Why do digital cables sound different?

As verified by the sonic signature of sound changing obviously with power cables, not just digital cables, changes to the electricity itself must occur from the material that it is going through.

Lvhjr1, Optical cables don't have problem of jitter cause by reflections on impedance boundaries but rather from jitter being result of system noise affecting slow transitions (inherent to low slew rate of transmitters). Noise also affects transition of signal thru receiver's threshold (causing jitter) in coaxial cables, but much less because transitions are faster.

This is a topic that gives me a flashbacks to circuits 101, 35 years ago. It was a difficult concept to grasp, even after completing 5 Calculus and 3 Physics courses, but let's simplify it into one expression, dynamic change. Any time you change the signal characteristics the sound will be different; that is the inherent nature of sound produced from electrical pulses. Digital cables are required to be Impedance matching at 75 ohms. There is no exact 75 ohm Impedance, since it changes with frequency and can be altered by materials and construction. The acceptance of the change is in the ear of the listener as to what sounds better. Coaxial cables will have more variation for interpretation.

In my opinion, optical cables should be a more stable pulse. However, most listeners feel that they are to brittle sounding. This is probably true unless you have a very smooth tuned DAC circuit converter. This leads us back to your personal taste as to what is more accurate. Comments are welcome.

After 11 years this thread is still alive. I didn't read all the response but I try to give you my contribution. I think The hirez music could have impact on the digital cable position into the system chain. The high frequencies and the amount of bit resolution need of cable capable to maintain the impedence between entire path. So, I think which digital cable could affect sound not as well as PC cable, for example, but in consistency way. Recently I had to replace Stealth varidig with Oracle MA. The difference was not like night and day, but in term of "resolution ".

the differences between digital cables may have as much to do with the cables as the listeners.

Maybe the differences in sound can be attributed to thick, heavy cables damping analog resonances on the transport or DAC. There may be mass-loading thing going on here. Also, its possible that in a high rez system and an undamped, sparsely furnished room, the cable may change room acoustics and wall reflections slightly.

I have never used Toslink but I have used glass cables and found sonic differences even in these.

Marc258 - I wonder if you read anything on this thread before posting. Toslink is not superior. Toslink is not more expensive. All is system dependent.

Hi Danielho,

The other type of digital audio cable is the optical cable. Optical digital cables are the premier choice for transferring digital audio signals between components. They do not use RCA style connectors; instead they use what are called Toslink (or EIA-J).

These cables use pulses of light to transmit data, instead of copper wire. Since they are immune to interference from electromagnetic and radio-frequency interference, the signals do not degrade and weaken over long distances. Distortion caused by resistance, inductance and capacitance is eliminated, with the result that the best reproductions of digital signals are made possible.

Even though optical digital cables are more expensive, for true audiophiles looking for a superior experience with audio, nothing beats optical digital cable technology.

Since these cables get damaged when bent, they fail to work optimally if installed incorrectly...

Good day...

hdmi cables

Once again, this thread rears its ugly head! Some threads never die. Let the fun begin. 8^)

And 11 years later . . . !

Recently upgraded to a new Benchmark DAC1. Amazing, especially for the $$.

Anyway, I've tried three different cables to see if I hear a difference. Granted, none of them qualify as expensive - all were less than $75, but I'll be darned if I hear any truly discernible difference. They all sound great - BUT - I think there's a tiny improvement with a standard interconnect and not the one designed specifically for the digital coax in/out from my cdp to the DAC. And I think even that may be my imagination since the apparent improvement is minuscule at best.

Cables!! Jeez!!

I want it to be placebo, but in my instance I hear a difference between digital cables between my Squeezebox Touch/Philips 963sa and Eastern Electric Minimax DAC.

I, and my wife who is not a hobbyist, can clearly hear a difference between optical, coaxial and rca -> XLR (aes/ebu). With the coax sounding the worse of the group... thats right, I've preferred generic tosh to a $100 coax in this setup.

I've just read the last page of this 8+ year old thread. I am essentially in agreement with the comments by Kijanki and Shadorne, and I think that Lightminer made an excellent first cut at a summary, which I think can be expanded upon a bit, and I've done that below.

