I've used Sigma Envelope Peak Detectors in a number of applications, but was intrigued by the "Accurate" one, which I hadn't paid much attention to before. It certainly looks the same as the more common (inaccurate?) one, but the Decay option seems to make no difference at all. Whether it's set to 1 or 1000, the output goes down to the new value exceedingly slowly. The two attached screenshots show these two devices in the Menu Tree, and my simple means of demonstrating the phenomenon. Just run an oscillator into the detector and look at the DC output with a level meter. Going from a 0dB output of the oscillator to a -10dB output shows the problem. With a Decay setting of 1000, a 'regular old' Envelope Peak Detector will drop in about 2ms, the 'accurate' one takes many seconds. I guess it just wants to be sure not to miss anything.