[Geardaddy]

Part I of "the sonic signature of jitter and how to conquer it" was a great success and generated some needed definitions, technical data, and the possibility of a test file to determine whether levels of jitter are discernable, etc.  What I am primarily interested in at this juncture is what fellow philes have experienced in regards to "anti-jitter technologies or tweaks???  This is an important question as we appear to be transitioning from CD-based digital sources to computer-based ones.  Proponents of the computer revolution or evolution insinuate that music servers and related products are inherently superior due to lower jitter levels, correction of reading errors, etc, etc. 
   

[Tweaker]

I have a GW Labs DSP which, among other things, is supposed to reduce jitter. The DSP feeds a DEQ2496 via an xlr balanced cable and the DEQ2496 uses ARSC which also is supposed to help make jitter go away. I dunno. I haven't experienced any of the issues that are described as being caused by jitter in my system (that I'm aware of), so I'm guessing something must be working.
Charles Altmann has a product that's been around for awhile that is also supposed to eliminate jitter:
http://www.jitter.de/english/jiscofr.html
My system also never ever gets anything but decaf coffee. HAHAHAHA .
haha...
Sorry.

[opaqueice]

Well, one interesting option in that regard is the Benchmark DAC1.  Personally I always take manufacturer's data with a grain of salt or three, but these plots look pretty clean:




(I hope it's OK to link to these images).

It's a little hard to read, but I think that second plot has an input jitter amplitude of 2075 ns, or 2 us - which is huge!  Now according to the little estimate I did in the other thread, with no jitter attenuation you'd have sidebands at 10-5=5 kHz and 10+5=15 kHz with an amplitude of 10 kHz * 1 us = 1/100, so at about -40 dB in power.  Given that there are no sidebands down to -140, that says their jitter attenuation is -100dB at least past what they would get with none....  not bad!

[art]

Gee, I could be wrong, but......

Judging from the pronounced dip in the noise response, around 10 kHz, my bet is that they ran it through a BPF before they made the measurement. That technique is widely used to prevent overloading of the measuring device, to extend useful range.

So, your conclusions may not be valid.

ASRCs do work. Some engineer type folks don't like them. Just take my word for it (please!), and don't ask me to 'splain why. (Ask someone who wants to decode HDCD why they don't like them.)

Pat

[opaqueice]

Gee, I could be wrong, but......

Judging from the pronounced dip in the noise response, around 10 kHz, my bet is that they ran it through a BPF before they made the measurement. That technique is widely used to prevent overloading of the measuring device, to extend useful range.

You're absolutely right - it says so right at the top of the plot.

But the jitter sidebands should be at 5kHz and 15kHz, and you can see from dip in the noise floor that the width of the filter is only 2kHz or so.

[Geardaddy]

So, theoretically, part of the Benchmark, anti-jitter magic involves their UltraLock design:

"The D/A conversion clock is totally isolated from the input digital audio clock in a topology that outperforms two-stage PLL designs. In fact, no jitter-induced artifacts can be detected using an Audio Precision System 2 Cascade test set."

Pat, do you have any comments on this....?

[Geardaddy]

I know this is a proverbial can of worms, but it is worth opening in the context of anti-jitter technologies.  The Nova Physics Memory Player created quite a stir, both good and bad, when it first appeared.  Many claimed that it was/is a glorified computer running EAC, and that NP was bilking gullible philes with non-proprietary technology.  The NP gang claims that in addition to RUR technology as found on EAC and other programs, the central issue controlling jitter revolves around error correction coding ("Reed Solomon codes"):

"Error correction codes CREATE jitter:

In short, more & more accurate clocking are baby steps when the most powerful creation of jitter is during the CD READING itself.
So a notably jittered signal is fed to the finest clocks but they cannot repair what they cannot see as the CD has already been read."

Is this crap?  Computer jocks...please chime in....

[mfsoa]

As far as anti-jitter tweaks go, how about burning onto different CD-R media?

I had fun the other night with a friend and my wife (audio fun, you pervs) listening to an original Aja CD, and copies burned (via EAC, at 4x speed) onto silver discs (Taiyo Yuden) and gold (Mitsui Audio Media, or MAM-A Gold - something like that). The burning was done on my plain old Dell 8300 stock internal drive - No fancy external burner hooked into a power conditioner, sitting on iso-pucks, pretreated CDs etc - Just pop in and burn, baby burn.

Without knowing what I was putting in my Rotel 1072 CDP, they were both consistently able to pick the Gold out as being superior to the Silver, which was clearly superior to the original. On the gold, the highs were more extended and the grunge was reduced, to speak in absolutely precise audio terminology.

