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| View Poll Results: did you hear some jitter? | |||
| Yea, I heard it |     | 21 | 38.18% |
| No never heard it |    | 34 | 61.82% |
| Voters: 55. You may not vote on this poll | |||
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12th June 2009
| #1 |
| Gear maniac  Join Date: Nov 2007 Location: Yunnan, Lijiang
Posts: 194
Thread Starter | Jitter!!! please let me listen some!!! So many post about jitter but still I don't know how it manifests!!! I can even read some authentic pros telling you cant hear it. Can you ? is it a ghost ? could some one who heard it post an A/B with and without ? thanks  F
__________________ Flober1970 http://www.myspace.com/flober1970 "If it's perfect, it aint jazz..." damn who said that? |
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12th June 2009
| #2 |
| Lives for gear  Join Date: Jul 2008 Location: new york city
Posts: 1,501
| I don't have any clips handy, but jitter is not so difficult to hear. But you don't actually HEAR it, you can tell it is there by a lack of stability of the center-imaging in the audio. Go listen to a top-notch pop track - say something like the Kate Perry singles. Then, open a session of yours and send as many files as you can out through your converters to be re-recorded into the same session. With the new files, set up a basic mix. Now go and compare how solid and in foucs the center of your material sounds with the Kate Perry track. There's the jitter. It may even show up if you just listen to the un-re-processed tracks. Of course, there are other things at play here. Best to do this test with all electronic sounds (VI) to remove some of the variables. Also, listen to your bass/low end - it may sound distinctly mushy. That's jitter too. Perhaps someone has some clips . . . |
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12th June 2009
| #3 | |
| 3 + infractions, forum membership suspended. Join Date: Oct 2008
Posts: 1,978
|  Quote:
Found: BLA Microclock vs. other test A/D D/A - without personal bias & without ears! An illustration of why multiple clocks must be synchronized Using an external clock with the FF800 RME 9632 Vs. Motu 828 Audio A-D Conversion Test & Redux Converters: Black Lion Sparrow vs. Behringer Ultramatch Pro Digital Cable Differences Lynx Aurora - Really Mastering Quality? Found: Lavry Gold AD122-96MKIII vs. Apogee AD-16x Black Lion Sparrow vs. Lynx Aurora Short converter test - Fireface vs UA 2192    | |
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13th June 2009
| #4 |
| Lives for gear Join Date: Jul 2008 Location: new york city
Posts: 1,501
| Space - Those graphs are pretty impressive - but I thought you were a big fan of the Drawmer M-Clock? The distortions to the waveform look pretty severe. |
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13th June 2009
| #5 | |
| 3 + infractions, forum membership suspended. Join Date: Oct 2008
Posts: 1,978
| Quote:
test A/D D/A - without personal bias & without ears! ... i like verry much the Drawmer M-Clock, but... the loop test is a combination of: the AD/DA converter chip design "brand & model" + the analog circuit design around that chip, software & drivers + wordclock signal controlling the data rate, transfer rate & bi-phase mark code. ... the same file is tested with same converters "Roland MMP-2", same cables, same exact settings, and with diferent clocks. RME SteadyClock(TM) internal vs. Drawmer M-Clock. also the converters are tested at +4dBu vs. -16dBu. analog setting level with same M-Clock. ... if i had an atomic clock around, i would be easy to see how good can be that AD/DA chip. how much distortion comes from the AD/DA chip or analog circuit design it self, very interesting to see other converters results. | |
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13th June 2009
| #6 |
| Gear maniac Join Date: Nov 2007 Location: Yunnan, Lijiang
Posts: 194
Thread Starter | Thanks for your post space, but... you show me some graphs... I download some of the examples and i cant here anything obvious... how would it affect MUSIC ?  F |
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13th June 2009
| #7 | |
| Lives for gear Join Date: Mar 2007 Location: Fano
Posts: 928
| Quote:
I think you're confusing "jitter" and "mixer" | |
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13th June 2009
| #8 | |
| Lives for gear Join Date: Mar 2007 Location: Fano
Posts: 928
| Quote:
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14th June 2009
| #9 | |
| Gear maniac Join Date: Nov 2007 Location: Yunnan, Lijiang
Posts: 194
Thread Starter | Quote:
 F | |
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14th June 2009
| #10 |
| Lives for gear Join Date: Jun 2009
Posts: 3,397
| it sounds like haze - lack of clarity - but it's really subtle. different clocks focus the spectrum differently. eg. big ben is a bit bottom heavy. |
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15th June 2009
| #11 | |
| 3 + infractions, forum membership suspended. Join Date: Oct 2008
Posts: 1,978
| Quote:
