Kelt Amplification is a French boutique tube amp builder founded by Thierry Labrouze, based in Brech near Lorient in Brittany. Every amplifier is designed, wired, and assembled entirely by hand by Labrouze alone — from chassis drilling and point-to-point turret board wiring to teak wood cabinetry joined with dovetail joinery. The brand name carries dual meaning: it references the Kelt line of sailboats, known for their simplicity and robustness, and "Kelt" means "Celtic" in Breton, a nod to the company's roots in Brittany.

The lineup spans a range of all-tube guitar amplifiers priced in the mid-€1,800–€2,500 range. The MostrO, a 50-watt two-channel head, is among the most recognized models, praised for its dynamic range from clean tones to aggressive lead saturation. Other core models include the F-Type, F-Type SVR, C-30, BobCat, V-Twin, and MostrO SuperLeggera. Kelt also produces several artist signature amplifiers: the MJ-10 for Michael Jones (of the French pop duo Jean-Jacques Goldman & Michael Jones), the Bluebird for blues-rock guitarist Nico Chona of The Freshtones, and a signature model for French rock artist Axel Bauer. The YG-MAX is built to the specifications of guitarist Yvan Guillevic.

Kelt amps are designed around simplicity and responsiveness, using premium components including F&T and Sprague capacitors, Jupiter signal caps, Switchcraft connectors, and carbon resistors in the signal path. The design philosophy emphasizes pedal-friendly platforms where tone shaping comes primarily from the player's hands, guitar controls, and pedalboard rather than from complex onboard amp features. Artists using Kelt amplifiers include Popa Chubby, Yarol Poupaud, SanSeverino, Izo Diop of TrusT, and Pat O'May.

Kelt has 3 products cataloged on Equipboard, including Guitar Amplifier Heads. Their gear is featured by 5 artists, with the strongest followings in Rock, Blues, and Pop. Notable users include Popa Chubby, Sébastien Chouard, and NeoGeoFanatic.