Moving Iron cartridges

Moving Iron, or variable reluctance cartridges are somewhere in the middle. A lower mass moving system with the higher output of a moving magnet, these are generally compatible, but not without their own set of complications. A small iron pole piece moves between the coils as opposed to a magnet.Think Grado, B&O, AKG, ADC, and a few others, these do not always work well on AC motor turntables. When the tonearm gets near the motor, a hum or buzz often occurs. This can happen with some of the VPI and early Linn Sondek  and AR tables.Especially with the Grados. This is generally not a problem with the majority of (DC) motor tables, which most are.