[regal]

Quote:

Originally Posted by Prog Rock Man /img/forum/go_quote.gif That reads as if Stereophile invented jitter and it does not actually exist. Is that really what you mean?

No, Jitter exists. Stereophile started the whole concept that Jitter is the only real difference in transport audio quality. I say jitter exists but it isn't what leads to transports sounding different.


I'm not disagreeing with Steve N or others that they are hearing differences. I just don't believe Jitter is the issue. There is something else going on, our ears can't hear picoseconds, thats like saying they are akin to a 3 mile particle accelerator. We have all accepted Stereophiles Jitter theories but they haven't been proven scientifically because the testing is too expensive.
I started my career as an empirical scientist (measurements.) Jitter can't be reliably measured on audio equipment in the ps range (ie. no ASTM standard). My thoughts are simply that know one has the answers on this controversial topic. Not at all saying the Steve's products aren't worth it, they probably do sound better, but no one can prove why, the egg hasn't been cracked.

 

[tosehee]

I don't think you are hearing the pico seconds, but the distortions that those differences in pico seconds affect to the original sound.

With that said, the difference is so minor it's nearly negligible, imo.

 

[nick_charles]

Quote:

Originally Posted by tosehee /img/forum/go_quote.gif I don't think you are hearing the pico seconds, but the distortions that those differences in pico seconds affect to the original sound.

Indeed, this can be a gloss of random noise that raises the noise floor if it is gross enough random jitter or distortion sidebands if the jitter is signal correlated, Benjamin and Gannon did some interesting tests on the effect of correlated jitter and found sidebands to be a long long way below signal until you hit several 100ns of jitter.

My question for the jitter-worriers is where are your figures and results derived from measurement and controlled listening tests that suggest that jitter as found in any barely competent digital device (using any spectra you like) is **actually** a problem for playback.

They ain't in the AES library, that's for sure, I know, I've been through it from end to end. There are some great theoretical papers which model jitter as audible in the ps level but these are *never* backed up with actual listening tests.

Ps "My Wife was in the kitchen and she could tell the difference with my new low jitter CD player" does not count as evidence !

 

[tosehee]

Quote:

Originally Posted by nick_charles /img/forum/go_quote.gif Indeed, this can be a gloss of random noise that raises the noise floor if it is gross enough random jitter or distortion sidebands if the jitter is signal correlated, Benjamin and Gannon did some interesting tests on the effect of correlated jitter and found sidebands to be a long long way below signal until you hit several 100ns of jitter. My question for the jitter-worriers is where are your figures and results derived from measurement and controlled listening tests that suggest that jitter as found in any barely competent digital device (using any spectra you like) is **actually** a problem for playback. They ain't in the AES library, that's for sure, I know, I've been through it from end to end. There are some great theoretical papers which model jitter as audible in the ps level but these are *never* backed up with actual listening tests. Ps "My Wife was in the kitchen and she could tell the difference with my new low jitter CD player" does not count as evidence !

+1.

I totally agree. I agree that jitters do affect somewhat, but they aren't audible in actual listening tests. It's like worrying about the cause of ripple effect that happened miles away. In theory, yes, it would have an effect, but
in reality, you are not gonna detect the cause of it.

 

[Prog Rock Man]

Quote:

Originally Posted by regal /img/forum/go_quote.gif No, Jitter exists. Stereophile started the whole concept that Jitter is the only real difference in transport audio quality. I say jitter exists but it isn't what leads to transports sounding different. I'm not disagreeing with Steve N or others that they are hearing differences. I just don't believe Jitter is the issue. There is something else going on, our ears can't hear picoseconds, thats like saying they are akin to a 3 mile particle accelerator. We have all accepted Stereophiles Jitter theories but they haven't been proven scientifically because the testing is too expensive. I started my career as an empirical scientist (measurements.) Jitter can't be reliably measured on audio equipment in the ps range (ie. no ASTM standard). My thoughts are simply that know one has the answers on this controversial topic. Not at all saying the Steve's products aren't worth it, they probably do sound better, but no one can prove why, the egg hasn't been cracked.

So the 'something else going on' is going to be down to the 1s and 0s as there is nothing else going on, or is there?

But it is easy to tell if it is the same 1s and 0s at the start (transport) as the end (DAC), or is that wrong?

