Why does my DAC sound so much better after upgrading digital SPDIF cable?

If you want a good Toslink cable, get this one:

https://btpa.com/TOSLINK-XXX.html

I have seen measurements showing jitter in Toslink, but they were showing >100kHz and even in the MHz range, so it has no influence on music.

Most jitter measurements are not useful if not even bogus. One number is insufficient unless there are plots to back it up.   When I reduced jitter from 22psec to 7psec with improvements to my Synchro-Mesh reclocker, the difference was easily audible to me and my customers.  You can never have jitter too low or inaudible IMO, at least not with todays technology.

It said these can effect jitter if all (cable and connector) are not 75ohm.

Very true, although the losses, dielectrics and even the conductor materials also have an effect.  The ONLY coax cable to be using is a BNC-BNC.  If you must have RCA connectors, use BNC to RCA adapters that are 75 ohms on the BNC end.  I verified last year that even Belden 1694A is not close enough to 75 ohms. I had used it as a reference for tuning my products and had to go back and retune all of them when I got an aerospace quality cable that is quite close to 75 ohms.

Steve N.

Empirical Audio

audioengr,
What you say makes sense. Do you have a recommendation for a high quality audiophile BNC to RCA adapter?

High-quality, not really, but you can get 75 ohm adapters at Markertek..com. They are a bit short for some component jacks, but they perform fine.

Steve N.

Empirical Audio

Also, I mixed psec with ns. Going from 22psec to 7psec is not audible. Some studies/trials have been done, and human audibility of jitter is >10ns (~20ns one study found), which is 10,000psec. And again, any good DAC would get rid of jitter to beyond audibility in the first place.

I've heard this mantra over and over.  You are believing the marketing BS.  It is audible. Here are the customer feedbacks to prove it:

https://www.audiocircle.com/index.php?topic=157348.msg1687192#msg1687192

https://www.audiocircle.com/index.php?topic=157348.msg1709284#msg1709284

https://www.audiocircle.com/index.php?topic=157348.msg1709326#msg1709326

https://www.audiocircle.com/index.php?topic=157348.msg1709507#msg1709507

The studies that have been done by AES and others are flawed. I have read them and pointed out flaws in all of them.

As for the DAC reclocking: in your dreams. The only DAC that I have encountered where a customer thought it was totally immune to incoming jitter was the Benchmark DAC3. This result was probably clouded by his system which was likely not resolving or low-noise enough.

Steve N.

Empirical Audio

I know a few psec makes a difference, and the measurements I was talking about showed digital coax around 100psec at 100kHz to 1.4MHz and Toslink at 500-1000psec for the same reason. However, that’s well beyond human audibility so it doesn’t matter.

It does matter.  Once you get a rig put together that is truly resolving, you can easily hear these differences.  Everyone has a system they believe to be resolving but it just isn't the case.

Show me the jitter difference between an Amazon Basics optical cable and then from an AudioQuest Diamond optical cable. I have seen one users measurements where he compared a ~$3 optical cable to a $200 glass one, and the $200 was 5psec less.

I don't have any way of measuring accurately Toslink cables, only coax cables.  Just spend $25 and get the Toslink I recommended.  You will hear the difference.

However, keep in mind any properly made DAC (I’ve seen $1000 ones perform worse than $100 ones) will get rid of jitter anyway, even the AudioQuest DragonFly USB DACs will reduce the jitter to be inaudible.

I definitely will not keep this in mind, because it's simply not true.  There is no such thing as eliminating all jitter, even if companies advertise this.  Most DAC's benefit from a reduction in input jitter, even if they have reclocking inside. I used to mod many different DAC's, so I have a lot of experience here. I'm not a fan of reclocking inside the DAC BTW.

Steve N.

Empirical Audio

Jitter is well documeneted. However, comparing jitter between DACs has nothing to do with if you are using a $20 generic digital cable (coax or optical) or a $4000 Nordost one.

It certainly enters into it. If the cable is really poor, the jitter added will swamp what the DAC will deliver in terms of jitter. See these plots:

https://www.audiocircle.com/index.php?topic=154425.0

Steve N.