when i purchased Emu 1820m becouse it had the same chips as Digi192io i thought it was damaged. did some loop tests with RMAA Rightmark, and was ok. i coudnt understand why sounded so strange "bad." many hours thinking, making test, until i decided to use my old Alesis Ai-2. and sudently i felt like a sunny day in my heart, had one of those enlighting moments. cables and clean ac power is another story. ... jitter creates sampling errors, harmonic cancelations, narrows the stereo image, also record & playback at wrong pitch. harmonic cancelation makes less louder sound, lifeless sound. depending on the clock used and the songs used for listening. better clock makes the same 101010 to sound truer/closer to the source. when you hear diferent clocks with big horn loaded far field speakers, with nice amplifiers, "concert / club / cinema speakers" jitter sounds BIG, jitter makes the same 10101 to sound deformed, collapsed. like standing in front of a deformed mirror. | |
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28th June 2009
| #12 |
| Lives for gear  Join Date: Mar 2009
Posts: 1,544
| Quote: I'm sorry to poop on your party but it seems the screenies are more telling about the filtering than about timing. Notice that the problems arise around the hard edges of the waveforms. Furthermore the artifacts seem to repeat with every cycle. Jitter would not produce these results. Imperfect filters would. |
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28th June 2009
| #13 | |
| 3 + infractions, forum membership suspended. Join Date: Oct 2008
Posts: 1,978
| Quote:
same cables, same signal, diferent clocks. diferent results. why dont you download the dry file and test your converters? and upload the results? | |
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28th June 2009
| #14 | |
| Lives for gear Join Date: Mar 2009
Posts: 1,544
| Quote:
Jitter would show randomness between cycles of the saw wave. What you posted does not, the pattern repeats. So it is not jitter. It may be caused by the fact that by using different clocks there is a small difference between when the DA is triggered compared to the AD. Actually, i just discovered that i was not talking about this screenshot. You don't see repeating cycles on this. I was refering to the pics here: test A/D D/A - without personal bias & without ears! But the story seems the same. In the DACTEST2.JPG he different waveforms are not the result of jitter. There is one sample that looks like it might be (3rd track, 5th sample) but you cannot say that with certainty. You'd need proper tests to find jitter. | |
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28th June 2009
| #15 | |
| 3 + infractions, forum membership suspended. Join Date: Oct 2008
Posts: 1,978
| Quote:
#2. this and that screenshot are the same screen shots. look the image properties www links. #3. wordclock latency? aperture error. http://www.gearslutz.com/board/4326967-post33.html  #4. please do the test, and upload the results. | |
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28th June 2009
| #16 | |
| Lives for gear Join Date: Mar 2009
Posts: 1,544
| Quote:
What i mean by latency is that the dac does not output a sample at the same time as the adc samples it. The difference seems sub-sample. It also seems to have the same offset throughout. So i can only conclude that it's not jitter but some sort of delay. But i need to get this clear, do you attribute the big differences between the waveforms to jitter? About the screenshots, i think that my browser didnt load the lower pictures with the multiple waveforms at the time i was writing the post  | |
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29th June 2009
| #18 |
| 3 + infractions, forum membership suspended. Join Date: Oct 2008
Posts: 1,978
| http://www.mother-of-tone.com/cd.htm         download this 21kHz tone by clicking here.  If we compare that to the 21kHz sample-diagram above, we realize, that the oversampling filter was able to reduce the beat amplitude. This is possible if the beat goes over few cycles of the sampled wave. If the beat frequency becomes slower, the oversampling filter is less able to filter it away. Just as in the following measurement of 22kHz: You may download this 22kHz tone by clicking here.  This looks very similar to the 22kHz diagram above. Note that the beat frequency can become infinitely small, as the sampled sine wave approaches a whole division of the sample-rate. This implies that the interpolation filter must process infinite samples at the same time, and it must ring eternally. Adding to the confusion is the fact, that DA converter designs, that employ less or no oversampling at all (that play all the beats undiminished), ususally can sound very good (more musical). This is believed to be related to the absense of filter ringing in a non-oversampling design. |
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29th June 2009
| #19 | |
| Lives for gear Join Date: Mar 2009
Posts: 1,544
| Quote:
