In the early 1970s, after condensing the classic 3U model EQP-1A into the 2U form-factor model EQP-1A3 (same components, same specs), Pulse Techniques introduced a solid-state line amp version of the EQP-1A3. These units have exactly the same front end (input transformer and passive EQ section) but utilize a solid-state opamp (API 2520) gain stage driving a Triad output transformer, just like the originals. 

This version of the EQP-1A3 is actually preferred by some engineers for certain applications (kick, snare, bass, piano, etc.) and also serves as the core for our 500-series EQs. Many users of this version of the Pultec describe them as “more punchy” and having “a tighter low end” than the tube version. Pulse Techniques, LLC is the only company licensed to use genuine API 2520 opamps in their products. These EQs deliver plenty of the punch and mojo of their tube-amp counterparts, with just a slightly different flavor.