But first let me say that I think that differences or lack of differences between digital cables are more easily explained, and are a lot more predictable, than differences between most other cables or power cords in an audio system. The key to it, though, is looking at it from a system-level perspective (as Kijanki and Shadorne, in particular, have done). Notwithstanding the observations some have offered about differences between particular cables that in their experience have been consistent across different systems, I think that (as the following summary should make clear) considering a digital cable as having a definable performance on its own, akin to a component such as a preamplifier or cdp, is wrong and is probably the underlying reason for a lot of the disagreements (based on differing experiences with different systems) which pervade this area.

That said, here is my embellished version of Lightminer's good summary:

If your DAC re-clocks really really really well (and most very modern ones focus on that now in varying degrees),
and
If your SPDIF cable is 1.5 meters or so (perhaps a bit more or less depending on the risetime and falltime of the output of the particular transport, and the exact value which the logic threshold voltage level that the receiver chip in the dac happens to have, within its rated tolerance),
and
A reasonably well-controlled 75 ohm impedance is maintained by the cable, the output stage of the transport, the input stage of the dac, and the connectors at both ends (bnc's being the best way of doing that; Canare rca's being a good second choice; ordinary rca's being marginally acceptable),
and,
the risetimes and falltimes of the transport output represent an optimal balance between being too slow (which would increase jitter due to the small amount of noise which inevitably rides on the signal) and too fast (which would increase emi and couple noise into circuit points within the system that could affect sonic performance, and also might worsen reflection effects),
and
the bandwidth of the cable does not significantly degrade risetime and falltime of the transport output,

then the difference in cables should be pretty minimal.

In that sense are we getting somewhere over the 8+ years!

But given the essential impossibility of assuring all of that, the best approach is to optimize as many of those factors as you can, then take into account the experiences of others who have worked with similar equipment (and take their experience with a few grains of salt), try a few different cables, go with what sounds best in your particular system, and don't worry about the conflicting experiences others may report with their own systems.

Re this question that Lightminer had:

Now that we are using 24/96 music and lets assume also 24/192, does that change the requirement on the "Freq Resp dc - 40 MHz" type of rating? What MHz is required? Interesting that Kimber D60 (quite expensive) is 40 MHz and the rest of their cables are 20.

Probably somewhat, but mainly just in the sense that the sonic advantages of the higher rez formats would be more significantly compromised by jitter than in the case of the redbook format. The clock rate of 24/192/2channels is a little under 10MHz, well within the cable bandwidths. However, what is important for any of the formats is that the cable bandwidth be adequate to not significantly affect the higher frequency spectral components that are associated with the signal risetimes and falltimes. If that were to happen, jitter would increase comparably regardless of format, although as I say the increased jitter would probably matter more in a higher rez format.

Based on certain assumptions that we don't have to go into here, because we are dealing with rough ballpark numbers, the 25ns rise/fall times of typical transport outputs corresponds to a "3db bandwidth" (meaning the particular frequency is attenuated by 3db) of 0.35/25ns = 14MHz. Faster rise/fall times, which are desirable in terms of jitter minimization until they reach the point where that benefit is overshadowed by emi problems or increased reflection effects, would have correspondingly greater bandwidths. So for any format it is desirable to have a cable that can pass that 14MHz (or higher) frequency without degradation. I would not assume, though, that the 14MHz number can be directly compared with the 20 and 40MHz numbers, because the cable bandwidth may not be specified based on "3db bandwidth," and (more importantly) may be based on the attenuation that results from a length much greater than what would be used in an audio system.

Many common types of coaxial cables used for video signals have 3db attenuation occurring at 100MHz at 100 feet! So I wouldn't be surprised if the 20MHz and 40MHz numbers were based on unspecified definitions that were designed to make the parameters sound relevant to an audio system, when in practice they are not.

Regards,
-- Al

Rja - Cable itself does not have jitter. It creates jitter by reflecting fast transitions on impedance boundaries or allows slower transitions to be contaminated by less than perfect shielding. It is impossible to test it without standard ambient noise source (and location) and standard output transitions (each transport is different).

I don't necessarily need the "best" but it seems that if the level of induced jitter is the primary criteria for judging digital cables and if this can be measured then these cables should much easier to select. Unlike other cables there would be much less subjective opinion to deal with and things could be simpler with less trial and error.
Digital cable reviews could read; 20 cables tested, here's the 3 with lowest jitter. Then the only things to choose would be termination and color. Maybe wishful thinking. 8^)

10 out of 10 on spoiled milk test ain't bad - I got 6/10 on the milk and 7/10 on rotten eggs.

