I built Offset-O-Matic a while ago for a similar purpose. It is an attenuator with variable gain, an inverter with variable gain, a buffer circuit or impedance converter and an adder allowing you to add or subtract a DC offset to a signal. An offset circuit is especially handy if you send a CV to a vactrol. The DC offset voltage will give the LED a bias voltage, and the AC part of the CV signal can then be used to modulate/control its brightness.
2 Likes