When a HPF Causes Clipping (Filtering, Phase, & Constructive Interference)

by SimonPosted on No Comments

How can a low-pass filter increase amplitude even though filters remove frequencies?

In this video, I explain how *phase shifts* introduced by your filters can cause constructive interference, increasing amplitude and even leading to clipping. We’ll explore:
-Why filtering can boost amplitude
-How phase changes affect waveform shape
-Strategies for filtering in synthesis and mixing

Understanding this concept can up the game of sound designers, mixing engineers, and anyone working with EQ or synthesis.

More synthesis and MIDI fundamentals here:

Pd Patch from Scratch: Filter Pinging

by SimonPosted on No Comments

Doing some filter “pinging” use the resonant [bob~] filter in Pd Vanilla.

Filter pinging is a synthesis technique where you sent a “pop” (i.e. an audible click) to a resonant filter to create a percussive plucking sound around that filter’s cutoff frequency. Since we’re in Pd Vanilla, the easiest way to get a resonant filter is with [bob~], the “Runge-Kutte numerical simulation of the Moog analog resonant filter.”

There’s no talking on this one, just building the patch, and listening to it go.

0:00 Setting up the filter
0:40 Filtering a sawtooth wave
1:35 Subaudio [phasor~]
2:04 Randomizing cutoff frequency each ping
3:33 Commenting the code
5:12 Oops

Pure Data introductory tutorials here: