Pendulum Audio is a New Jersey-based pro audio manufacturer founded by Greg Gualtieri in 1988. Gualtieri, a former Bell Laboratories semiconductor researcher with degrees from Columbia and Princeton, started the company to build amplification gear for acoustic instruments, releasing the HZ-10 — billed as the first rack-mounted acoustic instrument preamp — that same year.

The brand specializes in Class-A vacuum tube signal processors built in low volumes for studio and stage use. Its catalog spans microphone preamps, opto and variable-mu compressors, and acoustic instrument preamps, including the MDP-1 stereo tube mic preamp, the OCL-2 stereo opto compressor, the 6386 vari-mu compressor, the Quartet and Quartet II channel strips, the SPS-1 modular preamp system, the PL-2 tube line amp, and 500-series modules such as the OCL-500 and DS-500.

Pendulum gear is associated with high-end acoustic recording and mastering work, and the company's client list has included artists and engineers working with James Taylor, The Eagles, Bob Dylan, Jackson Browne, and Metallica. Gualtieri, an active recording engineer and producer himself, designs the products with a focus on tube circuitry, point-to-point construction, and acoustic-instrument fidelity.

Pendulum Audio has 14 products cataloged on Equipboard, including Effects Processors, Preamps, and Guitar Preamps. Their gear is featured by 14 artists, with the strongest followings in Electronic, Rock, and Pop. Notable users include Hannes Bieger, Jonny Buckland, and James Murphy.