S-30 Mk. 3.1

About the S-30 Mk. 3.1

The Atma-Sphere S-30 ver 3.1 is a state-of-the-art low power vacuum tube amplifier designed for audiophiles seeking supreme sound quality in a compact footprint. It features a balanced differential design with Class-A2 operation and a patented Circlotronic® direct-coupled (OTL) output stage, providing 30 watts per channel into 8 ohms and 45 watts into 16 ohms. The amplifier is hand-wired with precision components, uses only octal triode vacuum tubes (10 x 6AS7G output tubes and 6 x 6SN7 driver tubes), and includes automatic bias and a built-in VU meter for tube and output monitoring. It operates fully in Class A with very low distortion (THD typically 1% at full power, IM distortion under 0.04%) and a wide frequency response (1 Hz to 200 kHz within 3 dB). The chassis is finished in a classic open design with a black Wrinkletex™ finish. The 3.1 revision updated the voltage amplifier section to reduce distortion by about 90%, enhancing transparency and smoothness. The amplifier is stable with all loads above 8 ohms and is known for its reliability and sonic purity. Optional upgrades include power supply boost, premium coupling capacitors, and resistor packages. Dimensions are 13" deep x 17" wide x 8" tall, weighing 24 lbs without tubes. It comes with a three-year general warranty and one year on output tubes.