Headphone Amplifier

9i-92SA DAC/headphone Amp/Pre Amp

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..........9i-92SA "Golden Thrush" DAC / Headphone Amplifier / Pre-amp is a follow-up to the 9i-90SA "Lark". It is excellent both in performance and function. Its research and development lasted for half a year and made its debut at the Guangzhou International Audio Exhibition in 2018. ............This product has a high positioning. According to our plan, it is in the middle and high position of the desktop product series. Therefore, we have invested more resources in planning and design. The USB part is equipped with the most advanced solution, and the analog circuit is also carried out. Carefully designed to achieve a high level of performance.
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Product description

.      9i-92SA "Golden Thrush" dac / headphone amplifier / preamplifier is a desktop hifi product designed by Cen.grand. It integrates a variety of current advanced technologies and solutions, such as USB isolation technology, dual AK4497 decoder chip, etc., the audio quality is excellent, especially the quality of its headphone amplifier is very good, it can get very good effect in driving the mainstream headphones HD800S and T1-II


       This machine has many functions and performs well on the adaptability of the headphones. There are not only four types of headphone jacking, but also different output circuits for high and low impedance headphones. As a headphone hifi product, "Golden Thrush" is excellent both in performance and function.


       The 9i-92SA "Golden Thrush" consists of the following parts:

       1: USB interface. XMOS second generation XU208 + FPGA digital processing module is used, and isolation technology is used to isolate noise from the computer. Support for NativeDSD512  and PCM384 input.

       2: AK4118+ dual AK4497DAC. The SPDIF  has three interfaces: coaxial, optical, and AES, support  PCM 24bit/192KHz and DOP (DSD64) inputs.

       3: Headphone amplifier. It has 6.35 unbalanced interface and 4-core XLR balanced interface. It has four connections mode: standard, balanced, virtual ground and parallel.

       4: Pre-amp consisting of discrete components. "Golden Thrush" can be used as a pre-amp, the input interface is RCA and XLR, with infrared remote control.

       5: Power supply and display system.


      The following is a block diagram of the 9i-92SA "Golden Thrush":


      The figure above shows that there are 4 mode to connect the headphone . The sound of each mode has its own characteristics, and the difference is very obvious. This is a very useful  for the user, and the user can work optimally by selecting the most suitable mode. Under normal circumstances, high-impedance and high-quality headphones are suitable for balanced output mode, which can fully drive the headphones with powerful driving force. Some headphones that are easier to drive can use parallel or virtual ground mode. Here, I would like to introduce what is the "virtual ground" mode.


      The positive terminal of the headphone cable should be connected to the positive output, and the negative terminal should be connected to the GND. If we connect the input terminal of one amplifier to GND, the output will get 0 level, which is the same level as GND. At this time, the negative terminal of the headphone is connected to this 0 level, which is equal to GND. However, this is not the real GND, but the simulated GND, which is "virtual GND". This kind of connection can get a more unique sound, and the actual listening experience is warmer and softer, suitable for listening to human voice or string. In short, the "virtual GND" mode provides users with an effective tuning method that increases adaptability and entertainment.


      The second generation of XMOS is the latest XMOS solution, which is faster. Isolation technology refers to physically isolating the computer from the machine, and the ground wire is not connected, completely isolating noise  from the computer. This feature is very effective because there are a large number of switching power supplies inside the computer that generate a lot of noise, which can interfere with the analog circuit and degrade its performance. Isolating these noises can significantly improve the purity of the sound.


      The code inside the FPGA has several functions: data isolation management, clock distribution, and DOP functionality.


      The LPF is a balanced structure and the opAmp uses LME49720, a high performance opAmp. The analog output section is a discrete device architecture that has been carefully tuned to correct the sound. The volume control is PGA2311, controlled by MCU, and the range is -70db~0db. Its common volume section has been optimized, volume adjustment and listening habits are more coordinated, and there are reliable protection measures.


      The headphone amplifier uses a current feedback circuit. Headphone amplifier is actually a very simple technology, there is no too high technical content, the key is  adjustment. Drawing on our extensive experience in hifi  systems, we have achieved very good results when designing the "Golden Thrush" headphone amplifier. It not only has strong driving ability, but also sound balance, clear and delicate, strong sense of space, you can listen for a long time, forget the existence of headphones, just like listening to the big system. The output transistor of the headphone amplifier uses an expensive central metal package tube, which is a guarantee of performance. Careful adjustment makes this "Iron Hat King" fully exert its advantages and foster strengths and avoid weaknesses.


      The display is a customized VFD, the information displayed is complete, and the color matching is stable and beautiful.





                                         Use of 9i-92SA

      It is an excellent DAC. There are coaxial, optical, AES and other digital input interfaces, which can be used as a tool to upgrade CD player, or as an external DAC for digital players in your audio system. It has a volume adjustment function.
      It is a fully balanced pre-amp with one RCA/XLR input interface and one RCA/XLR output interface. Active speakers can be connected to build hifi systems and desktop systems. You can also connect to your power amplifier to build a large hifi system.
      It is a high performance, high current, pure headphone amplifier. It drives both high-impedance and low-impedance headphones with good musical expression.
      It is an advanced USB DAC with the second generation of XMOS. The driver is a customized version and is the best choice for pchifi players.

      The most common use of the 9i-92SA  : Connect this unit to your computer via a USB cable,the music data is transferred to the unit. USB supports DSD512/PCM384. Because the computer player is very compatible and powerful, it can play music in any format. Combined with this unit, it can form a perfect music playing system.

      The 9i-92SA's headphone amplifier has good quality and can drive mainstream high-end headphones. It has two  output circuits, respectively driving high-impedance and low-impedance headphones, and the output has four output modes, so the 9i-92SA has good adaptability to various headphones. Whether it is a 600 ohm high-impedance headphone or a 30-ohm low-impedance earphone, it can be well adapted.






                               Performance parameter


       Maximum audio support specifications:

                   Spdif input ----- PCM192

                   USB input ----- DSD512 PCM384

      Dynamic range: 115dB

      Signal to noise ratio: 115dB (A weighting)

       Frequency response: ±0.4 dB (20-20KHz A weighting)

      THD+N : -107dB (fs=96KHz /10KHz A weighting)

      Pre-level gain: 4db (volume is 0db)

      Output power: 2.1W (33 ohms distortion 0.9%) 0.5W

                              (600 ohms distortion 0.027%)

      Dimensions : 320mm * 100mm * 310mm (WHD)

      Power supply : AC 220V-230V 50-60HZ

                             (Fuse specification: 6.3A)

      Net Weight   : 5.9kg

      Total Weight : 7.3kg


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