I also made a 2nd silver copy, which I black magic-markered. This disc was also consistently preferred to the un-markered silver disc.

At the end, I markered the gold, which we all felt was better than the un-markered gold, but I didn't burn another gold for direct comparison since I'm running low on them (and they cost ~ 5x more than the silvers).

Perhaps what we were hearing was the result of less jitter? Like the (theoretically) superior quality of the Gold disc gave more accurate timing info to the CDPs speed control mechanism??  I read a paper the other week comparing the longevity and jitter characteristics of various CDRs, and the Gold was the best, IIRC.

So maybe the realm of different CD-Rs, CD polishes etc. are manifesting their differences in the realm of jitter reduction??

-Mike

[BrianM]

I don't have an opinion on the Benchmark DAC but I think you have to be suspicious about a product that advertises their anti-jitter device as the alpha and omega of digital to analog conversion.  What about the analog stage?  Stuff can get screwed up there, too.

[opaqueice]

"Error correction codes CREATE jitter:

In short, more & more accurate clocking are baby steps when the most powerful creation of jitter is during the CD READING itself.
So a notably jittered signal is fed to the finest clocks but they cannot repair what they cannot see as the CD has already been read."

Is this crap?  Computer jocks...please chime in....

It's probably crap, yes.  But regardless, all you have to do is rip the CD on a computer (into an audiophile approved lossless format, of course) and then later send it to a $300 squeezebox or transporter or sonos or whatever to isolate your music totally from any possible problems arising from reading the CD in the first place.  Unlike the Memory Player, those are solid state devices with no moving parts.  They're basically just a chip that converts TCP/IP to digital audio, a DAC, and some analogue circuitry, and they have very low jitter at the digital out (at least the SB and TP do).

And let me add that bit errors in the ripping process are essentially non-existent.  Every CD I rip gets checked against an online database of checksums, and they almost always match (the only exceptions are the occasional scratched disk which can't be read properly).

[Rx8man]

On page 13, part 1 of this series, Scotty had mentioned removing an external crystal and replacing it with a VCXO of the proper frequency.

The VCXO seems to be a relatively inexpensive way to reduce jitter to very low levels.

I'm not a design engineer, but this and reworking the power supply seem to be an attractive solution, any other thoughts ? 

[AphileEarlyAdopter]

Right, I dont trust the Nova Physics guys..It is just a EAC bundled in to hardware. I have had some interactions with these guys on audioasylum. Even some board members were critical of them. They were very evasive or equivocal on their technology.
Reg: burning on to CDR afer EAC, yes it makes  difference. Black markers, cd polishes, mats make a difference too. But this is too frustrating, especially for a guy with two young kids and a working wife. I just moved to Squeezebox.
Re: jitter being less with music servers - I think the major contribution is the lack of moving parts (like in Squeezebox or in the USB soundcard). Basically, it is my hypothesis that jitter spectrum keeps varying in a players, whereas in a Squeezebox or USB soundcard it is much more stable. Sonically, with the SB3 or soundcard, the sound is more smooth, pleasing or less edgy versus a CD/DVD player. Sometimes people might prefer a CD/DVD player sound. So there are some moot things in jitter too.
As far as tweaks go, I mentioned some in the previous thread. I will post more later.

[audioengr]

I know this is a proverbial can of worms, but it is worth opening in the context of anti-jitter technologies.  The Nova Physics Memory Player created quite a stir, both good and bad, when it first appeared.  Many claimed that it was/is a glorified computer running EAC, and that NP was bilking gullible philes with non-proprietary technology.  The NP gang claims that in addition to RUR technology as found on EAC and other programs, the central issue controlling jitter revolves around error correction coding ("Reed Solomon codes"):

"Error correction codes CREATE jitter:

In short, more & more accurate clocking are baby steps when the most powerful creation of jitter is during the CD READING itself.
So a notably jittered signal is fed to the finest clocks but they cannot repair what they cannot see as the CD has already been read."

Is this crap?  Computer jocks...please chime in....

Error correction is the exception, not the rule.  Very rare to need it unless you have a very scratched disk.

Steve N.

[audioengr]

As far as anti-jitter tweaks go, how about burning onto different CD-R media?

I had fun the other night with a friend and my wife (audio fun, you pervs) listening to an original Aja CD, and copies burned (via EAC, at 4x speed) onto silver discs (Taiyo Yuden) and gold (Mitsui Audio Media, or MAM-A Gold - something like that). The burning was done on my plain old Dell 8300 stock internal drive - No fancy external burner hooked into a power conditioner, sitting on iso-pucks, pretreated CDs etc - Just pop in and burn, baby burn.

