Spectral Audio is a Swiss synthesizer manufacturer founded in 1995, specializing in hardware analog instruments with MIDI implementation. The company built its reputation on hands-on, knob-per-function designs aimed at modern MIDI studios that wanted the character of vintage analog synthesis without the price tags of original gear from the 1970s and 1980s.

The lineup centers on a small catalog of monophonic synths and sequencers. The ProTone, the company's debut, is a 2U rackmount monosynth with two analog oscillators (saw and pulse waveforms with sync and ring modulation), a switchable high/low pass resonant filter with selectable 12 or 24 dB/oct slopes, and a flexible LFO. The Syntrack pairs a 100-waveform digital oscillator with an analog filter and adds patch memory. The Neptune and Neptune MkII (2003) are fully analog two-oscillator designs with a redesigned resonant filter, ring modulation, and onboard distortion. The Cyclus 3, released in 2007, is an analog-style MIDI sequencer with eight tracks, 112 patterns, and 30-song memory.

Spectral Audio's instruments are typically sold as rack modules without keyboards, and most of the synths intentionally omit patch storage so that the front-panel knob positions always reflect the sound being produced.

Spectral Audio has 2 products cataloged on Equipboard, including Synthesizers. Their gear is featured by 1 artist, with the strongest followings in Electronic. Notable users include Paul Birken.