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Topic: Questions: Velocity Filter and Low Pass Filter

  1. #1

    Questions: Velocity Filter and Low Pass Filter

    Hi all, sorry for my newbie mentality here, but I have a couple of quick questions as I see these terms more and more while doing research...

    1. Velocity Filter... What, why and how using the *.gig editor?

    2. Low Pass Filter... Is this pre-done at the sample when recorded, or is this an end-user thing to do and what exactly does it filter?

    Thanks all,

  2. #2

    Re: Questions: Velocity Filter and Low Pass Filter


    A Low Pass Filter is designed to shave tops off the signal, while leaving the bottom end intact. It\'s agruably the most important part of an analog synth. The main control affects the filter cutoff frequency, ie the frequency at which the filter starts to shave off the tops. There are different LPFs. Usually the difference has to do with how steep the \'dropoff\' is at the cutoff frequency. 2 pole LPFs drop off 12db for every octave you go above the cutoff, 4 pole LPFs drop 24 db. You can get steeper or shallower sloped filters. The minimoog has a 4 pole filter.The \'wow\' effect you hear on synths is a result of emphasising (adding resonance to)the cutoff frequency and then quickly moving the cutoff frequency up and down with an envelope or some other controller.

    You would almost never use this kind of filter at the recording stage, as it would remove sample information permanently. In Gigastudio the LPF is primarily used to help match samples recorded at different velocities, (making samples go from \'duller\' to their normal brightness), but there\'s nothing stopping you from using the filter to create synth effects.

    There are many types of filter other than low pass. Highpass, band pass, band reject, multimode, formant etc. Low pass is probably used because it has the widest range of applications in the area of music synthesis and is very quick to use.

    I\'m not sure where the term velocity filter occurs in Gigastudio, but I asume it refers to the practice of using keyboard velocity to move filter cutoff frequency. When you apply velocity to the filter as well as the amplifier (volume) you can get a credible dynamic response from a single sample. This is how most hardware sampled pianos work - a single sample on a key, with dynamics controlling volume and brightness. Play soft, and the sound gets softer - and duller. Play hard, and the sound gets louder and brighter. Of course, the low pass filter can\'t really make a sound brighter than it is. For that reason, developers of hardware piano units tend to use a sample which is a \'forte\' played note. That way they can use a filter and amp to dull the sample down to imitate pianissimo dynamcs. You may have noticed this when playing a hardware type of piano. When poorly done, it sounds like a piano which is played hard, but turned down, rather than a piano which is played softly.

    Thats one thing which is great about Gigastudio. Instead of one sample per key, you can have MANY (and probably more with V3). The idea is that you don\'t rely on a filter to fake a real dynamics change - which is not detailed enough for most instruments if you listen with more than a casual interest. You record the same note as many times as required to reproduce the metamorphosing nuances across the entire dynamic range of the instrument, then stack them on top of each other and have different samples play depending on your keyboard velocity.

  3. #3

    Re: Questions: Velocity Filter and Low Pass Filter

    Wooops, I think my response went to the wrong topic. Anyhow, thanks Chadwick!

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