iBasso D16 Portable DAC with 1bit Digital to Analog Conversion

The iBasso D16 Taipan is a portable DAC and headphone amplifier built around iBasso’s own discrete 1-bit DAC: 16 sets of cascaded 8E PWM-DACs, 128 in all, controlled by iBasso’s FPGA-Master 2.0, with measured THD+N below 0.0001%, which iBasso says is the best among current portable discrete DACs. A super Class A transistor amplifier, similar to the DX320MAX’s, gives up to 1,125mW per channel into 32Ω balanced.

FPGA-Master 2.0

FPGA-Master 2.0 brings together three years of iBasso’s algorithm work and is the reason for the D16’s breakthroughs:

• The FPGA reorganises and recodes the signal into PWM signals for the PWM-DACs.
• A noise shaper radically lowers the noise floor, as noise limits dynamic range once distortion is very low.
• Global clock regeneration: two Accusilicon femtosecond oscillators clock the FPGA, which regenerates the low-phase-noise clocks for the DSP and USB receiver. 1-bit DACs are very sensitive to jitter, and Accusilicon’s audio oscillator reaches −158dBc/Hz at 1kHz, 13dB lower than a typical femtosecond oscillator.
• Picosecond-level delay control compensates for the board’s wiring delay, so signals arrive at the DACs aligned and strictly synchronised.

Discrete PWM-DACs

Sixteen sets of 8E PWM-DACs are cascaded, four sets for each of L+, L−, R+ and R−, or 32 PWM-DACs per channel: more than 6.4 times as many as other portable discrete DACs. With such precise decoding and so many high-quality DACs, the D16 achieves THD+N below 0.0001%.

A hardware analogue FIR filter

Under FPGA-Master 2.0’s picosecond-level control, the 32 PWM-DACs in each channel run in “delay parallel” mode, together forming a hardware analogue FIR filter. Averaging the differences between many DACs minimises distortion, for more detail and density.

Super Class A discrete amplifier

The amplifier follows the architecture of the DX320MAX: a super Class A discrete circuit with 20 low-VCEsat (BISS) dual transistors and up to 2A of output current, for 1,125mW + 1,125mW into 32Ω.

Cutting-edge components

• 128 low-drift thin-film resistors, 0.1% precision and 25ppm.
• A 24-position, four-section stepped attenuator, with channel tolerance within ±0.1dB.
• Dual Accusilicon femtosecond oscillators, phase noise as low as −158dBc/Hz at 1kHz.
• A professional audio DSP with a theoretical dynamic range of up to 192dB and THD+N of −174dB.
• An ultra-low-noise analogue power supply, as low as 0.6µV.
• A 1.3-inch OLED display.

Good to know

• In the box: D16 Taipan, protective case, USB-C to USB-C and USB-C to Lightning OTG cables, and a mini coaxial connector.
• The iBasso D17 Atheris adds an R2R DAC and Nutube valves to a 1-bit DAC.