Remote switching triggered by audio

[soapamp]

Need some help to build remote switching triggered by audio.  Thank you for your help

[R.G.]

Filter the circuit to ensure that just audio gets through.
Full wave rectify and DC filter the band-limited audio.
Use a comparator to sense when the audio is above some threshold.
Use the comparator output to trigger the switching logic.

[soapamp]

Filter the circuit to ensure that just audio gets through.
Full wave rectify and DC filter the band-limited audio.
Use a comparator to sense when the audio is above some threshold.
Use the comparator output to trigger the switching logic.

Thank you for your advise