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542
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Ultimate Audio Playback / Playback Tweaks and Source related subjects / Re: Further Isolation of the Silverstone PCIe - USB Card
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on: January 28, 2014, 01:57:55 pm
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Possibly. If the traces were cut then we would also need to use the "condom" to separate the faceplate from pc ground, but that can be done. Then there are experimentations with clocks on the card, which seem to be beneficial.
Tonight I have managed to figure out that the "CLKREQ" wire can also be cut which leaves only the "Wake" and "PWR Good" wires that have a signal to the Silverstone card (apart from the differential pairs). I know that the "Wake" pin is optional in the PCI Express standard and therefore can be made redundant, but I need to do a bit of experimenting to see whether I can tie this pin to the PC ground (i.e. not connect it to the Silverstone card). Then there is the "PWR Good" pin that I may be able to link to the lab LPS but I am not sure about that one.
Anyway, there is still a bit to figure out.
Anthony
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544
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Ultimate Audio Playback / Playback Tweaks and Source related subjects / Re: Further Isolation of the Silverstone PCIe - USB Card
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on: January 28, 2014, 12:33:23 pm
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Hi Peter, Following is some information extracted from an Intel Powerpoint article about Differential Signalling: Any signal can be considered a loop is completed by two wires.
One of the “wires” in single ended signaling is the “ground plane”
Differential signaling uses two conductors
The transmitter translates the single input signal into a pair
of outputs that are driven 180° out of phase.
The receiver, a differential amplifier, recovers the signal as the difference in the voltages on the two lines.
Advantages of differential signaling can be summed up as follows
Differential Signaling is not sensitive to SSO noise.
A differential receiver is tolerant of its ground moving around.
If each “wire” of pair is on close proximity of one and other. electromagnetic interference imposes the same voltage on both signals. The difference cancels out the effect.
Since the AC currents in the “wires” are equal but opposite and proximal, radiated EMI is reduced.
Signals passing from one board to another are not subject to the local ground disturbances.
As frequencies increase beyond 1GHz, up to 80% of the signal may be lost, but difference still crosses 0 volts.
There are still loss issues for differential signaling but only come into play in high loss system. Most single ended systems assume approximately 15% channel loss.
So, it seems as though the differential pairs can be used successfully between pcb's of different and varying grounds (which is lucky) so I doubt that they ever were connected to ground on the USB board (not directly anyway). The differential pairs all go directly to the USB Host Controller IC which according to my understanding has separate ground (or at least separate sections for analogue and digital). I will try your suggestion about pulling the cable from the NOS1 to see if the usb still works shortly and let you know the results. Anthony |
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545
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Ultimate Audio Playback / Playback Tweaks and Source related subjects / Re: Further Isolation of the Silverstone PCIe - USB Card
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on: January 27, 2014, 10:45:15 pm
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Hi Anthony, My next thoughts are to the dexa clock guys. Can you give this a try? I just may give it a try but I do not have a power supply. I do have a linear 5v supply for the Molex and a 3.3v regulator. So I would have to find something to drive the 3.3v regulator it should not be impossible. If I were a betting man (I would be willing to bet Peter another bottle of whisky on this ha ha) my hunch would be that it will not affect the sound when the clock is a Dexa. The clock output of the Dexa is isolated & floating. The power supply is the Dexa and it too is floating. OK I know that is not the whole story but as this has to be all about jitter........... Nick and I have discussed a couple of times that the Dexa improvement could be about power supplies but there again who knows? Anyway I cannot do this straight away as I am busy just now but as soon as I can I will have a play. Cheers Paul Hi Paul, It would be much appreciated if you could give this a go. Perhaps you could use a battery? I _think_ that at least some of what I hear is to do with grounding rather than linear power or clocks, but who really knows at this stage? Regards, Anthony |
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547
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Ultimate Audio Playback / Playback Tweaks and Source related subjects / Re: Further Isolation of the Silverstone PCIe - USB Card
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on: January 27, 2014, 10:37:59 am
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So I have done a little bit of listening this afternoon and I must say that the change for me here is as big as minimising the o/s. My friend Dave was here as well. Dave is a music lover but not an audiophile (lucky bloke!) and has a good ear for music but does not spend any time reading a audio or visiting forums and such.
Anyway, Dave was convinced of the changes in my system with this tweak and heard them pretty much as I did. His most telling comment was that it was just "less noisy - more clear". My own comments are significantly increased clarity with a speed and separation that is easy to hear particularly in the voices and with normally harsh instruments such as the cymbals and bells. Remember this is with an isolated Silverstone card, which I did not like initially, but with further isolation from the PCIe bus the sound is sweet and delicate and dynamic and beautiful. The "sssss's" sizzle and decay but don't bite.
