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blakey72

Might be a stupid question but digital coax vs rca

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Can you use a regular rca ic to carry a digital coax signal from a cd player to a dac? Would you hear a difference?

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Yes, you can use it and no, the difference cannot be heard but it can be measured. The closest you can get with an RCA to what a digital COAX interface needs is a 75ohm cable like Belden 1694A combined with a Canare RCAP connector (http://www.canare.com/ProductItemDisplay.aspx?productItemID=40). That is still not a "true" 75ohm connection but it is as good as it gets for an RCA termination. For anything better you have to use a BNC termination. 

 

"Normal" or random RCA cables and connectors have an impedance of anything between 25 and 100ohm. That causes a so called reflection of the digital signal from the receiving end back to source due to an impedance mismatch. 

 

Now, lets wait for another 150 posts from bat-people at this forum who will claim  they can hear that and not only that but a difference between one 75ohm cable and another OR a cable of 0.5m and 1m in legth.   

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5 hours ago, blakey72 said:

Can you use a regular rca ic to carry a digital coax signal from a cd player to a dac? Would you hear a difference?

Yes, maybe.

 

Digital cable performance depends on tight control of impedance.   For analogue audio signals this is irrelevant.

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Posted (edited)
4 hours ago, Decky said:

 

Now, lets wait for another 150 posts from bat-people at this forum who will claim  they can hear that and not only that but a difference between one 75ohm cable and another OR a cable of 0.5m and 1m in legth.   

I’ve tried cheap $2.50 RCA,  dedicated 75ohms with BNC, and whatever I can get my hands on....  I’m just so unlucky not having “ bat ears”.      No wonder I keep bumping into things while walking in the dark! 😫   

 

I’m so jealous!

Edited by Addicted to music

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Yes,

 

In my experience most analogue RCA Cables work. Some actually sound better than a cheap true 75 or 110 ohm cable for coax or AES/EBU.

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8 hours ago, blakey72 said:

Can you use a regular rca ic to carry a digital coax signal from a cd player to a dac? Would you hear a difference?

 

You certainly can - but I would suggest (as you're obviously a DIYer - since you list RG213/U spkr cable in your equipment list) that you could easily make up a cable which sounded better.

 

Use a standard 75ohm coax - at least 1m long - and some good, metal-barrelled RCA plugs.  One very good cable is Belden 1506A (solid-core centre and teflon dielectric) - although it's hard to get hold of in small quantities.  I bought 100' of it recently and can sell you a metre - PM me, if you're interested.

 

Andy

 

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Posted (edited)
5 hours ago, Decky said:

Yes, you can use it and no, the difference cannot be heard but it can be measured. The closest you can get with an RCA to what a digital COAX interface needs is a 75ohm cable like Belden 1694A combined with a Canare RCAP connector (http://www.canare.com/ProductItemDisplay.aspx?productItemID=40). That is still not a "true" 75ohm connection but it is as good as it gets for an RCA termination. For anything better you have to use a BNC termination. 

 

"Normal" or random RCA cables and connectors have an impedance of anything between 25 and 100ohm. That causes a so called reflection of the digital signal from the receiving end back to source due to an impedance mismatch. 

Interestingly, only yesterday I re-terminated one end of my digital coax (Apogee Wide-Eye) cable to simplify connection to the Audiophilleo USB converter I use. Previously the cable had the Canare RCAP rca connectors on both ends and I was using a BNC adaptor on one end. 

 

I don’t claim to have bat ears and am aware of expectation bias but, can definitely say I hear a difference from just replacing the RCA connector and BNC adapter with a proper BNC connector.  

 

Of of course it is all system - particularly DAC-specific...

Edited by krebetman
Can’t bloody get anything right on my phone

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COAX cables are cheap. What's the point of even trying to use RCA? 

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27 minutes ago, Irek said:

COAX cables are cheap. What's the point of even trying to use RCA? 

