NEC USB controller card with low-jitter clock

[Oystein]

This is a typical question for the ones who are familiar with USB implementations ... so please give me your opionion / experiences

 

I picked up my parts for a HTPC including a PCIe USB 3.0 card with the NEC D700200 controller.

 

Looking at the data from this chip I see it needs a clock of 24 MHz. On the PCB I can see the crystal reading 24.000

Is this clock responsible for the jitter of the USB out ?

I will discard my cd player which I modified some time ago with a Tentlabs clock and why not re-use it for this USB card ?

 

If at least the USB signal to my USB DAC will benefit from it.

 

 

 

 

[1audio]

1) Yes, the clock will be partly responsible for jitter on the USB communications BUT

2) There are many other contributors to jitter in the chain AND jitter on the USB may not affect jitter at the DAC, it all depends. . .

3) I don't think anyone has a USB 3.0 DAC yet. USB 3.0 uses different wires and a completely different protocol to move data vs. USB 2 or USB 1. The USB 3.0 card will not offer a benefit over a USB 2 solution for audio.

The Tent Labs clock probably is the wrong frequency for any of these other applications.

 

[Oystein]

Thanks for the feedback.

 

I know USB 3.0 is not needed for my DAC but this was the only model I could find with low profile bracket to fit in my HTPC.

It is backwards compatible with USB 2.0 and USB 1.1 so no problem.

The current oscilator on the Tentlabs clock is 16.3944 MHz but I could replace the oscilator for a 24 MHz 25ppm model … if I can find one as an end-user … Tentlabs does not mention this frequency in the available oscilators.

 

If I understand correct the result wilt be unpredictable and maybe hard to implement at all …

 

 

[Wavelength]

Guys,

 

This has nothing to do with jitter related audio errors!!!!!! Investing in a TENT clock for this is not going to do anything for audio and will probably screw up the USB 3 board.

 

That 24Mhz is then multiplied by 20 to get 480Mhz and then again it's feed into another PLL for 3GHz. Believe me when I tell you that 24Mhz clock is going to look like crap, but it's suppose to.

 

Please start to understand what Audio Related Jitter is before just poking around in something that has nothing to do with it.

 

Thanks

Gordon

 

[Oystein]

Dear Gordon,

 

That is why I ask such kind of questions ...

 

I have an idea but have no clue if I am on the right track or onto a dead end. I have no experience in designing computer harware ;-)