It would be fun to ABX the Kimber D60 (almost 1k at 2m) with the Blue Jeans Belden 1694 $14 dollar or whatever cable. I'll have the Blue Jeans one, anyone got an extra D60 they can lend? He he. And don't misunderstand, I'm a Kimber fan overall, definitely. (FWIW, and I think we aren't supposed to talk about this, shhhhh, but I do 'believe' in ABX. I tried it with spoiled milk and normal milk and got it right 10 out of 10 times.)

Rja - AFAIK jitter is the only difference between digital cables. I don't know of anything else that can affect the sound. Jitter can be measured but many factors can change it - like level of electrical noise around, amount of system noise etc.

One cable might work very well, having perfect impedance matching, with fast slew rate outputs while the other might offer perfect shielding - important with slower transitions especially in noisy environment. In addition there are preferences of flexibility, color and overall quality. There are, of course, identical performance cables offered by different companies - same as with analog interconnects.

Why do you want to establish absolutely the best ($$$$)? My system and my ears are perhaps not good enough to appreciate the best cables (analog or digital).

I would still trust my ears or reviews more than measurements. Don't spend money if you cannot hear the difference.

So may I assume that the less jitter a digital cable induces the "better" that cable will "sound"?

Is this induced jitter measurable from cable to cable? Could an absolute "best" be established using the lowest jitter criteria. And if this is true, why are so many digital cables (100s or more) available?

Or, is this purely a theoretical discussion?

Lightminer - If DAC reclocks like Benchmark (asynchronous upsampling) then quality of the cable is not of importance. Benchmark tested it with thousand feet of CAT5 network cable and it did not show any audible effect. The reason for that is few Hz jitter bandwidth of the Benchmark providing suppression in order of -100dB at the frequencies of interest (kHz) on the top of already low level of jitter (order of -80dB).

For traditional non-upsampling DACs I would look for 1.5m coax (Toslink gives about 2x jitter) double or even triple shielded with high quality connectors. I would also look for the transport with slew rate in order of 5ns instead of typical 25ns and very good power supply (to minimize system noise induced jitter).

It is possible that we could summarize a few points:

If you DAC re-clocks really really really well (and most very modern ones focus on that now in varying degrees)

and

If your SPDIF cable is 2 meters or so (not less)

and

It is rated somehow to maintain 75 ohms within very tight tolerances every few mm along its length

and

its termination methodology maintains the 75 ohm aspect

then the difference in cables should be pretty minimal.

In that sense are we getting somewhere over the 8 / 9 years?

Rja

Question has been answered many times. Digital cables introduce jitter. Jitter creates sidebands at very small level not harmonically related to root frequency. It is basically noise in time domain. Noise is reducing resolution, imaging, clarity etc.

Jitter is induced in coaxial cables by external noise or characteristic impedance mismatch (signal reflects on impedance boundaries). In Toslink jiiter is induced by system noise in presence of slow rise/fall time (slow transmitters and receivers).

Original post on 12-01-00: Why do digital cables sound different? After much discussion, may I venture that, as of 07-02-09, the question has not been answered?
Could it be possible that no one knows? 8^)

I have a (hopefully) simple question. Now that we are using 24/96 music and lets assume also 24/192, does that change the requirement on the "Freq Resp dc - 40 MHz" type of rating? What MHz is required? Interesting that Kimber D60 (quite expensive) is 40 MHz and the rest of their cables are 20.

Also, I can't find that value for the Belden 1694A, does anyone know? It seems like that is a great reference digital cable at extremely low cost - yet *many* of the issues raised here have been addressed, by degree, by that cable. At an insanely low cost ala Blue Jeans and others.

although a digi cable only trasmits "0" and "1" - a beat of music may take 10k digits so the pace and accuracy will imprint themselves to the dac which will convert these to differing sounds. A simple a/b of different cables will produce much different sounding examples.

In my experience, not only to different digital cables sound different, they actually have distinctive sounds. For example, I have a Goldmund cable that is consistently bright sounding, and a transparent Audio reference cable that is consistently warmer, smoother and more organic sounding.

I actually took a break from the hobby for several years and became skeptical of a lot of my audiophile beliefs, including my belief in the potential efficacy of cables and accessories. I was auditioning two components using both of the above digital cables, and the one using the Goldmund was simply bright and harsh. So, with much skepticism, I decided to switch the cables and wouldn't you know, the component that previously sounded harsh now sounded smooth and rich with the Transparent cable. It was like a different system.

Juanpablocuervo -

Electric current is not a "travell of electrons" - they move only about 1/2" per second and is also not a charge moved from electron to electron (wave) since they are spaced 10000 time their size apart. One theory says that electrons emit photons but this doesn't work either. Check Wikipedia!!!

While you describe properties of the cables why don't you mention inductance of the cable? It would be nice to mention characteristic impedance.

"in extreme capacitance, cuts more, making holes from the tiny bits&Bytes traveling at 3Mhz. and then paste on top of other bits, creating dissorder, or a blurr effect , creating digital errors, micro data lost. clock sync lost." - You must be kidding!!!!

EASY....
digital cables sound diferent becouse are diferent, diferent materials, diferent quality, diferent lenghs, diferent manufacturing process, etc..
without the technical stuff, i will be looked like a dumb.
but thats the real answare, plain and simple.

to understand deeply why,
must understand the diferences between analog audio, and digital audio, and the diferences between good and bad cable.
in the end your ears will be the judge.

for example:
usually analog sound has 24khz bandwith, and two cables, one for L & R. "red & white RCA cables"
line level has arround 1 to 5v p-p aprox. and arround 50ohms to 600ohms for the emmiter and 10k to 20k for the receiving unit. those are electrical parameters.
some vintage analog gear its 600ohms all the way, and some rack gear has switches, like aphex dominator 2 720. for 600ohm or 10/20kohms signals.
and sound verry similar.

digital = s/pdif, sony philips digital interface.
has 1 cable for 2 audio signals if used in PCM mode, and if used for RAW/AC3 mode has 6 channels.

digital has some problems like jitter, wordclock accuracy, and cable performance.
becouse digital audio travels in serial, not parallel.
all affects the digital signal, digital has a travel bandwith of 3MHZ up to 25MHZ, but an audio bandwith of 44.1k for both L&R = 22050hz, the other bandwith its used for the 16/18/20/24-Bits or each sample in 1 second.
depending on the resolution used, 44.1-16bits up to 192k-24bits.
digital sound needs aprox. 3million of bits, "1s and 0s" per second for a 44.1khz - 16 bit signal.
spdif was original designed maxium for 20bits audio and other 4bits for unknown/user data.,

the 24khz/24.000Hz analog audio signal must be transformed into serial information represented by gruoups of bits & Bytes,
and for all those 1s and 0s to sound at the same time!!, must travel pretty fast.

digital 1 and 0s, travel at a verry tiny rate.
controlled by a wordclock, or masterclock.
every digital device has a wordclock, from ipod to the soundcard of my pc,
usually its a quats crystal vibrating at a fixed rate.

the wordclock signal is a tiny square waveform with a frequency of minium 3MHZ. = 3000.000Hz digital audio for 44.1-16bits stereo signal vs. 24.000hz of analog audio.
with near "same" information.

also wordclocks have problems, most are not perfect,
have side effects like wrong pitch and jitter.
bad designed wordclocks have lots of jitter.
from bad power supply or crystals contaminated with micro dust at the manufacturing process, or low quality/purity crystals selected, bad or cutting, to fluctuations of the frequency created by unstable internal operating temperatures, that expand and contract the crystal, affecting its vibration.

jitter does not affect digital sound when its in digital format, BUT when its tranformed/converted from analog sound to digital or from digital to analog, affects totally!!! the harmonics, creating harmonic cancelations. or the blurr efect, over the entire frequency range. depends on the jitter and the .wav .mp3 file being listened. or the instrument recorded.
also affects stereo separation becouse both channels are in serial. LRLRLRLRRLRLRLRLRRLRLRLR, jitter blurrs the line of that separation between L&R.
but some people like digital jitter, sounds "more analog."

analog sound its a representation of the air molecules in electrical alternate current impulses/vibrations form.
Analog sound/line level sound emulates exactly as posible the frequency/movement/vibration of the air molecules.

the tiny square waveforms of the wordclock need something called slew rate that is the rise time from 0 to max 0.5v.
at that level 0.5v 75ohms. rise time. bad slew rate = not a square waveform, more like a 50% sine wave form 50% square.

s/pdif digital cables have 2 important values,
velocity of propagation, that should be ideal equally to the speed of light, but in the best cables its arround/less than 85%, and worse cables near 50%,
also cables have something called capacitance.

