What is the difference between 2-filter and 4-filter metal detectors?
The first Motion based discriminators were of the so-called 4-filter type. These detectors had to be swung almost as fast as a golf club to get maximum depth. The newer so-called 2-filter types do not need to be swung nearly as fast for maximum depth. The names of these detectors are a misnomer, since they both generally have the same number of filters. Basically, the more modern slow sweep units generally use a filter consisting of a 2-pole configuration. The older types used a configuration more in line with a 4-pole filter. Since the average detectorist doesn’t understand the difference between 2 poles or 4 poles, the name was changed to 2-filter and 4-filter. I don’t know why, because the average detectorist still doesn’t know the difference between 2 filters or 4 filters, does he? At any rate, the 4-pole filter will have a much sharper cutoff rate between signals that get through and signals that don’t. But the cutoff rate isn’t really that important, and since 2-pole filters are
