Confirmed : PC Damping

[PeterSt]

Brian, I now can see why your wife moved you to upstairs.

More seriously it looks like you only recently started this hobby ! and you could do that because you had the opportunity to move to upstairs. I mean, such things in the living room ?


PS: Strange to see "live" photos coming up while I am actually staring at the same NOS1 right at this moment over here. We'll Blax it !

[PeterSt]

So, first question regarding your jitter images in post #3 above.  Can you be sure that your exercises did not affect the measuring equipment as well as well as the dac?  Or perhaps one more than the other?

Hi Anthony - very good point. And of course I can't tell with 100% guarantee. All I know is that the scope was on a very large kuschen for the purpose.

Keep 'm coming because mistakes are made so easily !
Peter

[Nick]

So, first question regarding your jitter images in post #3 above.  Can you be sure that your exercises did not affect the measuring equipment as well as well as the dac?  Or perhaps one more than the other?

Hi Anthony - very good point. And of course I can't tell with 100% guarantee. All I know is that the scope was on a very large kuschen for the purpose.

Keep 'm coming because mistakes are made so easily !
Peter

Peter hi,

Could you set up so that you are playing music from the PC into the NOS1a but without your speakers switched on. Then try tapping the PCs chassis whilst watching the audio clock waveform to see if the taps on the PCs case / Mobo produce a transient spreading of the audio clock's trace line.

If vibration levels in the PC is linked to the audio clock jitter trying this might eliminate unintended variables between tests, and would really demonstrate a link between vibration stimulus of the PC and audio clock jitter in the DAC.

Regards,

Nick.

[PeterSt]

Nick,

Virtually impossible. We will be talking about sub-ps differences here and that at 45M cycles per second. So think like that refresh rate and then what.
So no, sorry.

Peter

[Nick]

We will be talking about sub-ps differences here and that at 45M cycles per second. So think like that refresh rate and then what.

Hi Peter,

See what you mean, the scope is fast and could overwrite a transient response to the tap given the 25m refresh.

My thinking was that stimulus of a "tap" to the chassis is going to last for ~0.1 - 0.2 seconds (or you could drum your fingers continually).

Even with the exceptionally high refresh rate refresh there should be a good chance of seeing some transient reaction on the scope if the change in audio clock jitter performance is related to vibration within the PC.  The stimulus of drumming on the PC case should be large compared to vibration based feedback from playing of music, so if the jitter is vibration related you would think it would show itself.

Regards,

Nick.

[juanpmar]

Besides the isolation feet under the audio PC and the NOS1 maybe you should consider also to isolate the NOS1 plates as I did when upgrading to Blaxius. Although I couldn´t test it yet maybe it would be something to consider.

Juan

[Nick]

Peter hi

I came across this paper on the relationship of environmental vibration on oscillators. Its fascinating reading.

http://cdn.intechopen.com/pdfs-wm/5975.pdf

Take a look at Fig 1 (PDF page 3), the figure and explanation are linking environmental vibration of an oscillator to increased phase noise at a phase noise offset frequency of the environmental vibration. Just look at the 100hz side bands in that plot ! So vibrate the crystal at 100hz and see the phase noise performance of the crystal get worse at 100hz offset. Or put another way audio or any frequency vibration results in similar frequency phase noise.

The paper is using high vibration G levels to prove the relationship but says it’s possible to work out a vibration susceptibility level which can be used to predict phase noise response to lower vibration G levels.

I'm not saying that the damping jitter effect is defiantly linked to oscillator vibration, there are plenty of other components in the PC that might be impacted leading to the jitter, but it’s interesting to see this. I guess also that the environmental vibration issue the paper discussed holds for any oscillator, so the audio oscillator in the DAC as well as the PC.

Now where did I put those isolation feet ? 

Regards,

Nick.

[PeterSt]

Nick, I don't know what needs to happen before I read and understood this all ... ! pfff.
But yes.
And seems to go beyond floating on water. Haha.

