Allo BOSS - Raspberry Pi "Master" DAC v1.2
The Raspberry Pi has one major problem with audio - The clocks coming from CPU can only output one frequency clock perfectly, resulting in problems such as jitter with audio files sampled at 44Khz.
So what's the solution? Enter the master mode for i2s. Instead of the Raspberry Pi giving the clock on the line, the BOSS DAC itself sends the clocks and the Raspberry Pi sends the data!
Our BOSS DAC is unique; First we separate the power on 3 channels and filter it: one for the digital side, the second for analog and third for the clocks themselves. Then we take the filtered power and use a second filter (LDOs) to further quiet the noise. Note that we use some of the best LDOs on the market (LT3042 from Linear). In addition, we use Japanese oscillators from NDK for a very low jitter clock - almost as good as famous Crystek.
Finally, on the analog stage the BOSS DAC uses a film capacitor (not ceramic) for a quiet DC to feed the TI IC (ceramic exhibits some piezo distortion, not what you want in analog stage). Not happy with this, we have added a supercapacitor for an extra kick when analog stage is asking (like deep bass).
What we have achieved, in our opinion, is the best analog implementation of the PCM5122 on the market, while at same time correcting the clock problem from RPI.
The BOSS DAC is a very solid implementation of the PCM IC that will give you the greatest bang for your buck. It will sound great no matter what you throw at it - this was our goal and promise to you.
- BOSS is a Master DAC (Master DACs are compatible only with RPI)
- Compatible with RPI2 and RPI3
- Dedicated 384 kHz/32bit high-quality DAC PCM5122 for best sound quality
- Audio output connectors: 2 x RCA (Left & Right ) & Allo Volt Amp header
- HAT size
- DAC SNR is 112dB
- DAC THD+N @ -1dBFS are –87dB
- Full Scale Output of DAC is 2.1Vrms
- Dynamic Range of DAC is 112dB
- Sampling Frequency ranges from 8 kHz to 384 kHz
- Ultra-low-noise voltage regulators & LPF for optimal audio performance
- Noise level: 66.27uVrms
- Integrated EEPROM for automatic configuration (with write-protection)
- Automatically switching frequencies according to the input I2S signals
- Dual low jitter NDK crystal oscillators for Master Clock generation
- With 45.1584/49.1520 MHz Ultra Low Phase Noise Oscillators