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Computer Upgrade

I have been using a mini Mac book for years. I now feel that it is time to do an upgrade. Would you mind to chime in and let me know the pros and cons between new Mac, new Window Laptop, and new window desktop in term of performance effected the sound?

Thanks in Advance
houstonreef
kijanki's avatar
kijanki
4,450 posts
 
I'm not sure what is the "Packet Noise" and what
it has to do with the quality of the computer (faster
computers tend to create more of electrical noise).
Computer sends frame of data to DAC every millisecond
increasing or decreasing number of samples per frame upon
signal coming from the DAC when amount of data in the buffer
is below or above certain value (over/under flow control).
This data from the computer goes to buffer on digital side
of the DAC. Buffered data goes to A/D converter and is
clocked at internal DAC clock that is COMPLETELY independent
from the computer and the whole transfer operation. This
clock should be well isolated from the system noise and if
it isn't and becomes jittery then buy another DAC, because
this one is poorly executed.
arh
366 posts
 
Kijanki,
Do some research on packet noise and you will see that reclocking is not the perfect answer. It helps if the clock is really stable but that can vary even in real expensive dacs. The Uptone Audio Regen is a device design to reduce packet noise which is generated by the dac reclocking
Alan
kijanki's avatar
kijanki
4,450 posts
 
Yes, you might find some USB port noise sensitivity in some DACs:

http://archimago.blogspot.com/2015/05/measurements-usb-hubs-and-8khz-phy.html

..and he finds one DAC in certain setting producing artifacts of noisy USB HUB but the same time he states that he had never seen this before:

Okay, to end off... Let me remind everyone one more time that what I'm measuring with the 8kHz noise here is because of the Emotiva XSP-1's sensitivity to noise through the "Home Theater Bypass" input. The 8kHz tone is NOT something I have ever heard / measured coming out of a reputable DAC's analogue outputs! Nor is it something that's found in Stereophile USB DAC measurements. If it were not for this noise sensitivity, I would not even have bothered with looking at ways to attenuate the computer USB noise. Nonetheless, I think this is an interesting real-life demonstration of the noise pollution that can come out of the computer's USB port and a solution that works reasonably well. I did not bother with jitter tests this time as I have never seen the Dunn J-Test change in any substantial fashion with the use of a hub with an asynchronous DAC (see the measurements last time). Think you have a jitter issue? Save up the cash and buy a better asynchronous USB DAC - forget cables and tweak products IMO.

Last sentence is exactly what I'm saying. Also look at Stereophile test of, for instance, Ayre QB-9 especially jitter test (Fig. 14).
http://www.stereophile.com/content/ayre-acoustics-qb-9-usb-dac-measurements#rgvqgdT0kSAdPz8x.97

It shows no effect of jitter down to -125dB and the only visible jitter artifacts below that are from 120Hz switching noise of linear power supply (120Hz spaced sidebands). This could be fixed by using high quality SMPS. DacMagic behaved poorly in this test.

Coupled noise is usually a common mode that can be effectively defeated by even such simple devices like comment mode chokes. You can optimize your system running USB thru quiet Hub (faster computer will make it worse) but the proper thing to do is to find better DAC.
kijanki's avatar
kijanki
4,450 posts
 
It should be "common mode chokes" - my spellchecker plays
games with me.
cerrot's avatar
cerrot
1,700 posts
 
Its not just jitter. Tough to explain but very easy to listen for. You will just not get the easy going emotion from the sound youre suposed to get. USB is the worse interface you can use. Add a few grand in USB to spidf converters, cables, reclockers and you still have those crappy packets.
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