Will try to digest it !
Thanks,
Peter

[acg]

So, first question regarding your jitter images in post #3 above.  Can you be sure that your exercises did not affect the measuring equipment as well as well as the dac?  Or perhaps one more than the other?

Hi Anthony - very good point. And of course I can't tell with 100% guarantee. All I know is that the scope was on a very large kuschen for the purpose.

Keep 'm coming because mistakes are made so easily !
Peter

Second question Peter.  Is it possible to "measure" the jitter for the different PC damping solutions to get some idea about the relative contribution of various vibrations to the change? Such as the two images you posted above...although it would be ideal to be able to generate a histogram on the jitter spectra rather than rely on the fuzziness of the line on the scope.

Perhaps change one variable at a time: usb cable routing and type; proximity to the soundroom; various types of "damping" et cetera.  I know that is a lot of work, but it is a nice linear workflow that may be able to shed light on which vibrations matter.

As as aside, your observation that softer damping of the PC works best seems to correlate with the idea of removing or minimising low frequency vibrations from the floor/rack.  Softer damping generally means that lower frequencies are absorbed by the damping.  Harder footers probably serve more of a "tuning" function and in my opinion based on my limited knowledge of this subject those sorts of "tuning" footers are "tweaks" rather than solutions. 

Cheers,

Anthony

[PeterSt]

Hi Anthony,

Measuring of jitter as you suggest of course is possible, *if* I had the gear for it. And I have not; too expensive (think 150K+ euros for the jitter levels we talk about here).
Otherwise I am under the limits of the scope I use for it (3ps) so nothing much more to do at his moment but listen.

In my view you are correct about the footers and when they become "tweaks". This is why I never like to experiment (still did not change a thing since) and rather reason out the exact "how". Well, you know. But I really can't do all at the same time so we must be patient somewhat.

Thanks and regards,
Peter

[acg]

Ok, I understand that but what is the way forward?  Just stuff and stressed "sandwich" under the pc and some soft springs under the sandwich to damp frequencies under 5hz or so?

Is listening the only way to quantify a change in SQ?

[PeterSt]

Anthony - Yes, I'm afraid so. But what's the difference with damping/footers under the DAC and other gear ? Persoanlly I think we shouldn't be hyped because now I started with this and created a topic for it. Of course, I try to have some reasoning along with it, but I surely shouldn't be regarded as someone who found something new and it now needs further exploration. All I say is that it matters (even quite a lot) plus that I don't know how to control it. Or at least not in general fashion (working out for everybody I mean).

Meanwhile my change from now over a week ago is still in and I still hear the virtues of it. Btw I think it is on the edge of too much snappyness but I wouldn't know how to make that less (or more for that matter). Of course all it takes is putting some different matererial under it but since I don't see the sense of that (which could be telling you what to do), why do it. May come across as too negative but it is and remains so that I never do anything for myself only here and I rather not create a "Yahoo!" for myself because I would have psychological problems with not being able to share.

But isn't it enough if you guys yourself know that you can experiment ? Or did you but didn't hear a difference (and don't tell about it ) ?

During typing another (related) experiment slipped into my mind. So maybe I will apply that and report about it ...

Regards,
Peter

[acg]

I just came across this article in AudioBeats using Ikea bamboo cutting boards.  It is worth a read...

http://www.theaudiobeat.com/blog/ikea_aptitlig.htm

The suggestion is basically to couple the equipment to a mass that randomly resonates (the layered bamboo).  We don't have an Ikea anywhere near us here but it might be something to try.

[PeterSt]

The suggestion is basically to couple the equipment to a mass that randomly resonates

Hi Anthony, Yes, that would be my idea about such things; must be as random as possible.

No bamboo either out there ?

Thanks !
Peter

[acg]

Well you would not credit this timing, but a mate gave me a call out of the blue today from of all places Ikea.  I said "how about you spring me a couple of bamboo cutting boards, the big 3 layer ones".  He says "you would not believe it, I'm standing right next to them"

So I have two on the way!