But i don't think you get it. Look at this pdf, page 9, right side. It sais: "Jitter: Jitter refers to the amount of aperiodicity in a clock signal, and is generally measured in ‘nanoseconds’ (ns or 10-9 s)." Jitter is not periodic. The screenshots you showed were periodic differences, not aperiodic. Therefore it cannot be jitter. Is it clear now? Jitter would result in a different waveform being sampled every time. | |
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29th June 2009
| #20 | |
| Lives for gear Join Date: Mar 2009
Posts: 1,544
| Quote:
High frequency signal (close to Nyquist) . If you resample that you will notice random amplitude differences between cycles. This is the result of jitter. By the way, this page does not discuss jitter. | |
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29th June 2009
| #21 | |
| 3 + infractions, forum membership suspended. Join Date: Oct 2008
Posts: 1,978
| Quote:
Q: does it matter what clock I use? This is a complicated issue, and some important aspects are not very well understood by some audio engineers. Digital clocking is used to maintain synchronization between different digital devices. There are two primary purposes for clock synchronization:
Sample rate synchronization is required for proper digital transmission, and is relatively easy to maintain. Basically, there must be only one "clock master" for all devices running at the same clock rate connected together. This is done by setting one device in "master-mode" (i.e. transmit clock, and synchronize to internal clock); setting every other device in "slave-mode" (i.e. receive clock, and synchronize to external clock), and then routing the appropriate clock signal between the master and slave devices. Keep in mind that any device, whether it's the clock master or a slave can send or receive data once everything is synchronized correctly. When doing digital conversion, it's best to have the converter be the clock master. For example, if you're recording, clock everything off the A/D converter. Likewise, if you're mixing, clock everything off the D/A converter. If you're running multiple converters, clock them all off the same high-quality master clock. For all-digital transfers, e.g. a digital transfer from one DAW or storage device to another, clock synchronization is maintained by simply setting up the proper master-slave relationship between devices. Digital transfers can be affected by clock jitter, but not in the same way clock jitter affects analog conversion. This is a widely misunderstood concept we'll discuss in detail below. Clock jitter is short-term variations in the edges of a clock signal, and clock drift is long-term variations in the clock rate. A clock could be very stable over the long-term, but still have jitter, and vise versa. Timing variations are caused by noise and/or interference. If the noise/interference is a high-frequency signal, you get clock-jitter, and if the noise/interference is a low-frequency signal, you get clock-drift. A car with an out of balance wheel may drive straight, but you'll get lots of vibration (jitter), conversely, a car with a loose steering wheel might have a smooth ride, but it'll drift all over the road. Clock drift affects long-term synchronization, like sound to picture, and can introduce slight pitch variations in the audio. Usually however, the drift is so slow that these pitch variations are only tiny fractions of a cent, and thus unnoticeable. Clock jitter affects digital transmission and digital conversion differently. Clock jitter in digital transmission can be caused by a bad source clock, inferior cabling or improper cable termination, and/or signal-induced noise (called "pattern-jitter" or "symbol-jitter"). Digital signal formats like AES/EBU, S/PDIF, and ADAT all embed a clock in the digital signal so the receiving device can synchronize to the transmitted data bits correctly. The clock used for data-recovery is extracted from the signal using a clock synchronization circuit called a phase-locked-loop (PLL). This data-recovery PLL must be designed to respond very quickly to attenuate high-frequency jitter and avoid bit errors during reception. This clock from the data-recovery PLL cannot be used to generate the clocks used for digital conversion without further clock conditioning! This is a very common design flaw in most low- and mid-range digital converters. Clock jitter in digital conversion is what most people refer to when they discuss jitter. It's easily observed on a digital signal by looking at its spectrum in the frequency domain. A jittery signal will have "side-lobes" around each frequency, and/or spurious tones at random, inharmonic frequencies. Usually, the jitter will be worse with higher signal frequencies. You can test your converters by sampling a high-quality 10kHz sine wave, and viewing it the frequency domain (available with any good wave editing software package). All modern over-sampling digital converters require a clock (called "m-clock") that is many times (typically several MHz) higher than the sample clock. M-clock is easy to generate when the converter is the clock master, but quite difficult to generate correctly when the converter needs to