PCM2903 recording function does not work

Hi Uwe,

In my opinion PCM2903C have volume control only for DAC and not for ADC. In some newer operating systems like Windows7 you can see software volume control. You probably don't want to change volume on the digital input because you distort digital audio signal. It is possible that you have somewhere in sound system of windows muted audio input from this soundcard. I built soundcard only with PCM2902 that there can be some differences in power supply part and reset of chip. Did you used schematics from a datasheet?

I don't like Windows sound system which tried to isolate user from a hardware. In Windows7 is everything much worse (read automatic) ;-) Sometimes help only clearing of everything records about USB soundcards in a Register. You can also try another operating system like Linux.

Hi Pavel,

thanks for your reply. Yes, it is the basically the Self Powered Configuration from the data sheet. I would appreciate when there is no volume control for the audio input. The digital signal shall be left untouched.

Meanwhile a colleague helped me and we are a little further: With a program called GraphEdit he was able to link the audio input of the PCM2903 to its output. But:

a) This works only from the analog input to the output. The automatic switchover between S/PDIF and analog does not work.

b) I still don't get the input signal to any other Windows application like the Sound Recorder or my FFT analyzer.

There are still these questions:

1. What does "CD-Player" in the Mixer mean? Is it a) an input anywhere else in the PC intended for a CD-player, or b) is it  meant to be the PCM2903's audio? In the first case this would mean that the PCM2903's audio input can not be heard life on the PC (catastrophe!), it could only be recorded. In the second case this would just be an awfully misleading naming.
   
   
2.  In chapter Digital Audio Interface is written:
   When the device detects an S/PDIF input and successfully locks on the received data, the ... source is automatically selected from S/PDIF itself; otherwise, the data source selected is the ADC analog input.
   This feature is a customer option. It is the responsibility of the user to implement this feature.

What does this last sentence mean? Does it it mean that the (automatic) switchover does not work without any (for me up to now unknown) measure? With the PCM2902 this used to work as expected without any difficulties. Or does it simply mean that the user has to supply an S/PDIF signal? No, that's too trivial.

BTW, Linux instead of Windows: It is not up to me what the customer will use. Would I built it for me, I wouldn't change to Linux either. I also wouldn't want change my whole life and to move to a foreign country just just for an improvement in a minor feature.

Best regards

Uwe

Hi Uwe,

1. Usually onboard soundcard have 4 pin analog input connector for connecting of audio from CDROM. I don't know, if it is your case.

2. In my opinion it must works same like on the PCM2902. It means that if you connect some correct S/PDIF signal to the S/PDIF input that chip automatically disable analog input and switch to the digital input. When you remove digital signal that input is switched automatically back to the analog input.

Best regards,

Pavel

Hi, Pavel,

Thanks for contributing to this thread!!!

-d2