5+5 Stereo Tube Amplifier

Free Download - Build your own high quality tube/valve audio amplifier. Non-commercial use only

Many of these amplifiers have been built over the past year with excellent results and stable trouble-free operation. Please check the experience level required and also please read the section on valve safety. Have fun!

The information contained in this website is free to download and use by individuals for non-commercial purposes. Please read the disclaimer below.

The Red Roo Amplifier

RedRoo is a high-quality, single-ended, 5 Watt per-channel, Class-A valve amplifier that can power loudspeakers or low-impedance headphones. It can also be configured as a 10 Watt mono-block. 

The circuit is a no-compromise design using a two-stage Constant Current Draw Amplifier (CCDA) as the input stage. The CCDA draws a constant current from the power supply, and provides a low impedance drive to the output stage which (we believe) produces a cleaner sound if amplifier is pushed hard into overload.

The circuit also uses DC heaters and a unique power supply design that produces no buzz or hum and extremely low background noise. The output transformers are unusually large for the power level, which ensures strong and accurate base reproduction with 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.

The selection of quality components and the professionally designed 2mm thick double-sided printed circuit board leads to trouble-free construction. With a little patience and skill you will have a superb sounding amplifier you can be proud of, at a fraction the cost of a similar commercially built amp.

The PC Board, and the HV power supply module are available from this website. Supply details are provided for suitable output transformers.

Please let us know what you think. 

Why Tubes?

Many musicians and audiophiles still prefer the sound of an old-fashioned thermionic valve (aka Tube) amplifier. Valves have a typically "warm" and "open" sound produced by the synergy of many factors that solid-state devices just cannot simulate.
A RedRoo valve amplifier lets you experience your favourite recordings just as the original musicians and their sound engineers intended.

Is DIY for Me?

The difficulty level for this amplifier is 4. The number relates to the information in the table below. Levels 1 and 2 do not require previous experience. Levels 3 and 4 require some knowledge of electronic components and skilled construction. Level 5 is for the experienced and skilled constructor.
If you don't have the necessary experience you should either seek help from someone who does, or you should at least build a few simple electronics kits first. Easy steps!
Please also read the section on valve safety.

Valve Safety

Valve amplifiers are safe unless they are physically damaged, misused, poorly located, or are being worked-on without taking appropriate safety precautions. 

Electrical Safety - Hazardous Voltages
Valve equipment contains hazardous voltages, (several hundred volts, or more), and it can hold that high-voltage charge for a very long time after the power is switched-off. If you are working on valve circuitry make sure it is switched-off and the high voltage power supply is fully discharged.

Burns or Fire Risk
Valves operate very hot and can cause a nasty burn. They can also ignite materials that come into contact with them, such as flapping curtains etc.

● Position valve equipment well away from combustible materials. Leave at least 200 mm clearance on all sides and the top for adequate ventilation.

● Never leave a valve amplifier switched on when unattended. Keep out of reach of small children

Read more about valve safety on the kit information page.


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