Filter by Lunacy is a free standalone filtering plugin built for both routine mixing moves and more creative sound design. Alongside familiar low-pass, high-pass, band-pass and EQ-style responses, it adds comb and formant modes that can push a source into pitched, resonant and vocal-like territory. The interface stays deliberately direct, making it easy to use as a basic tone-shaping tool or as a more obvious effect.

Classic Filters for Everyday Mixing

Lunacy includes the core responses producers expect from a modern filter: low-pass, band-pass, high-pass, low shelf, bell, high shelf, peak and notch.

That makes the plugin useful on almost any source, whether the goal is removing low-end rumble, softening a bright synth, creating a transition or carving space in a layered arrangement.

Comb and Formant Modes for Creative Processing

The more distinctive side of the plugin comes from its comb and formant filters. Comb filtering can introduce strongly pitched resonances and metallic coloration, while the formant mode can create vowel-like tonal changes.

These modes are particularly effective on synths, vocals, percussion and effects where the filter should become part of the sound rather than simply correct it.

Adjustable Slope From 1x to 8x

Filter slope can be scaled from 1x to 8x, allowing the same filter type to move from gentle spectral shaping to much steeper frequency separation.

A softer slope can sound natural on buses and instruments, while higher values are better suited to dramatic transitions, isolated bands and surgical creative effects.

Note Snap Turns Frequency Into a Musical Parameter

The Note Snap feature quantizes the selected filter frequency to musical pitches. This is especially useful with resonant, comb and formant settings because it allows the filter to reinforce notes that relate to the key of the track.

It also makes automated sweeps easier to control when a completely free-running cutoff would create unwanted dissonance.

Stereo Image Control Adds Width Options

Lunacy includes stereo-image modification directly in the plugin, so filtering and spatial shaping can be handled in the same stage.

Used carefully, this can help widen atmospheric layers or make a creative filter movement feel larger without adding a separate stereo processor.

20 Presets and Standalone Plugin Formats

The free download includes 20 presets designed as useful starting points for conventional and creative filtering. Lunacy distributes Filter as its own plugin, so BEAM is not required.

• VST format
• AU format
• AAX format
• macOS support
• Windows support
• 20 included presets

At a Glance

Developer: Lunacy

Type: Creative and classic filter effect

Filter types: Low-pass, band-pass, high-pass, shelves, bell, peak, notch, comb and formant

Slope: 1x to 8x

Musical control: Note Snap frequency quantization

Stereo tools: Stereo image modification

Presets: 20

Formats: VST, AU, AAX

Platforms: macOS and Windows

Price: Free

Download Lunacy Filter for Free

Get the current free version directly from the official developer page.

Official Download Page

Final Thoughts

Lunacy Filter is useful because it covers both sides of filtering well. It can perform the ordinary low-pass and high-pass work every producer needs, but comb, formant and note-snapped frequency control also give it a more creative identity. For a free standalone effect, the feature set is unusually complete without making the interface feel overloaded.