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Music servers and other computer based digital audio technologies.

Alternate design: Ethernet » FPGA » I2S » DAC

OK. Read the material.

I think what you suggesting will yield excellent results. It's a 3 box approach (Server, Router & FPGA DAC) - you may add a 4th for remote control. With Ethernet, one could have music streamed to multiple rooms from a single music server. Overall this design will grow in popularity where homes are wired for Ethernet (alternatively, one could use a wireless LAN). Streaming 24/192 may be a challenge with a data rate of 1.1MB ps on a LAN (with Gb LANs this may be less of an issue).

Does this design yield best performance? No. The way I see it, this design substitutes SPDIF for Ethernet. We already have a similar concept in USB (including Async USB). SPDIF offers least complexity (as its unintelligent) but requires the clock to be embedded. USB and Ethernet are heavier protocols and allows for local clocking. Put another way, instead of encoding / decoding SPDIF, we do the same with Ethernet (i.e. encode / decode data packets).

The challenge still remains the same in that the overall chain needs to be streamlined and efficient. That is, the FPGA DAC benefits from cleaner upstream components. Issues like having a dedicated or minimalist LAN becomes relevant (less CSCD overheads). Server side changes will eventually affect SQ (although Ethernet does a good job of isolating the streamer).

From a cMP² viewpoint, the soundcard is replaced by Ethernet (we just need an ASIO driver which can be developed). That is, we've done a full circle which gets us back to managing the full value chain. My take:

Highest performance is achieved when classical notions of DAC as “Master” or “Slave” are superseded with the design principle of creating a partnership wherein both DAC chip and Computer Transport are slaved to the XO. Jitter is tamed when our “string” is shortest and audio is streamed under minimal stress.


Imagine a direct I2S feed from Southbridge or Hub chipset...


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