The OpticTone MK2 is an improved revision of our original module, combining a 12dB multi-mode Vactrol VCF and a Vactrol VCA. This unique circuit is inspired by the distinct characteristics of Vactrols and Lowpass gates, celebrated for their fluid and natural character.

The Filter section offers the three essential filter types: Lowpass, Bandpass, and Highpass. A new Range Switch allows you to select between high, mid, and low filter ranges, with the High position providing the wider filter range. The Resonance knob, equipped with a voltage control input, offers improved modulation flexibility. The feedback knob interacts with the Resonance path, serving as a resonance compensation control, allowing you to adjust from smooth, creamy resonance to wild self-oscillation.

The OpticTone MK2 introduces a new switch to select between series and parallel configurations for the VCA and Filter. In parallel mode, the VCA comes first. Both the VCA and Filter are controlled by the Freq/Amp knob, its voltage-control input, and touch control via the 3 lines on the panel below the knob. The combination of signals can be crossfaded with a dedicated knob.

The new circuit is designed to allow the user to produce low pass gate pluck sounds. To achieve Lowpass gate pluck sounds, send a short trigger (about 20ms) to the Freq/Amp CV input and utilize the Vactrol’s slow, envelope-like decay. You can use the crossfade knob to mix the VCA and VCF signals, allowing you to balance and fine-tune the pluck effect.

The Frq switch inverts the filter frequency control, allowing the filter to “close” when the VCA is “opening,” and vice versa.
The Ping input allows you to generate the distinctive percussive sounds characteristic of vactrol filters. Pinging a filter involves sending a short trigger or gate signal to the filter, causing it to briefly resonate and produce a percussive sound. This technique is often used in modular synthesis to create drum-like or plucked sounds. The Ping frequency is controlled by the Freq/Amp knob, offering a wide range of tones from deep kick drums to high-pitched bongos.
The module also features a pre-filter Drive knob, offering a range of sonic textures from subtle warmth to intense distortion, adding rich harmonic content to your sound.

Features:

• Vatrol based 12dB multi-mode Voltage Controlled Filter: Lowpass, Bandpass and Highpass.
• Vactrol Based Voltage Controlled Amplifier.
• Crossfade knob to mix the VCA and VCF section.
• Voltage controlled Resonance.
• Improved circuit for Lowpass Gate pluck sounds.
• Ping Input for percussive sounds generation.
• Filter Range switch.
• Switch to set VCA and VCF in Parallel or Series.
• Filter Frequency polarity inversion switch. Doesn’t change VCA polarity.
• Overdrive and Feedback controls.
• Attenuator/inverter knobs on all voltage controlled inputs
  Touch control over Frequency and Amplitude.

Specs:

• Width: 10HP
• Depth: 33mm
• Power consumption: 55mA +12 / 55mA -12
• Eurorack Format
• Doepfer power connection

Check OpticTone MK2 manual here