Is there anyone with high quality firewire dac and adaptive usb dac that can run an experiment?

[Mr.C]

I'm wondering if it is possible to improve the jitter in adaptive usb by making the computer the slave to the firewire device as an aggregate device in OSX. Basically, one would set up an aggregate device with both usb and firewire dac and the firewire dac as the master clock. Alternatively, one can use any firewire device with a high quality clock (some master clocks have firewire, or an ADC) or potentially an async usb device. I only have a low quality firewire ADA so I can't tell if it improves on the computer's clock via usb into my BDA-1.

 

Thanks!

 

[cfmsp]

interesting theory.

 

unfortunately, or rather fortunately (for me), my USB DAC is also asynchronous

 

I am curious as to what impact this might have.

 

clay

 

[idiot_savant]

but I can tell you it's very unlikely make any difference...

 

When people talk about the PC "locking" to the asynch DAC/firewire DAC, it isn't actually the PC clock becoming synchronous - it's asynch because the audio stream is asynchronous to the transport stream. The upshot ( in terms of audio ) is that the PC merrily keeps it's clocks separate from that of the firewire DAC, but the buffers at either end synchronize the audio to the DAC clock.

 

An adaptive USB DAC synchronises to the USB frame, which won't change in this scenario...

 

 

your friendly neighbourhood idiot

 

[Mr.C]

Thanks for the input IS,

 

You obviously know a lot on the subject. If I may, I'll tap your brain with a few questions. My understanding of adaptive usb was that it could improve with a better clock like with the empirical audio products. If the aggregate device is pointed towards the firewire dac as clock source, will the computer use that clock to send information to the usb dac (theoretically using a better clock)? The jitter in adpative usb comes from mistiming of frames right? What controls that timing?

 

This works with some firewire dacs which can be synchronized to a clock from another firewire dac, is this dissimilar to that?

 

Thanks to anyone who answers!