F_EQUZ

F_EQUZ — 8-Band Stereo Equalizer with Mod Matrix is a fully stereo equalizer featuring eight independent bands and an interactive EQ curve. The module is designed to function both as a precise corrective EQ and as a dynamic, modulation-driven sound shaping tool. All changes are immediately visible in the graphical display and directly audible in the audio signal.

The module provides left and right audio inputs (IN L and IN R) and left and right audio outputs (OUT L and OUT R). Incoming audio is processed per channel through all active EQ bands and then routed through a global output gain stage to the outputs. Processing is fully stereo, with separate filter instances for the left and right channels to preserve spatial integrity.

F_EQUZ contains eight EQ bands, each of which can be configured independently. For every band, the following parameters are available:

• Frequency (center frequency of the band)
• Gain (boost or cut in decibels)
• Q (bandwidth or resonance)
• Filter Type (Bell, Low Shelf, High Shelf, Notch, Highpass, Lowpass)

Each band can be muted individually. A muted band is bypassed in the signal path while its settings remain intact. Muted bands are visually indicated by hollow diamond-shaped nodes in the EQ display.

The EQ canvas is the central interaction surface of the module. Each band is represented by a draggable node on the curve. Dragging a node horizontally adjusts the band’s frequency, while vertical movement adjusts the gain. All movements update the audio and the visual curve in real time.

Additional mouse interactions provide fast access to advanced functions:

• Single click on a node selects that band.
• Double-click toggles the mute state of the band.
• SHIFT + double-click resets the band to its default settings.
• ALT + double-click activates solo mode, muting all other bands; repeating ALT + double-click exits solo.

When dragging a node while holding the SHIFT key, the interaction mode switches from frequency and gain control to Q control. Vertical mouse movement then adjusts the band’s Q value. Moving upward increases Q for a narrower, more focused band, while moving downward decreases Q for a wider response. This allows intuitive bandwidth editing directly on the curve without using the Q knob.

The selected band is visually highlighted in the display. The Band selector knob determines which band is currently active for parameter editing. All parameter knobs and labels always reflect the selected band and stay synchronized with the graphical representation.

The control section includes the following knobs:

• Band: selects the active band (1–8)
• Type: selects the filter type
• Freq: sets the center frequency
• Gain: sets boost or cut in dB
• Q: controls bandwidth
• Out: global output gain

F_EQUZ features a built-in modulation matrix with eight modulation inputs. Each MOD input has an assign button that determines its modulation destination. Available destinations include:

• Global output gain
• Frequency (per band, in octaves)
• Gain (per band, in dB)
• Q (per band, multiplicative scaling)

Multiple modulation inputs may target the same parameter. In that case, modulation signals are summed (or multiplied in the case of Q) to produce the final modulation amount. Modulation is always applied as an offset on top of the manually set values.

Frequency modulation is handled in octave space to ensure musically meaningful results. Gain modulation is applied linearly in decibels. Q modulation uses exponential scaling to maintain stability across a wide range of values.

The EQ curve and band nodes visually respond to modulation. A dedicated visualization cache updates the display at GUI rate, allowing smooth movement of curves and nodes without affecting audio performance. The total EQ curve always represents the combined effect of all active bands, including modulation.

All parameters, including band settings, mute states, and modulation assignments, are fully stored and recalled with presets and variations. This ensures consistent behavior across sessions and reliable use in complex modular patches.

F_EQUZ is designed as a central sound-shaping tool within Voltage Modular. It is equally suitable for subtle tonal correction, creative sound design, dynamic filtering, and modulation-driven motion. By combining direct graphical interaction, extensive modulation options, and true stereo processing, F_EQUZ provides a powerful and flexible equalization environment.