Empirical Audio

I didn’t say the DAC would eliminate jitter, I said it would reduce it to beyond audibility.

Just take a second (pun intended) and just think how short a nanosecond is, and then a picosecond. Sorry, but no, we can’t hear a difference.

I know exactly how small a nsec and psec is, 10-9sec and 10-12 sec.

Who is we? You mean you I think.

I get this all the time on the forums. People with unresolving, noisy systems that think they have something great. All it takes is an inexpensive preamp to prevent you from hearing most of these differences. I have had systems for a decade that can discern easily the difference between a wav file and FLAC, AIFF and even uncompressed FLAC files. I can easily hear the difference in files with different offsets. You probably don’t know that this is. Some people reading these posts have much better systems and they can benefit from my advice.

I have been designing digital systems and managing design groups for 42 years as an EE. I know what I’m talking about.

Just got another feedback today:

https://www.audiocircle.com/index.php?topic=157348.msg1715109#msg1715109

Steve N.

Empirical Audio

So, it should be obvious that if 2 million psec is not easily differentiable with music playing, than your original statement of going from 22psec to 7psec being a drastic difference should show you why I stated it was bogus, even if your gear and room are near silent,

It is not bogus. I have been demonstrating differences in jitter for 10 years at RMAF, THE Show, LA Audio Show and others. I can measure it and I can hear it with my systems. My customers feedback proves that these differences are audible. You need a system that provides pinpoint imaging and deep wide soundstage. You cannot get with this an iPhone.

Of course, given your job, I highly doubt you would state otherwise

What the hell is that supposed to mean?  Is this a personal attack?

Steve N.

Empirical Audio

Jitter is an issue with every piece of digital gear, even Toslink.  Toslink has the additional issue of conversion from electrical to optical and optical back to electrical.  Each of these stages adds jitter.  Even a single gate adds jitter.

If you don't think you can hear these differences, fine.  I have hundreds of Synchro-Mesh customers that do hear the difference.  I don't need your business.

The only reason that I respond to your posts is to debunk what you are saying, which may lead other audiophiles down the garden path.

It's like debunking the record crowd size claimed at the Trump inauguration.  Somebody has to do it.

Steve N.

Empirical Audio

Maybe the paper referenced below will shed some light on the complexity of jitter for those that believe that a simple value in some clock or DAC datasheet can Trump this effect for good.
Audibility of some forms of jitter on DACs and ADCs have been investigated, but I believe that the improvements that most of us hear when jitter is reduced tend to indicate that audibility thresholds are not so easy to define and greatly depend not only on the technology used inside the chips, but also on the implemented circuitry around those chips (e.g. power supply management).
My 2 cts worth, /patrick

https://statics.cirrus.com/pubs/whitePaper/WP_Specifying_Jitter_Performance.pdf

A good start.  I agree with:

practically meaningless. Jitter specs should always

identify what measure of jitter they are referring to,

as in "Period jitter 200 ps RMS" for example."

All of my jitter measurements are direct and of the period.

wideband jitter and baseband jitter, it can be measured

directly in the time domain, i.e. without filter hardware.

You simply use a scope, and examine the waveform

one period after the trigger point. Many scopes can plot

period jitter histograms and extract RMS values."

I do not agree with this however:

appropriate for some purposes. We see here that it is

entirely inappropriate as a general measure [14]. This

is because it is basically blind to low-frequency jitter."

This depends on the measurement system and how it measures the jitter.  Mine measures the jitter of the data, not the clock, so it factors in the fact that the period changes.  It selects one period and locks onto this.

measurements with very large N. Modern digital scopes

are excellent for such measurements."

I do not believe my measurement system can do this easily, but it is important.

that gets modulated. It is everything that crosses the

boundary between the continuous-time domain and

sampled-signal domain. This can include out-of-band

interference (in ADCs), incompletely attenuated images

(in DACs), and "zero-input" internal signals such as

shaped quantization noise and class-D carriers."

cause problems if they are up at high frequencies."

causes a converter that should have more than 100 dB of

dynamic range to deliver e.g. only 80 dB. In such cases

the jitter is interacting not with the audio signal but with

an internal signal such as shaped quantization noise.

