Smoothie Audio Smear Eurorack All-Pass Filter Module

We say...

It's not often that we come across something genuinely new and innovative in Eurorack these days, but Smear is just that - a pair of stereo 98-pole all-pass filters that open up all sorts of strange sonic territory. Brilliant!

Manufacturer's description

Smear is Smoothie Audio’s first Eurorack module - a dual stereo 98-pole allpass filter unlike anything else in your rack.

At its core, Smear takes a deceptively simple concept - the allpass filter, usually buried deep inside reverb algorithms — and refines it into a playable, sculptural processor. A single allpass subtly shifts the phase of incoming audio while passing the entire signal unfiltered. Stack 98 poles in series, and the effect becomes striking: frequencies across the spectrum are delayed by different amounts, creating a rich spectral delay that can smear, morph, and transform sound.

Smear can be become different effects, according to how you set the parameters:

• Transient Smearing & Spectral Delay that reshapes transients, can add punch
• Resonator & Percussion Voice for metallic, physical-modeling tones when pushed into feedback territory
• Morphing filter & Phasor for animated timbral movement

Interface & Controls

The panel is laid out symmetrically, with two identical sections (Left and Right). By default, stereo audio flows left → right → out, but a dedicated Split Mode allows each side to process audio independently.

Each section offers three core parameters — Frequency, Resonance, and Stages — each with dedicated CV inputs. Frequency and Resonance have attenuverters for precise modulation. A global Feedback control (with CV) unlocks resonant, flanger-like, and physical-modeling behaviors.

The Stage sliders reveal Smear’s hidden depth: with LEDs indicating crossfade modes between filter poles, you can dive into complex notch filtering, animated flams, and evolving timbral movement. Modulate them, and the module comes alive with unpredictable, dynamic filtering effects.

• Built on the Daisy platform by Electrosmith
• CV inputs -5V to 5V
• 48kHZ sampling rate