The external amps for my sub do NOT have signal sensing or other means of auto on/off. I am looking for a box that senses the receiver's audio signal and either puts out a 12V signal (that I can use for a high amp 110V relay) or already has a relay included. Only boards I find are from Israel or China and take forever to get here.
Its quite simple. A simple rectifier with germanium or Schottky diodes plus a transistor is all you need. Plus some form of time constant to prevent switching between silence periods.
1. If the receiver has a 12V trigger output, you can use a power relay module to power the sub amp.
POWER RELAY MODULE 4-OUTLET
2. DIY or buy a active subwoofer audio signal detecting module.
3. Connect the receiver front pre-out or parallel the sub-out to a signal activated automatic switch, and use its SPDT contacts to a relay to power the sub amp.
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