This little wonder is a phantom powered, high quality preamp preceding the microphone cable, improving the sound quality of a dynamic microphone. It establishes an overall increase of sound quality and a change of tonal character towards a more open, controlled sound.

FetHead Filter is a Fethead version with a (standard) built-in 6dB/octave high pass filter with a corner frequency of 220Hz.
Mine has a 180 Hz cutoff, made for my specific microphone (Rode M1) & voice combination.
It is specially designed for microphones which exhibit an excessive proximity effect / low frequency response, like long motor ribbon microphones. The components which make up the filter are not directly in the signal path but are applied to the components which set the gain of FetHead Filters amplifier, thus making it frequency dependant. This way the sonic character which makes a normal FetHead attractive to the ear is preserved.

The technical features that mean anything for me, as non-technician:
Class A JFet amplifier, 20db amplification, balanced output, lots of headroom, needs phantom power.

Check out the Triton website for this and other great products!