capacitors store energy and then release it, like cut & paste, a capacitor its made by isolating two electrical currents, ironically thats exactly what a cables is.

in extreme capacitance, cuts more, making holes from the tiny bits&Bytes traveling at 3Mhz. and then paste on top of other bits, creating dissorder, or a blurr effect , creating digital errors, micro data lost. clock sync lost.

also capacitors are used in audio crossovers, usually passive crossovers found in most 2/3 way pasive speakers,
if capacitors are used in serial or parallel to the audio signal becomes a hipass or a low-pass filter at near -3 to -6dB per octave. = 1-pole, also same happens with resitors and inductors.

the capacitance affects the point "cutoff" of the low-pass filter.

if the capacitance its high, has a low frequency cutoff point, for example: lets say 10kHz. ive heard audio XLR cables that have less highs than others. that why i choosed 10Khz.

that means that at a frequency of 20kHz the same cable has -6dB, and at 40kHz has -12dB, and at 80khz has -18dB, at 160kHz has -24dB, 320k-30, 640k-36, 1280k-42dB, 2560khz will have -48dB
and the s/pdif digital signal travels near 3Mhz = 3000Khz.
up to 25MHz.
and digital s/pdif has a power of 0.5volts
capacitance makes a weak signal, weaker.!
measured per x meters. longer distances are worse = more capacitive and resistive.

thats why there are baluns from ets and canare and neutrik to transform AES/EBU to s/pdif and back.
aes signal its stronger than s/pdif 5v vs. 0.5v but impedance of 110ohms vs. 75ohms. and twisted pairs vs. coax cable makes things diferent.

...components:
silver its the most electric conductive material, in pure form. unless its mixed with some other chemicals like artic silver 5 cpu thermal grease, it becomes capacitive, non conductive.

2nd best its 99.9999% OFC Copper, 3rd best its 24k Gold, gold does not oxidate like silver or copper, thats why its used in connectors.
oxidation makes harder for electrons to pass through.

for example, dean connectors for R/C cars, have a blend between silver, copper & gold.
and blow away any other tamiya aluminium connectors, becouse generates less heat, becouse its more conductive, less resistive.

a dirty contaminated silver cable, its worse than a pure high quality copper cable for example.
OFC oxigen free copper, was invented as a measure for the quality/purity of copper.
some cables say OFC, but only true OFC will make s/pdif sound better/transparent/clean/detailed.

a bad quality copper cable, has oxigen micro holes that makes the cable last less years and making electrons harder to travel, also bad copper has diferent micro densities, not uniform, making like a open road, harder to travel for electrons, making harder for electrons to move unobstructed.
bad manufactured copper cables are not enought to be error free digital signal.
bad copper cable can have a Velocity of propagation of 50%
verry resistive!!

also insulation between the center and the shield of the coax s/pdif cable.

also the material of the shield of the coax s/pdif cable.
most manufacturers use aluminium shield becouse its cheap, but its not 100% Radio Frequency shielded.

almost anything generates external RF interference.
from the sun, your tv, to the electric wires in your house inside the walls, the invisible AM/FM radio waves, cell phone waves, microwave ovens, fluorescent bulbs, etc...
true RF elimination its from a copper mesh.
that was discovered by someone hundred years ago.
cant remember its name.
anyway,
the insulation material affects also.
a bad insulation material between center and shield can make incredible BIG distortions in the digital signal.

some manufacturers use esoteric meterials, and hi tech fabrication process.in the search for the best insulation, low loss cable.
= cables are far from perfect.
like:
abbey road and empirical audio, that has pure silver cables, $800usd. meter. holosound2bp, or something. with teflon or another hi-tech esoteric insulation material.
cant remember if the shield its silver or copper.

zaolla, and others has mixed silver & copper center.
vovox digital has pure copper ofc, silver coated/plated. center.

etc..etc..etc.. thers lots of esoteric brands out there.
if you search yahoo/google.
but few make velocity propagation and capacitance tests above 1Mhz.

