Serpent Audio Chimera 500-Series Opto Compressor - Used  From Serpent

While not as popular with the clone-building community as the LA-2A, the solid-state opto LA3A offers a very similar simplistic design and smooth, natural sounding compression, but with a more transparent tonal palette that lends more flexibility. As an LA3A clone, the Serpent Chimera follows through with that standard but offers a bit more “meat” to the signal. In every source we heard the Chimera on, this added thickness and color was a welcomed addition that made a vocal “pop” with more focus and edge, a kick drum “thump” with more thunder, and a rhythmic acoustic guitar become more rounded and, well, interesting sounding. 

The Chimera provides just one degree of control up from the simple original LA-3A units, making it slightly more powerful yet still easy enough to use as a tracking compressor without spiraling into a never-ending gear dialing sessions. Comp/Limit switching gives you a more aggressive voicing while the high-frequency sidechain boost turns the unit into more of a de-esser, and not just for vocals (think aggressively bright overheads or even electric guitar amps).