Elekit TU-8900E & TU-8900VK 300B / 2A3 Single Ended Tube Amplifier kit
Directly-heated triode tubes like the 300B and 2A3 enjoy an enduring popularity among audiophiles. The 300B with its rich mid range and extended bass - and 2A3 with its delicate expression and gentle tone - they offer a very special sonic experience. These 2 tubes, similar in appearance but very different in characteristics, can both be used in TU-8900 without any special changes in amplifier settings. Many manufacturers are producing 300B and 2A3 tubes so users can enjoy trying the various versions available in the market. PLEASE NOTE- TUBES ARE NOT INCLUDED with THE TU-8900 KITS.
Automatic detection of 300B and 2A3 tubes
300B and 2A3 tubes look similar but their respective filament voltages and operating parameters are totally different. Their supply voltages need to be adjusted depending on which of these tubes are used in the same amp. In TU-8900, the tubes installed are detected automatically and the correct filament voltage and voltage of B-power are automatically set. When 300B tubes are installed, the LEDs on the sides of the volume knob will light up in blue. If 2A3 tubes are installed, the volume knob LEDs will light up in green. Additionally, these LEDs on the right and left side of the volume knob will turn red when there is excessive current due to defective tubes, etc., and the current is shut down to protect the amplifier. The red LEDs will also diagnose the problematic tube- the right side of the volume knob turns red when excess current occurs in the right channel, and vice versa.
Tube friendly Design
Warm-up time for directly-heated tubes and indirectly-heated tubes are different. In most designs, directly-heated tubes warm up faster than indirectly-heated tubes. So directly-heated tubes are often overloaded. With TU-8900, the voltage is gradually raised and reduces the level of overload to the directly-heated tubes.
Ample space for upgrading the decouplier capacitor
Coupling capacitors can have a big effect on the sound quality. For the TU-8900, high quality conductive polymer electrolytic caps and polypropylene film caps are provided. However, changing for another coupling capacitors is also possible. The maximum size of the caps that can fit in the space is 22mm in diameter x 44mm in length.
Matching headphone impedance / volume levels
You can change the headphone impedance/volume levels by simply removing the front panel and change the position of a short pin.
Newly designed circuity from the TU-8600
The power transformer has independent windings for the right and left channel to minimize the interference between channels as much as possible. The filament power uses the latest DC-DC converter with extremely low noise and high efficiency. Schottky barrier diodes and fast recovery diodes are used as rectifying diodes that reduce even the most negligible noise spikes. Listeners can enjoy music free from noise even when using a pair of high efficiency headphones. The main circuit of the power unit is unitized per channel as a module.
Easily change the feedback setting to NON-NFB
Many triode tube amps use negative feedback in their design. The TU-8900 has an option for listeners to hear the triode tube sound without negative feedback. In TU-8900, changing the position of a short plug on the PCB can change the setting to NON-NFB. The gain level increases by approx. 8dB when NON-NFB setting.
High heat-resistant polycarbonate tube cage
The IEC (International Electrotechnical Commission) sets guidelines on thermal limits on materials and parts, such as a chassis and the tube cage. The TU-8900 tube cage top can heat up to 100 degrees C due to the heat from the output tubes. A robust polycarbonate tube cage with high heat resistance is used to meet the IEC standard.
The kit is available in 2 versions. The TU-8900E uses the Elekit E & I output transformers, whereas the TU-8900VK (available mid-November 2021) is supplied with the amorphous C-core LL2785CAM output transformer from Llundahl.
- Tubes - 300Bx2 or 2A3x2, 12AU7x2 or 12BH7Ax2 * Tubes are not included
- Rated output - 8W+8W ( 300B ) 3.5W+3.5W (2A3)
- Rated input - 1Vrms (300B) 650mVrms (2A3)
- Residual noise - 15μVrms（IHF-A）
- Frequency response - 7Hz-90kHz（With NFB） / 12Hz-45kHz (No NFB)
- Input impedance - 50kΩ
- Output impedance - 4-6.3Ω, 8-16Ω (Select by the SW on the rear)
- Input terminal - LINE x 1
- Output terminal - Speaker output terminal：Gold-plated screw terminal (Banana plug compatible)
- Headphone terminal - 6.3mm headphone jack
- Power voltage - AC115/230V 50/60Hz (3P inlet)
- Power consumption - 95W (300B+12AU7) / 65W (2A3+12AU7)
- Dimensions - W356xH214xD320mm (incl. projections)
- Weight - Approx 11.2kg (excl. power cable)
Price (1 off, excluding VAT & P&P) not supplied with valves or IEC lead
TU-8900E - £1095.00
TU-8900VK (with Lundahl OPTs) - £1630.00