PCM to DSD conversion

[liz]

Hi everyone

I need a means of converting a standard SPDIF output from PCM (probably just 24bit I2S to start with) into left and right DSD data streams with the appropriate clocks.

I've tried using a signal converter from dCS but this proved unsuitable for the application so I'm thinking of developing an FPGA-based solution.

Just wondering if anyone has developed or even just used a PCM to DSD converter? Any recommendations?


Thanks

Liz

[fmak]

Just wondering if anyone has developed or even just used a PCM to DSD converter? Any recommendations?


---------------------------------------------------------
I have used the dCS972 and the 3 wire sdif2 interface works well. Can you convert this into what you want; there is adequte info on sdif2.

[liz]

Thanks for the reply fmac.

I'm trying to ***** the performance of a DSD device using a signal source that originates as PCM data, so the conversion process needs to produce a very stable output and so far I've found the dCS972 SDIF2 IF to be too jittery for this application.

[fmak]

I'm trying to ***** the performance of a DSD device using a signal source that originates as PCM data, so the conversion process needs to produce a very stable output and so far I've found the dCS972 SDIF2 IF to be too jittery for this application. [/B][/QUOTE]
------------------------------------------------------

Can you not relock? I'd like to know what level of jitter you have found as I don't particularly like the sound of upsampled DSD on the 972/954. However, the 954 is supposed to have dual pll and you may be able to get the recovered data streams from there. I have found the cable connections to be very important.

Is the new firewire type interface any better?

[phase_accurate]

Since DSD is basically a SD-signal at 2.8.... Ms/s some 64x oversampling DA converter might probably be "misused" for this purpose.

Regards

Charles

[fmak]

[QUOTE]Originally posted by phase_accurate
[B]Since DSD is basically a SD-signal at 2.8.... Ms/s some 64x oversampling DA converter might probably be "misused" for this purpose.

-----------------------------------------------------------
Can you plrease explain how this relates to Liz@s and my posts?
Thanks.

[fmak]

Originally posted by liz
Thanks for the reply fmac.

I'm trying to ***** the performance of a DSD device using a signal source that originates as PCM data, so the conversion process needs to produce a very stable output and so far I've found the dCS972 SDIF2 IF to be too jittery for this application.

-------------------------------------------------------------

I looked up the 972 manual and the DSD data stream looks good. I have also examined the clock out on a scope and it seems to be one of the best I have seen; very square, well damped and no broadening.

One aspect about the dCs connection I have doubt about is the twisted pair connections inside the unit which is far from tidy. May be worth running true 75R outputs from, the pcbs.