Audible stepping in DaisySP phaser

Hi,

I’m trying to build an Eurorack phaser effect module, using DaisySP’s Phaser. The problem I’m facing is that at low LFO speed or if I slowly modulate the phaser frequency using a knob, I hear audible steps in the modulation of the phaser frequency. I thought I could get away by changing the Phaser to use doubles instead of floats in the frequency modulation part, but without success. Any tips?

Hey sems!
I would be happy to look at this closer with you!

How low of an LFO speed would you need? I just tried

phaser.SetFreq(5.f);

in the phaser example (DaisyExamples → seed → DSP → phaser) and didn’t hear steps. I also tried 0.5 as well (though I don’t hear steps necessarily, this low of a frequency just leads to a detuned effect and not really phaser-like). I hope this is the LFO frequency you were talking about.

This forum allows you to share audio files, so feel free to post a clip of what you are hearing.

As for the knob, could you share the modification that you made to the code? Thanks!

I used frequences below 1hz to hear stepping, but you can also hear it if you manually modulate the phaser frequency using SetFreq. I finally identified the source of the stepping: phaser.cpp uses a DelayLine (DaisySP/phaser.cpp at master · electro-smith/DaisySP · GitHub), whose Allpass method takes an integer amount for the delay. Then, the stepping is when the float is converted to size_t when Allpass is called (DaisySP/delayline.h at 6ad2e5928b1b0af924ae7e6cd23d08967acb8864 · electro-smith/DaisySP · GitHub). I ended up adapting another Phaser which doesn’t use Allpass with integer delay and it works well!

2 Likes

I’m having similar issues with the phaser on my guitar pedal project. Would you mind sharing the phaser you ended up using to solve the stepping issues?

I got some inspiration from this one GitHub - MrBlueXav/Daikrispator: Dekrispator on Electro-smith Daisy platform.
I can send you my code later when I’m home.

1 Like
1 Like