XHRA-2HPA-TQ64 custom project - debugging advice
Posted: Sun Oct 29, 2017 6:13 pm
Hello everybody,
I've managed to finish my prototype DAC based on XHRA-2HPA reference platform hardware manual.
First of all, the sound is amazing, as I expected.
Second, I've made some changes, so I got troubles.
The first problem was the heating of LDOs, since I didn't want to have PWM buck converters in the circuit, but I fitted some heat sinks on them, as you can see in attached picture. Problem solved.
The second issue that I'm trying now to figure out how to fix seems to be a big problem: for the first 4-6 minutes from power-on, so when the circuit is cold, everything is perfect, but after that all the sample rates based on 24.576 MHz clock are scratched.
All 44.1, 88.2, 176.4 and DSD files sound excellent, I've been tested them for hours.
After few minutes from power on, all 48 kHz files have minor and rare scratches, 192 kHz files have minor and often scratches, and 96 kHz files are practically impossible to listen to. All these symptoms start gradually as much as the circuit is warming.
I thought there are some problems with oscillators, so I replaced them with other brand, but problem remains. After that I thought that the problem is the location of oscillators, near the DAC chips - where they should be, on the clean side of the circuit, but 22.5792 MHz clock is in that location too, and it works perfect.
What is happening when the DAC is warmer, and why only 24.576 clock based files have scratches?
Where to start the debugging?
Thank you in advance!
Adrian
I've managed to finish my prototype DAC based on XHRA-2HPA reference platform hardware manual.
First of all, the sound is amazing, as I expected.
Second, I've made some changes, so I got troubles.
The first problem was the heating of LDOs, since I didn't want to have PWM buck converters in the circuit, but I fitted some heat sinks on them, as you can see in attached picture. Problem solved.
The second issue that I'm trying now to figure out how to fix seems to be a big problem: for the first 4-6 minutes from power-on, so when the circuit is cold, everything is perfect, but after that all the sample rates based on 24.576 MHz clock are scratched.
All 44.1, 88.2, 176.4 and DSD files sound excellent, I've been tested them for hours.
After few minutes from power on, all 48 kHz files have minor and rare scratches, 192 kHz files have minor and often scratches, and 96 kHz files are practically impossible to listen to. All these symptoms start gradually as much as the circuit is warming.
I thought there are some problems with oscillators, so I replaced them with other brand, but problem remains. After that I thought that the problem is the location of oscillators, near the DAC chips - where they should be, on the clean side of the circuit, but 22.5792 MHz clock is in that location too, and it works perfect.
What is happening when the DAC is warmer, and why only 24.576 clock based files have scratches?
Where to start the debugging?
Thank you in advance!
Adrian