12-22-2024, 06:11 PM
(This post was last modified: 12-22-2024, 06:26 PM by trebtek.
Edit Reason: typo
)
Hello everyone, this is my first post on this forum. Glad to be with you.
A year ago, I built a ProtoDAC:
Kit sold by Mark on EBay
+ RPI-4B
+ iFi Power supply
+ Roon Bridge renderer
+ No DSP, No Camilla or anything
I am very very pleased with the results, sound quality is great for the money, so a big Thanks to Mark and everyone involved in this great DIY project.
But last month, I started noticing some occasional crispy noise, that seemed to be random, not related to the level of the music being played, and often present at the beginning of a new song - but not always. I was able to isolate the root cause to the ProtoDAC itself after successively playing music without Roon, replacing the microSD card, and replacing the RPI. (I also checked and retouched a few solders without any audible effect.)
Only then did I search this Forum, to find out that others have apparently experienced the same problem, and that odds are the TDA1387x8 is misbehaving. So I ordered 2 new modules from AliExpress... awaiting delivery.
In the mean time, I decided to run some tests on the ProtoDAC, and share the results with you.
I connected an old RPI to the ProtoDAC via GPIO, installed RaspiOS on the RPI and used the ALSA speaker-test utility to generate a 400 Hz sine wave to the I2S interface. I then connected the RCA of the ProtoDAC to the input of my Behringer DAC/ADC and collected the signal into REW wich allowed me to use the scope and capture the following screenshots.
It looks like after a second or so of normal behaviour, some distortion appears, and then the P-P voltage strangely rises, with more distortion being apparent on close-up, and then after some time, PP voltage comes back to its initial value and distortion gradually disappears.
That’s it. I thought I’d share this with you guys. I’m sure some of you are much more competent than me to perhaps comment on this.
A year ago, I built a ProtoDAC:
Kit sold by Mark on EBay
+ RPI-4B
+ iFi Power supply
+ Roon Bridge renderer
+ No DSP, No Camilla or anything
I am very very pleased with the results, sound quality is great for the money, so a big Thanks to Mark and everyone involved in this great DIY project.
But last month, I started noticing some occasional crispy noise, that seemed to be random, not related to the level of the music being played, and often present at the beginning of a new song - but not always. I was able to isolate the root cause to the ProtoDAC itself after successively playing music without Roon, replacing the microSD card, and replacing the RPI. (I also checked and retouched a few solders without any audible effect.)
Only then did I search this Forum, to find out that others have apparently experienced the same problem, and that odds are the TDA1387x8 is misbehaving. So I ordered 2 new modules from AliExpress... awaiting delivery.
In the mean time, I decided to run some tests on the ProtoDAC, and share the results with you.
I connected an old RPI to the ProtoDAC via GPIO, installed RaspiOS on the RPI and used the ALSA speaker-test utility to generate a 400 Hz sine wave to the I2S interface. I then connected the RCA of the ProtoDAC to the input of my Behringer DAC/ADC and collected the signal into REW wich allowed me to use the scope and capture the following screenshots.
It looks like after a second or so of normal behaviour, some distortion appears, and then the P-P voltage strangely rises, with more distortion being apparent on close-up, and then after some time, PP voltage comes back to its initial value and distortion gradually disappears.
That’s it. I thought I’d share this with you guys. I’m sure some of you are much more competent than me to perhaps comment on this.
