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Directional Digital Cable

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1 hour ago, MLXXX said:

He is rather non-commital on the topic in that video, though doesn't rule out the possibility altogether.

I think that means he has a commercial interest in not discouraging potential (aka "gullible") customers. 

Despite this forum being quite technical and informative on how everything works, we have sponsors and other 'hidden' businessmen trying to stimulate the snake-oil market... such as power cables 

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10 hours ago, Sir Sanders Zingmore said:

 

and yet ….there you are 

And yet so are you. You are part of the objectivist mob so I suppose you have to poke your nose in at some point. You guys are ruining stereonet one thread at a time. 

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9 minutes ago, scumbag said:

And yet so are you. You are part of the objectivist mob so I suppose you have to poke your nose in at some point. You guys are ruining stereonet one thread at a time. 

Maybe I’m just being an objectivist, but I don’t see any evidence that SNA is  being ruined. 

 

There’s healthy debate which for the most part, is respectful (you should look at some other forums to get an idea of how good it is here).

 

Of course people sometimes disagree but that’s a good thing in my opinion. I’ve learnt far more from people who’ve challenged my ideas and beliefs than from those who simply agree. 

 

We need more GTGs and beer 😀

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1 hour ago, Sir Sanders Zingmore said:

 

 

We need more GTGs and beer 😀

@Sir Sanders Zingmore

I agree with the GTG.  Maybe some red wine also.  Subjectivist me looks forward to seeing you somewhere soon.

John

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2 hours ago, Sir Sanders Zingmore said:

Maybe I’m just being an objectivist, but I don’t see any evidence that SNA is  being ruined. 

 

There’s healthy debate which for the most part, is respectful (you should look at some other forums to get an idea of how good it is here).

 

Of course people sometimes disagree but that’s a good thing in my opinion. I’ve learnt far more from people who’ve challenged my ideas and beliefs than from those who simply agree. 

 

We need more GTGs and beer 😀

It seems that you and others on this forum have either forgotten or never really grasped the concept of "discussion" or "debate" and as such these threads always descend into the same name calling and brow beating. Ironically you called me out about participating in this debate in my first post when I was not responding to the OP's question so by definition I was not involved in any debate or discussion about cable directivity.

Note the lack of people posting any alternate viewpoints on this thread. But then again, I guess that's how you guys like it.

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7 hours ago, MLXXX said:

 

 

I see that that link which may be easier to find at https://www.youtube.com/watch?v=sX4Cr8sfFkg&feature=youtu.be is Paul McGowan, highly experienced and persuasive presenter on audiophile matters, discussing cable direction.  He is rather non-commital on the topic in that video, though doesn't rule out the possibility altogether.

 

@AussieMick, for coaxial cable simply used for SPDIF signals, there's usually even less reason to worry about supposed subtle differences related to "cable direction". The device receiving the digital stream very possibly tidies it up and buffers it. If it is a good quality DAC, it will do that to the digital stream and reclock it. And even an amplifier with a built-in SPDIF coaxial input ought to be able to tidy up the signal.

 

So for the peace of mind of an audiophile who has acquired a relatively expensive length of coaxial cable just to carry a SPDIF signal, it would probably be best for them to avoid a listening test comparing their "high performance" 75 ohm coaxial cable with a similar length of ordinary audio grade 75 ohm coaxial cable with RCA connectors. (People have been known to report hearing no differences, disturbingly often. )

 

And if it's a short run of cable that's involved, the audiophile possessing an expensive 75 ohm coaxial cable should probably avoid substituting ordinary shielded audio cable for 75 ohm coaxial cable, as there is a strong chance that the ordinary shielded cable would work perfectly well; leaving all bits readable, ready to be buffered and reclocked by the device receiving the SPDIF stream. Such a result could be confronting and disappointing.

A cable stated as being 75 ohms, IMO stands a much greater chance of being 75 ohms from a recognised 

manufacturer of cable, such as Belden. To then place RCA's which are NOT 75 ohms either end, is telling you the cable is a fashion item, and not designed for proper operation. Physics dictates a true 75 ohm link will be provided with 75 ohm BNC connectors, requiring you to sometimes awkwardly also change to BNC where the cable connects.  

