DIY SE Tube amplifier kit ELEKIT TU-8850VK

900,00 1721,50  exc. VAT

Single Ended Power amplifier kit with automatic bias system which allows to use various types of octal base pentodes and beam tubes without need to manual bias change. It contains all required parts including enclosure. Kit itself in this version (VK) is doesn’t contain standard output transformers, so you can buy and use Lundahl OPT transformers or your own ones.

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TU-8850VK is a power amplifier kit which allows users to try various types of octal base (US8P) pentode and major beam tubes. In this amplifier, the bias condition is kept at an optimal level for the output tubes installed without a complicated bias adjustment by “Active Automatic Bias Adjustment System“. In addition, the amplifier is equipped with a power mode switch at the top panel. Selecting from three operation modes, HIGH, MID and LOW, users can try various types of output tubes, small to medium tubes, such as 6L6 to bigger ones like KT150, KT170, etc.

Elekit TU-8850 Phones Level

Headphone noise correspondence

In recent years, various types of very high sound quality head-phones and earphones became available in the market. This amplifier is for those who have an aspiration for enjoying such high quality sound from a tube amplifier. Thorough countermeasures for hum noise, such as well-established FET ripple filter and DC-power for voltage amplifying tubes, are taken, which realizes a noise free performance even with high-efficiency speakers. In addition, a headphone level adjustment system is equipped to cope with very high efficiency headphones and earphones with which a residual noise is easy to be recognized. The level can be easily adjusted by a jumper socket.

Gain switching jumpers

This is a power amplifier basically used in conjunction with a preamplifier. However, gain switching is enabled by switching a jumper socket position and it is possible to connect the amplifier directly to a LINE output of a sound source device without a preamplifier in between.
Elekit TU-8850VK with KT170 Front

Elekit TU-8850VK Cap Upgrade

Ample space for larger coupling capacitors

Coupling capacitors can have a big effect on the sound quality. For TU-8850VK, high quality conductive polymer electrolytic caps and polypropylene film caps are adopted. The maximum size of the caps to fit in the space is 22 mm in diameter x 44 mm in length.

8850 E vs 8850 VK models

Standard version of TU-8850E is equipped with standard output transformers which are very well suited to the circuit. Although if you want to achieve the best possible sound quality, there is a version of this amp labelled VK – TU-8850VK which is not equipped with output transformers. To have the fully working amp, you can add your own transformers or buy a special Lundahl OPT upgrade kit for TU-8900VK. This additional kit contains two highest quality, hand-made Lundahl transformers as well as required PCB’s and wires.

Output tubes operation mode switching system

For pentode and beam tubes, Triode connection is accomplished by connecting the screen grid to the plate. This amplifier has an operation mode SW at the top panel so that users can easily enjoy the sound difference in 2 different modes, UL (Ultra Linear) and Triode modes.



Voltage amplifying tubes: 12AU7 (ECC82, 6189) x 2 pcs
Output tubes: HIGH mode: 6550, KT88, KT90, KT120, KT150, KT170, etc.
MID mode: 6L6GD, 5881, 7581, KT66, KT77, EL34 (6CA7), etc.
LOW mode: 6L6, 6L6G, 6L6GB, WE350, etc.
Mode switches: Power mode: LOW, MID, HIGH
Output tube operation mode: UL (Ultra-linear), TRIODE
Max. output (8Ω load, THD 10%) HIGH mode: 2 x 16 W (KT170, UL), 2 x 13 W (KT88, UL), 2 x 9 W (KT88, TRIODE)
MID mode: 2 x 9 W (KT88, UL), 2 x 7,5 W (EL34, UL), 2 x 6,5 W (KT88, TRIODE)
LOW mode: 2 x 3,5 W (6L6G, UL), 2 x 3 W (6L6G, TRIODE)
Rated input (HIGH mode, KT88): UL mode: 850 mV rms (standard NFB), 400 mV rms (HIGH-GAIN)
TRIODE mode: 820 mV rms (standard NFB), 450 mV rms (HIGH-GAIN)
Frequency response (-3 dB, UL, standard NFB): 15 – 60000 Hz
Residual noise (IHF-A, 8 Ω load, standard NFB): 33 μV rms
Input terminal: 1 x RCA jack stereo
Output terminal: Speaker output: Binding terminal (Gold plated, banana plug compatible)
Headphone output 3-pole standard jack (6,3 mm)
Speaker impedance: 4 – 16 Ω
Headphone impedance: 8 – 600 Ω, unbalanced
Power voltage: AC 110 – 120 V or AC 220 – 240 V 50/60 Hz (3P inlet)
Rated power consumption: 115 W (HIGH mode, KT170)
80 W (MID mode, KT88)
45 W (LOW mode, 6L6G)
Dimensions: W 356 x H 214 x D 320 mm (incl. projections)
Weight: Approx. 11,2 kg (assembled, excl. tubes and power cord)

Additional information

Weight 14,1 kg
Dimensions 49 × 41 × 28 cm
Tubes set

JJ Set (KT88 x 2 + ECC82 x 2), Without tubes

Output transformers


Assembly service



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