Difference in sound between copper and silver digital cables?


Is there a difference in sound between copper and silver digital cables, or purely in the implementation?
pmboyd
... could it be possible that the impedance of the RCA only has to be greater than 50,75,101 ohms?

@williewonka

Hi Steve,

Thanks for providing the additional background. But no, for accurate minimally distorted transmission of digital waveforms, the "characteristic impedance" of a digital cable, the output impedance of the component providing the digital signal, and the input impedance of the component receiving the signal, should all be very close to being exactly the same.

In saying that, I should emphasize two things. First, this has nothing to due with accurate conveyance of the digital bits, which figures to be perfect in any half-way reasonable interconnection. Second, the distortion of the waveform that is received by the destination component does not by any means have any **direct** relation to distortion that may result in the sound that is eventually heard, as it might in the case of transmission of analog signals. But what may happen is that the frequency components corresponding to that distortion of the digital waveform, which will be well into the RF region, probably at several tens of MHz or even more, may find their way past the receiving circuit (via grounds, power supplies, stray capacitances, etc.) and contribute to timing jitter at the point of D/A conversion, or to intermodulation or AM demodulation or other such effects at analog circuit points further downstream. All of this being very much dependent in unpredictable ways on the particular components, on the normally unspecified "risetimes" and "falltimes" of the signal provided by the source component (i.e., the amount of time required for the signal to transition between its two voltage states), and on the length and several other characteristics of the particular cable.

Ground loop effects between interconnected digital components can also be cable-sensitive, btw, potentially resulting in low-level high frequency noise being injected into the DAC or other receiving component, with consequences similar to those I’ve described above.

All of this is completely different than the potential effects of cables conveying analog audio signals, due to the vastly higher frequency components of digital audio signals. In the latter case bit rates are already well into the RF region (roughly between 1.5 and 10 MHz or so, depending on whether it is redbook data, 24/192 data, etc.), where imprecise impedance matching can degrade waveform quality due to signal reflection effects. But the frequency content of the risetimes and falltimes of all of those signals are at even much higher frequencies, at several tens of MHz even for redbook data as I said.

One thing that follows from all of this, IMO, is that any similarity that may be observed between the sonic effects of various metals and various geometries as used in analog audio cables vs. as used in digital audio cables is entirely coincidental.

And, finally, I would approach with a great deal of skepticism any claims that a specific wire type can simultaneously be optimal for 50 ohm, 75 ohm, and 110 ohm digital applications. And I feel pretty certain that nearly all other experienced digital circuit designers would agree with me. While it may not make any difference in some systems, or it might even make a difference in some systems that seems to be subjectively preferable, why do what amounts to introducing a known design flaw into the system?

Best regards,
-- Al

@almarg - I too wondered about this aspect of digital cables design.

It all started about 5 years ago when KLE Innovaitons contacted me about their products.

I built a very good analogue cable and wondered  how it would perform in the digital realm - so I simply tried it and  it worked great.

I contacted Keith Louie Eichman and we exchanged several emails on the subject. But although he assured me that his RCA's are perfect for digital application because of their impedance, he would not reveal the actual impedance. So I am unable to comment on this aspect in any further detail.

Apparently - they work extremely well with 50, 75 and even 110 ohm applications.

After a lot of reading from the web - could it be possible that the impedance of the RCA only has to be greater than 50,75,101 ohms? 

Perhaps it is the design of the actual RCA ?
 i.e.the neutral connection is very small compared to other RCA's 

I have tried a few different KLE Innovations RCA's in digital applications  and they all worked extremely well.

Sorry I could not provide more details - Steve


@david_ten - Ooooops sorry about that….
@williewonka Steve: within the parameters of (the "experiment" / components / systems) you tested them, correct? Thanks.
Yes - I was testing with digital audio files up to and including 24/192. They connected a Schiit Bifrost DAC and a Musical Fidelity V-Link192 USB-S/PDIF Converter and an Apple PC as the source of the digital files via USB.

The amp was a NAIM 5i Mk II and the speakers are the Gershman Acoustics Sonogram model

I could not discern any degradation in audio quality at those sample rates, higher sample rates may have issues, but I am unable to test ot those rates.

