ADAU 1761  control output volume by input

Hello Kevin,

If I understand your application, you wish to regulate your sweep generator's level via feedback from a microphone. You can do this with any of the External Detector Input compressors in what's called a side-chain arrangement. Set up the compressor's graph for a constant output level over a wide input range, as shown. Audio from the sweep generator goes into the compressor's green input pin. The compressor's output drives your sound system. Your mic picks up the resulting sound, and this signal runs back into the compressor's detector input (red pin). The compressor varies its gain to maintain a constant level at its detector input, thus closing the feedback loop on your output level.

I used a headphone as a mic at the ADC input, and another headphone at the DAC output. Pressing the ear-cups together closes the loop. The "mic" needed a 40 dB gain to provide sufficient feedback -- the needed gain will of course vary with your setup.

The Real-Time Display graph shows how the acoustic gain of my speaker-mic combination varies with frequency, forcing an inverse output from the compressor.

Best regards,

Bob

Many thanks Bob, I will give this a try first thing Monday morning!

With thanks

Kevin

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