Slovenski netopirji

[vintagesonic]

V sosednji temi, kjer se trejo mnenja okoli fenomena Jitter, bi bilo mogoče zanimivo prebrati tudi razmišljanje nekoga, ki se je stvari lotil malce bolj akademsko. V izogib napačnim interpreatcijam, ga objavljam v originalu. Za nekoga mogoče malce dolgočasno in dolgovezno, ampak vseeno………………….

Jitter: Variation in Distance

Another way to look at jitter is as a change in distance from the speaker to the listener. If that distance changes, because the listener is moving, then that is effectively the same as jitter. One audio sample takes N seconds to travel from the speaker to your head, and the next audio sample take M seconds. The difference (N-M) is easy to calculate. It is simply the speed of sound times the jitter.
If we have 1 ps of jitter, times the speed of sound (340.29 meters/second), we get 340 picometers (pm, a trillionth of a meter). Let’s put this into perspective. A single atom of gold is 135 pm in diameter. If you move your head by the thickness of 2.5 atoms of gold then you are introducing 1 ps of jitter!
Looking at it slightly differently, if your audio sample rate is 96 KHz, and you move 340 pm for each sample then get a speed of 0.033 mm/second. So, if you move your head back and forth at a speed of 1/30th of a millimeter per second then you are causing 1 ps worth of jitter.
At 2 ns of jitter, that distance is 0.68 um (micro-meters). While 2000 times larger than 340 pm, this is still super small. A red blood cell averages 7 um, so this distance is 1/10th of that. Your ear drum is 30 to 120 um thick. The wavelength of red light is about 0.65 um.
What this means is that if your sound system was absolutely perfect, your own body and it’s tiny movements would cause the equivalent of 1 ps to 2 ns worth of jitter (and probably a lot more). When you put your finger on your neck you can feel pulsing though your arteries and veins. There are cameras that can actually detect this and determine your pulse rate from a distance. That same force will cause your eardrum to move, ever so slightly, with each beat of your heart. That movement is much larger than 0.68 um, and way more than 340 pm. That’s why, in a quiet room, you can hear your own heart beat.

The audio jitter effects caused by your heart is greater than what 2 ns of clock jitter will cause.

Jitter: The winds of change

We now know that 2 ns of jitter is the same as changing the distance by 0.68 um, and that our body will do that naturally. But what else can cause that? Wind, for one. Sound waves can be blown around by the wind, especially the high frequencies. This is commonly seen in outdoor concerts where the high frequencies can actually be “away” from the audience. If you’re sitting on the edges of the audience, at the back, you might hear this as the high frequencies disappearing and then reappearing.
We’re listening in our living room, not at an outdoor concert. So what is the minimum air speed that could cause the equivalent of 2 ns of jitter? For this experiment, let’s assume that the listener is 2 meters away of the speaker. Going through the calculations, we can see that it is an air-speed of 0.116 mm/second. This is a tiny fraction of the speed of air coming out of your HVAC system. And a tiny fraction of what you cause by breathing. Even just the convection currents in the room, caused by your warm body, will be more than 0.116 mm/second!
Of course, these numbers were for 2 ns of jitter. For 1 ps, divide the numbers by 2000.
I’ll admit I’m somewhat glossing over the details here. To really have an effect the air should be turbulent, with some parts moving much faster than 0.116 mm/second, and other parts moving slower or in the opposite direction. Reality is that this does happen, and 0.116 mm/second is so slow that just about anything will make air move faster. It’s just that the math gets really nasty and I didn’t want to go through that labor. The important point is that the air speed required to “sound like jitter” is not just achievable, you can’t prevent it!

Jitter: Taking an excursion

Your speaker doesn’t sit still. If it did, it wouldn’t be called a speaker. It moves. It moves much faster and farther than anything we’ve discussed so far. A typical 6 inch driver at moderate volume levels is moving about 2 mm (peak to peak). Even your tweeter is moving much more than 0.68 um.
Look at it this way: lets say that your one-way speaker is outputting a 1 Khz sine wave and a 20 KHz sine wave. At 1 Khz, that speaker cone is moving in and out. On top of that, is the 20 KHz sine. The movement of the cone at 1 KHz is causing a variation in distance to the listener for the 20 KHz sine.
In a nice listening room, your speaker is probably the biggest contributor of jitter!

