[sdiy] Yet another analogue synth

[John L Marshall]

Unfiltered White Noise has even noise energy per Hertz. That means that
White Noise has as much noise energy in the 10 KHz to 20 KHz octave as it
does from 0 Hz to 10 KHz. This energy slope is +3 dB per octave.

Noise that is filtered to yield equal noise energy per octave is Pink Noise.
A -3 dB filters take some engineering and additional components to
accomplish, a series of R's and C's will approximate.

It is easy to add a -6 dB per octave filter to White Noise. This will give a
net -3 dB per octave slope which a Red Noise.

My view noise is noise is noise and you will tweak and filter and mash the
heck out of it anyway. Choose bright sounding White or mellow sounding Red.

John


----- Original Message -----
From: Magnus Danielson <cfmd at swipnet.se>
To: <rob at sleep-dream-die.com>
Cc: <synth-diy at node12b53.a2000.nl>; <ka4hjh at gte.net>
Sent: Wednesday, May 23, 2001 1:42 PM
Subject: Re: [sdiy] Yet another analogue synth


> From: "rob " <rob at sleep-dream-die.com>
> Subject: Re: [sdiy] Yet another analogue synth
> Date: Tue, 22 May 2001 18:23:53 -0400
>
> > Exactly what does this happen to do with a noise source that has even
less high frequencies than a pink noise source? ;)
> > Rob
>
> You go from white to pink to red to brown...
>
> > PS what is the filter cutoff frequency/slope to produce red noise?
>
> Pink noise is assumed to have the -3 dB/Oct so I guess red noise is
> assumed to have -6 dB/Oct.
> Consider brown noise as a variant where frequencies below 10 Hz or so
> is dominant, basically, a lowpass filter of 10 Hz from a white-noise
> source, but pink or red could also be used since the slope has no real
> assumption.
>
> Hey, this list is becoming very noisy!!!
>
> Cheers,
> Magnus
>