Uploaded May 2021 | Updated September 2026, 2 weeks ago
Pink noise or 1/f noise is used in audio applications from room acoustic profiling and studio track mixing, to calming nature sound emulation.
Using a common pink noise filter circuit structure that achieves the required -3 dB/octave roll off response, here's one way to go about determining the component values needed to filter white noise into pink noise.
The circuit consists of three phase lag compensator networks and an RC low pass filter. Using LTSpice to observe the filter design as it progresses, the individual phase lag transfer functions are used to calculate the position pole and zero frequencies to shape the filter response until it matches the target -3 dB/octave from 20 Hz to 20 KHz, with an overall +/- 1 dB variation.
0:00 What is pink noise all about?
2:11 Pink noise sounds: Water & Wind (attempts)
3:00 Filter basics - roll off, poles & zeros etc
6:47 Phase lag compensator transfer function/usage
7:19 Getting started with component selection for a pole and zero
11:22 Insert a second pole/zero pair
14:11 Insert a third pole/zero pair
15:38 Move poles/zeros around to optimize
17:45 Insert a final pole with an RC low pass filter
19:27 More pole/zero relocation assistance
23:48 The final zero for the win
25:05 Breadboard scope measurements
Useful links:
Types of noise en.wikipedia.org/wiki/Colors_of_noise
Circuit transfer functions, poles and zeros, bode plots https://web.njit.edu/~levkov/classes_files/ECE232/Handouts/Frequency%20Response.pdf
https://lpsa.swarthmore.edu/Bode/BodeHow.html
https://lpsa.swarthmore.edu/Bode/BodeRules.html
Phase Lag Compensator Info
https://people-ece.vse.gmu.edu/~gbeale/ece_421/comp_freq_lag.pdf
tutorialspoint.com/control_systems/control_systems_compensators.htm
Online equation editor for formatting math text quicklatex.com
Equipment I regularly use (support the channel by shopping through these affiliate links - I may earn a small commission and it doesn't cost you extra):
JCD 8898 Soldering and Hot Air Workstation banggood.com/custlink/DKKYOoeKg7
Mustool MT315 Digital Microscope banggood.com/custlink/KKvhiw1F6F
946C Solder Hot Plate 200mm x 200mm banggood.com/custlink/K3DyiNZy0l
ANENG AN8008 True RMS Multimeter banggood.com/custlink/KKDh9267Fz
Minleaf NPS3010W Power Supply banggood.com/custlink/KKKdtaNN9A
FY6900 Dual Channel 60MHZ Signal Generator banggood.com/custlink/vGKR9r6RkR
Siglent SDS1104X-E 100Mhz Digital Oscilloscope 4 Channels Standard decoder
Amazon.com: amzn.to/36fH1ui
Amazon.ca: amzn.to/36fNWUc
Support me on Patreon: patreon.com/gadgetreboot
LBRY/Odysee: odysee.com/@GadgetReboot:4
Pink noise or 1/f noise is used in audio applications from room acoustic profiling and studio track mixing, to calming nature sound emulation.
Using a common pink noise filter circuit structure that achieves the required -3 dB/octave roll off response, here's one way to go about determining the component values needed to filter white noise into pink noise.
The circuit consists of three phase lag compensator networks and an RC low pass filter. Using LTSpice to observe the filter design as it progresses, the individual phase lag transfer functions are used to calculate the position pole and zero frequencies to shape the filter response until it matches the target -3 dB/octave from 20 Hz to 20 KHz, with an overall +/- 1 dB variation.
0:00 What is pink noise all about?
2:11 Pink noise sounds: Water & Wind (attempts)
3:00 Filter basics - roll off, poles & zeros etc
6:47 Phase lag compensator transfer function/usage
7:19 Getting started with component selection for a pole and zero
11:22 Insert a second pole/zero pair
14:11 Insert a third pole/zero pair
15:38 Move poles/zeros around to optimize
17:45 Insert a final pole with an RC low pass filter
19:27 More pole/zero relocation assistance
23:48 The final zero for the win
25:05 Breadboard scope measurements
Useful links:
Types of noise en.wikipedia.org/wiki/Colors_of_noise
Circuit transfer functions, poles and zeros, bode plots https://web.njit.edu/~levkov/classes_files/ECE232/Handouts/Frequency%20Response.pdf
https://lpsa.swarthmore.edu/Bode/BodeHow.html
https://lpsa.swarthmore.edu/Bode/BodeRules.html
Phase Lag Compensator Info
https://people-ece.vse.gmu.edu/~gbeale/ece_421/comp_freq_lag.pdf
tutorialspoint.com/control_systems/control_systems_compensators.htm
Online equation editor for formatting math text quicklatex.com
Equipment I regularly use (support the channel by shopping through these affiliate links - I may earn a small commission and it doesn't cost you extra):
JCD 8898 Soldering and Hot Air Workstation banggood.com/custlink/DKKYOoeKg7
Mustool MT315 Digital Microscope banggood.com/custlink/KKvhiw1F6F
946C Solder Hot Plate 200mm x 200mm banggood.com/custlink/K3DyiNZy0l
ANENG AN8008 True RMS Multimeter banggood.com/custlink/KKDh9267Fz
Minleaf NPS3010W Power Supply banggood.com/custlink/KKKdtaNN9A
FY6900 Dual Channel 60MHZ Signal Generator banggood.com/custlink/vGKR9r6RkR
Siglent SDS1104X-E 100Mhz Digital Oscilloscope 4 Channels Standard decoder
Amazon.com: amzn.to/36fH1ui
Amazon.ca: amzn.to/36fNWUc
Support me on Patreon: patreon.com/gadgetreboot
LBRY/Odysee: odysee.com/@GadgetReboot:4
