New Balancer PCB and Kit

Stereo MFB Active Tube-Based Crossover

Active Tube Crossovers and Filters
The punch line is that the MFB filter is a better active filter, which explains why it is often used in demanding audio applications, such as high-dynamic-range ADC input stages. It is slightly more complicated than the equivalent non-inverting Salen-Key filter, so it is largely unknown to most audiophiles.