By hwj
Mon May 18, 2026 7:15 pm
What initially caught my attention here was mainly the analog input/output section.
The analog audio section of the MPC appears to be thoughtfully designed and functionally divided. The OPA1678 op-amps are most likely used for the sonically critical stages around the ADC and DAC signal conditioning, such as filtering, buffering, and clean level conversion. Both their position on the PCB and their modern low-noise characteristics fit this role very well.
The JRC4580 op-amps, on the other hand, are located directly near the audio jacks and seem to be mainly used as robust output drivers for the main outputs. This matches their characteristics, since they are relatively high-current and stable under load, making them well suited for driving cables and low-impedance outputs.
The single 4558 (U9) does not appear to play a major role in the main signal path. Based on its position between the primary audio section and the MAX9728(U4) headphone amplifier, it is very likely used as a simple mixing or buffer stage for the headphone or cue path. The MAX9728 then handles the actual headphone power amplification.
Overall, the architecture does not look randomly assembled, but rather like a deliberately balanced design: modern precision op-amps(OPA1678) where audio quality matters most, robust older devices (JRC4580) where drive capability is important, and simple standard components for secondary internal functions.
The PCB layout strongly suggests a modern embedded audio architecture built around a dedicated ARM-based computing platform and a separate analog audio section. At the center of the digital section is a Rockchip RK3568 SoC, which most likely runs the complete Linux-based operating system and handles nearly all digital processing tasks inside the MPC, including the GUI, sequencing engine, sample playback, effects processing, audio routing, storage management, USB (-sound), and MIDI functionality.
Next to the processor is a SK hynix memory chip providing system RAM, while the smaller Rockchip RK817 chip acts as the power-management IC responsible for generating and sequencing the various supply rails required by the processor and memory subsystem.
The analog section appears to be clearly separated from the digital processing area.
There is also a complete additional chip circuit (U29) based on an STM32G0 70CC6T (Arm Cortex-M0+, 32 KB flash, 8 KB RAM). I haven't looked into the external circuitry any further, but I imagine it handles the control of the pads and other controls, as well as the display.
Also note the charging circuit for the battery and its type Polymer-Li-Ion Pouch-Cell (not LiPo) 3,85V nominal 4,25-4,35 cut-off charging voltage.
Be careful with the ribbon cables; they're hard to reinsert. I haven't examined everything in the specific context of the PCB trace routing. Much of the functionality is therefore just speculation. Please let me know if you have more detailed information so I can clarify or correct anything.
Thank's