FetHead Filter is a Fethead version with a built-in 6dB/octave high pass filter with a corner frequency of 220Hz (other cutoff frequencies available on request). 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 FetHead attractive to the ear is preserved.
Protects the microphone
Some ribbon microphones do not tolerate phantom power. FetHead's circuit uses 48v phantom power but shields it from the microphone, so the microphone is protected.
"Can I use the FetHead on the preamp side of the signal chain?"
"I would like to boost my Røde NT1a. I see you sell the regular Fethead, the Fethead Phantom and Fethead Filter. The Røde NT1a is a condenser microphone, so I think the Fethead Phantom is best. Which Fethead would you recommend?"