Synthetic Sound Labs (SSL) is a modular synthesizer manufacturer based in the United States, run by Doug Slocum, who has been building and modifying analog synthesizers since the early 1970s. Slocum's early work included custom modifications of Minimoogs and other instruments for artists such as Manfred Mann, David Sancious, Chick Corea, and Michael Urbaniak, as well as a heavily modified Minimoog used by Tom Coppola to create the three-note Duracell sound logo. The company name is a nod to the SteamSynth, a large steampunk-styled modular instrument Slocum built that gave SSL's panels their distinctive aesthetic.

SSL produces synthesizer modules in both 5U (MU/Dotcom) and Eurorack formats, alongside tabletop devices and DIY parts. The catalog includes the Model 1015 Lowpass Gate, the 2655 Geo-Gruvn six-channel Euclidean rhythm and gate sequencer, the 2140 Thundrum FM drum voice, the 1651 MINI Sequencer II, the 2530-S Tube VCA/Timbral Gate, the SampleCorder, the Segwencer, and the 1200 VCO. The 5U line was named Module Manufacturer of the Year in 2012 by the Muff Wiggler forum community, and the brand has a following among 5U/Dotcom-format builders looking for unusual utility, sequencing, and percussion modules.

Synthetic Sound Labs has 2 products cataloged on Equipboard, including Modular Synthesizers. Their gear is featured by 1 artist, with the strongest followings in Electronic. Notable users include Deadmau5.