Profile: Pendulum Audio Systems, Inc. specializes in hand-built vacuum tube recording equipment and electronics designed for amplifying stringed instruments. Our PL-2 is a stand-alone two channel version of the solid-state peak limiter in the Quartet II. It uses a novel approach to brick wall limiting, one that is fast enough to prevent digital over in the analog domain. The Quartet is an all-purpose recording tool designed with the ultimate in sound quality and flexibility in mind. The OCL-2 is a two channel electro-optical compressor/limiter designed for the utmost in transparency, detail and versatility. Our short signal path design uses a custom optical input attenuation network in front of an all tube class A gain stage.