HiFi Shield 2

One dedicated S/PDIF interface supports up to 192kHz/24bit resolution via Optical (Toslink) output.

Using the I2S expansion port on the C2 / C1+ / C4, we save a USB port and allow the user to select their audio playback system of choice, such as Volumio, Debian(DietPi) for HiFi audio playback.
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Functional introduction:

• Volume control via I2C interface is great feature to keep the great audio quality with various audio output volume.
• The output ports include gold-plated stereo RCA terminals
• An ultra-low noise dropout regulator is populated for the power supply, significantly reducing power supply noise and greatly increasing the signal to noise ratio.
• The I2S interface allows for direct decoding of the digital input to analog output using master clock synchronization.
• The PCB surface is comprised of gold-plating on top of 2 oz. of copper, ensuring signal continuity and reducing signal reflection and refraction.
• Balanced(differential signal) audio output soldering pads are available.
• The dedicated S/PDIF interface is newly added which supports up to 192kHz/24bit resolution via new Optical (Toslink) output.

* ODROID-C1+ supports up to 384Khz while the ODROID-C2 supports up to 192Khz.

* This HiFi Shield 2 is partially functional on Android. The output format is fixed at 44.1Khz/16bit stereo. There is no Analog volume control capability either due to limited AOSP audio HAL implementation.

– Ubuntu/Linux setup guide : https://wiki.odroid.com/accessory/sound/hifi_shield

– Official Volumio OS support : https://volumio.org

– Official Runeaudio OS support : https://runeaudio.com

– PCB mechanical drawings (AutoCAD format) : Download HERE

– Schematics : Download HERE

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Package include

– HiFi Shield 2 Board
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BOARD DETAIL

The audio output is the other way as standard. Red : Left, White : Right

BLOCK DIAGRAM

ODROID-C2 / C1+ / C4 7PIN I2S PINMAP

The HiFi Shield 2 is a high-resolution Digital to Analog Converter(DAC). This is a special sound card for the C4, C2 and C1+, that is optimized for the best fidelity audio playback quality. It delivers a nicely balanced sound, solid, deep, wide and nicely layered.

We’ve analysed the the audio quality of the HiFi Shield 2 DAC output with the famous industry standard equipment, Audio Precision. The Audio Precision is a high performance audio analyser optimized for the digital audio product.

The analog output of the HiFi Shield 2 is connected to the equipment and measurement data shows on the host PC.

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Test conditions
Volumio 2.002 image runs on the Odroid-C2 with HiFi-Shield 2.  192KHz audio test files were used.
Audio Precision Input : Analog unbalanded 2ch, 600ohm

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Hardware volume/mixer settings
Analogue : -6.00 dB (amixer -c 1 sset Analogue 0)
Digital : -3.00 dB (amixer -c 1 sset Digital 201)
Deemphasis Filter : On (amixer -c 1 sset Deemphasis on)

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Software volume settings
Volumio UI volume : software volume 100 (maximum full scale)

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Set-up with ODROID-VU5

Set-up with ODROID-3.5inch Touchscreen Shield

The Signal to Noise Ratio (SNR)

The Noise Level in dBm

The Frequency Response and RMS output level in dBV

The Total Harmonic Distortion + Noise Ratio  (THD+N)

The Frequency sweep THD+N Ratio

The FFT spectrum analyzer for 1Khz signal

This is a great idea if you want an audiophile set-up with ODROID-C2/C1+. Enjoy a variable output connecting directly into a power amp or active speakers.