ADAU1761 - Signal envelope attack and decay in db/s

Hello,

Likely you need a quick Attack rate (such as 120 dB/s), and a slower Decay rate (perhaps 20 dB/s). The schematic below compares two envelope detectors -- a plain RMS Envelope block on top, and a RMS Envelope block followed by a homemade Decay stage below. In the two-stage detector, the RMS Envelope block provides the usual Attack rate and Hold time. Set this block's Decay rate as fast as possible (the same as the Attack rate) so that the following stage determines the overall Decay time.

Calculate the gain b according to the desired overall Decay rate (dB/s) with this formula:

b = e^ - [(dB/s) * ln10 / 20 * fs] Example: fs = 48000, dB/s = 20, b = 0.999952

Compare the plain RMS Envelope block's response to that of the two-stage design:

Best regards,

Bob

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