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Deep Abyss Audio (14) - MC Profiles and Demo: ProAudio‑Spec PopoDAC (USB DAC) DIY

‹ 2026/01/13 ›

Hello everyone.

We’ve finally reached Part 14 — the final chapter of the PopoDAC design & development series.


And yes… as promised, this last chapter includes a real hardware demo.



Before we get there, let’s walk through the concept of MC Profiles and how they shape PopoDAC’s playback behavior.


PopoDAC enters the operational phase

At the time of writing, PopoDAC has already moved into the operational stage.

I’ve prepared three different MC Profiles, each with its own personality and playback philosophy, and I’m enjoying tuning and switching between them.


What is an MC Profile?

MC Profile (Mission Control Profile) is the profile set that defines the behavior of the PopoDAC CCC engine — specifically the GNC and TDP phases.

Its actual form is a modular structured type:

mission_core_profile_t

typedef struct {

    char name[20]; // Profile name

    TimelineAdjuster_t   tla; // PCNT front-end (outlier removal / smoothing)

    FeedbackUplinker_t   ful; // PCNT back-end (uplinks error to ASRC)

    TimelineDynamics_t   tld; // ASRC core (worldline control engine)

} mission_core_profile_t;


This mission_core_profile_t represents the entire MC Profile.


Among PopoDAC’s three‑phase engine,

  • two modules belong to GNC, and
  • one module belongs to TDP.

These three components collectively determine PopoDAC’s playback character.


In other words, by preparing profile sets tailored to your listening preferences, you can dramatically expand the reproducible domain of PopoDAC.


GNC‑Phase Profiles

The profiles related to the GNC phase form the first constraint in PopoDAC’s personality — they define “where D.J.Popo stands” in the time‑axis worldline.


The structure is two‑layered:

  • Front‑end: behavior between RTS → TLA
  • Back‑end: behavior between TLA → FUL


More concretely, based on the effective fS and its fluctuation characteristics, the profile determines:

  • the optimal MTL (Master Timeline) plateau to lock onto
  • the “stickiness” or “elasticity” of that plateau
  • how strongly PopoDAC resists or embraces timeline drift


For example, depending on the parameter settings, PopoDAC may:

  • discover an ideal plateau at MTL = 96000, yet
  • decide that Plateau “2” (MTL = 96007) offers a more comfortable operational state, and continue navigation there.

This is the kind of personality shaping that GNC profiles enable.


TimelineAdjuster_t

typedef struct {

    uint32_t warmupCountdown;      // Acquisition warmup countdown

    uint32_t inRangeGainPermil;    // Outlier detection gain (permil)

    uint32_t normalPermil;         // Nominal smoothing coefficient (permil)

    uint32_t normalMinusPermil;    // Reduced smoothing coefficient (permil)

} TimelineAdjuster_t;


TimelineAdjuster_t is the control parameter set for the first stage of the GNC phase.


This stage is not where you pursue listening preference.

Its role is simply to secure a region of behavior that maintains compatibility with the USB host.


FeedbackUplinker_t

typedef struct {

    uint32_t lsbStep;              // LSB Step Gain

    uint32_t lsbSubStep;           // LSB Subdivision Factor

    uint32_t ltErrReduction_mHz;   // Long-Term Error Reduction (mHz)

    uint32_t deadband_mHz;         // Deadband Window (mHz)

    uint32_t deadbandScale;        // Deadband Scaling Factor

    uint32_t intervalMs;           // Feedback Transmission Interval (ms)

    uint32_t lockThresh_mHz;       // Lock Threshold (mHz)

    uint32_t unlockThresh_mHz;     // Unlock Threshold (mHz)

    uint32_t lockErrMax_mHz;       // Instantaneous Error Limit (mHz)

} FeedbackUplinker_t;


FeedbackUplinker_t is the first parameter set that introduces actual “preference” into PopoDAC.


The subsequent TDP‑phase parameters build upon this set, allowing you to shape D.J.Popo’s personality.

It is no exaggeration to say that the skeleton of the character is determined here.


Concretely, this module defines:

  • the step size for plateau exploration
  • how short‑term fluctuations are absorbed
  • how long‑term drift is attracted or corrected

From these behaviors, PopoDAC determines the landing point and tolerance of the MTL — in other words, D.J.Popo’s footing and stability.


