PCM2902 USB interface

Rocky · 7th July 2004, 04:07 PM

I have a question regarding the PCM2902 chip. What I want to do is using it for a USB->SPDIF converter. I've read some articles regarding powering of the chip, where it has been recommended NOT to use the USB voltage, but this is all in cases where people have built the USB-SPDIF-device with the chip's integrated DAC capabilities, wich I will NOT be using.

So... In cases where the DAC section of the PCM2902 is NOT used, is there any noise problems with powering the circuit from the USB line, and then maybe wire my DAC ground to the USB ground with a small resistor value like 10 ohms or something to keep noise down? I am thinking this will not be a problem as the SPDIF signal is still digital...?

Rocky · 7th July 2004, 04:43 PM

I guess it would be something like this:

Rocky · 10th July 2004, 01:39 PM

Overwhelming response.. Well, if someone has something sensible to say about this matter somewhere in time and space, please let me know. I guess I'll just have to figure this one out myself.

5th element · 10th July 2004, 02:06 PM

I made something similar to this however I fried the PCM2902 by mistake. With this in mind I cannot offer any helpful comments on how well it works. But I am going to use it off the 5v USB supply with the grounds all wired to the star earth. Im waiting for another chip to arrive and will comment on it when it does. But until then I think it will work fine. MWP made it in pretty much the same way and had good success.

Rocky · 10th July 2004, 06:54 PM

Thanx 5th. I've read your DAC thread, and I've also looked through some of MWP's DAC work. Thank you for the star ground tip, I'll test it versus a resistor I guess.

With this circuit one can get quite a number SPDIFs very cheap, but are there any software filters that can utilize USB (Windows or Linux)?

7th July 2004, 04:07 PM	#1
Rocky diyAudio Member Join Date: Apr 2004 Location: Kongsberg/Oslo	PCM2902 USB interface I have a question regarding the PCM2902 chip. What I want to do is using it for a USB->SPDIF converter. I've read some articles regarding powering of the chip, where it has been recommended NOT to use the USB voltage, but this is all in cases where people have built the USB-SPDIF-device with the chip's integrated DAC capabilities, wich I will NOT be using. So... In cases where the DAC section of the PCM2902 is NOT used, is there any noise problems with powering the circuit from the USB line, and then maybe wire my DAC ground to the USB ground with a small resistor value like 10 ohms or something to keep noise down? I am thinking this will not be a problem as the SPDIF signal is still digital...?

10th July 2004, 02:06 PM	#4
5th element diyAudio Member Join Date: Oct 2002 Location: England	I made something similar to this however I fried the PCM2902 by mistake. With this in mind I cannot offer any helpful comments on how well it works. But I am going to use it off the 5v USB supply with the grounds all wired to the star earth. Im waiting for another chip to arrive and will comment on it when it does. But until then I think it will work fine. MWP made it in pretty much the same way and had good success. __________________ What the hell are you screamin' for? Every five minutes there's a bomb or somethin'! I'm leavin! bzzzz! Droggon Attack!

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10th July 2004, 01:39 PM	#3
Rocky diyAudio Member Join Date: Apr 2004 Location: Kongsberg/Oslo	Overwhelming response.. Well, if someone has something sensible to say about this matter somewhere in time and space, please let me know. I guess I'll just have to figure this one out myself.

10th July 2004, 06:54 PM	#5
Rocky diyAudio Member Join Date: Apr 2004 Location: Kongsberg/Oslo	Thanx 5th. I've read your DAC thread, and I've also looked through some of MWP's DAC work. Thank you for the star ground tip, I'll test it versus a resistor I guess. With this circuit one can get quite a number SPDIFs very cheap, but are there any software filters that can utilize USB (Windows or Linux)?

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