Vongon Paragraphs: Low Pass Filter with Envelope Generator

Paragraphs is an analog four-pole resonant low pass filter with an attack, decay (AD) envelope generator designed with focus on simplicity and flexibility.

Low Pass Filter
The heart of the filter circuit is the AS3320 analog chip — a modern replica of the same component used in analog classics like the Sequential Prophet 5, Pro-One mono-synth, Elka Synthex, and the LinnDrum. Cutoff spans the full audio spectrum and resonance starts to self-oscillate at about seventy percent.

Modulation
The envelope generator offers modulations in an uncommonly wide range of frequencies — starting as low as 0.05 hz for slowly evolving 20 second long cycles, and reaching up to (and past) the audio threshold at 300 hz for a wave shaping effect similar to sounds found on west coast style synthesizers (“think Buchla”).

Flexible Gain Stages
Paragraphs accepts instrument and line level signals. Dedicated controls for input (drive) and output level make it easy to move between a crystal clear clean tone and and a clipping fuzz. A multi-color LED provides a visual representation of the signal level. Red indicates clipping. Orange flashes indicate the start of overload. Green indicates the presence of signal at or below the nominal level.

CV and MIDI
Inputs for Control Voltage (CV) and midi are available to remotely trigger the envelope generator. This enables your Paragraphs to stay in rhythmic synchronization with external systems like midi sequencers, euroracks, and digital audio workstations.

Specifications
1/4” mono input/output jacks
2.1mm DC Connector
5.7” x 4.7” x 1.5” enclosure dimensions
true bypass
input impedance: 1MΩ
output impedance: <1kΩ
power supply: 9 to 9.6 VDC center negative
current draw: 100mA max