TDP‑Phase Profile

The final stage of the MC Profile influences the thruster output.

This is where PopoDAC decides “how D.J.Popo moves his hands.”


I’ve illustrated this “handwork” concept again in the diagram (in the original article).


For example, with 96 kHz sampling, the audio stream contains mixed components — 100 Hz, 1 kHz, and so on — and PopoDAC extracts them in 1/96 slices.


Here, D.J.Popo:

  • receives samples from UAC
  • picks out the 1/96‑sized slices
  • rearranges them based on the MTL determined in the GNC phase
  • and generates thruster fuel (the ASRC output)


Depending on the parameter settings, D.J.Popo’s:

  • reach
  • agility
  • precision of rearrangement
  • all change.


These traits strongly affect imaging, localization, and instrument separation, giving the final output its unique character.


(In contrast, EQ or DSP systems further decompose these slices vertically into frequency bands and perform frequency‑domain operations.)


TimelineDynamics_t
typedef struct {

    float lockCountMax;      // Lock Acquisition Window (cycles)

    float lockBand;          // Lock Stability Band (LSB-equivalent)

    float unlockThreshold;   // Unlock Divergence Threshold

    float alpha;             // Loop Filter Coefficient (IIR)

    float maxStep;           // Slew Rate Limit (fractional)

} TimelineDynamics_t;


This module defines the allowable range of handwork within the stable footing established earlier.

If you want sound that is closer to the original recording, you would prefer minimal movement from TLA.

If you want stronger instrument separation, you allow more freedom in the handwork.


The Essence of MC Profiles

Ultimately, unless you drastically break the structural boundaries of the parameter sets, MC Profiles are no longer a matter of “technical correctness.”


They become:

  • a canvas for expressing your own sensibility and preference —
  • crafting the final landing point of D.J.Popo’s worldline.


PopoDAC’s MC Profile system is not just a configuration.

It is a creative instrument for shaping time‑axis behavior.



My Favorite 3 Profiles - Demo

And now…!


Thank you for waiting — truly.

Let’s finally move on to the demo.


Here we go. 😊


YouTube Demo

Video URL:https://www.youtube.com/watch?v=3Ayq-Jfzpyw


In this demo, I showcase my three favorite MC Profiles, each representing a different playback philosophy within PopoDAC’s worldline engine.

You’ll hear how the GNC and TDP phases — and ultimately D.J.Popo’s “footing” and “handwork” — shape the final sound.




PopoDAC USB-DAC Mission Control Profiles – Listening Comparison

DDC: MPU (ESP32‑S3), Timeline Locking with a Real BLCK Pulse Counter and implementation of the I2S Thruster Output

DAC: PCM5102A

MC Pro. (Mission Control Profiles): Three profiles prepared based on my personal preferences

Audio Quality Preset: 96 kHz / 32 bits / 512 fS


🌑 BlackEdge‑78

Keywords: blackness, focus, tension, speed

Low range: tight with deep extension; quality over quantity

Mid range: the strongest vocal core; sharp imaging

High range: defined edges without harshness

Soundstage: stronger front‑to‑back depth than lateral width

Groove: the strongest; the essence of TL78

The timeline exhibits the least fluctuation, giving sharp rhythmic attack.


⚡ DarkThunder‑78

Keywords: impact, thickness, density, thunder‑like drive

Low range: more quantity than BlackEdge

Mid range: added thickness; vocals sound “fatter”

High range: slightly rounded but with strong energy

Soundstage: high density with strong forward push

Groove: more “bold and powerful” than BlackEdge

The timeline remains stable, with strong forward‑pushing energy waves.


🌫 SoftVeil‑80

Keywords: width, looseness, naturalness, flow of light

Low range: soft and natural

Mid range: vocals spread gently

High range: the smoothest, with a sense of light particles

Soundstage: the widest among the three

Groove: calm, but the beauty of the flow stands out

The quantum flow (Quantum Flow) is the most beautiful and easy to listen to.


Please enjoy the demo!

And with that—

we’ve reached the end of the PopoDAC series.


How was it?


If you found yourself thinking:

  • “That was fun!”


…then you’re probably one of us — a true audio maniac. 😊


Thank you for following this long journey through timelines, worldlines, and D.J.Popo’s universe.

Let’s meet again in the next story.