Adaptive versus asynchronous DAC´s

[nbaptista]

In theory (and IMO in practice) the asynchronous one should sound clearly better.

Here we go again. This article explains well why the adaptive might be a good alternative
http://www.gspaudio.co.uk/blog/jitter-isochronous-or-asynchronous-dacs_post57.html
"With adaptive isochronous - like S/PDIF - there is no "hand-shake" to check the data packets - it just plays. It would play errors if it lost synchronization with the clock signal, and yes, that would introduce jitter, but adaptive means that a special device is used to lock onto the clock signal.

The special device is called a PLL or phase locked loop. Over the first few data packets - each lasting 0.001 of a second in USB audio - there will be jitter-a-plenty and illustrative measurements taken at this stage can obviously be used against the isochronous transfer mode.

However, PLL’s lock onto the clock after a number of data packets just like S/PDIF and can quickly recover from data glitches without interrupting playback or simply stopping. It's able to recover in a fraction of a second - so fast you'll not notice any jitter.

High quality PLL’s are included in adaptive isochronous DAC’s just like they are in S/PDIF receivers. The result is extremely low jitter and not the absolute mess the asynchronous marketing men would have you believe."

 

[Yomanze]

Intersting this article. It seems that asynchronous is not so superior
http://www.gspaudio.co.uk/blog/jitter-isochronous-or-asynchronous-dacs_post57.html

It depends, for example the Wavelength code seems to work great. My Halide Bridge has 10ps jitter for my 44.1kHz files & 25ps clock drift, which is extremely low! I am a long-time user of USB to SPDIF & used an adaptive HagUSB for many years, which was great, however, the best asynchronous USB to SPDIF devices sound better.

EDIT it's called Streamlength.

 

[jirij]

Intersting this article. It seems that asynchronous is not so superior
http://www.gspaudio.co.uk/blog/jitter-isochronous-or-asynchronous-dacs_post57.html

With all due respect to the article author, the post is just wrong. It mixes up transfer and synchronization modes (http://www.pinkfishmedia.net/forum/showpost.php?p=2439866&postcount=66) without ever looking at the wire traffic or the UAC1/2 spec, but the main idea that "hey, adaptive isn't that bad" is fine. The problem is that a clearly superior technology is available. It's like arguing "hey, ATA isn't that bad" when we have SATA - it's true, but it doesn't make ATA a better alternative to SATA.

edit: http://www.usb.org/developers/docs/devclass_docs/ , "Audio Devices Rev. 2.0 Spec and Adopters Agreement"