General Information
1704 is the high-grade model in the traditional audio DAC(Inverted T-shaped R-2R resistor network),it is a real 24-bit DAC chip, in order to play the same performance index,the requirements of the peripheral circuits,the development of design requirements and the overall costs is higher more than the Σ-Δ (sigma- delta)type DAC.For these reasons,to the PCM1704,the DAC chips in such structure had no further developed. Now it is replaced by the Delta-Sigma type DAC which is easy to produce and can support 24-bit theoretically.(In recent years, most of the audio DAC produced use the Sigma-Delta DAC type.) The sound performance of PCM1704 is very natural and have lasting appeal,the Sigma-Delta DAC type of can not surpassed fully.Now only the flagship's model with no cost uses the PCM1704. With the help of the dScope Series III digital audio analyzer with powerful audio analysis capability,in order to get the satisfactory results on the performance index and the sence of listening,Yu_Long Audio spent six years developing and comleting the DAC based on PCM1704 through numerous proofing and adjustment. The main functions of DA1704 are as follows
A conversation,it can carry out high-quality USB decoding and headphone amplifying output, at the same time it is equipped with optical fiber and coaxial input port. RCA output:it can be used as a single decoder(the pure decoder version without the headphone amplifying circuit is available). The reception part of DA1704 uses the TAS1020B as the USB interface.The TAS1020B with excellent sound quality supports 24BIT/96KHZ Sampling Rate . It can send the I2S signal to the digital filter chip DF1704,to carry out the Digital Filter Treatment,for PCM1704 DA conversion , the machine will get the best voice only in the USB mode. The optical fiber and the coaxial input use the CS8416 to handle and output the I2S signal to the DF1704 to sample and filter,after that the PCM1704 begin to DA Conversion. The analog part use two OPA627 and OPA134 of BB to handle the I/V,process the LPF and output the buffer. The part of the headphone amplifying uses the buffer circuit that consist of the OPA2134 and eight transistors whose output current can reach up to 800ma to drive the headphone. The DA1704 uses star topology GND .Digital signal ground,digital power supply ground,analog signal ground and analog power supply ground are all wiring independently,they are connected together to a point to the ground by the star topology. Between the digital ground and the analog ground,the technology of Copper Pour floating GND The power supply uses Canada PLITRON Transformers， mulitiple sets of secondary stabilized voltage , to suppy.These measures can allow the PCM1704 to give full play to the best performance. The style of voice is as follows:vigorous and generous,wide sound field,fine and sweet,the whole frequency is equivalent,natural and endurable.
A conversation,it can carry out high-quality USB decoding and headphone amplifying output, at the same time it is equipped with optical fiber and coaxial input port. RCA output:it can be used as a single decoder(the pure decoder version without the headphone amplifying circuit is available). The reception part of DA1704 uses the TAS1020B as the USB interface.The TAS1020B with excellent sound quality supports 24BIT/96KHZ Sampling Rate . It can send the I2S signal to the digital filter chip DF1704,to carry out the Digital Filter Treatment,for PCM1704 DA conversion , the machine will get the best voice only in the USB mode. The optical fiber and the coaxial input use the CS8416 to handle and output the I2S signal to the DF1704 to sample and filter,after that the PCM1704 begin to DA Conversion. The analog part use two OPA627 and OPA134 of BB to handle the I/V,process the LPF and output the buffer. The part of the headphone amplifying uses the buffer circuit that consist of the OPA2134 and eight transistors whose output current can reach up to 800ma to drive the headphone. The DA1704 uses star topology GND .Digital signal ground,digital power supply ground,analog signal ground and analog power supply ground are all wiring independently,they are connected together to a point to the ground by the star topology. Between the digital ground and the analog ground,the technology of Copper Pour floating GND The power supply uses Canada PLITRON Transformers， mulitiple sets of secondary stabilized voltage , to suppy.These measures can allow the PCM1704 to give full play to the best performance. The style of voice is as follows:vigorous and generous,wide sound field,fine and sweet,the whole frequency is equivalent,natural and endurable.