Haha cause I haven't got one atm and it's the weekend. I live in the bush :)

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I've tried an rca that someone made for me. Don't know what he used but it sounds superb. Maybe it is a 75ohm, he works repairing and fitting hifi equipment. Be interesting to see if it is and if not, how it compares to a 75ohm.

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A digital cable will work for analog b/c it exceeds analog spec. The other way around: maybe.

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If in doubt and if there is an option always use AES/EBU. It has 110ohm impedance but the signal is TTL 5V through a balanced line, compared to the SE coax 0.5V. That makes the whole arrangement much less sensitive to interference and dependent on the cable length or quality. 

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9 hours ago, Addicted to music said:

I’ve tried cheap $2.50 RCA,  dedicated 75ohms with BNC, and whatever I can get my hands on....  I’m just so unlucky not having “ bat ears”.      No wonder I keep bumping into things while walking in the dark! 😫   

 

I’m so jealous!

You need a pair of these, then you'll hear the difference.

http://www.realhd-audio.com/wp-content/uploads/2015/02/150222_audiophiles_def.jpg

 

Cheers George

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On 07/10/2018 at 2:56 AM, Decky said:

Yes, you can use it and no, the difference cannot be heard but it can be measured. The closest you can get with an RCA to what a digital COAX interface needs is a 75ohm cable like Belden 1694A combined with a Canare RCAP connector (http://www.canare.com/ProductItemDisplay.aspx?productItemID=40). That is still not a "true" 75ohm connection but it is as good as it gets for an RCA termination. For anything better you have to use a BNC termination. 

 

"Normal" or random RCA cables and connectors have an impedance of anything between 25 and 100ohm. That causes a so called reflection of the digital signal from the receiving end back to source due to an impedance mismatch. 

 

Now, lets wait for another 150 posts from bat-people at this forum who will claim  they can hear that and not only that but a difference between one 75ohm cable and another OR a cable of 0.5m and 1m in legth.   

 

You forgot to mention cable directionality.

 

Tsk, tsk, tsk

 

 

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On 09/10/2018 at 9:49 AM, jeromelang said:

 

You forgot to mention cable directionality.

 

Tsk, tsk, tsk

 

 

No such thing with digital cables - fortunately, may I say. No great benefit out of that even with analogue signals, let alone digital ones . 

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On 07/10/2018 at 4:27 PM, Decky said:

If in doubt and if there is an option always use AES/EBU. It has 110ohm impedance but the signal is TTL 5V through a balanced line, compared to the SE coax 0.5V. That makes the whole arrangement much less sensitive to interference and dependent on the cable length or quality. 

And ...... then  Try the super doper optical solution, most dac will have both optical and coax input.   

 

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8 hours ago, Decky said:

No such thing with digital cables - fortunately, may I say. No great benefit out of that even with analogue signals, let alone digital ones . 

 

Have you ever heard of sarcasm?

 

tongue of which the user speaks of something the complete opposite of what the user means. It often has the best comedic value.
 

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11 minutes ago, TerryO said:

 

Have you ever heard of sarcasm?

 

tongue of which the user speaks of something the complete opposite of what the user means. It often has the best comedic value.
 

I suspect he was being deadly serious. No sarcasm at all

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3 minutes ago, Sir Sanders Zingmore said:

I suspect he was being deadly serious. No sarcasm at all

Time will tell.

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On 11/10/2018 at 4:34 PM, TerryO said:

 

Have you ever heard of sarcasm?

 

tongue of which the user speaks of something the complete opposite of what the user means. It often has the best comedic value.
 

I am terribly sorry, but my vast experience on this forum taught me that assuming sarcasm or, a higher power forbid, using it, is a very dangerous path that no person should attempt to follow.  I rather sound socially inapt and autistic than engage in mindless ego battles 🤐. I was vaccinated as a kid so at least  I have an excuse for it 😉😋.

 

To correct myself- of course that directional cables work - there is an arrow on them! The question is - where should I point it at. 😕

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On 15/10/2018 at 12:15 PM, Decky said:

The question is - where should I point it at. 😕

East. I'm absolutely NOT being sarcastic.

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