PARAM POD (POD-1)

MagSafe Audiophile DAC & Headphone Amplifier
Part of the PARAMWORKS Open Hardware Collection

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Overview

PARAM POD is a portable, high-fidelity digital-to-analog converter (DAC) and headphone amplifier designed to snap magnetically (MagSafe) directly to the back of your smartphone.

Most high-end portable audio dongles and DAC bricks create two major problems: they drain your smartphone's battery in a few hours, or they require awkwardly rubber-banding a heavy, separate power brick to your device. Additionally, a separate power source helps provide a cleaner audio signature by preventing electrical noise from phone USB-C power delivery.

PARAM POD solves both:

1. Zero Phone Drain & Cleaner Audio Signature: Its onboard ~2,500 mAh LiPo pack powers the power-hungry DAC and analog output stages independently—keeping your phone's battery intact while shielding sensitive audio circuitry from noisy phone USB-C power rails.
2. Emergency Reverse Charging: Featuring a bidirectional USB Power Delivery (USB-PD) controller, it can reverse-charge your phone at up to ~1A when you are in a pinch.
3. Bit-Perfect Lossless Playback: Uncompromised UAC2 audio transmission from bit-perfect apps (Roon ARC, Tidal, Qobuz) directly over a short, low-profile right-angle USB-C bridge.

 Phone (Roon ARC / Tidal) ──USB-C, UAC2──▶ NXP i.MX RT1011 ──I2S──▶ AK4493SEQ DAC ──▶ Balanced Amp ──▶ 3.5mm / 4.4mm
        ▲                                        ▲                       ▲
        │                                        └────── MCLK (DAC Master)
        └── USB-PD Power Path (Bidirectional) ── TPS25750D ⇄ BQ25792 ⇄ 1S LiPo Cell (~2500 mAh)

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Visual Design & Hardware Renders

Final Product (MagSafe Snapped to Smartphone)

Exploded Enclosure & Hardware Stack

Audiophile PCB (Matte Black Solder Mask · ENIG Gold Finish)

Raytraced 3D render of the Rev 1 PCB featuring the AK4493SEQ Velvet Sound™ DAC, NXP i.MX RT1011 USB core, TI BQ25792 charger, and TI TPS25750D USB-PD controller.

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Technical Specifications

Parameter	Specification
DAC Architecture	Asahi Kasei AK4493SEQ Velvet Sound™ 32-bit Stereo DAC
Microcontroller / USB Core	NXP i.MX RT1011 (ARM Cortex-M7 @ 500 MHz, 128KB SRAM)
Clocking Architecture	Ultra-low phase noise dual audio oscillators (22.5792 MHz & 24.576 MHz) · DAC side clock master
Audio Protocol	USB Audio Class 2.0 (UAC2) Asynchronous · Zero driver installation required on iOS/macOS/Linux/Windows
Analog Outputs	3.5mm Single-Ended (TRS) & 4.4mm Pentaconn Balanced (TRRRS)
Power Controller	Texas Instruments TPS25750D USB Type-C and USB PD Controller
Battery Charger	Texas Instruments BQ25792 I2C Controlled 1S-4S NVDC Buck-Boost Charger with OTG / Reverse Boost
Internal Battery	1S LiPo pouch cell (~2,500 mAh with integrated PCM protection)
Mounting	Embedded MagSafe array (36-magnet ring + alignment magnet)

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Repository Structure

├── 3d-printing/                # Ready-to-print STLs for MagSafe enclosure
│   ├── pod_box.stl             # Main enclosure body with MagSafe ring pocket
│   ├── pod_lid.stl             # Snapping top lid
│   ├── cap_tree_nubs_0_15.stl  # Tactile button caps (0.15mm tolerance)
│   └── cap_tree_nubs_30_45.stl # Tactile button caps (0.30mm tolerance)
├── renders/                    # 3D product and black ENIG PCB renders
│   ├── pod_assembled.png       # Final MagSafe assembled product view
│   ├── pod_exploded.png        # Exploded enclosure stack
│   └── param_pod_black_enig.png# Raytraced black solder mask + ENIG PCB
├── schematics/                 # Reference schematics in PDF format
│   └── param-pod-schematic.pdf
├── firmware/                   # Open-source UAC2 firmware for NXP i.MX RT1011
│   ├── CMakeLists.txt
│   ├── board/                  # Board clock, pinmux, and SAI configurations
│   ├── src/                    # TinyUSB audio descriptor stack and AK4493 driver
│   ├── build.sh                # Compilation script
│   └── deps.sh                 # NXP MCUXpresso and TinyUSB dependency fetcher
└── LICENSE                     # MIT License

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3D Printing & Enclosure

Enclosure files are located in 3d-printing/:

• Recommended Material: MJF Nylon PA12 (Black) or High-Temp SLA Resin.
• Magnets: Standard 54mm OD × 46mm ID × 1.5mm MagSafe neodymium ring + vertical orientation bar.
• Fastening: Snap-fit lid with internal alignment ribs and captive battery cradle.

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Firmware Compilation

The firmware is built on top of TinyUSB and the NXP MCUXpresso SDK.

cd firmware

# Fetch external dependencies
./deps.sh

# Build ARM Cortex-M7 binary
./build.sh

Flashing is handled via SWD during factory testing, or over USB via the NXP ROM bootloader.

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Philosophy & Licensing

Built with zero telemetry, zero cloud dependency, and local-first architecture by PARAMWORKS.

• Software & Firmware: Licensed under the MIT License.
• Reference Schematics & 3D Models: Open hardware reference design under MIT.