Have you noticed nobody talks about Jitter

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Travis,

> what does jitter sound like in your experience? <

Not to be the only nay-sayer, but jitter is a total non-issue. It doesn't matter. Not even with a $25 Soundblaster live card made 7 years ago. :D

Seriously, jitter is expressed the same as other artifact - as being some number of dB below the music. Jitter is typically 120 dB below the music, which is about 25 dB below the inherent noise of a CD. Have you ever been bothered by the noise floor of a CD? I didn't think so. Well, jitter is a whole lot softer than that.

When people say they've heard the effect of jitter they are mistaken. This is not to say that all sound cards sound the same! Some are definitely better than others. At least ten years ago some were better than others. But it was never about jitter. What varied was distortion in the A/D/A convertors, and possibly ringing and other artifacts from poorly designed anti-aliasing filters.

--Ethan
 
TravisinFlorida said:
i'm just wondering if jitter is likely to be an issue for those of us that don't run alot of tracks in a typical home project.
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Jitter is so far down the list of sound quality issues for even the most track-intensive home recording projects that it shouldn't even be on your radar.

In other words: No, it wouldn't be an issue.


Jitter is what you worry about after you've already mastered the art of cranking out radio-ready recordings and are at the stage where you're dumping an extra $10,000 into your room treatment and looking at those $1500 per-channel pre amps.
 
> Jitter is so far down the list of sound quality issues for even the most track-intensive home recording projects that it shouldn't even be on your radar. <

Indeed, and I should have mentioned earlier that the same goes for dither. :eek:

Of all the things to fret about, those are at the very bottom of the list. Far more important is having accurate monitoring in a well treated room.

--Ethan
 
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Ethan Winer said:
Indeed, and I should have mentioned earlier that the same goes for dither. :eek:
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That might be going a hair too far. At least dithering versus truncation is semiaudible. Jitter... if you think you're hearing the effects of jitter, there's about a 100% chance that you're really hearing something else.

I mean, the cheapest wristwatches drift only about a second every month. That's a tolerance of +/- 0.0000380265176%, and that's for cheap consumer crap that's mass manufactured by child labor in China somewhere.

Even with such bargain basement oscillator designs, that would still only be a maximum variance of +/- 0.02 samples per second at 48kHz. You are simply -not- going to be able to hear that no matter how good your ears are. And I'd expect the oscillator circuits in even the cheapest $10 audio interface to be at least as good as (if not better than) the ones in a $5 wristwatch. For a decent audio interface, I'd expect them to be a -lot- better.

Jitter ranks right up there with using special oxygen-free copper reference power cords or wooden volume knobs. :rolleyes:
 
Ethan Winer said:
> Jitter is so far down the list of sound quality issues for even the most track-intensive home recording projects that it shouldn't even be on your radar. <

Indeed, and I should have mentioned earlier that the same goes for dither. :eek:

Of all the things to fret about, those are at the very bottom of the list. Far more important is having accurate monitoring in a well treated room.

--Ethan
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I have most certainly heard dithering noise when mixing down some of my own home recordings, which were recorded in a crappy room and monitored with low budget speakers. This was in Cubase SX using it's supplied dithering plugin. I have'nt noticed any dithering noise while working on similar projects in Cool Edit. The dithering noise that I heard sounded like staticy, white noise and was low in volume in comparison to the tracks being mixed, but it was VERY apparent. A/B'ing between a truncated mix and a dithered mix, I prefer the truncated mix in Cubase. I won't use the dithering plugin in Cubase, even with my half baked, sloppy home recordings. I don't know what your experiences have been with dithering so I won't pass judgement on your opinion. It could be that the dithering plugin in Cubase is total crap.
 
This is an excerpt from an article title 'Choosing A PC Audio Interface' in Sound on Sound.
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Ironically, one audio interface parameter that I've found affects audio quality quite significantly is one very rarely mentioned in specs: clock jitter. However stable an oscillator circuit is, its frequency will still vary by a tiny amount over time, due to random noise, temperature variations and the like. Since the accuracy of the clock frequency determines how uniformly the samples are clocked out during playback, any timing variation will result in some sampled points being heard slightly early and others slightly late.

The result is a less 'focused' sound that is particularly noticeable with high-frequency attack transients on drums and percussion. You also tend to lose subtle detail such as spatial information, so you can't listen 'into' the music and hear what's going on deep into a reverb for instance. Over the years I've reviewed various audio interfaces that sound noticeably more focused than others, so it surprises me that jitter figures aren't more widely quoted, except in the case of really expensive gear. RME are an exception in making a feature of their jitter figures — I first spotted this with the lower than 1000pS (Picoseconds) of their Hammerfall HDSP9632, measured at 44.1kHz using the optical input. I also persuaded Emu to provide me with figures for their 1820M, which are 795pS via the optical input and 596pS using the internal crystal clock.

Both of these interfaces exhibit a clear, focused sound, and trawling back though the comments in my archived audio interface reviews I'm reasonably sure that other products with similarly low-jitter clocks include Aardvark's Direct Pro 24/96 and Q10, Echo's Layla and Mona, Edirol's DA2496 and UA1000, Egosys' WaMi Rack 24 and 192X, M Audio's Delta 1010, MOTU's 24 I/O, Soundscape's SSHDR1 and RED, and of course the Lynx One and Two.

Perhaps the reason for the lack of audio interface jitter figures is that manufacturers are wary of quoting them when those of single fixed-frequency clocked devices such as CD players tend to be significantly lower (my budget Cambridge Audio 640C CD player, for instance, quotes lower than 260pS). As soon as external sync circuitry enters the picture, overall jitter performance tends to drop, even when using the internal clock option. However, given that internal clock jitter is so important to the audio quality of even budget audio interfaces, I hope any manufacturer whose products are mentioned above will be encouraged to release some figures in the future.

Finally, before I end this section, it's important to note that you may not hear these subtle differences unless you have reasonable acoustics in your listening room — lots of stray audio reflections from desks, walls, ceiling and other gear may muddy the stereo image so much that they mask the improvements offered by a lower-jitter clock.

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Is Sound on Sound a reliable source of info?
 
Travis,

> The dithering noise that I heard sounded like staticy, white noise and was low in volume in comparison to the tracks being mixed, but it was VERY apparent. <

If it was "VERY" apparent then it was not dither. I wasn't there to listen in person so I can't say what it was caused by. But if you heard it (without increasing the volume at least 20 to 40 dB), then I'm certain it was not dither.

> It could be that the dithering plugin in Cubase is total crap. <

I suppose that's a possibilty too, but still seems unlikely. No competent DSP engineer would add dither that's louder than 90-odd dB below the music.

--Ethan
 
sync said:
The result is a less 'focused' sound that is particularly noticeable with high-frequency attack transients on drums and percussion.
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The guys at SOS magazine know what they're talking about much more so than writers for most audio magazine. But in this case he's simply wrong. This kind of stuff comes up all the time where things like "subtle detail" and "spatial information" seem to change with the phases of the moon. :D This article explains what I believe is the most likely cause of such reports:

www.ethanwiner.com/believe.html

Again, jitter is typically 120 dB below the music, and present only while the music plays. So how could it possibly be audible?

--Ethan
 
So Ethan,

You are saying jitter is an artifact, like tape hiss, or something, it doesn't contribute to the accuracy of reproduction?
 
Jitter ranks right up there with using special oxygen-free copper reference power cords or wooden volume knobs.
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Holy crap. I'm in the wrong business. I would really like to talk to someone who actually purchased a $485 wooden knob.
 
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