I did drop down to the copper Harmony RCA and there was also no degradation, but I the silver plating on the copper harmony may wear off after 30 insertions, so I do not use them for anything.

My Silver Harmony RCA’s had been inserted around 40 times to that point without wearing to the copper underneath the plating. But this very much depends on the quality of the socket they are plugged into.

For all analogue cables I only use Harmony Absolute RCA’s

Hope that helps

Williewonka 1-3-2020
The geometry of the cables is an advance Helix design, so that probably made a significant contribution to the performance of the cable.

Steve, I always have great respect for the very extensive work you’ve done with cables over the years. But in this case I’m wondering how or if you might have established what IMO is the requisite 75 ohm "characteristic impedance" for an unbalanced digital cable, using the helix geometry you have used for your analog interconnects.

Also, IMO, if the characteristic impedance of the cable was not known to be an accurately controlled 75 ohms the sonic consequences of the resulting mismatch to the impedances of the components being connected figure to be even more dependent than usual on the designs of those specific components, and probably also on the length of the particular cable. Making the sonic effects of the particular cable pretty much random and unpredictable among different digital applications, IMO.

Best regards,
-- Al

Do you mean after they’re broken in? Before or after cryo? Yes I know what you’re thinking, “Are you hot dogging me?”
@williewonka Steve: within the parameters of (the "experiment" / components / systems) you tested them, correct? Thanks.

With this design using a silver conductor seemed to offer no advantage.

Yes you are right Doug! Always outlier experiences and who knows why? System? Ears? Break in? Bad pizza? 
I tried an experiment a few years back...
- I built an extremely good digital cable with silver signal wires and exceptional RCA plugs
- I then "stepped back" the design by replacing the signal wire with copper - there was no change
- I then stepped back the design once more opting for a more affordable RCA plug - again there was no change.

The geometry of the cables is an advance Helix design, so that probably made a significant contribution to the performance of the cable.

The RCA’s finally used are silver coated copper, KLE Innovations Silver Harmony RCA and the copper wire was from Neotech.

With this design using a silver conductor seemed to offer no advantage.

With other geometries there may be some benefit to using silver conductors

Hope that helps - Steve
Your system’s current sound and what you want more or less of determines the type of cable you should buy. Yes cables can be used like seasoning in the hands of a chef. You’re a sound chef. While design, solid vs. stranded, cotton vs Teflon and on and on all impact sound, silver does have a sound personality that always comes through. It is marked by sharp, crisp, and clear leading edges, slightly leaner overall presentation and the perception of increased speed and inner details. Place silver in cotton and silver becomes more open, natural and not quite as lean. However, it still exhibits the general silver sound in relation to pure copper.

Copper tends to deliver more mid-bass body and weight and is not as well defined in terms of leading edge detail. Bass is a tad more rounded and yes this can vary, but in general is accurate.

So you have sonic must haves and preferences. Your system does or does not meet these preference as well as you like so start cooking!

Caps and resistors, well most parts, also have a sound. One can dial in a system by seasoning with these parts and cables. This is my particular area of interest and one that I have many thousands of hours of experience in. Many Aphiles don’t believe this to be true or possible, but if one spends enough time, effort and due diligence on this area of study, then they would learn first hand just how real it is.

Take a simple tube dac with an output cap right before the RCA outputs. Try placing a Vcap Odam cap vs. say a Jensen copper foil cap in paper and oil and I can assure you this same dac will sound quite different depending on your choice. No ear straining is needed to hear the difference. My point is that materials matter and do indeed have a sound. Same is true for cabling.  


If the Bits is Bits theory was true, which it’s not, optical digital cables would sound just as good as copper or silver digital cables, which they don’t. That’s because the signal is not really Bits. Duh! 😳 Besides, as I’ve been counseling, by the time the signal gets to the DAC it’s too late. The signal has already been degraded during the laser reading process due to a number of problems that have always been there.
Yes, there is a difference, but it largely comes from the implementation. There are copper conductors, silver, and copper coated or copper infused with silver. The design and material used in the  dialectric also contributes to sonics.