Conclusion

Saying that “jitter in the femtosecond range is audible” is laughable at best. Jitter of 1 ps is barely measurable in the audio data. Jitter of 2 ns is easy to achieve but most equipment is better than that.
Before worrying about 2 ns of jitter, you need to remove the other sources of “jitter” in your listening room. To do this: Stop breathing, stop your heart, cool your body down to room temperature, seal the room from any outside air, turn off that hot Class-A amp, and disconnect your speakers. That’s all!

In short: anybody who claims to be able to hear 2 ns of jitter is either a mistaken, a liar, or a zombie.
I’ll assume the best by assuming that they are a zombie!


LP

P.S:

Zombie ni v nikakršni korelaciji z "demokratičnimi" izjavami vodje SDS v Sloveniji.

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[ambasador]

Saj ne gre za analogni jitter. Gre za napako pri dekodiranju. Jitter se lahko sprehaja (je beseda za neenakomeren takt, aritmijo, če hočeš) a znotraj določenih okvirov - zaželjeno je, da takta pri konverziji ne preskoči. To je vse.

Mater koliko besed. Je prav nataknjen..
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Carpe Diem

[mestn pu]

Nisem si mislil, da je še kdo toliko nepismen, da ne bere kaj so zombie companies(paradni konji SLO naciiteresa, ki so tako nekonkurenčni in zapufani, da jih držimo pri življenju davkoplačevalci z stalnim dofutranjem-dokapitalizacijo državnih bank) in kaj je zombie banking, ki tako subsidira neproduktivne(to poznamo že desetletja) v škodo produktivnih.

Za vse prebivalce SLO vasi, ki še kar ne vedo ne vedo kaj je "zombie"..

http://www.bbc.co.uk/news/business-20262282

http://en.wikipedia.org/wiki/Zombie_company

Zakaj nikomur od nas na forumu ne rata, da bi nas subsidirali leta in leta, mi pa bi fino denar lifrali v davčne oaze, tajili davke in fasali še subvencije v obliki "nepovratnih kreditov"?

Že izraz "nepovratni kredit za sposobne menežerje" pove, da gre za vero v čisti idiotizem, saj vsak od nas kredit vrne, če ne ga rubijo.
Sposobni bi morali vrnit kredit še prej, če ne so-nesposobni, pika in konec debate.

Jitter na signalu je eno, mehanske mikroscilacije pa so povsem nekaj drugega, se pa "izrazijo" na izhodu-zvočnikih, zelo podobno kot jitter.

Tudi zato bo bolj togo grajen dvojni MKP kondenztor, kot so recimo Mundorf Supreme in podobni, bolj imun na mehanske mikrocilacije, kot nek poceni MKP.

Enako velja za celo vrsto kvalitetnejših delov za motorje, od letalskih do avtomobilskih.

Boljši materijali in izdelava, manj vibracij, prenesejo večje obremenitve od povprečnih delov iz potrošniških programov.

Slepa vera, da je audio pri delih z višjo stopnjo obdelave in materijalov neka izjema med vsemi tehnologijamiin in da so deli s police elektroštacune enaki delom z višjo stopnjo obdelave, je smešna, ker je pač-slepa.
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Great people talk about ideas, average people talk about things, small people talk about other people.

[vintagesonic]

[ambasador]

@vintagesonic

ne razumem zakaj si prilepil tisti članek, rekoč da se v sosednji temi dajemo okoli tega. V nalimanem članku ni ne duha ne sluha o temu kar se tam pogovarjamo. Tip govori čisto druge stvari...

Jitter kot časovni odmik od takta v katerem deluje konverzija je nekaj desetega. Takt je 44.100Hz in jitter označuje samo čas trajanja (časovno zamaknitev) ko bi moralo priti do preskoka ali pa ga je prehitelo.

To ni nekaj zabetoniranega in nepremičnega - ker potem bi ali delovalo perfektno ali bi sploh ne delovalo - ampak se stalno spreminja. Pri meritvi jitterja se izmeri statistično v katerih okvirih se giblje.

Kot rečeno, on se lahko spreminja, važno samo da ne zamudi ali prehiti takta. Pa če že to počne, kar itak je normalno, da vsaj to ne dela prepogosto.

