The Electro-Voice 668, released in 1964, was touted for its lightweight and variable equalization settings. Designed for use on a boom for TV and film, its appearance is very similar to EV''s flagship radio mic, the RE20.
The tail of the mic could be removed to access the “computer-style programming pins” that could be moved to change the equalization from flat (from 40Hz to 12kHz), bass or treble rolloff, treble boost, and 80Hz or 8kHz cutoff. The impedance was also selectable for 50, 150 or 250Ω via a pin selector.
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The 668, like the RE20, featured a Variable-D design to create its cardioid polar pattern. Its foam windscreen made it look very much like a Shure SM5, although the suspension is very much like the EV 309A, which is used for an RE20.
The 668 was used as part of the audio pool feeds at the 1964 Republican and Democrat National Conventions on the lectern.