Radial Tonebone Plexitube

[zosotone]

Can be a good addition. Maybe similar to the BK Butler? Two channels, many voices and effect loop! Here the schematic from FSB http://www.freestompboxes.org/download/file.php?id=5414

[ξεναγος νεκροπολης]

can someone say what this VDX is on 4007 ic at the schem?
i can only see vdd