Tube Amplifier Kits

Free Design Information - Build your own high quality tube/valve audio amplifiers.
Non-commercial use only

RedRoo amplifier kitsets are no-compromise valve designs for electronics enthusiasts, audiophiles, and 'makers'. RedRoo uses top quality components with unusually large output transformers for extended frequency response.  They sound terrific, don't cost an arm and a leg compared to similar pre-built amplifiers, and should last you a lifetime. 

No matter if you're a beginner or an experienced audiophile, RedRoo amplifier kits will impress you and your friends. Many of these amplifiers have been built over the past few years with excellent results. There is nothing like saying "I built it myself".

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

The RedRoo SE5 Stereo Amplifier

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, and other suppliers.

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 amplifier kitset 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 3. 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 their usage, and moderate construction skills. Level 5 is for those who have experience handling very small electronic components and analysing complex circuitry. (We have recently reduced the experience level down from 4 to 3, as so many have been made without any apparent difficulty).

If you don't feel you do not have the necessary experience you should either seek help from someone who does, or you should 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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