sync to an external clock. External clock is either from a BNC clock input, or from the digital AES/EBU, S/PDIF or ADAT receiver. The BNC clock cannot be used by the converters until it's multiplied up to the m-clock rate. This requires a PLL or other frequency multiplier circuit which will either be cheap and jittery, or expensive and clean, depending on who makes your converter. As we said earlier, the clock recovered from the digital inputs is unsuitable for use as the converter's m-clock, but because it's conveniently at the same frequency, many designers don't bother cleaning-up this signal. Since the clock recovery, clock multiplier, and clock conditioning circuitry define the jitter for analog conversion, no external clock source can cleanup the jitter introduced by these circuits, regardless of how perfect the external source clock is. The best they can do is avoid making it any worse, but this is hardly worth the cost: It's much better (and less expensive) to get a good converter than it is to try and fix a bad one with an expensive master clock. The only reason to spend money on a high-quality master clock is to ensure multiple devices are synchronized correctly. This is essential for working with audio for film/video, or when synchronizing multiple high-quality converters. A poor master clock can affect imaging and clarity in a multi-track environment. The 2192 provides high-quality analog conversion for recording and/or playback, master clock generation, resynchronization and distribution, and digital transcoding (format conversion). With its pristine audio path, high-quality clocking, and simple front panel controls, it makes the perfect master audio interface for your digital studio, and is a very cost effective way to improve your overall sound quality. - Joe Bryan | |
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29th June 2009
| #22 |
| Lives for gear Join Date: Mar 2009
Posts: 1,544
| Ok, you must be some audiophile or something. Mother Of Tone presents: The Altmann BYOB Site This page you posted talks about electric guitars sounding bad because they have plastic in the pick-ups. You see, it all must be wood and natural laquers to sound good at all otherwise there is bad distortion going on...  |
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29th June 2009
| #23 | |
| Lives for gear Join Date: Mar 2009
Posts: 1,544
| Quote:
I know all this stuff. Why do you assume i don't ? I know there is always jitter. But your screenshots are not proof of lots of jitter. | |
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29th June 2009
| #24 | |
| 3 + infractions, forum membership suspended. Join Date: Oct 2008
Posts: 1,978
| Quote:
Clock jitter in digital conversion is what most people refer to when they discuss jitter. It's easily observed on a digital signal by looking at its spectrum in the frequency domain. .../... Usually, the jitter will be worse with higher signal frequencies. You can test your converters by sampling a high-quality 10kHz sine wave, and viewing it the frequency domain (available with any good wave editing software package). Screenshot - Wikipedia, the free encyclopedia | |
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30th June 2009
| #25 | |
| Lives for gear Join Date: Mar 2009
Posts: 1,544
| Quote:
Your waveform screenshots are in Time Domain. | |
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30th June 2009
| #26 | |
| 3 + infractions, forum membership suspended. Join Date: Oct 2008
Posts: 1,978
| Quote:
anyway... i hear it BIG. can you? i just try to show what i hear so "Clearly." | |
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30th June 2009
| #27 | |
| Lives for gear Join Date: Mar 2009
Posts: 1,544
| Quote:
I understand you can hear it (like me) but the screenshots do not show jitter. It is very difficult to show jitter with screenshots of waveforms. | |
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30th June 2009
| #28 | |
| 3 + infractions, forum membership suspended. Join Date: Oct 2008
Posts: 1,978
|  Quote:
like clock jitter values. RME SteadyClock(TM) 800ps. M-Clock <1ppm 31° with clean power and 99.997% true OFC cables. RME: Support TechInfo        Square wave - Wikipedia, the free encyclopedia Abstraction - Wikipedia, the free encyclopedia Relation of Ideas - Wikipedia, the free encyclopedia Reasoning - Wikipedia, the free encyclopedia Deduction board game - Wikipedia, the free encyclopedia Fluid and crystallized intelligence - Wikipedia, the free encyclopedia | |
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30th June 2009
| #29 | |
| Lives for gear Join Date: Mar 2009
Posts: 1,544
| Quote:
Maybe there is a separate clock stabilizer cirquit for DA and AD. I have no idea, i would have to see the schematics of the card. | |
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30th June 2009
| #30 |
| Lives for gear Join Date: Mar 2009
Posts: 1,544
| But remember one thing: Jitter is random time differences. Your screenshots of your re-sampled waveforms show periodic differences. |
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