Jitter - What does it sound like?

Judging by a lot of the posts I've read on the subject, jitter sounds ... tedious.

Sorry, couldn't resist. Someone claiming to be knowledgeable will come along to grind their soon.

Like Steve says there are so many threads about, I'd thought George would have been inundated with replies.
Of course it may just be a discussion item and actually has no effect on the music at all.

Dear BigH.

I suspect it an axe-grinding point of little significance unless dealt with completely incompetently. The digital domain is much more robust in terms of consistency than analogue, and I do await with interest a chapter and verse description of its sonic significance, rather than some suggestion of some nugatory effect of no real significance.

Still interested, though!

ATB from George

quote:

Originally posted by Steve Bull:
Judging by a lot of the posts I've read on the subject, jitter sounds ... tedious.

George,

I cannot really answer your question directly regarding what it sounds like. But I know they are timing errors with respect to how the digital data is read and passed along to other components.

It is just one of many measurements that explain why the CDS's are among your favorite CDPs you've ever heard. But surely it isnt the only factor.

I imagine you can find a website (or youtube) with tracks with various levels of jitter. I am guessing at a certain point if it is bad enough you will get a very unmusical digital sound not unlike the old analog cell phones when they broke up.

There are many other "measurements" similar to jitter that you might read about, all of which play some part in how different sources sound. It really isn't any different from vinyl replay. They are just different and foreign to you an me. They could be microphony?, RFI, vibrations, jitter, messing with bit perfection (up/down/over sampling that makes the music sound sterile and fake), etc....

Im am sure Andy will come along and expertly explain everything you could possibly want to know.

For what its worth the 555 does not have the lowest jitter out there in the world of CDPs, so pinch of salt you know....

-patrick

How do you describe distortion? Hard to do, but you know it when you hear it.

From what I've read, the effect of jitter is not analogous to the irregularities of vinyl. Jitter does not cause changes to pitch accuracy or timing. It causes unrelated sideband distortion.

Here's an interesting quote from the cmp2 web site (Chapter 3 - Jitter the scourge of digital audio):

"Periodic jitter is more offensive than random jitter as its sidebands are not related to the harmonics of the tone being reproduced (i.e. they are ‘aharmonic’). Since any musical note’s harmonics extend well into the high frequencies, the sound of a decaying tone is distorted by periodic jitter: its ‘bloom’ is lost. Jitter is most damaging at high frequencies, i.e. when large voltage swings occur (slewing) as it leads to greater signal amplitude errors."

There is a ton of information about jitter on the web. Almost all of it is technical (and a lot of it is boring). But there does seem to be a consensus that the effect of jitter does (at some level) become audible.

I recall seeing a Japanese study from some years back where listeners with headphones were seated at computer terminals with 3 sound buttons to push. A reference button and two others. One of the two buttons matched the reference exactly, while the other had a higher level of jitter. Once the jitter got above a certain threshold, the lion's share of listeners could tell the difference.

So, I guess it just sounds....wrong.

Hook

There is a pretty strong school of thought that contends that the jitter level of even half-decent digital systems is inaudible. My understanding is that (if audible at all) it sounds like distortion, but not in a creamy, crunchy Marshall Tube amp way. In a BAD way. Harsh and brittle.

Quote from How does jitter sound?

quote:

The tests were always jitter vs. less-jitter or in other words Altmann-UPCI not installed or installed.

We tested with CD (16 bit, 44,1kHz) and DVD (24bit, 96kHz) recordings.

Here the results:

1) It makes a big difference. Everybody (with intact ears) can hear it.

Once heared, one can differentiate within the very first second if the reproduction is jittered or not. It is a totally different sound quality.

2) "Less jitter" sounds better, much better!

Auditioners testified:

improved ease of listening
increased clarity
improved high frequency response
better instrument separation
more information
better timing
better soundstage
improved overall audio performance
At this point i would like to refer to the measurements.

quote:

A measurement result of Watson and Kulavik is: "What happens is that the width of a given fundamental will increase in the presence of word-clock jitter. In a jitter free environment a fundamental frequency tone would show up on a spectrum analyzer as an impulse. As jitter is introduced this impulse begins to spread".

-
aleg

In the immortal words of Edwin Star ...

Jitter! huh-yeah
What does it sound like?
Absolutely nothing

Or am I confused??

Eloise

quote:

Originally posted by Aleg:
Quote from How does jitter sound?

Nice article aleg!

I liked this snippet from it too (the boldening is in the original article):

quote:

This was accomplished by an external microcontroller that was programmed to increment the number on a 4 digit display on every interpolation or hold. With this tool we had the accurate count of all uncorrected samples that were output during the track or the entire CD.

The funny thing is, that the low cost CD723 player is able to read any CD or CD-R that is not severely scratched without any interpolation or hold. You can even put it upside down, there will be zero interpolation /hold.

I.e. cheap players are generally bit perfect....

Quote]You can even put it upside down, there will be zero interpolation /hold.[/quote]

I would imagine there would be no sound either!

From what I've read, the effect of jitter is not analogous to the irregularities of vinyl. Jitter does not cause changes to pitch accuracy or timing. It causes unrelated sideband distortion.

If this is the case, then it will never concern me to reduce it further than the standard available with modern digital replay. Music is fundamentally about rhythm and pitch which is the sine qua non for effective expression to emerge, both in live performance and replay of musical recordings. As such it may be argued that reducing timbral distortions and even recording/replay noise, such as 78 crackle, analogue tape hiss, and LP surface noises, and presumably also jitter is a sensible aim. But the fact remains that noise in digital replay is not something that has ever concerned me in any replay that I have heard.

I am glad to have this explained to me as I was at a loss to understand what the effect of jitter might be.

No recording is perfect and no replay, but the standards achieved nowadays as near perfect as to be no impediment to enjoying music for me!

Thanks for all the contributions. Best wishes from George

Jitter sounds like the Benchmark dac.

Never heard one! {:¬)

Quite like the little one I have though. It does very well!

ATB from George

quote:

Originally posted by GFFJ:
From what I've read, the effect of jitter is not analogous to the irregularities of vinyl. Jitter does not cause changes to pitch accuracy or timing. It causes unrelated sideband distortion.

If this is the case, then it will never concern me to reduce it further than the standard available with modern digital replay.

That is exactly how a feel about vinyl replay. I would be very happy with a stock P3 or Project Debut, and use the stock tonearm and supplied cartridge. All played through my 102's phono boards.

The difference between this and a fully spec'd LP12 may be great but not enough to affect my enjoyment of the music.

There really is no difference between vinyl and digital replay in this manner. Some of us just strive for more perfection in one area or another. Not only for the SQ, but also for the hobby, and the fun of a little tweakery.

Also, just because we have little understanding of what jitter is, but we do get how tracking errors/variable pitch results can affect sound, does not mean that jitter is insignificant.

To me the physics behind how a TT works is just as mystifying as a DAC or CDP. It is all beyond my comprehension.

Managing jitter is simply the digital equivalent of a using Trampolin or whatever they are called.

take care,
Patrick

Timing is something I find wrong with much of digital. I'm sure the causes are varied.

25yrs ago it was tracking/rack angle of the arm now its jitter.it all sells new stuff