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  • Model: Classic No.16.4
  • Shipping Weight: 20kg

Classic No.16.4, No.16.6 and No.16.8 high performance vacuum tube integrated tube amplifiers, newly developed by Beijing Yushang Audio Technology Co., Ltd. Classic No.16.4, No.16.6 and No.16.8 vacuum tubes: 6L6/KT66, No.16.4,6550A/KT88, No.16.6 and 2A3 No.16.8 as push pull amplification of final stage.

The 3 versions adopt the same chassis design, appearance and similar electric circuit. There are just some little distinctions between the 3 amplifiers being different tubes, transformers and circuit parameters.

The Classic No.16.6 with 6550A/KT88 vacuum tubes is portrayed below as an example to make a brief introduction to the new Classic No.16.4, No.16.6 and No.16.8 series.

To get lower distortion, better amplitude-frequency and phase-frequency characteristic, its input stage adopts SRPP circuit consisted of the 12AT7. And inverter stage adopts constant current source mode of long tailed inverter circuit consisting of an integrated circuit and the 12BH7, which has a more excellent characteristic on AC balance than a typical long tailed inverter circuit has, it also reduces phase distortion. This inverter stage also has enough dynamic margin to the improve overall system distortionless output power. Final stage is a power amplifier stage consisted of the 6550A/KT88, which can be converted between ultra linearity and triode amplifying mode. Grid employs fixed bias mode.

It is worth mentioning the output transformer that Yushang Company, newly developed. With an output power of 65W 30Hz and primary impedance 4.5K it perfectly matches with 6550A. Both its synthetic technology parameter and sound quality have proved that it can bear head to head comparison with some well known output transformers. Its primary inductance runs up to 210H .5K 50Hz and only has a 3.95mH of primary leakage inductance. Primary impedance is exactly flat between 1K-10KHz frequency range and at other frequency ranges the impedance variation is minor as well. This transformers power frequency response is 5Hz-150KHz(-3dB), primary resonance frequency 240KHz and distributed capacitance below 100Pf. To ensure the transformer has both high function and quality, Yushang spares no expenses to use the best silicon steel material that is imported from Japanese Nippon Steel, and after being stamped out and tempered by Yushang, its permeability can be 1.9T. So it is impossible for silicon steel in general use, Z10 Z11, to be a rival to it. All of these make our transformers have many acoustic advantages, such as deep and clarity bass, full and stout mid rang, and rigorous and spread high frequency.

Because the Classic No.16.6 was designed so rigorously, reasonable settings like terrestrial current distribution, sampling points of loop negative feedback and local negative feedback make the overall systems open loop characteristics have strong performance. Also because the crossfire signal that goes into signal line is well controlled it can perform producing a clear and precise sound quality. Although its total loop negative feedback is 6dB, due to our superb design the parameters of the overall system keeping the highest level.

On appearance its design is unique with becoming height. Considering that tubesĄŻ plate current will change within their lifetime, a digital Ia meter is equipped to help users monitor the working mode of the final stage tubes. Practice proves that this function is essential for audiophile to have.?

Our toroidal power transformer uses Nippon silicon steel Z11. No.16.6 has a high-voltage time delay circuit from the moment it is turned on, choking winding, electron filter and remote controller shaped from aluminum.

As an option an elegant guard cage is available from Classic to protect your Classic No.16.4, No.16.6 or No.16.8 vacuum tubes.

Output Power: 55W(RMS ultra linearity mode) 25W(RMS triode mode)
Frequency Response: 5Hz-88KHz(-3dB 8W)
Power Frequency Response: 12.5Hz-80KHz(-3dB 55W)
Harmonic Distortion (THD+N):0.21%(1KHz 8W) 0.47%(1KHz 22W) 0.92%(1KHz 55W)
S/N without weight:95dB
Input Sensitivity: 0.3V(RMS)
Output Impedance: 4 and 8ohm
Static Consumption: 130W
Used Tubes: 6550A*4/12BH7EH*2/12AT7*2
Net Weight: 20Kg
Dimensions: 420*337*116

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