also stranded vs. non stranded, vs. diferent kind of stranded forms to avoid the skin effect.
that make the high frequencies travel at the outside of the cable, or so they say.
most tv & radio stations use Belden 1694a or gepco.
anyway.
i think apogee wyde-eye its gepco with canare connectors.
abbey road studios use custom pure silver cables. etc..
lots other brands...
also RCA connectors make a big diference.
plastic vs. metallic, aluminium with gold plated, vs. copper vs. gold platted, vs. pure copper OFC.
etc..
also the connectors must be OFC., thers no point in OFC cable without OFC connectors.
seems that size of the shield of the interconnects also affects.

the more V.P. the cable has, and less capacitance, the electrons organized in tiny square wave forms with a rate/vibration of 3mhz, those bits can travel easier = more accurate.
if you have a <1ppm wordclock like Drawmer M-Clock, apogee big ben, dcs995,verona, mutec iclock, etc.. or more accurate wordclock like 0.03ppb Antelope Atomic 10M clock, digital will sound more transparent, detailed and real, blurr will disapear completly,
but the highs will sound "strange" 10101010 at near 22050hz, aka.44.1khz.
if you record low jitter and reproduce with jitter will sound better. than recording with jitter and reproducing with jitter, becouse its twice jitter! and its not 100% exactly the same.

some cables adds a kind of jitter that makes the digital sound more "analog" in the highs, but blurr in the mids, and weaker in the lows.

BUT the realism you get in the mid frequencies, and the added loudness, and stronger bass with a jitter-less system, makes you forget the ear piercing 1010101, in the verry highs.

the "solution" for bad s/pdif cables was introduced i think by toshiba, the Toslink, = optical s/pdif.
specs where added later for raw signal 6 channels AC3 and for 8 channel ADAT 48-24bits & MADI optical formats. and later updated again for smux 96k and smux2 192k, BUT... optical has problems too.

has no capacitance but has added Jitter. in some cases multiplied by x8 or x64 times more jitter.
electric to optic to electric adds jitter to the signal.
external wordclock must be used.
becouse wordclock is multiplied.by the optical interface and divided again at the reciving unit, creating jitter.
also fiber optis have something similar to velocity of propagation, that measures the energy loss of the 640nm laser beam light.
so an external wordclock also must be used to avoid optical added jitter.
= again back to cables...
BNC Wordclock cable its "the same as s/pdif cable"
75ohm,

s/pdif can be used for BNC WC cable with optional copper center BNC male to RCA female adapters, easy.

anyway...
i have found a "secret" cable that blows away any other s/pdif or bnc cable!!! i have tested so far.
it does not add jitter!!. and its not silver.

finally i could hear my wordclock what trully sounds like.
1010101010101010.

remember that digital audio its in real time, not like downloading/uploading stuff in the internet, that does not need to be 100% realtime accurate.
in a online radio station maybe they have a super internet connection and you also, thats why buffer was invented for, but if the soundcard has jitter...

in the end, all you have to do its find the s/pdif & BNC cable that sounds good to you.<---------------
its verry fascinating to heard diferent cables,
most cables will sound in the same level/league.
some people cant hear the diference, anyway.
some others dont care.

09-05-08: Rja
Palerider,
Why do you assume no one here has used AT&T digital cables?
And why do you consider it better than other digital interconnects?
You keep making statements with no supporting information."

- as I sayd..

Hi Neilejhunt, thank you for your explanation of the jitter issues with S/PDIF. I have a question. How about the new wave of using Ipods with the docking stations that can extract the digital information right off the Ipods? What is here the difference with a CD-player? Is using an Ipod + docking station a superior way of digital music reproduction in comparison with the optical way? This is quite difficult to believe for me because when CD data is stored into a hard drive the data should be read first using an optical device, so you can't skip this procedure.
CD --> optical read out --> I2S signal --> S/PDIF --> Ipod (hard disk) --> DAC receiver --> D/A conversion.
Btw, the Ipod/Wadia 170 combination sounds as good as my expensive MBL 1621 transport! This is plain weird, why should we buy such expensive transports in the first place? Does any of you have the same experience?

Chris

Palerider,
Why do you assume no one here has used AT&T digital cables?
And why do you consider it better than other digital interconnects?
You keep making statements with no supporting information.

If you`ve ever had the opportunety to use a AT&T digital as a reference you would know what I mean.

I'm not making ANY statements or claims about digital cables although I've listened to and owned quite a few including a number of very highly thought of cables.
You're making statements and expressing opinions on both digital cables and peoples perceptions of them. I don't think it's unreasonable to ask what you're basing your opinions on, is it? Simply put, what is your experience with digital cables? Is that just too crazy a question to ask?
I put more value in posts that state: Here's the cables I've listened to with such and such equipment, here's what I heard and here's what I think. That I can accept. Such opinions have some value to many of us.
Blanket statements with no reference point are pretty much meaningless. Nuff said!

