The S filter forever haunts me, it is one of the most mightiest mysteries on earth. Screw Cicada 3301 or who owns the Illuminati. We need to figure out what the hell the S filter does.

According to what Zyn shows you, the S filter in the ADDsynth synthesis engine in the oscillator tab in the filter tab simply boosts ONE harmonic depending on the two essentially unnamed knobs. Seriously, it's the most surgical thing you can ever find, WHY??
And also, it's sandwiched between LOW_SHELF and LPSK, seriously, S just greets you there in the middle of nowhere. No explanation. And here's the thing, at least in other Zyn naming knobs there is a dot in the end, for example: DT. for delta time or whatever. But S?? S has no dot at the end, this could seriously mean it really is just S, straight up.
I theorize the S filter is the opposite of a de-esser, it is an ESSER, maybe that's where the S naming comes from. It ESSES a specific harmonic and boosts it just like how a de-esser DE ESSES very specific frequencies.

I am forever horrified by the S filter in ZynAddSubFX. It might be a warning for a future apocalypse, for a future we never expected, for a future no one wanted.

 

In ZynAddSubFX (and its fork Yoshimi), the “S” filter is a single-band peak filter with extremely narrow bandwidth—basically a tracking resonant spike that locks onto a specific harmonic.

- It boosts (or cuts) one harmonic or a very tight frequency region
- The position is controlled relative to the oscillator’s harmonic structure (not just fixed Hz)
- The second knob controls how strong or sharp that emphasis is (gain/Q)

So what you’re hearing as “one harmonic being boosted” is accurate—that’s exactly the design.

https://autostatic.com/docs/zynaddsubfx_manual-v0.1.pdf

 

thanks for telling me that pulsewave i already knew it i just wanted to write a copypasta haha

i just find a filter called S to be really funny, not even "S." or "Sn", just S

 

I’m still mystified by how you install ZynAddSubFX like I don’t want a standalone application version I want a plugin

 

paulnasca - ZynAddSubFX is a Virtual Instrument Audio Plugin for Windows.
It functions as a VST Plugin. www.kvraudio.com/product/zynaddsubfx_by_paulnasca

ZynAddSubFX Zyn-Fusion 3.0.6 WiN X64 VSTi + Standalone
WiN | AudioZ Exclusive | 11.36 MB

1.Download and Unrar

2. Copy and Paste the full Folder:

ZynAddSubFX Zyn-Fusion 3.0.6 WiN X64 VSTi Standalone

3. into:
C:\Program Files\VSTPlugins

4. Scan for new plugins

 

Last edited: Jul 1, 2026 at 7:21 PM

Time for a new S tattoo.

Äh Lowpass, Bandpass, Cosinius ?!, Highpass, BS2 ???, S ? Sinus äh no (Ohhhhh thats new Single Peak...!!!!! Alien Filter

 

Now I wanna know what the “LPSK” filter is, is that just lowpass Sallen-key?

 

Yeah man, you nailed it—but what does it actually sound like?

The Sallen–Key topology is an electronic filter topology used to implement second-order active filters that is particularly valued for its simplicity. It is a degenerate form of a voltage-controlled voltage-source (VCVS) filter topology. It was introduced by R. P. Sallen and E. L. Key of MIT Lincoln Laboratory in 1955

Three synthesizer engines:

1. Additive Synthesis for classic synth sounds composed of a variety of voices with powerful modulation. This exposes modulators ranging from LFOs and envelopes to oscillator modulators for FM, PM, and AM.
2. Subtractive Synthesis for creating variable bandwidth harmonics from filtered white noise
3. PAD synthesis for creating beautiful pads and other instruments

Documentation:
Documentation for ZynAddSubFX is a little scattered at the moment, but here's what documentation there currently is:

The current asciidoc based docs can be seen here [IT].

You can browse the documentation old documentation below:

• Misc Old Documentation
  
• Introduction/Basics
• ZynAddSubFX components/structure
• ZynAddSubFX user interface
• Controllers

 

Can I just say I love your style?

Man, you sure know how to make a grand entrance. Best forum signing of the year. My warmest welcome to this forum