But the most important improvement for me is the "presence"...I am getting more nuance, micro-detail, clarity and believability. It is a beautiful sound and a major step forward in my system.
So, what is causing this? Is it that the ground for the USB card is now separated from the XXHE pc? Is it that the cheap lab LPS is injecting cleaner power into the Silverstone card which in turn is helping the USB Host Controller IC and clock to perform more optimally? Is it a combination of the above? I don't know. All that I know is that it is a major step forward in sound quality and it is something that I can make easily and it is something that Peter could also make easily.
My next thoughts are to the dexa clock guys. Can you give this a try? I will post a more detailed procedure to get this to work. What I want to know is if this further isolation of the UCB card improves your sound with the clock mods. If there is no change then we may be able to say that the clock mods account for the just about all of your improved sq and my isolation scheme is not warranted in that setup. What I would like to hear (but of course I want the truth) is that this isolation scheme helps further with your setups and that the clock quality is not the be-all-and-end-all, although that would make things easier!!
Cheers,
Anthony
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548
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Ultimate Audio Playback / Playback Tweaks and Source related subjects / Re: USB to PC chassis ground ? (noise) - The biggest change ever !
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on: January 26, 2014, 10:41:54 pm
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Hey Paul, That's one less job to do here then! I would guess that the Crystal on the Silverstone card is a little better than on other standard cards. Remove and use an external clock and the advantage may be levelled out. Regards position of the dexa clock, crystals are hugely ambient and electrical noise sensitive. As an example whilst trying to tune two DIY built clocks to run at the same speed at either end of the USB link the clock speed would go haywire just putting a hand or screw driver near a to a VCXO module that I was trimming on the 'scope the wave form also became slight less stable. I finally got round to implementing proper shielding of my audio and 2 USB Dexas clocks today. There are some new components in the clocks now that need to run for a few days, but even with this the difference in performance already is massive. I just cannot believe what has happened  its given about half the benefit of upgraded clocks again .... I'll post on this properly soon. Nick. Nick, you could try a card using the TI controller. The newer tech may prove useful but it is a long shot I think. Anthony |
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549
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Ultimate Audio Playback / Playback Tweaks and Source related subjects / Re: USB to PC chassis ground ? (noise) - The biggest change ever !
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on: January 26, 2014, 09:47:27 pm
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I needed a PCIe USB3 card for another PC so I took the opportunity to get hold of a Silverstone. I removed the clock from the Silverstone and connected a Dexa coax. With two PCIe cards each hooked up with coax leads for the Dexa a quick swap was now possible for comparison purposes. So I could swap the cards almost in the time it takes to reboot.
The result I can hear no difference at all nothing, zippo, zilch not a sausage (probably that does not translate in to Dutch ha ha).
But it is possible to hear the very smallest of differences in this system (as both Nick and Mani will confirm) - if I move the PCIe Dexa clock just a few inches away from where it is mounted the sound clearly is not as good (presumably RFI affecting the clock).
So there a couple of interesting results: -
1. With Q5=1 if I move the PC Dexa clock to a worse location (i.e. more jitter) it is clearly audible.
2. With Dexa clock applied to a Silverstone I can hear no difference compared with a.n.other PCIe card.
Maybe this is not exhaustive but interesting none the less.
By the way removing the clock from the Silverstone card is a doddle (with 2 soldering irons) it would be my first choice card for applying a Dexa mod - much easier than the other cards I have looked at.
P
Thanks for this report Paul...it is something that I have been wondering about. Seems to me that this is some evidence that the Silverstone "sound" is being caused by clock quality i.e. the clock on the standard Silverstone card may be a better quality than the clock on other cards. Cheers, Anthony |
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553
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Ultimate Audio Playback / XXHighEnd Support / Re: Unattend Playback Reboots Win8
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on: January 25, 2014, 04:45:47 am
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I reckon what is happening is that windows is logging you off, not necessarily rebooting you. I have this problem when windows thinks it is not activated and I un-minimise, reactivate windows (does not require internet) and then minimise again. Happens about once a week for me.
Anthony
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555
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Ultimate Audio Playback / Playback Tweaks and Source related subjects / Re: USB to PC chassis ground ? (noise) - The biggest change ever !
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on: January 24, 2014, 10:20:31 pm
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Hi Paul,
In quick AB testing removing the USB bracket made very little difference to me. However, when I listened to it for a number of days it became unbearable to me (and to Peter it seems) but there are elements to the Silverstone sound that are excellent and so some persistence too get to the bottom of it should be worthwhile. Removing the bracket on my ppa card made a much smaller difference but in a similar vein till the Silverstone.
Regards,
Anthony
Time for my morning swim...back in an hour.
PS Paul, you fits finally won a game of cricket yesterday!!
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