[sdiy] Equal power law

[Rutger Vlek]

Hi everyone,

Inspired by the lin/exp/log thread, I've been wondering about implementation of other curves, most specifically those used for equal power law and BBC panning law (center at -3dB or center at -4.5dB).

Are there simple ways to approximate these curves in analog domain (e.g. without using a VCA). I've been playing in Spice with an approximation of the curve using a simple opamp circuit with back-to-back zeners. The zeners already have a rather 'soft knee', but I'd like to know if there are ways to get the shape even closer to what's needed for an equal power law curve.

Rutger