RedRoo SE5 Stereo Amplifier
The RedRoo SE5 is a compact, high-quality, 5 Watt RMS, Class-A, tube stereo amplifier kitset. It can power loudspeakers or headphones.
Each channel uses a two-stage triode Constant Current Draw Amplifier (CCDA) driving a single ended EL34 output stage. There are two sets of RCA inputs, a 3.5mm jack input, and a Bluetooth input for streaming from your smartphone or computer. Dual 4 ohm and 8 ohm speaker outputs will easily match any loudspeaker impedance, and an internal headphone attenuator matches to common 32 ohm headphones (can easily be changed for other headphone impedances).
The EL34 output stage can be configured in either triode, pentode, or ultra-linear modes. Ultra-linear is the mode we use as it provides a compromise between the lower distortion of triode-mode and the higher power of pentode-mode. Experiment yourself.
The SE5 amplifier is simple to build yet very compact, measuring only 185mm wide, 215mm deep, and 165mm high. It doesn't take up nearly as much shelf-space as other tube amplifiers that are usually large, heavy and cumbersome compared to other types of equipment.
For those who want the ultimate experience, a weekend amp-camp is available in the Blue Mountains west of Sydney. Why not come with a friend and build one each.
Only the best quality components are used in RedRoo kits. Audio grade polycarbonate coupling capacitors, low ESR conductive polymer hybrid aluminium electrolytic cathode-bypass capacitors, unusually large output transformers, and an ALPS R-27 volume control, all preserve the delicate detail of the music and ensure strong and accurate base reproduction.
The front panel holds a large solid metal volume knob and toggle switches for power on-off and three-way input selection (2 x RCA inputs - second input with a switching 3.5mm jack - and a Bluetooth wireless input), and a 1/4inch headphone jack. Blue LED's shine up under the tubes when the power is on (can be changed for any LED colour).
The rear panel holds the input connectors, speaker connectors (which will accept either bare wires or banana plugs), a speaker impedance switch (4-ohm/8-ohm), and a feedback on/off switch. The feedback switch, which switches in/out 5 dB of negative feedback, alters the damping factor, output impedance, and distortion characteristics of the amp. You can choose what sounds best for your particular speakers, listening environment, and music choices.
For added safety for kit builders, mains power does not enter the chassis. The unique power supply design, DC heaters, and earth-loop protection, means that there is no power supply induced hum or buzz from the speakers. It's a surprisingly quiet low-noise amplifier.
The PC Boards are extra thick (2mm) with 2-oz copper tracks for enhanced durability and heat transfer.
The RedRoo SE5 will impress with the energy and dynamics from such a compact and affordable tube amplifier, and there is nothing like saying "I built it myself".
We rate this kitset difficulty level 3 out of 5. The circuit does contain hazardous voltages up to 280V DC.
*You can also buy a set of PC boards with the power supply module and full build information- for those who like to supply their own components and build their own bespoke chassis.
The following items can be purchased separately
The standard output transformer and power supply are in the kit.
$106.70 - RedRoo 10W Single Ended Transformer with UL taps, in an attractive steel case.
Click to order. (approx US$80)
This is our standard output transformer supplied with the kit. It gives excellent performance in the RedRoo SEs design and aligns with pre-drilled holes in the RedRoo chassis.
Single ended output transformer for Pentode, Triode and UL operation
Power Handling: 8W (30Hz),
Frequency response (no negative feedback): 15Hz-25KHz, -3dB
Primary impedance: 3.5K with 30% screen grid taps. (5k also available)
Primary copper resistance: about 400Ω (B-P),
Primary inductance: with Measuring equipment CHROMA3302, frequency 1KHz inductance of 38H
Primary maximum DC current: 100mA
Secondary nominal impedance: 4/8Ω
Core Size: EI66 stack thickness 35mm,
Material: Japan Z11 steel sheet, European oxygen-free copper wire
Dimensions (mm): 83 x 68 x 90 high
1-4 weeks depending on stock
Replacement for the standard transformer. Lopent OPT with extended high frequency response in same attractive metal case as the Standard transformer. Lower DC winding resistance gives slightly higher power output and increased loudspeaker damping.
No screen taps - triode and pentode mode only. A good choice if you have audiophile grade speakers and play quality uncompressed source material.
Frequency response: Pentode Connection: -3dB 20Hz-60KHz Triode Connection: -2dB 10HZ-75KHz
Power Handling: 10W @ 20Hz,
Primary nominal impedance: 3.5KΩ,
Primary inductance: 28H @40Hz, 5Vrms, Test machine HIOKI 3522-50 LCR Meter,
Primary Max DC primary current: 75mA
Primary DC resistance: 215Ω
Secondary nominal impedance: 0-4-8Ω,
Secondary DC resistance: 4 Ohm tap 0.77ohm，8 Ohm tap 1.05ohm
Metal core size: EI76 thickness 40mm，material: 35H360 (H14)
Dimensions (mm): 83 x 68 x 90 high
1-4 weeks depending on stock
This assembled power supply module is used to convert 12V DC to the high voltage required for the tubes. It does not produce any 50Hz hum and, as mains power does not enter the amplifier chassis, it is safer for home constructors. Ideal for use in small Class-A amplifiers up to about 20 Watts. output.
Input voltage: 12 VDC nominal. Current load dependent.
Output voltage: 115/200/220/280 V AC or DC selectable by links.
Output Power: 150 Watts max. Over 100 Watts requires extra cooling.
Switching Frequency: approx. 40kHz (no 50Hz hum in output).
Optional enable input (for amplifier kill-switch).
Dimensions (mm): 68 x 62 x 28 high.
Always in-stock