Original Universal Audio 550-A Filter Pair

Offered here is an exceptionally rare Universal Audio 550-A high-pass filter module pair from the late 1950s, designed by the legendary Bill Putnam Sr. These early UA modules were built during the formative years of the modern recording industry and are almost never seen on the market today—especially in clean, functional condition.

This is a true piece of recording-history hardware, representing the era when UA, Fairchild, and Pultec were defining the sonic character of an entire generation of music.

Very close serial number pair: 287 & 291