09-03-08: Rja
I am asking your experience with digital cables since you seem to know quite a bit about them as well as peoples perceptions of them. Surely your opinions must be based on something. Very simple Palerider."

Really? From where do yoy get that? To repeat myself; I avoid spending time on confusing theorys trying to tell why they sound different, I only conclude they shure do.
When some find it hard to hear any difference it might be simply because the involved cables do not vary that much, most doesn`t. To evaluate a digital coax you`ll need an AT&T optical reference. They outperform any overpriced mumbo-jumbo "hifi-coax" I`ve ever heard. All but the TV-coax Vivanco KX-710 :P

This thread started 12/01/00. I love it!!!

Eldartford - assuming ideal square pulses spikes/distortions will happen to every pulse, but in reality signal has jiiter all the way thru with electrical noise etc. Imagine signal with slightly different rise time from bit to bit and cable with mismatched characteristic impedance. This will result in creation of staircases (transmission line efect) different at different bits since slew rate is different. Different shapes of different bits will be converted to jitter. Cable with perfectly matched characteristic impedance won't produce jitter in this scenario.

Second possibility is noise. Imagine shielded digital cable in the presence of electrical noise. Amount of jitter (caused by limited slew rate + noise) will depend on quality of shielding and will be different for different cables.

Third possibility - limited bandwidth. There is inherent noise on the top of digital signal (power supplies etc). Cable with limited bandwidth will reduce rise time and make this noise "visible" to receiver (gate will recognize level at different times on the slope of rising signal). Perfect cable with very high bandwitdh won't reduce slew rate and noise won't be visible.

I suspect that cable experts might bring many more explanations - I'm not an expert. It is, in my opinion, much more difficult to explain why power cables help with imaging but I don't question that they do. Audio is very subjective thing. How one knows that other person only "thinks" he hears difference? Trying to find scientific reasoning is a noble thing but we shouldn't question experience of others.

Shadorne...If a cable causes a pulse risetime anomaly (such as a spike) it will happen for every pulse. All will be delayed or trigered early by the same amount, so jitter is not the result.

What if the shape of the leading edge changes according to the signal pattern.

"Most digital audio links have a limited bandwidth. This attenuates the higher frequency components of the digital audio interface signal, and slows rise and fall times. A transition delay is introduced, and this varies depending on the data pattern in the previous time slots."

See this paper for more details.

This is probably why Ed Metiner uses "preamble jitter" for clocking, as preamble jitter is usually less. At the end of the day, since interface jitter is a fact of life then the best approach is to design a PLL clock that does not "jump around". So in the end, it is the quality of the PLL loop in your receiver that will determine how well it maintains sychronization whilst making a steady and unjittered clock. (The simplest approach being asynchronous - the data is passsed to the receiver digitally in perfect form and then receiver does D to A with its own superbly accurate clock)

The paper concludes "Digital audio equipment has to be designed to cope with jitter from its synchronisation source, as this is a characteristic of the interface. This is particularly important for the recovery of sampling clocks from interface signals."

Therefore either

One has equipment that is well designed and which can cope with jitter and all decent quality cables will all sound the same (jitter below audibility).

or

One has equipment that is not that great at rejecting jitter and cables and anything might make a subtle difference...you can blame the cables but in the end, since jitter is a fact of life - it makes more sense to blame the equipment.

Much of the jitter problems come from power supplies - so if you can clean up the power then it may be enough.

Once again - you'll notice a common theme with my posts - I tend to blame equipment or equipment interface issues for observed differences in quality rather than the interconnects and cables. (In a sense one cable may work well with one setup but not at all in another...a lot depending on the gear quality.)

Since jitter has been well known since the late 80's early 90's - my suggestion (for those who are worried that they are getting digital hash from jitter)is to

1) stick to gear made after 1995 or later (once manufacturers got robust PLL loops working well that could handle all this jitter).
2) use asynchronous approaches (like a USB DAC)
3) consider a reclocker - particularly with older classic digital gear that might be expected to be rather jittery (you know older stuff that does not upsample etc. before the engineers go their heads round all this)

Shadorne...If a cable causes a pulse risetime anomaly (such as a spike) it will happen for every pulse. All will be delayed or trigered early by the same amount, so jitter is not the result.

