In a digital audio system, all chips run in accordance with the beat of the master clock. The master clock is the time reference of the entire system. To obtain perfect playback sound quality, digital-to-analog conversion must be performed at the correct time. We call the instability of the master clock system (that is, the timing a little earlier or a little later than the correct time) as jitter time base jitter.
The main effect of jitter on the sound quality is the distortion of the playback waveform, which is a phase modulation phenomenon, which is reflected in the sound quality as high-frequency harmonic distortion. Jitter is a stumbling block to improve sound quality. For the 20-bit 8 times over-sampling system, the sampling value time interval is about 2.83μs, and the 20bt resolution on the time axis requires jitter to be less than 2.7ps (if it is 16bt time base resolution, jitter is less than 43ps), high-priced The CD system can reach below 20ps, which means that it can reach a time base resolution above 16bt.
Although many advanced DACs claim to have internal jitter elimination design (master clock stgen colk). But if the digital signal transmitted by the turntable contains a large amount of time-base jitter components, no matter how good the design is, it cannot be eliminated (in fact, there will be no elimination circuit, because this is originally a one-way transmission). Therefore, to fundamentally solve the jitter problem, two major transformations must be made to the turntable.
The first is to replace the original ordinary quartz crystal with a high-precision and high-stability clock source.
Second: It&x27;s like this department performs special processing on the digital output port. Through the above processing, it is possible to upgrade a better quality CD or LD machine to a HIEND turntable. Many famous foreign Hi-end manufacturers have done this (Wadia23 and EAD T1000 are modified with Pioneer CD, EAD T-800 and Theta DataIII are modified with Pioneer LD, MarantzDT40A is modified with Marantz LD,...).
The general digital signal transmission is free of error and distortion, but the S/PDIF digital output signal is different. Because this signal contains audio data and clock, audio data can be completely transmitted, and has little to do with the transmission method (optical fiber or coaxial cable), and the clock signal is subject to transmission due to the rising or falling edge of the corresponding bidirectional modulation signal The impact of the system is very large. A rising edge/falling edge appears earlier or later to cause jitter.
The digital output port of the low-priced machine only uses one resistance level conversion, and the medium-priced opportunity uses a transformer or 74HC04, but the transformer is difficult to have good performance like an optical fiber transmitter, and the output current of a single gate of 74HC04 is too small, and there are multiple gates. Parallel connection cannot guarantee the same time delay. Therefore, these machines only implement the digital interface function, with relatively little consideration of performance.
The DS26LS31 used in this board is an RS422 transmission system, which is used by both Mark Levinson and Wadia, both of which are expensive in CD players, which can effectively eliminate the serpentine distortion in digital transmission. We also specially ordered 26LS31, a super-grade ceramic seal, which has several grades higher performance than plastic seals.
Size: 105mm*45mm