix is overcrowded. Many instruments will overlap each others' frequency regions. Filters are really useful in such situations to make room in the song and get a more transparent output.

A pad, for example, usually doesn't need much low content, so you can high-pass filter it. When soloing a pad with a high-pass filter it can sound thin, but when played together with the rest of your song it will probably sit well in the mix.

Kicks and basslines are perfect subjects for low-pass filters. Often the bass department of a song sounds muddy. You can decide whether the kick or the bassline should be filtered out. Let's say you want to duck the bassline on every kick, to get that popular pumping effect:

1. use a low-pass filter on the kick
2. put a band-pass filter on the bassline
3. adjust the low cut of the band-pass filter to make room for the kick

A lot of people are after some nice kicks for their songs. One method is layering a couple of them, then use filters on the layers to extract the interesting parts for your new kick.

Maybe you have found some useful information here. The filter settings ofcourse depend on your taste and on the sounds you use, so experiment a bit. Feel free to comment and add your own tips.