Need some help to build a harmonic distortion module.

[JBain94]

Hi, first time posting to the forum.

Having a lot of trouble trying to build a harmonic distortion module. Have a little experience using Flowstone but I think I've got a little bit out of my depth with this one.

Really just looking for any help or advice in making one.

Thanks in advance.

[oddson]

Typically distortion is added with some kind of soft-clipping wave-shaper.

There are two built in component modules -- Overdrive and Distortion -- but if you're looking for over-the-top guitar-distortion like effects you'll need to go inside and tweak the knob parameter for the gain.

Click the 'P' (for parameter) icon at the bottom-right corner and change the maximum to something more like 5 (instead of 1).

But be advised... you will be adding aliasing to the signal as there is nothing to stop frequencies above the Nyquist from being generated.

You will find that FlowStone does not deal with oversampling very easily because its DSP code is limited to the sample rate and so oversampling is tricky at best. If you run at very-high sample rate you may be able to put a low-pass filter on that will get rid of the worst of the aliasing.

(Since you're question is very general it's difficult to answer without knowing about your level of understanding of DSP. Mine is pretty limited but I think what I've said above is reasonably accurate.)

[JBain94]

I'm looking to replicate analogue warmth through distortion or saturation more than anything.

My knowledge of dsp is fairly limited too but thanks for your help.

[rocknrollkat]

Jan. 20, 2016
It's been my experience that those 'distortion' modules actually overdrive your soundcard, which is NOT what you want.
Here's how I found that out.
I was measuring 'distortion' from one of these modules with an external scope, and sure enough, it was clipping like mad. When I lowered the system gain, the distorted wave SHOULD have gotten smaller, but still distorted.
Instead, it turned into the sine wave I was using to run the test !!
So I patched in an internal scope into the schematic, and sure enough, the signal INSIDE of Flowstone just got bigger and bigger, a HUGE sine wave, with NO distortion.
The external scope was showing clipping like mad, indicating that the soundcard was being driven into hard clipping,which is NOT what you want.
This all led to my 6AU6 pentode tube emulator module which is still under development, but it's great fun to pull the internal gain down and still have the desired clipping INSIDE of Flowstone, where it belongs.

Stay tuned,

ROXY