I have recently received the ADAU1761 evaluation board. One thing I have noticed is that the RMS results using the RMS squared envelope and then the square root function work fine for frequencies above 50Hz. When I try an input frequency of 2Hz using the tone input, the results go up and we end up with a 30% error. I have found that if I can the TC of the envelope down to 5, reults are beeter with a 2% error. The problem with that scenario is the response time of the function. Changing the sampling rate did not affect the results either. Any suggestions will be appreciated.