300B Two-Stage Monoblocks
Four chassis, two per channel. A 45 drives the 300B through an interstage transformer.
This is our most ambitious amplifier. The design follows the thinking of Bruce Berman, who generously consulted with us during the build. Each channel uses a 45 tube to drive the 300B through an interstage transformer, so there is no coupling capacitor anywhere in the signal path. The driver and output stages each get their own power transformer and rectifier, built on a separate chassis so hum and vibration stay away from the signal.
- Topology
- 45 interstage-coupled to 300B, single-ended
- Chassis
- 4 units: 2 amplifier + 2 power supply
- Input transformer
- Tamura
- Interstage & output
- ISO/Tango
- Rectification
- 83 full-wave + 6AU4GT damper per stage
- Filter
- LCLCLC, all ISO/Tango chokes
- Power
- ≈ 8 W per channel
- Wiring
- Point-to-point, Western Electric wire
Includes 45 drivers and rectifier tubes. 300B pair quoted separately or supplied by you.
From your room to your rack
01Your room
We start with your speakers, your room and the music you play, then draw the circuit around them.
02Chassis and wood
Panels are cut, drilled and engraved here, and the frame is made from Thai hardwood.
03Hand-wiring
Every joint is wired and soldered by hand, point to point. You get photos as it comes together.
04Burn-in and listening
Each build runs for days on the bench and is measured and listened to before it ships.
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