RedRoo SE5 is a high-quality, single-ended, 5 Watt per-channel, Class-A valve stereo amplifier designed in Australia by Phil Wait. It can power loudspeakers or low-impedance headphones, and can also be configured as a 10 Watt mono-block amplifier.
The circuit is a no-compromise design using a two-stage 12AT7 Constant Current Draw Amplifier (CCDA) for the input amplifier driving single ended (SE) EL34 output stages. The CCDA draws a constant current from the power supply, and provides a low impedance drive to the output stage, (TubeCad CCDA article). Audio grade polycarbonate coupling capacitors, and low ESR conductive polymer hybrid aluminium electrolytic capacitors on the cathodes, all help to preserve the fine sound detail.
For added constructor safety, no mains power enters the amplifier. DC heaters and a unique power supply design ensure that there is no hum or buzz in the speakers, and extremely low background noise.
The output transformers are unusually large for the power level, which ensures strong and accurate base reproduction while retaining delicate high frequency details. You can try different types of valves and each output stage can be configured as either a triode, pentode, or ultra-linear stage. There is also provision on the PC Board for an optional Bluetooth input module, if streaming from your smartphone or laptop is your thing.
Professional-quality components and the use of a 2mm thick, 2-oz cu, double-sided printed circuit board aids trouble-free construction. With a little patience and skill you will have a superb sounding amplifier you can be proud of that will last you for a very long time, and at a fraction the cost of a similar commercially built amp.
The RedRoo amplifier kitset is available from this website. For those that want to roll-their-own, most components are available from Digikey.com, EVACTO.com.au and other suppliers.
Please let us know what you think.