CDXL Envelope Filter

Jovi Bon Kenobi

Well-known member
That's a vactrol. Not sure which specific one though. It's a LED and LDR in a box. It's possible to make your own but you'd need a schematic.


Well-known member
I wonder if you could roll your own version of the vtl5c4/2 with an LED and 2 LDRs wired together to make a 3 legger?

Huh, the beavis schematic calls for a 5c9 instead. Strange.

I Love Music

New member
Can we post schematics from other places ? I believe this is very, very close to what you want. Use Xvive Audio VTL5C3/2 Dual Element Opto-Coupler.


Chuck D. Bones

Well-known member
That johnk schematic has typos. Turns out the Beavis one is wrong too. This one looks correct. The PedalPCB board is wired for true bypass, this schematic is not.

Dod 440 envelope filter.gif