 

[choka]

I had very similar experience. I used to believe there is no difference in transport as long as I am using optical out, so for the longest time I was using a 30 dollar philips dvd player from walmart. Late last year there was a deal on a yamaha SACD player, and because I already have some hybrid SACD lying around, I bite.

Same amp, same headphone, optical out as well, the SACD player sounds totally different, so much better, that I was completely blown away. AND I WASN'T LOOKING.

I was making the same argument that optical should be the same... I guess I can only blame myself from buying stuff from walmart.

 

[audioengr]

Quote:

Originally Posted by Prog Rock Man /img/forum/go_quote.gif So the 'something else going on' is going to be down to the 1s and 0s as there is nothing else going on, or is there? But it is easy to tell if it is the same 1s and 0s at the start (transport) as the end (DAC), or is that wrong?

There is generally nothing else going on. All things get back to jitter.

Sometimes the impedance matching is lousy on a component and this can cause some RFI to be generated in the component, but the effect is really subtle or has no effect IME.

If anyone has an engineering explanation of what might be causing this other than jitter, I'd like to hear it.

Steve N.
Empirical Audio

 

[n3rdling]

Quote:

Originally Posted by choka /img/forum/go_quote.gif I had very similar experience. I used to believe there is no difference in transport as long as I am using optical out, so for the longest time I was using a 30 dollar philips dvd player from walmart. Late last year there was a deal on a yamaha SACD player, and because I already have some hybrid SACD lying around, I bite. Same amp, same headphone, optical out as well, the SACD player sounds totally different, so much better, that I was completely blown away. AND I WASN'T LOOKING.

That's not comparing transports...that's comparing sources and (likely) different mastering on the disc. Unless you fed them both to a DAC you didn't mention.

 

[choka]

right, both are fed into the same DAC.

 

[n3rdling]

What disc was it? I know many SACDs have different mastering on the dual layers...surely you can see why your conclusion isn't entirely valid if this was the case with the disc you listened to?

 

[choka]

no no. i was just playing regular CDs and there's the difference.

 

[regal]

Quote:

Originally Posted by audioengr /img/forum/go_quote.gif There is generally nothing else going on. All things get back to jitter. Sometimes the impedance matching is lousy on a component and this can cause some RFI to be generated in the component, but the effect is really subtle or has no effect IME. If anyone has an engineering explanation of what might be causing this other than jitter, I'd like to hear it. Steve N. Empirical Audio

Me too, but there really isn't any scientific evidence proving Jitter is the issue. It has kind of become accepted by ruling anything else out, whats left is the ghost in the machine.

I think building any electronics using good PS and solid engineering design like Empirical Audio does, just results in good SQ, why hasn't been proven.

I could setup The Stones concert stage and play 1khz 1pS test tones at 140dB's all day and no one would hear it.

 

[krmathis]

Different designs, different components, ...
Just like why amplifiers sound different while handling the same analog audio signal.

 

[audioengr]

Quote:

Originally Posted by regal /img/forum/go_quote.gif Me too, but there really isn't any scientific evidence proving Jitter is the issue.

Sure there is. The analyis shows that jitter and data errors are the only issues with digital transmission.

Some components suffer from other things, such as ground-bounce and RF susceptibility, but even these manifest themselves ultimately as jitter at the D/A input.

Quote:

I could setup The Stones concert stage and play 1khz 1pS test tones at 140dB's all day and no one would hear it.

Of couse not, its not correlated to anything and its not amplitude modulated. Besides, it would take at least 100psec of frequency modulation even with a good test track to make any jitter easily audible. This is like saying a 1kHz test tone is sufficient to characterize an amplifier.

Steve N.
Empirical Audio

 

[AudioCats]

Quote:

Originally Posted by audioengr /img/forum/go_quote.gif Sure there is. The analyis shows that jitter and data errors are the only issues with digital transmission. Some components suffer from other things, such as ground-bounce and RF susceptibility, but even these manifest themselves ultimately as jitter at the D/A input. ...

Interesting. So jitter reduction is not just a lower-ppm clock module, it has a lot to do with everything else (power quality, wiring, signal reflection in the cable, optical sending/receiving modules, etc)?

which means the digital signal from different transports' digital-out are not exactly the same, even if the data stored on the CD is identical and the disk read-out is 100% correct?

If that is the case, then a flash/harddrive system will still have the same problem, different digital-out will sound different.