motion Discriminate mode. White's Classic series is a 2-filter type ONLY in the Discriminate mode. When you're working that excellent XL Pro in the GEB Norm (no auto-tune) or GEB/SAT mode (auto-tune) it is the same as working a Classic III SL or IDX Pro, or Tesoro Bandido or any other make/model in a conventional ground balanced, All Metal mode. That is, there is no real function of the "filtering" in All Metal.
Thus, in general terms, the XL Pro, WHEN IN THE MOTION DISCRIMINATE MODE, is a 4-filter type and by design they have a longer "ring time." That's the descriptive term describing how long a signal will "ring on" until it recovers and restores itself in order to respond to another target. Oh, it can still respond to a target during this "ring time", but the operator will not usually hear it because a 4-filter detector, by design, is not a quick response and recovery circuit.
Knowledgeable operators know, however, that by going to a smaller search coil, such as the excellent 6