Why use USB from streamer to DAC?

[kevin1969]

With S/PDIF the clock is recovered from the data stream. This means clock is generated at the server and will always deteriorate by the time it reaches the DAC DIR.

I understand what you're saying, but the idea that we don't have the technology available today to guarantee a continuous bitstream of data over a 6 meter cable is ridiculous.

All of these bit timing problems were solved years ago using far more rudimentary solutions then are in use today over far greater distances.

Don't even get me started about the absurdity of audiophile grade Ethernet switches

 

[chelgrian]

I understand what you're saying, but the idea that we don't have the technology available today to guarantee a continuous bitstream of data over a 6 meter cable is ridiculous.

All of these bit timing problems were solved years ago using far more rudimentary solutions then are in use today over far greater distances.

Don't even get me started about the asurdity of audiophile grade Ethernet switches

Exactly all forms of Ethernet over UTP also recover the clock from the data stream using a variety of different methods depending on the generation. 1000BaseT uses PAM-4 encoding which results in a data rate of 250Mbit/s over each of 4 pairs with a nominal 125MHz pulse clock.

These days you can do essentially bit perfect transmission at 1GE over 100m of Cat5e UTP.

The physical layer for various versions of USB works in the same way.

 

[alc]

There is another interface that is starting to emerge - Analog Devices A2B. This interface can support 32 channels at 48k, 16 channels at 96k or 8 channels at 192k with full bit depth. It has a maximum distance of 30M for each node up to 300M with the newest chips.

Just like AES3, S/PDIF, HDMI & Ethernet, you still should consider jitter with A2B.

USB UAC2 works well when the external device is close and there is only a one to one connection requirement.

Al

 

[chelgrian]

There is another interface that is starting to emerge - Analog Devices A2B. This interface can support 32 channels at 48k, 16 channels at 96k or 8 channels at 192k with full bit depth. It has a maximum distance of 30M for each node up to 300M with the newest chips.

Just like AES3, S/PDIF, HDMI & Ethernet, you still should consider jitter with A2B.

USB UAC2 works well when the external device is close and there is only a one to one connection requirement.

Al

This looks like it's designed for things like automotive and the custom install market. They seem to have tried to broaden the addressable market in 2019 by adding it natively to SHARC DSPs.

 

[alc]

Chelgrian, you are correct that its main market is for automotive networks where ADI has traction. This makes sense because semiconductor companies need scale.

New versions and support staff at ADI are focused on expanding this mission.

A2B is essentially a distributed TDM interface with I2S, I2C and SPI capability. I has low latency and is inexpensive when compared to Ethernet solutions like Dante.

A2B is not native to SHARC or sigmaDSP. It clearly can interface to these devices but other processors and devices will work as well. I think the built in ASRCs that the ADI processors have will be useful features for jitter attenuation.

Full Disclosure: Danville Signal, my company has a close relationship with ADI and we have products planned in this area.

Al