The Official Sequential/DSI Forum

SEQUENTIAL/DSI => Tempest => Topic started by: Simple Rabbit on December 03, 2019, 09:12:08 AM

Title: Filtering noise but not sample
Post by: Simple Rabbit on December 03, 2019, 09:12:08 AM
Hi there! I'm trying to accomplish something but having trouble:

I'm using osc3 as a 130hz sine wave which I don't want to be filtered. But I also want some noise that goes through the filter.

It seems if I use a sample on osc4, both are routed through the pre/post filter equally. So I tried using noise to mod osc1 to filter, but that has 2 problems: the quality of the noise is really inconsistent between hits and not very lush. Also with the filter completely closed and the oscillator mix knob completely at zero for osc1 and max for osc2, I'm still hearing noise coming through?!

Is there a good solution or tricks to accomplish this? And why is noise coming through my analog oscillators even with the mix and filter shut off?
Title: Re: Filtering noise but not sample
Post by: John the Savage on December 03, 2019, 08:35:06 PM
Well, depending on the range of notes you need to play, and how much you need to close the filter on the noise, technically you can't really filter a sine wave, since it contains no upper harmonics.  So, theoretically, you could filter the noise and the sine wave together, with little consequence to the actual sine tone.

Otherwise, I would just pick the colour of noise that works best, modulate its level independently in conjunction with the filter, in whatever ratio gets you close to the effect you're looking for.

You could also try using noise to modulate the filter cut-off directly, controlled by an envelope or LFO.

Title: Re: Filtering noise but not sample
Post by: muleskinner on December 05, 2019, 12:29:08 AM
You can also get different 'flavours' of analog noise by setting an LFO at as high a rate as it'll go and modding osc1 and osc2 pitch with it. Play around with the base frequency of the oscs, it makes a big difference. Maybe use this in combination with 'noise' as a mod source.

I don't know why you can still hear the noise (it's not actually from one of the digital oscs is it?) but another tip, if you're just using one analog osc, is to set the waveshape of the other to 'none' and use osc mix as a level control.