Ayre QB-9 USB DAC

Drewh1,

very interesting, can you elaborate on why the SPDIF interface would be flawed, I have a very hard time thinking this since its what most studios do.
Also how did they implement a asynchronous USB, what chip was used for this?
Tks

even if the spdif is in fact flawed, the berkeley also has aes3.

i have heard this argued before and always get confused. i think some think spdif is great and some believe it faulty, same with aes, same with usb, same with firewire.....dunno!

they all sound great to my ears with the right gear. i use aes3.

AES/EBU is just balanced S/PDIF.

Ayre's asynchronous USB implementation is courtesy of the software written by Gordon Rankin of Wavelength Audio, which Ayre licensed. dCS also has a true asynchronous USB implementation and apparently Resolution Audio's new unit does also. Some other companies throw the term around but I don't think they are legit async USB.

The Weiss Minerva mentioned above, which is now replaced with the new DAC202, uses Firewire, not USB.

Yes aes is the same as spdif but takes more electronics to implement so aes is worse for shorter cables.

Afaik there is only one real asy USB chip in existence in the world and i think none of the mentioned companys use it?

I would refer you back to Hansen's white paper on clocking of data and how SPDIF clocks vs the USB Asynchrounous mode previously mentioned by Almarg.

The only problem with all of this is that some DAC chip designers have designs that are very tolerant of jitter because they already buffer the data onto the chip. IN the case of the Pico seconds of jitter as on SPDIF, the data is already de-jittered by the chip. This is what some video chip designers do.

So, the impact of jitter is not absolute but depends on the chip and implementation. Having said that, the best way around any issues with jitter is to buffer data and reclock it with a new master clock. As long as the device feeding the data (the computer in this instance) is able to keep up with the buffer requests, the DAC will never have to deal with a loss of data condition.