Wire properties can certainly affect digital pulse characteristics. But, up to the point where a data "one" can be misinterpreted as a "zero" pulse characteristics don't affect the information which goes into the D/A converter.
So I don't find it "mysterious" at all that various cables sound the same. The mystery is why some folk think they sound different.

The only possibile explantion is increased jitter that you can get from passing signals between devices. I agree about the "ones and zeros" - these should be recognized properly and completely (so the bits are the same).

In this case, it may not be the fault of the cable but the way in which the components clock timing interacts.

Perhaps a device with superior PLL & timing/receiver ciruitry might sound the same with any cable when connected to a digital source (even a relatively jittery one).

Perhaps a device with poor PLL & timing/receiver ciruitry might sound different (more or less jitter depending on characteristics of signal received)...

I am asking your experience with digital cables since you seem to know quite a bit about them as well as peoples perceptions of them. Surely your opinions must be based on something. Very simple Palerider.

quote me:

"Anyone can hear the difference if just the right and wrong cables are put up against eachother. But most cables are about the same, no big diff. "

Strange; do I say they all sound the same? Or do I say most cables are much the same, but some stick out in either direction..

It seems Paleriders opinion is that all digital cables sound the same and (I assume ignorant) people are just pretending they sound different.
Palerider, what digital cables have you tried and between what equipment before you arrived at your opinion?
Is it unreasonable to ask what experience you've had on which you base your opinion?

Palerider - if you cannot understand just read more.

Myself, if I cannot hear the difference I modestly admit it without saying that everybody else only "THINK" they hear a difference (that would be an arogance on my part).

"The question is : why people pretend to hear a difference ?

Or why they THINK they heard a difference ? "

Anyone can hear the difference if just the right and wrong cables are put up against eachother. But most cables are about the same, no big diff.
And the confusion gets complete when folks starts to make up theoretic "answers" to why.

Added bits would be extreme case of impedance mismatch. It's more to preserve shape of the pulses to avoid crossing threshols at different times causing jitter. Jitter creates sidebands not harmonically related to root frequency (audible). Even double Phase lock Loop cannot compensate for fast changes.

I don't know if this response has been given before but this is what I know. For digital signal paths the frequencies of concern (pulse rate, pulse edges, etc.) are outside (higher) than the normal audio domain. In fact, they behave more like RF. So, the digital cable is essentially a specialized RF cable. At RF frequencies it is the cable impedance, especially at the interfaces (connectors) that is important because mismatches with the commected components can cause signal reflecttions. What this means, obviously, is that phantom bits may been ADDED to the digital stream. So, a good quality digital cable is just as important, if not more so, than your analog interconnects!

The question is : why people pretend to hear a difference ?

Or why they THINK they heard a difference ?

No need to look further

Eldaford - if they affect digital pulse characteristics (different bandwidth) then they produce different amount of jitter. Shielding also affects the jitter since noise causes changes in threshold levels. Some DACs are not sensitive to jitter (like Benchmark DAC1)at all but others are. Impedance matching also plays a part. Many cables ends-up with an RCA connector that is not 75 ohm.

Wire properties can certainly affect digital pulse characteristics. But, up to the point where a data "one" can be misinterpreted as a "zero" pulse characteristics don't affect the information which goes into the D/A converter.
So I don't find it "mysterious" at all that various cables sound the same. The mystery is why some folk think they sound different.

I`ve done a test like Osgorth did, and with optical AT&T as a reference.(A-B-C test) First; optical outplayed any "high-end" (high price) coax, actually no match. Even if we could observe some minor differences between the coaxes, they was totally outplayed by the clean open sound from/through the optical cable.
Tryed out some DIY`s too, air-insulated coax and stuff, but none came close to the AT&T digital. Until I made up a coax of my reference IC; the TV-coax Vivanco KX-710. And for some reason this coax just does it all right. Now we were up in the same league as the optical, and after some switching we could observe that the Vivanco-coax was definetly a bit cleaner in both ends, much like the same way it outperforms all other IC`s, then in twin configuration.

Even if I have my thoughts about why they sound different I woun`t try to come up with some answer/guessing. But one thing is clear; there`s a lot more to soundreproduction then what those "theory-heads" comes up with :P