Model number TU-8850
Price JPY 151,800 (incl.tax)
[JPY 138,000 (excl.tax)]


TU-8850 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 SW at the top panel. Selecting from 3 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.

■ 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.

■ 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.

■ Headphone noise correspondence
In recent years, various types of very high sound quality headphones and earphones became available in the market. This amplifier is for those who has 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 conducted, 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.
Phone Level_s.jpg

■ Ample space for larger coupling capacitors
Coupling capacitors can have a big effect on the sound quality. For TU-8850, high quality conductive polymer electrolytic caps and polypropylene film caps are used. The maximum size of the caps to fit in the space is 22mm in diameter x 44mm in length.
Cap Upgrade_s.jpg


■ Corresponding tubes
Voltage amplifying tube: 12AU7 (ECC82, 6189) x 2pcs
Output tube : [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
*Those of HIGH mode group tubes can be used in MID and LOW modes, and those of MID group can be used in LOW mode.

■ Mode switch
[Power mode] LOW, MID, HIGH
[Output tube operation mode] UL (Ultra-linear connection), TRIODE (Triode connection)

■ Max. output (8Ω load, THD 10%)
[HIGH mode] 2 x 16W (KT170, UL mode), 2 x 13W (KT88, UL mode), 2 x 9W (KT88, TRIODE mode)
[MID mode] 2 x 9W (KT88, UL), 2 x 7.5W (EL34, UL), 2 x 6.5W (KT88, TRIODE)
[LOW mode] 2 x 3.5W (6L6GC, UL), 2 x 3W (6L6GC, TRIODE)

■ Rated input (HIGH mode, KT88):
[UL mode] 850mV rms (standard NFB), 400mV rms (HIGH-GAIN)
[TRIODE mode] 820mV rms (standard NFB), 450mV rms (HIGH-GAIN)

■ Frequency response (-3dB, UL, standard NFB): 15-60,000Hz

■ Residual noise (IHF-A, 8ohm load, standard NFB): 33uV 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 (6.3mm)

■ Speaker impedance: 4 - 16ohm
■ Headphone impedance: 8-600ohm (corresponds to high impedance headphones as well), unbalanced
■ Power voltage: 100V AC 50/60Hz, IEC standard 3P inlet type
■ Rated power consumption:
115W (HIGH mode, KT170),
80W (MID mode, KT88),
45W (LOW mode, 6L6GC)
■ Dimensions: W356 x H214 x D320mm (incl. projections)
■ Weight: Approx. 11.2kg (assembled, excl. tubes and power cord)