Spartacus 300B

About the Spartacus 300B

The Thrax Audio Spartacus 300 (often listed as Spartacus 300B) is a high-end monoblock vacuum-tube power amplifier built around directly heated 300B triodes. It uses a two-stage, transformer-coupled circuit with a parallel push-pull output stage, operates in pure Class A, and is specified for up to 50 W into either 4 or 8 ohms. Thrax states that there are no capacitors in the signal path and no global feedback; the design uses custom Japanese Permalloy-core output transformers, a tube-rectified choke-input supply, individual constant-current-fed shunt regulation stages, auto-bias/servo control, microprocessor supervision, and controlled-current filament supplies. Each monoblock employs six 300B tubes: one input/driver tube, four output tubes, and one 300B shunt-regulator tube. The chassis is a sealed, machined aircraft-grade aluminum construction, offered in black or silver anodized finishes. It is a power amplifier, not an integrated amplifier, and provides one balanced XLR input plus one pair of loudspeaker binding posts per chassis.