The Red Roo SE5 Tube Amplifier Kit
The Red Roo SE5 tube amplifier kit is a top-quality, compact single-ended class-A stereo amplifier that can power loudspeakers or headphones.
It has a 5 Watt RMS output and uses a two-stage triode Constant Current Draw Amplifier (CCDA) driving a single-ended (SE) EL34 output stage. The kit includes two sets of RCA inputs, a 3.5mm jack input, and a Bluetooth input for streaming from your smartphone or computer.
The EL34 single-ended output stage can be configured in triode, pentode, or ultra-linear modes, with ultra-linear being the recommended mode for a balance between low distortion and high power.
The tube amplifier kit is easy to build and measures only 185mm wide, 215mm deep, and 165mm high. It uses high-quality components such as audio-grade polycarbonate coupling capacitors, low ESR conductive polymer hybrid aluminium electrolytic cathode-bypass capacitors, and large output transformers for accurate bass reproduction.
The front panel has a large solid metal volume knob and toggle switches for power on-off and input selection, and a 1/4-inch headphone jack. The rear panel has input connectors, speaker connectors, a speaker impedance switch, and a feedback on-off switch.
The tube amplifier kit is designed for safety, with mains power not entering the chassis and a unique power supply design, DC heaters, and earth-loop protection to eliminate power supply-induced hum or buzz from the speakers. The PC Boards are extra thick with 2-oz copper tracks for enhanced durability and heat transfer.
The kit is available as a solderless option, as a full kit of individual parts, or as a weekend amp camp in the Blue Mountains west of Sydney.
Care is required as the circuit contains hazardous voltages up to 280V DC.