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 preampli- fier. 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.
• 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 adopted. The maximum size of the caps to fit in the space is 22mm in diameter x 44mm in length.
• 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 adjust- ment 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.