STATE VARIABLE FILTER

[Emeka]

Hello.Can someone help me?I'm a beginner to flowstone, I know almost nothing. I am trying to produce a synth which produces a tremolo sound that can be filtered. I used the state variable filter but I am at a loss on what module or primitive to connect to its cutoff input section to vary the cutoff frequency. Do I use an ADSR? If yes, why? what is the theory behind how an envelope varies a frequency? I will really appreciate your help.

Secondly, what is the difference between frequency and pitch in flowstone? Based on prior knowledge, pitch is perception of frequency; why then does flowstone differentiate them?

PLEASE, HELP A BROTHER

[Spogg]

Hi Emeka and welcome to the forum!

In Flowstone you can take “pitch” to mean the MIDI note or key number and it will have a range of 0-127. This range describes all possible notes in the MIDI spec. For example a pitch value of 60 is middle C on a piano-style keyboard.
Frequency in Flowstone can be defined either as Hz or lying within the range of 0-1, and which one is used depends on what is required for a given module or Prim. For 0-1 the value of 1 represents a frequency of half the sample rate, so for the standard 44100 Hz, 1 represents 22050 Hz.

There are modules which can translate freely between any of these.
On some types of modules you can specify an output type so it’s very flexible. You must pay attention to which system is used because if you mix them up you’ll get very odd results!

Pitch is useful for specifying what is a log relationship with a linear scale. So for example if you increase pitch by a value of 12 you double the frequency and go up 1 octave.

Regarding the state variable filter you can modulate its cutoff from anything that produces a suitable range, normally 0-1. So this could be an envelope generator or an LFO with unipolar output for example.

Maybe you need a general guide to synthesis so is there anyone else here who could recommend a good reference book or PDF?

Cheers

Spogg

[Emeka]

Thanks Spogg.I really appreciate. Yh, any reference book would help.

[martinvicanek]

Check out some of the references at the Flowstone Guru site:
http://flowstone.guru/resources-2/