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True symmetrical fully discrete R2R ladder DAC wwith built-in regenerative power supply.
New features and improvements
It's been 3 years since the R-8 was released in 2018. Thanks to the R-8's fully programmable circuitry, we've continuously updated the firmware to improve the owner's experience.
The R-8HE MK3 was developed and tested in the first months of 2021, which was followed by more than half a year of continuous auditioning and software and hardware fine-tuning.
The R-8HE MK3 uses the latest discrete, servo-stabilized power supplies, whose performance is comparable to that of batteries after more than a year of calibration and optimization of every part of the circuit.
The DA parts use these new discrete servo stabilized power supplies, the analog circuits are still powered by pure Class A power supplies to achieve the best sound as determined by listening tests.
Production and sale were not planned until we were fully satisfied with the realistic sound. The improvement compared to the previous generation is quite obvious.
1. Fully discrete components are used in a truly balanced power transfer design. Four sets of fully discrete and independent DSD hardware decoders.
Eight sets of fully discrete R-2R DA modules to form a symmetrical two-channel push-pull decoder. The DA circuits are powered with the latest discrete, servo-stabilized power supply. The noise level is comparable to that of a battery, but without its dry and thin sound characteristics, so the product's operating temperature is significantly lower than that of the previous model. The analog circuitry is still powered by a pure Class A regulated power supply to achieve the best sound results (New Upgrade)
2. Through listening and studying the sound of a turntable for a long time, we managed to integrate the sound characteristics of analog vinyl into this product, which is optionally possible via the front panel. (New function)
3. Both the USB and HDMI inputs are equipped with isolators and two sets of linear power supplies that separately power the USB and HDMI modules before the isolators to avoid interference from signal sources.
a, USB uses a two-way transmission isolator, which not only transmits the IIS signals to the FPGA processor, but also receives the synchronous clock signal sent from the FPGA processor.
The USB interface itself is no longer equipped with clock generators. The synchronous clock is used to make the signal transmission more accurate and raise the sound quality to an excellent level. The sound quality is now actually better than the previous generation R-8 2020 powered by the DI-20 (though not quite as good as the DI-20HE).
b, the HDMI module is now equipped with an independent isolator to improve the HDMI input sound quality.
4. Function to display the sampling rate of the input signal. (New function)
5. The digital circuitry of the entire DAC consists of an FPGA and five CPLDs (both programmable devices), which allow separation of the various functional circuits and prevent interference. The FPGA works in parallel data processing mode.
The IIS signal is a serial data transmission. Each data bit requires one clock cycle. A frame of left and right channel data requires 64 clock cycles, so stability over 64 clock cycles is required.
Parallel mode only needs one clock to transmit and process the 32-bit left and right channel data, which greatly improves the processing speed and is less affected by the stability of the clock.
The IIS input data (USB and HDMI-IIS) is reorganized into two parallel 32-bit datasets as soon as they are input. After the SPDIF signal has been demodulated, it is also passed on to the next processing stage via two parallel 24-bit data sets.
DSD data is also reorganized into two groups with 64-bit parallel processing as it is input.
According to listening comparisons, the parallel processing mode can make the sound clearer and more neutral, with better dynamics and a more analog flavor.
6. Two top-of-the-line Accusilicon TCXOs with frequencies of 90 and 98 MHz ensure synchronization of the entire device and are used for playback of all data rates without PLL upscaling. The clock management design of the new architecture ensures a more stable clock, resulting in higher transparency and more details.
7. DSD uses the built-in asynchronous clock to improve timing, which significantly increases playback clarity and dynamics.
8. SPDIF supports DOP playback.
9. All digital mode settings can be changed live from the front panel.
10. There is a firmware upgrade port on the back of the device (no need to open the cover to upgrade the firmware).
Fully analog regenerative power supply
A regenerative power supply is like a private generator built into the machine. It can largely filter out the noise on the power line, provide the audio components with super-pure power, and return consistent and impressive bass and high-analog signal to the audio system and end users.
In the regenerative power supply implementation, the 120V/220V AC power is converted to DC power through the input regenerative transformer, which is then supplied to the regenerative waveform generator and driver through a parallel stabilized Class-A power supply.
A set of symmetrical regenerative waveform generators produces an extremely low-distortion 50Hz sine wave. After a balanced gain stage and a powerful driver stage, three regenerative output transformers output a pure voltage that is stable in both amplitude and frequency.
Two sets of parallel regulated Class A power supplies independently power the analog output stages of the left and right channels as well as the digital audio parts with their various processing functions. Both the regenerative waveform generator and the driver are powered by a stabilized class A power supply, so their work is not affected by mains fluctuations and interference.
The Class A shunt regulator has a very high input impedance to block interference and prevent noise on the power line from entering the audio circuit and affecting the sound quality; it also avoids the crosstalk generated by the power supply from the left and right signals, improving isolation. The low output impedance has excellent linearity and speed, which also allows for an excellent design for a regulated power supply. Audio gd's
Renewable power supply design arguments:
1. Through the internal design analysis and actual test comparison of the AP SYS-2722, the distortion of the purely analog regenerative sine wave generator is much lower than that of digital synthesis generators.
2, The digital drive stage can have higher power conversion efficiency, but the all-analog drive stage has a more analog flavor.
3. The regenerated waveform frequency of 400Hz has higher power conversion efficiency. However, the regenerated waveform frequency of 50Hz is farther from the sensitive range of human hearing than 400Hz, and the sound quality is therefore smoother and more natural with 50Hz.
The advantages of the R-2R DAC:
- R-2R does not convert the clock signal to the output signal.
- R-2R is immune to jitter while delta-sigma is very sensitive.
- The output signal level of R-2R is more accurate than delta-sigma.