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Digital Cables Make No Audible Difference

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BrainiacV
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Unbelievable!
BrainiacV   11/18/2013 11:48:23 AM
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Next you'll be telling me the stablizing rings for CDs won't give me better sound since the data is clocked in by a crystal instead of analog like my turntable. :-)

And what about that DVD rewinder?

A wise man said something like, "A potential customer is born approximately every sixty seconds."

To which my boss said, "Surely not that infrequently!"

vvc0
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If Only...
vvc0   11/18/2013 1:39:27 PM
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If only Bob Pease was still with us, he would have had plenty to say about cable (even though he wasn't a digital guy). He spent quite a bit of time trying to get the audiophiles to submit to a blind test involving standard and so called Oxygen free copper cable. They never would, though. And they wouldn't with this cable either, from what some of the "convinced" commenters had to say.

betajet
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HDMI, on the other hand...
betajet   11/18/2013 1:57:33 PM
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I have found an occasionally important problem with cheap HDMI cables.  HDMI is supposed to have individual ground wires, one for each differential pair and one for the low-speed control signals, plus an outside shield that's connected to the connector shells at both ends.  Most HDMI devices connect all these grounds together at both ends.  Cheap HDMI cables take advantage of this practice by implementing a single foil shield that's only connected to the connector shells, and don't connect anything to the individual grounds.  This works fine in most cases, particularly with short cables.  However, you occasionally find a device that needs individual grounds and only works with some cables.  That's lots of fun to debug until you find out about cheap cable contruction.

MeasurementBlues
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Re: HDMI, on the other hand...
MeasurementBlues   11/18/2013 2:01:26 PM
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@betajet, I've done some studies of cheap Apple knockoff 30-pin connectors. One of the says the knockoff save money is my using vewer ground pins than Apple. If you like, I can post them here.

chanj0
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Re: HDMI, on the other hand...
chanj0   11/18/2013 9:17:13 PM
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As far as I remember, HDMI delivers data in differential pair. They have to be separated otherwise the integrity of data is going to be affected.

abraxalito
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You're assuming a perfect DAC
abraxalito   11/18/2013 11:53:45 PM
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Whilst its demonstrably true that digital cables don't change bits, they can and do present different common-mode impedances to RF noise in a system. Many DACs are sensitive to common-mode noise on their digital inputs due to poor grounding and noise control design decisions - so that for example adding a ferrite clamp to a digital cable can make an audible difference.

ChristophZ
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Re: You're assuming a perfect DAC
ChristophZ   11/19/2013 2:27:05 AM
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That is one reason why I prefer optical cables over the coax variant, you get a proper galvanic isolation between the high frequency digital device (TV, Blueray Player, PC etc.) and your analog system (The DAC has to be designed like a analog device...).

My DAC at home is from the studio market, not consumer, it has a galvanically isolated coaxial input. This helps too to control the output signal quality independent of the cabling in use (lenght, noise on the way).

 

abraxalito
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Re: You're assuming a perfect DAC
abraxalito   11/19/2013 7:19:03 AM
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Galvanic isolation is a step in the right direction - however its only providing perffect isolation at DC. Check the interwinding capacitance of your S/PDIF transformer - the ones with the best isolation sport a figure <1pF. If yours is higher you still might gain improvement in fitting a CM choke to your cable (or clamping on a ferrite). Also check to see if internally there's a dedicated ground wire going to the digital input termination (75ohms) from the mains trafo secondary. A lot of DACs just use their internal groundplane to carry the CM noise current, impacting the sensitive analog circuits using that groundplane as their 0V reference.

abraxalito
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On a more philsophical note.....
abraxalito   11/19/2013 12:14:40 AM
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Your title here is an example of denialism. Based on what you write in the piece, a more accurate title would be 'I currently know of no way for a digital cable to make an audible difference'. Surely engineering is about finding ways to deliver satisfactory products to customers - if the customers are hearing someting then its our remit to explore the reason for that rather than lapse into knee-jerk denials of what they say they hear?

MeasurementBlues
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Re: On a more philsophical note.....
MeasurementBlues   11/19/2013 9:15:10 AM
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'I currently know of no way for a digital cable to make an audible difference'.

Too long for a title, but perhaps in the text. We agonize over titles because they must be short, yet have enough info to get you to read.


abraxalito
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Re: On a more philsophical note.....
abraxalito   11/19/2013 8:41:51 PM
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How about a question with the same word count - 'Can digital cables be audibly different?' ?

bobzz0
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Audioquest is garbage
bobzz0   11/19/2013 12:47:13 AM
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I hope this cable is better than the audio cables I have tested from Audioquest. Audioquest RCA audio cables exhibit significant microphonics, so much so that vibrations from my home theater subwoofer created an oscillator. Yes certainly on long runs cables can be a factor in digital AV, but the garbage I have seen from Audioquest is not tha answer.

 

 

David Ashton
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Re: Audioquest is garbage
David Ashton   11/19/2013 1:44:14 AM
@bob.....this is, as you say, garbage.    Unless there is a lot of noise, crosstalk or some other very good reason, these cables will perform no better than the ones you buy at the $2 shop.

However....the guys who can sell these cables to the people with more money than sense will wind up richer than all of the posters on this column.  If they can do that, good luck to them.  Why didn't I think of this? :-)

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