Wadia with isochronous Wadiastream USB input. Any experience/thoughts?

[kamil]

Apparently all new Wadia players have an option to have USB input. Wadia claim in their forums it is unique with their own WadiaStream technology but that it is different from the asynchronous approach of Wavelength and Dcs. Has anybody heard this? Any more thoughts on why a company with so much experience in digital would go isochronous instead of the more faddish async?

 

[cfmsp]

"Any more thoughts on why a company with so much experience in digital would go isochronous instead of the more faddish async?"

 

uhmm,,,perhaps because it's much easier to implement?

 

I'm just learning about USB audio transmission - due to purchasing Gordon's Proton as a secondary DAC - so I'm certainly no expert on USB, but allow me to share this from wikipedia about the much-preferred (by me) Firewire communications capabilities.

 

"FireWire is capable of both asynchronous and isochronous transfer methods at once. Isochronous data transfers are transfers for devices that require continuous, guaranteed bandwidth. Isochronous devices require constant, uninterrupted bandwidth. Asynchronous data transfers are for devices which use a buffer, such as streaming video, speakers and CD drives. To support both elements, FireWire dedicates a certain percentage to isochronous data and the rest to asynchronous data. In IEEE 1394 80% of the bus is reserved for isochronous cycles, leaving asynchronous data with a minimum of 20% of the bus."

 

One important point being, isochronous and asynchronous modes are not mutually exclusive. Presumably this info is similar for USB communications, although apparently there are four modes of USB communication (not even including Asynchronous) - control, bulk, interrupt, etc.

 

EDIT: I just realized after posting that these modes could be different between Firewire and USB given that Firewire operates peer-to-peer (i.e. without computer intervention) and bidirectionally.

 

clay

 

 

 

[bordin]

Whether it is isosynchronous or asynchronous communication, the bottom line is to have a "single" (very low jitter) clock that drives the D/A conversion. That's it.

 

[idiot_savant]

The USB Audio Class ( i.e. DACs that don't need drivers ) defines the audio transport stream as being Isochronous. This basically means that the PC & the DAC agree how much bandwidth is required, and if there is enough, that bandwidth is reserved for that connection. It is the same meaning between Firewire & USB.

 

So, a company saying their DAC is isochronous is the same is saying that it works with USB with no drivers ( i.e. all of the current hi-fi crop ). If they don't make a fuss about it being asynchronous, it probably isn't....

 

It is absolutely true that the only thing that really matters is the clock at the DAC, but this is almost impossible with adaptive ( as it's "adapting" to match the PC ), and only hard with async...

 

 

your friendly neighbourhood idiot

 

 

[kamil]

dCs has a patent GB0817141.5 which supposedly describes their asynchronous approach but documentation of it on the internet is scarce. Maybe this could shed light on their approach.

 

All I can pick up from the reviews is that it seems to handle jitter very well.