tag:blogger.com,1999:blog-4781727111866727703.post301887868408861653..comments2024-03-28T00:31:13.472-07:00Comments on <em>Archimago's Musings</em>: MEASUREMENTS: The hunt for load-induced jitter...Archimagohttp://www.blogger.com/profile/08642574001287787545noreply@blogger.comBlogger10125tag:blogger.com,1999:blog-4781727111866727703.post-46158266974485681032016-01-30T07:29:51.107-08:002016-01-30T07:29:51.107-08:00I always thought transmission jitter is not exactl...I always thought transmission jitter is not exactly a problem as long as there's adequate buffering done at the receiving end. In absolute terms this kind of jitter has to be large enough to cause intermittent signal lock loss between the interfaces resulting in audible drops. <br />More concerning is conversion jitter stemming from clock instability, more precisely, right output value at theBogdanRhttps://www.blogger.com/profile/00663037434629829279noreply@blogger.comtag:blogger.com,1999:blog-4781727111866727703.post-6198203844649886872015-12-09T17:47:45.523-08:002015-12-09T17:47:45.523-08:00Great test and enjoyed the video, too! Brilliant.Great test and enjoyed the video, too! Brilliant.Gadgetyhttps://www.blogger.com/profile/06408665507545437257noreply@blogger.comtag:blogger.com,1999:blog-4781727111866727703.post-68185798259557177662013-03-12T19:46:23.723-07:002013-03-12T19:46:23.723-07:00Well, actually I don't think it totally invali...Well, actually I don't think it totally invalidates the graphs posted. The reason being that the jitter sidebands can be found in very jittery gear even without the J-Test modulation (for example my recent Pioneer DV-588a DVD-A/SACD player); it's just that the J-Test stimulates it further and makes it even more obvious.<br /><br />The fact that straining the computer CPU and the USB Archimagohttps://www.blogger.com/profile/08642574001287787545noreply@blogger.comtag:blogger.com,1999:blog-4781727111866727703.post-34034775437865618272013-03-12T13:36:03.837-07:002013-03-12T13:36:03.837-07:00But does it not invalidate your test i.e looking f...But does it not invalidate your test i.e looking for differences when OS is loaded Vs when idle? Surely you should be using a test that will stress the USB interface to see any changes which will be subtle, if they exist.<br /><br />Just because others such as Stereophile use the J-test for USB DACs doesn't mean that it is correct to do so.dweeb4https://www.blogger.com/profile/12032456345061578726noreply@blogger.comtag:blogger.com,1999:blog-4781727111866727703.post-44519567478257399612013-03-12T12:10:04.962-07:002013-03-12T12:10:04.962-07:00True, Julian Dunn's original paper(s) on the J...True, Julian Dunn's original paper(s) on the J-Test focused on the AES-3 digital interface and variants thereof.<br />http://www.nanophon.com/audio/jitter92.pdf<br /><br />Nonetheless, the spectrum measured is the spectrum measured :-); and the adaptive USB is clearly poorer compared to the asynchronous. Even if the J-Test is unable to stimulate a "worst case" situation through USB Archimagohttps://www.blogger.com/profile/08642574001287787545noreply@blogger.comtag:blogger.com,1999:blog-4781727111866727703.post-32538697432473978182013-03-12T02:23:33.554-07:002013-03-12T02:23:33.554-07:00Yes, agreed - things can be measured that are not ...Yes, agreed - things can be measured that are not necessarily audible & the corollary seems to exist also - things are heard which currently we don't seem to have the correct measurement for - this being an example of a new measurement that reveals some changes which had remained unmeasured up to now.<br /><br />BTW, I believe that using the J-test for USB jitter is mistaken as it was dweeb4https://www.blogger.com/profile/12032456345061578726noreply@blogger.comtag:blogger.com,1999:blog-4781727111866727703.post-21457278377954524332013-03-11T00:31:19.094-07:002013-03-11T00:31:19.094-07:00Nice link and methodology!
Here's the link of...Nice link and methodology!<br /><br />Here's the link of the Halide vs. DacMagic results:<br />http://www.audiomisc.co.uk/Linux/Sound3/TimeForChange.html<br /><br />A nice, elegant way of comparing the audio output of 2 USB interfaces. Yes, too bad he didn't do measurements looking at CPU activity given his hypothesis.<br /><br />From what I can see, the DACMagic is an adaptive USB Archimagohttps://www.blogger.com/profile/08642574001287787545noreply@blogger.comtag:blogger.com,1999:blog-4781727111866727703.post-40906147926197931872013-03-11T00:23:19.085-07:002013-03-11T00:23:19.085-07:00I'll have to look into this in time; should be...I'll have to look into this in time; should be able to run this off a VirtualBox Linux install since the actual recording can be done on the PC side I think (will have to look more into the methodology).<br /><br />Interesting!<br />Archimagohttps://www.blogger.com/profile/08642574001287787545noreply@blogger.comtag:blogger.com,1999:blog-4781727111866727703.post-68532130204589300702013-03-10T06:51:23.169-07:002013-03-10T06:51:23.169-07:00He never did run any further tests to see if his c...He never did run any further tests to see if his conclusion was valid or not i.e does varying OS load vary the output? The software to run these tests are available on his site - just need compiling for windows. Maybe you would like to satiate you obsessiveness to get to the heart of this by using this test? I do believe it is far more sensitive than what you are using.dweeb4https://www.blogger.com/profile/12032456345061578726noreply@blogger.comtag:blogger.com,1999:blog-4781727111866727703.post-10490658002698280562013-03-10T06:41:39.418-07:002013-03-10T06:41:39.418-07:00If you are obsessive & want to get to the bott...If you are obsessive & want to get to the bottom of this, why not try a test which has proven itself to reveal measured differences between USB devices - Jim LeSurf's IQ-Test http://www.audiomisc.co.uk/Linux/Sound3/TheIQTest.html<br /><br />He has measured differences between the outputs from DacMagic & Halide bridge http://www.audiomisc.co.uk/Linux/Sound3/TimeForChange.html<br />And dweeb4https://www.blogger.com/profile/12032456345061578726noreply@blogger.com