Please note this is hardware version 1.0. Version 1.2 includes an additional power input jack.
Compatible with Raspberry PI B+\2\3 and with Sparky SBC
We all live in a society obsessed by brand names and the latest gadget. Sometimes with reason sometimes with none.
The RPI has one major problem with audio. The clocks coming from CPU can only output one frequency clock perfect (very close), resulting in major problems with audio files sampled at 44Khz (and multiple). Too much jitter on i2s clocks. So Allo invented the Kali, but there is a second way.
Enter the master mode for i2s. Instead of the RPI giving the clock on the line, the DAC itself sends the clocks and RPI sends the data (file to be played). Since Allo used 2 clocks the problem above disappears. Allo's is not the first master DAC on the market, there are others... read on.
Allo's BOSS DAC is unique, because of the way they have implemented the design. First they 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 they take the filtered power and use a second filter (LDOs) to further quiet the noise. Note that they use some of the best LDOs on the market (LT3042 from Linear). In addition, they use Japanese oscillators from NDK for a very low jitter clock - almost as good as famous Crystek.
Finally, on the analog stage they are using a film capacitor (not ceramic) for a quiet DC to feed the TI IC (ceramic exhibit some piezo distortion, not what you want in analog stage). Not happy with this, they have added a supercapacitor for an extra kick when analog stage is asking (like deep bass).
What they 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.
Yes we live in a society obsessed with the latest gadgets. The BOSS however, 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 Allo's goal and promise to you.
Features
- 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