Envelope Follower (ENVF)

Envelope follower that I built for my DIY modular synth techno rack. My main stakes in this module are being able to side chain and create duckings on voices when the kick hits. Someone in a techno production subreddit recommended me this after hearing some audio from my synth 👍🏻

Features

• ✅ Attack, realease and gain controls
• ✅ Non-inverted and inverted out
• ✅ Only 2hp wide

Specifications

Controls:

Left and right view on the module:

Control board (bottom):

Main board (top and bottom):

Implementation:

• The smoothing to create the envelope is based on peak detection, see https://www.youtube.com/watch?v=jllsqRWhjGM for instance.
• The attack isn’t a real attack from my perspective. Meaning it does not delay the time when the signal peak is reached. It rather smooths the entire signal like an attenuator. I decided to call it “Attack” anyways since I’ll use it mainly to reduce natural pops at the beginning of an envelope. Any loss in amplitude coming from this can be compensated with the gain 😊

Resources

Revision 1

• Schematics (PDF)
• Feedback on Reddit and Modwiggler

Revision 2 (breadboard prototype)

What’s new? I added variable release (poti).

• Schematics (PDF)
• Showcase and feedback on Reddit and Instagram

Revision 3 (PCB prototype)

What’s new? I brought it on PCB level.

• Video Demo: Sidechaining On Bass Line
• Video Demo: Bass Line From Hihat Beat
• Schematics (PDF)
• BOM (XLS)
• Showcase and feedback on Reddit and Instagram
• Improvement potential: The main thing here is that I that I set the pins of the thonkiconns wrong way around on the PCB 🤦 With some tweaking and bending I could fix that, but will not publish the spoilt Gerber files of this revision here.

Revision 4

What’s new? Adjusted to real 2hp (9.8mm wide), changed decoupling capacitors to smaller ones, fixed Thonkiconn twist.

• Build Document (PDF)
• BOM (XLS)
• Improvement potential on Github (issues)