Early one-bit DACs were particularly sensitive to this.

More-recently the inclusion of switched-capacitor filters

and the move to multi-bit designs has eased things.

Above ~200 kHz, the quantization noise is largely white

at its point of injection. When you factor in the DAC's

sin(x)/x frequency response and the effect of the internal

switched-capacitor filter stage, its spectrum becomes

more like the upper trace in figure 10 (taken from [17]).

By applying the already-mentioned 6dB/octave tilt,

one can estimate the region of greatest jitter sensitivity.

It is typically somewhere around ~0.5 or ~1 MHz for

DACs that use high-order noise shaping."

relate entirely to signal components that are above the

audio band."

So as you can see, the DAC itself is sensitive to jitter that is way out-of-audio band.

Steve N.

Empirical Audio

Am I right to think that gold connectors for digital cables are pointless?

The contacts are the important part in a BNC or RCA.  If both the shield and center conductor contacts are gold-plated, this is good enough.  Any non-oxidizing conductor material will do.  The shield is usually not gold-plated or having 360 degree contact unless you get a high-end connector, like the Neutrik BNC.

Steve N.

Empirical Audio

Am I to understand that the cable is causing jitter to a flashing pulse of light and that the digital info being received by the amp is not totally correct? Or is jitter to do with extra devices and connections and distance between the source and the amp?

The info is correct, but the timing of the info is not optimum.  Everything adds to the jitter a little, the optical to electrical converters, the cable and every active device inside the components.  If the cable delivers a less than optimum signal, this will affect jitter because the receiver will have a slower risetime in reponse to the optical signal transitioning states.

Why don't you just try this excellent inexpensive cable and hear the difference:

https://btpa.com/TOSLINK-XXX.html

Steve N.

Empirical Audio

I find that Tidal hi fi sounds different than CD. I've grown to prefer it.
But I would think having an all in one CD player would minimize jitter.

All-in-one player is no magic bullet.  Still has the same jitter problems as separates.

I had a modified sonos connect streaming Tidal, and I could never tame the splashy treble. It was running on a switching power supply.

Digital signals are only about jitter, nothing else.  Sonos jitter is reduced 100X using a Synchro-Mesh.  Jitter plots:

https://www.audiocircle.com/index.php?topic=154310.0

Steve N.

Empirical Audio

I’ve got a comparably modest digital source setup:

Allo Digione RPi
to Schiit Modi Uber 2
to NAD C316BEE
to Tekton Lore speakers

Did an a/b test with each cable upgrade:
no-name cheapo rca analog interconnect to ZU audio mission from dac to amp = huge improvements.

Then the same with digital rca: 
monoprice 1.5 meter to amplifier surgery 1.5 meter from Digione RPi to dac = huge improvements.

Here are jitter measurements of your Digione.  I also have one, not the latest premium version BTW:

https://www.audiocircle.com/index.php?PHPSESSID=g252r6cln0acu9kqv4f29356n6&topic=154299.0

Steve N.

Empirical Audio

Also, here are some measurements of different Toslink cables: http://archimago.blogspot.com/2013/05/measurements-toslink-optical-audio.html?m=1

Including a freebie one, an intentionally poorly made one, an all glass one,etc.

Guess what? They are 99.9% identical, and jitter all below 100dBFS. So yeah, I stand further by my claim that the poster simply fell prone to placebo.

Worthless measurements.  Why? Because they are woefully insufficient to characterize the system, much less the jitter difference.

Most classical analog measurements are insufficient to show small differences in dynamics or soundstage.  This is a fact supported by hundreds of reviews in Stereophile where the measurements were very poor and yet the review with music was stellar.

The ONLY accurate way to make jitter measurements on a digital source is to do it directly, not through a DAC or analog system.  This requires a 5-10GHz B/W measurement system, not an AP.

Steve N.

Empirical Audio

As one person noted, a digital cable actually carries an analog signal. However, the magic is the software. When a digital signal is sent it is sent with what are called stop bits and a checksum. The hardware at the other end recalculates these values and compares them. If they don’t match, it requests the sender to re-send it. This way it is VERY rare, and i mean VERY rare for an incorrect packet to be get by this protocol.