Without knowing what I was putting in my Rotel 1072 CDP, they were both consistently able to pick the Gold out as being superior to the Silver, which was clearly superior to the original. On the gold, the highs were more extended and the grunge was reduced, to speak in absolutely precise audio terminology.

I also made a 2nd silver copy, which I black magic-markered. This disc was also consistently preferred to the un-markered silver disc.

At the end, I markered the gold, which we all felt was better than the un-markered gold, but I didn't burn another gold for direct comparison since I'm running low on them (and they cost ~ 5x more than the silvers).

Perhaps what we were hearing was the result of less jitter? Like the (theoretically) superior quality of the Gold disc gave more accurate timing info to the CDPs speed control mechanism??  I read a paper the other week comparing the longevity and jitter characteristics of various CDRs, and the Gold was the best, IIRC.

So maybe the realm of different CD-Rs, CD polishes etc. are manifesting their differences in the realm of jitter reduction??

-Mike

These are all addressing jitter reduction: re-writing, mats, polishes, treatments etc..

Steve N.

[audioengr]

"Error correction codes CREATE jitter:

In short, more & more accurate clocking are baby steps when the most powerful creation of jitter is during the CD READING itself.
So a notably jittered signal is fed to the finest clocks but they cannot repair what they cannot see as the CD has already been read."

Is this crap?  Computer jocks...please chime in....

It's probably crap, yes.  But regardless, all you have to do is rip the CD on a computer (into an audiophile approved lossless format, of course) and then later send it to a $300 squeezebox or transporter or sonos or whatever to isolate your music totally from any possible problems arising from reading the CD in the first place.  Unlike the Memory Player, those are solid state devices with no moving parts.  They're basically just a chip that converts TCP/IP to digital audio, a DAC, and some analogue circuitry, and they have very low jitter at the digital out (at least the SB and TP do).

And let me add that bit errors in the ripping process are essentially non-existent.  Every CD I rip gets checked against an online database of checksums, and they almost always match (the only exceptions are the occasional scratched disk which can't be read properly).

The SB has one of the lowest jitter outputs of the various WiFi devices, but far from inaudible.  Reclocking it makes a huge improvement.
Even these kinds of devices can have high jitter if the clock used is not an expensive clock and the S/PDIF output is not executed well.  Sonos is a case in point.
Steve N.

[audioengr]

On page 13, part 1 of this series, Scotty had mentioned replacing an external crystal and replacing it with a VCXO of the proper frequency.

The VCXO seems to be a relatively inexpensive way to reduce jitter to very low levels.

I'm not a design engineer, but this and reworking the power supply seem to be an attractive solution, any other thoughts ? 

VXCO's are typically very jittery compared to fixed oscillators.  Far from inaudible IME.  Precision frequencies and low jitter do not always come in the same package either, such as atomic clocks etc..

Steve N.

[jhm731]

The SB has one of the lowest jitter outputs of the various WiFi devices, but far from inaudible.  Reclocking it makes a huge improvement.
Even these kinds of devices can have high jitter if the clock used is not an expensive clock and the S/PDIF output is not executed well.  Sonos is a case in point.
Steve N.

I agree.

Running a stock SB3 or Duet's digital output thru my upgraded Digital Lens makes a nice improvement. 

[art]

Gee, I could be wrong, but......

Judging from the pronounced dip in the noise response, around 10 kHz, my bet is that they ran it through a BPF before they made the measurement. That technique is widely used to prevent overloading of the measuring device, to extend useful range.

You're absolutely right - it says so right at the top of the plot.

It probably does. It is too small to read. (There is a reason why most nerds have really thick glasses.)

Pat

[art]

The SB has one of the lowest jitter outputs of the various WiFi devices, but far from inaudible.

It does? Hate to see the rest of them.

  Reclocking it makes a huge improvement.

Yes. And not hard to do.

Even these kinds of devices can have high jitter if the clock used is not an expensive clock and the S/PDIF output is not executed well.

Or it has a really noisy power supply.

Sonos is a case in point.
Steve N.

So, I guess I should consider myself lucky that I have never found one show up in the mail. Right?

Pat

[NewBuyer]

The SB has one of the lowest jitter outputs of the various WiFi devices, but far from inaudible.  Reclocking it makes a huge improvement.
Even these kinds of devices can have high jitter if the clock used is not an expensive clock and the S/PDIF output is not executed well.  Sonos is a case in point.
Steve N.

I agree.

Running a stock SB3 or Duet's digital output thru my upgraded Digital Lens makes a nice improvement. 

Similar here - Running the stock SB3 digital output through a GW Labs DSP brings noticable improvements in my system as well, in either 44.1kHz or 96kHz mode (but especially in 96kHz mode)...