Earthworks was formed by David Blackmer, the founder of dbx™. Earthworks Precision Audio focuses on inventing new technologies for microphones, preamplifiers and monitor speakers. The company is best known for its line of “High Definition” omnidirectional microphones, characterized by extended high-frequency response (25–40kHz) and fast “impulse response.” With respect to “supersonic” frequencies, reputable persons, such as Rupert Neve, have suggested that many people can “hear” a difference between recordings bandlimited from 20 to 20K compared to recordings with a wider frequency range. All the Earthworks omnidirectional microphones use a 6mm electret capsule. The difference between the models begins with selection. The higher-end models incorporate passive electronic as well as resonant mechanical filters that can be tuned to allow the microphone to produce these models’ flat, extended frequency response. Therefore, even though the capsules themselves roll off above 20kHz, the microphone can produce a flat response through a much higher frequency. Earthworks’ products are made in the USA.