At both ends the data is buffered (stored) to accommodate a fair number of error/resend cycles. After all the transmission speed is MUCH higher than required for high definition audio or even HD video. If you have a LOT of errors, then you will run out of buffered data and get ’skipping’ or some other sort of artifact.

If you find that cables made a difference, then you either had defective cables or ones that were insufficiently shielded, allowing enough errors to empty the buffer.

We are not talking about dropping bytes or getting bit-errors here. This is about timing inaccuracies. The timing of the digital signal must be extremely accurate, from word to word, in order for the D/A to reproduce a low-distortion waveform.

Steve N.

Empirical Audio

MW - There are several techniques. Lets address each of them:

Synchronous buffering:

With synchronous buffering, the same clock is moving the data in and out of the FIFO buffer, so the incoming clock jitter matters.

Local PLL clock:

If you have a local clock that is locked to the incoming clock with a PLL to clock the data out of the FIFO, then the PLL filter loop is affected by the jitter.

Bang-Bang bracketing system:

If you have a bang-bang system that clocks the data out of the FIFO using a local clock which moves the frequency slightly up and down to bracket the frequency of the incoming clock, then this has the potential to minimize the effects of incoming jitter. IT is actually not meeting the spec. for sample-rate frequency though. This is one of two techniques that can actually be immune to incoming jitter. The problem is that it takes 12 custom oscillators, all with low jitter to pull this off. If one designs it any other way, then the jitter of the local clock is the problem. There are a couple of DACs out there that do this, but their jitter is not very low.

Resampling system:

A resampler uses separate local clocks to reclock the data at a new frfequency after it is synchronously buffered to achieve a small delay. Resampling is the second technique that in theory has the potential to be totally immune to incoming clock jitter. It maintains the proper sampling frequencies. The reality is that even the best reclockers, including mine are still slightly affected by incoming jitter. This is likely due to the implementation of the resampling chips.

Steve N.

Empirical Audio

leemaze - the Toslink I recommend uses a high-quality polished plastic fiber.  I experimented with many glass fiber cables, but I realized that this plastic cable just sounded better.  Usually it's the light distortion in the cable that causes signal degradation due to imperfect polishing of the ends or imperfect polishing of the outer fiber.  This cable evidently delivers the light with less reflections and distortions. It may also have to do with the index of refraction of this particular plastic.  It is unlike other plastic cables.

Steve N.

Empirical Audio

If you don't notice a difference straight away and I'll give some of you two days time and it is not patently obvious to you that there is a massive difference then please take a tip from me and sell your stuff because you plainly cannot hear properly.

I agree, and they can stop posting drivel on these forums too. It's getting aggravating.

Steve N.

Empirical Audio

•  Edit
•  Delete

It should not really matter because one should never drive a DAC with a Toslink anyway.  Too much jitter.  Go Toslink to a Synchro-Mesh and then a good BNC coax cable from Synchro-Mesh to the DAC.

Steve N.

Empirical Audio

When mzkmxcv makes comments like:

"A $10,000 speaker wire won’t sound better than a $50 one, and a $2000 USB cable won’t sound better than a $20 one"

and:

" One debunked myth is that silver cables sound brighter than copper cables, they don’t, they just conduct electricity a bit better so decibel loss is a tad less over the same distance, and yet going a single gauge better for copper will have even less loss and cost a heck of a lot cheaper. "

He loses all credibility.  It is obvious that either his hearing is impaired or that his system cost is much less than $20K.  Maybe he has never experienced HiFi sound quality.  Everyone I talk to says that around $30K is the threshold to enable Hi-FI sound quality versus mid-Fi sound.  I agree with this based on 22 years of anecdotal evidence and experience.  Everything in the system matters.  It is a system, not just a collection of parts.  One deficient component or cable can change everything.

It is also obvious that he understands nothing about the physics of audio cabling when he claims conductivity and wire gauge are the only concerns.

We all know better.  Perhaps a more appropriate forum for him to post on is:

https://www.avsforum.com/forum/index.php

Steve N.