External Filter vs. Native Filter

[Libertine Lush]

With that in mind, I find running the left channel of the synth through one external filter, running the right channel through a different filter, then blending the two together leads to some very interesting, highly-customizable sounds. This signal path puts the filters in parallel rather than in series.

Ah, so that's what a parallel filter is. I've come across the term, but had yet to use such a setup, so I wasn't entirely sure how it would be configured. Thank you.

[Libertine Lush]

Not sure if i get the question right, but also a point to consider is that the synths internal filter, if there's no option to completely bypass, or turn it off, will always affect the sound, even if cutoff is fully opened. I don't know if that's valid for every filter, but most of the ones i came along in soft synths already take away some of the upper frequences spectrum fully opened. So, if you don't want the internal filter to alter the sound, turn it off if possible.

Great to know. I was aware that was the case with one of my hardware synths, but didn't realize that's the norm.

[Libertine Lush]

No, not necessarily. The internal filter may be modulated by many things, the external filter will not. This effect can be particularly noticeable if the resonance is capable of being modulated. You may have some complex set of interactions going on with the internal filter such that just changing the cutoff materially changes the timbre of the sound in a way that is different from just adding an external unmodulated filter. You may want that timbre to remain intact over the course of the sweep. I do this quite a bit with my synthacon filter in my modular. It's really animated and everything interacts with everything else so it's not just as simple as sweeping its own cutoff to just get a darker version of the same sound.

With what you said in mind, I set up something to test it out. I clearly understand what you mean now—I can hear it and understand why the difference exists. Thank you again for your really helpful explanations.

[BDeep]

With that in mind, I find running the left channel of the synth through one external filter, running the right channel through a different filter, then blending the two together leads to some very interesting, highly-customizable sounds. This signal path puts the filters in parallel rather than in series.

Ah, so that's what a parallel filter is. I've come across the term, but had yet to use such a setup, so I wasn't entirely sure how it would be configured. Thank you.

This would be an example of parallel filters. You could also route both left and right through two parallel filters. Useful for sounddesign.

[Libertine Lush]

You could also route both left and right through two parallel filters. Useful for sounddesign.

Does that mean both channels of a synth are being processed by two filters simultaneously?

Are there yet more possible parallel filter configurations?

Thanks.

[BDeep]

Yeah that's what I meant, you could do that with external filters but it's more common with a synths own internal filters. A synth like Massive for instance allows you to route different oscillators to different filters (inside Massive).

It's useful if one if for instance a comb filter and the other an lowpass. Or two bandpass filters in parallel.
It's probably easier to experiment than to break your head about all possible combinations and the effect they have

[Libertine Lush]

A synth like Massive for instance allows you to route different oscillators to different filters (inside Massive).

It's useful if one if for instance a comb filter and the other an lowpass. Or two bandpass filters in parallel.

Thank you. The examples are very helpful.

[whyterabbyt]

Might also be useful as an emulation of what happens(*) in a polyphonic acoustic instrument; the per-voice filters give you the specific resonations/character of each string/tine/bar/whatever, but in a real life instrument those 'sources' are also filtered in total by the body of the instrument, ie a global resonator/filter.

(*) ie not specifically for physical modelling, though of course its relevant to that.