OTA Low Pass VCF
OTA Low Pass VCF
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OTA Low Pass VCF (Voltage Controlled Filter)
The OTA Low Pass VCF Eurorack PCB and Front Panel Kit is a DIY analog low-pass filter inspired by the classic MS-20 filter topology. Designed for Eurorack modular systems, this filter delivers warm, juicy tones and rich resonance, making it ideal for adding analog character to any modular synth setup.
Key Features
- Eurorack PCB and front panel kit
- Inspired by classic MS-20 style low-pass filter designs
- 2-pole (12dB/octave) voltage-controlled filter
- Built around the LM13700 OTA for musical, reliable performance
- Warm, resonant analog sound
- 8HP Eurorack format
Sound & Filtering
This OTA-based VCF provides smooth, musical filtering with rich resonance and expressive sweeps. The 12dB/octave slope offers a versatile response suitable for everything from subtle tone shaping to aggressive analog filtering, making it a flexible low-pass filter for Eurorack systems.
DIY Build & Calibration
This DIY Eurorack VCF PCB and front panel kit is intended for intermediate builders. For optimal performance and to achieve the signature warm sound, careful calibration is required.
Important build notes:
Component correction: C3 = 1µF, R32 = 22K
Input Level Calibration
- Set the Frequency control fully clockwise
- Set the Resonance control fully counter-clockwise
- Adjust the In-Level trimmer so the output signal is slightly lower than the input signal, providing sufficient headroom for resonance
- Start with the trimmer at its lowest setting and slowly increase
- Avoid overly hot input signals, as this may cause instability or unwanted screeching
Frequency Resolution Adjustment
- Use the Frequency Resolution trimmer to fine-tune the response of the frequency potentiometer
- Adjust for heavy filtering when the pot is fully down and minimal filtering when fully up
Technical Specifications
- Format: Eurorack
- Width: 8HP
- Skill Level: Intermediate
Video Demo
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