Slišni učinki trenutkov ko pride do napačne KONVERZIJE (kadar zaradi jitterja prehiti ali zamudi takt konverzije) pa so nekaj drugega. Ti ne poslušaš pikosekund jitterja, ampak napake, ki jih nestabilen/nesinhroni clock proizvaja.
Kaj ima pulziranje srca opraviti z D/A konverzijo ne vem. In zombiji s pulziranjem srca tudi ne. In politika in podjetja in mestn. Pa še netopirji povrhu.
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Carpe Diem

[vintagesonic]

[ambasador]

Hm, so ljudje, ki mislijo da štiritaktni bencinski motor samo enkrat poči po vžigu svečke - in potem stvar deluje sama. Sicer ne vedo kako..
Morda tudi jitter preskoči za eno nanosekundo - in potem vse tiho. Kako bi kdo vedel da se je to zgodilo tisto bogo eno samo osamljeno nanosekundo - še zaposleni v zombi podjetju ne, čeprav jim ne utripa srce in imajo teoretično možnost slišati nanosekundo med dvemi atomi zlata..


CD je perfekten. Jitter ne dela problemov. V bistvu problema sploh ni. Problem smo ljudje, ki o problemih govorimo. Verjetno si jih kar izmislimo, da nam ni dogčas.
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Carpe Diem

[stormsonic]

Eh, tista tema je totalno zabluzila, meni se ne da več tam pisat.

Ja, zanimivo razmišljanje zgoraj. Ampak tale je pozabil, da kadar govorimo o jitterju, moramo govoriti tudi o frekvenci. Če je npr. govora o 5 pS jitterja, to ne pove nič otipljivega, če ni podatka, na kaj se ta jitter nanaša, kaj je bilo merjeno.

Recimo, da imamo clock 24.576000 MHz, ki ima 10pS jitterja v območju med 0.1 in 1000 Hz. Če to prenesemo v slišno audio območje, recimo bas pri 100 Hz, potem se bo jitter meril v uS, torej 1000000x (milijon-krat) več.
Kot bi poslušal muziko, žena bi te držala za glavo in jo obračala levo-desno, otroci bi migali zvočnike levo-desno, hišo pa bi stresal potres

Grem zdaj hitro, preden pride Bojc in napiše, da je on to že dolgo vedel oziroma da je on izumil jitter
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My DMM will go only to 10, maybe your DMM can go to 11?

[vintagesonic]

[joztom]

Kupim CD, ki ima ogromno jitterja, da se mu posvetim. Mislim da sem ga zanemaril in upam da ne bo zameril. Z meni dostopno tehniko tega ne morem prepoznavati, imam samo en star vintage HP osciloskop 40MHz

[stormsonic]

Zunanja zvočna kartica za računalnik, baterijsko napajan ojačevalec za slušalke in tvoj osciloskop bo čisto dovolj
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My DMM will go only to 10, maybe your DMM can go to 11?

[ambasador]

Dragi moji - nasvidenje, odhajam iz te teme

Kot sem rekel, nisem v digi vodah in sem samo prenesel, kar sem zasledil v italijanskih revijah, katere kupujem.
Z vami se ne bom prerekal. Kar sem napisal je tisto, kar me je prepričalo in se mi tudi potrdilo v praksi.
Poleg tega da tudi druge informacije iz neta potrjujejo to.
Torej vam ne verjamem. Še posebej ker iz vaših izvajanj ne morem izluščiti nobenega odgovora/razlage za dogajanje v praksi, niti kaj si pomagati s tem pisanjem

lp

Tole spodaj niso nanosekunde, ampak konkretni nasveti kako prepoznati player s slabim jitterjem:
Italijani so takole rekli:
prva trpi dinamika. Vedno in krepko. Naslednje je bas ki ne gre globoko kot bi moral, nima dovolj energije (ni prave teže, mogočnosti) in ni prav definiran. To so glavni znaki slabega jitterja, ki so vedno prisotni. Potem so še druge napake in napakice, ki so od primera do primera različne,
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Carpe Diem

[vintagesonic]

[jacoby]

Vintage

ti si en navaden provokator, nekaj prebiraš, v elektroniki pa v bistvu nimaš pojma, tako kot še nekaj frajerjev tukaj...sami filozofi...povzetki...citati...
Me zanima kaj bi bilo, če bi se soočil z enim od naših "slovenskih netopirjev" brez neta in googla...

[vintagesonic]