502DAC3 - Pro Audio Shield
The 502DAC3, designed and manufactured by Pi2Media (a division of PI 2 Design), is a professional I/O Shield designed to bring high resolution, audiophile quality sound to the Raspberry PI ® family of Single Board Computers. The 502DAC3 converts the Raspberry Pi ® I2S Port to High Resolution Pro-Audio, Analog and Digital simultaneously.
Designed around the ultra-high performance PCM1792 24-Bit@192Khz DAC and the WM8804 digital audio transmitter, these devices ensure the highest quality audio sound from the Raspberry Pi. Dual ultra-low noise clock oscillators are used to ensure that files based on 44.1K or 48K frame rates play flawlessly. The LME49720/LME49600 based headphone amp drives up to 8Vrms @ 200ma, with ultra-low noise and distortion allowing the use of sensitive IEM's, dynamic and even low impedance, low efficiency planar magnetic headphones. The integrated DC Servo circuit insures no DC offset will harm your expensive headphones!
The 502DAC3 was designed to be plug-and-play with all of the major Raspberry Pi media players and multimedia platforms (Volumio, Moode, Roon, OSMC, etc.). Industry-standard WM8804 drivers work without modification or configuration. This ease-of-use ensures that you will be up and running and delivering high resolution stereo from the Raspberry Pi quickly and inexpensively. The 502DAC3 delivers the highest quality digital audio sound available on the market, with analog output designed to meet or beat high end discrete DAC equipment.
- 24-Bit DAC – Professional Grade -106db THD/123db SNR PCM1792 running in Slave Mode converts the I2S Stream to Analog at 24-Bit up to 192Khz Frame Rate
- DIGITAL AUDIO – Industry standard WM8804 running in master mode converts the I2S stream to Pro-Audio Standard AES/SPDIF formatted data at 24-Bit up to 192Khz Frame Rate
- ULTRA-LOW NOISE CLOCKS – Two NDK NZ2520SD Oscillators feed the WM8804 I2S Master to insure the lowest possible Jitter and Phase Noise
- ANALOG OUT – 2Vrms Stereo Line Out, buffered with a pair of LME49720's, is available via Dual RCA Gold Plated Jacks
- HIGH POWERED HEADPHONE AMP – A pair of LME49720 Op Amps and LME49600 Buffers drive up to 8V RMS output and can handle high and low impedance headphones with ease.
- BALANCED OUT – Isolated Balanced AES/EBU Pro-Audio is via ¼” Connector (XLR Male Adapter included)
- COAX OUT - A BNC COAX connector provides single ended, isolated S/PDIF with selectable Output levels for both Pro and Consumer (RCA Adapter included)
- OPTICAL OUT – Via TX179 TOSLINK Transmitter
- HIGH-PSRR LDO – A Low-Noise Linear Tech LT3042 delivers 3.3V to all sections with 88db+ PSRR from 10hz to 100khz
- EXTERNAL 5V – This option allows the 502DAC3 to be powered from an external low noise supply if desired
- EXPANSION CONNECTORS – A number of JST XH connectors allow access to analog signals for panel mount and GPIO for IrDA, Rotary and Power Control
The 502DAC3 has been exhaustively tested using our state of the art dScope IIIe Audio Analyzer. All test waveforms are 24-bit@ 96Khz unless otherwise noted. 0db reference is 2Vrms. For these tests, the 502DAC3 was powered from the Raspberry Pi 2 using an off the shelf 5V@3.5A USB supply. Depending upon the headphones used, it is recommended to use an external 5V@5A supply to power the Pi and 502DAC3. Low noise regulators insure highest quality results from most off the shelf switchers.
Example of test plot: Analog Out, 1Khz Sine Wave, 24-Bit@96Khz, -6db into 600 ohm