syn08
Senior Member
I started this project over one year ago; went through several false starts (AK4499 MIA due to the AKM fire, relied on the TI ADS127L01 ADC (which proved to be improper to audio due to the high noise), tried the AKM AK5572 ADC, distortions were too high, plus the ever annoying (for measurements) noise shaping, the ES9822 datasheet hell, the ES9311Q chip hell, etc...).
Now that I retired I obviously have more time to assign to this project - and here's the first prototype, ES9038PRO DAC, ES9822PRO ADC, XMOS USB 384k interface. DAC/ADC are both dual mono in this prototype. So far, this is nothing but at at best a glorious USB sound card on three boards, there's no analog I/O yet, no autoranging, etc..., DAC and ADC are in an analog loop. A single board (4.4" x 3.9") version is in the factory, due next week, (with both DAC and ADC in stereo mode), the analog I/O design is on the whiteboard... it will require some magic to match the digital side performance
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See the attached first measurements using REW (Vrms was not calibrated). No gimmicks, no filtering, no distortion trimming (I concluded it is a useless exercise, being so dependent on level and frequency; I may eventually consider lookup tables in the firmware, though), no notch filters, just the raw data, therefore this is pretty much the worse case performance (up to the analog I/O).
Even on this first prototype the design target for the analog loop was met (THD<-120dB, THD+N<-105dB), for both metrics the limitation being mostly the ES9822 ADC. I am expecting the single board version to get slightly better.
The Arta measured values are in pretty good agreement with REW although, for whatever reason, the spectral components are visually slightly lower. But I concluded some time ago that anything around -120dB is essentially very hard to reproduce exactly. Of course, some golden ears claim they can hear such differences :rofl:.
Some schematics were already published on the other side, where I was banned from. As soon as the project is completed, it will be uploaded as Open Source, both hardware (schematic, Gerbers) and software. There's no IP to protect here, other than the good layout practices and the effort to navigate through the ESS documentation nightmare.
Now that I retired I obviously have more time to assign to this project - and here's the first prototype, ES9038PRO DAC, ES9822PRO ADC, XMOS USB 384k interface. DAC/ADC are both dual mono in this prototype. So far, this is nothing but at at best a glorious USB sound card on three boards, there's no analog I/O yet, no autoranging, etc..., DAC and ADC are in an analog loop. A single board (4.4" x 3.9") version is in the factory, due next week, (with both DAC and ADC in stereo mode), the analog I/O design is on the whiteboard... it will require some magic to match the digital side performance
.See the attached first measurements using REW (Vrms was not calibrated). No gimmicks, no filtering, no distortion trimming (I concluded it is a useless exercise, being so dependent on level and frequency; I may eventually consider lookup tables in the firmware, though), no notch filters, just the raw data, therefore this is pretty much the worse case performance (up to the analog I/O).
Even on this first prototype the design target for the analog loop was met (THD<-120dB, THD+N<-105dB), for both metrics the limitation being mostly the ES9822 ADC. I am expecting the single board version to get slightly better.
The Arta measured values are in pretty good agreement with REW although, for whatever reason, the spectral components are visually slightly lower. But I concluded some time ago that anything around -120dB is essentially very hard to reproduce exactly. Of course, some golden ears claim they can hear such differences :rofl:.
Some schematics were already published on the other side, where I was banned from. As soon as the project is completed, it will be uploaded as Open Source, both hardware (schematic, Gerbers) and software. There's no IP to protect here, other than the good layout practices and the effort to navigate through the ESS documentation nightmare.
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