Teia Synthesizers - OpticTone MK2

The OpticTone MK2 is a vactrol-based 12dB multimode filter and VCA, but with more going on than that label implies. Filter modes cover lowpass, bandpass, and highpass, and a central Freq/Amp control governs both sections at once, with a crossfade knob to set the balance between VCF and VCA. You can switch between series or parallel routing, plus there's also a mode for frequency inversion, which lets the filter close while the VCA opens.

The drive stage sits before the filter and goes from warm to wrecked. Resonance has its own feedback path and the filter self-oscillates when cranked all the way up. There's a separate input to ping the filter as well. Three jumpers on the back are worth knowing about: one toggles between tame and aggressive resonance behavior (labeled "Polite" and "Uncivilized"), another routes ping into the frequency CV for pitch-bend effects, and "Crooked Poles" deliberately mismatches a filter stage for a "wrong-on-purpose" response. There's also a resistive touch strip in the middle of the panel, which adds direct fingertip control over frequency and amplitude.

A solid filter module from Portuguese maker Teia — good for gating, vactrol plucks, pinged percussion, and overdriven filter work alike.

Features:

• Vactrol-based 12dB multimode VCF: lowpass, bandpass (6dB), highpass
• Vactrol-based VCA with exponential response
• Crossfade knob to mix VCF and VCA sections
• Series / parallel routing switch for VCA and VCF
• Filter frequency inversion switch (does not affect VCA polarity)
• Three-position filter range switch (High / Mid / Low)
• Voltage-controlled resonance with CV input and attenuverter
• Feedback knob (resonance compensation / self-oscillation control)
• Pre-filter drive
• Ping input for percussive vactrol sounds
• Freq/Amp CV input with attenuverter
• Resistive touch control for frequency and amplitude
• Three rear jumpers: Resonance Manners (Polite / Uncivilized), Ping to CV (On / Off), Crooked Poles (On / Off)