 

 

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20 minutes ago, stereo coffee said:

To then place RCA's which are NOT 75 ohms either end, is telling you the cable is a fashion item, and not designed for proper operation. Physics dictates a true 75 ohm link will be provided with 75 ohm BNC connectors, requiring you to sometimes awkwardly also change to BNC where the cable connects.  

The official SPDIF requirements are for a 75 ohm impedance.  Traditionally, RCA connectors have been used in conjunction with coaxial cable intended for a SPDIF connection. The baud rate for audio signals sent via SPDIF is relatively low and the discontinuity in impedance at the RCA connector would be considered to have a negligible impact for this low baud rate application, from an engineering viewpoint.

 

But yes, use of  75 ohm cable is perhaps overkill. I certainly remember times when I've used a short length of ordinary shielded audio cable for a coaxial SPDIF connection without any apparent ill effects, if there was no coaxial cable on hand.

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Posted (edited)
1 hour ago, MLXXX said:

The official SPDIF requirements are for a 75 ohm impedance.  Traditionally, RCA connectors have been used in conjunction with coaxial cable intended for a SPDIF connection. The baud rate for audio signals sent via SPDIF is relatively low and the discontinuity in impedance at the RCA connector would be considered to have a negligible impact for this low baud rate application, from an engineering viewpoint.

 

But yes, use of  75 ohm cable is perhaps overkill. I certainly remember times when I've used a short length of ordinary shielded audio cable for a coaxial SPDIF connection without any apparent ill effects, if there was no coaxial cable on hand.

Each of these giving in's to marketing machinery, ie using RCA's and your suggestion of  "using a short length or ordinary shielded audio cable for a coaxial SPDIF connection without ill effects "is explained in Malcolm Hawksfords You Tube lecture. Malcolm explains many of the short cuts manufacturers take, and looks and asserts the science and steps very much needed,  with doing digital properly.    

 

 

Edited by stereo coffee

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1996 is a long time ago. I know physics hasn’t changed, but hasn’t measurement? Both tools and the idea of what’s important to measure?

 

As for directionality, I know one manufacturer simply marks the direction in which the cable was drawn, and suggests people can make up their own minds as to which way might sound better, if at all. Pragmatic.

 

I hear differences in cables. I think most do. Attaching better/worse labels is probably personal and system dependent.

 

I have heard dramatic difference in cable direction, but I haven’t experimented with digital cable. Perhaps I should. If I can hear a repeatable change, but can’t find a suitable scientific/engineering reason, than that causes me to think we’ve not discovered what to measure in order to explain it. After all, that’s just scientific curiosity. Quite important in the history of the human race, wouldn’t you say?

 

 

 

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Posted (edited)
35 minutes ago, AussieMick said:

but I haven’t experimented with digital cable.

What audio signal would you be sending through the coaxial cable e.g.  44.1kHz 16 bit stereo from a CD transport, 96kHz 24 bit stereo from the internet, 5.1 channel Dolby surround from a DVD player?

 

Most importantly, can you tell us what device you'd be using to receive the digital stream?  [If it's an advanced DAC, it should thoroughly "recondition" the signal.]

Edited by MLXXX

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Sometimes the crap is consumer driven. Permeate free milk anyone?

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39 minutes ago, Darren69 said:

Sometimes the crap is consumer driven. Permeate free milk anyone?

Yes I can't help feeling that some audiophiles will never be satisfied that jitter through a SPDIF cable can be dealt with, or that streamed audio can be received bit-perfect, buffered, and then reclocked with a rock steady clock. And there are other audiophile preoccupations over extremely minor differences.

 

Meanwhile we routinely watch movies and U.S. sitcoms on our 50Hz television system in Australia with the sound running 4% fast, and yet most viewers seem to be completely unaware of the anomaly. (I notice the anomaly more these days with so much of my viewing being at correct speed via Netflix or from Blu-ray discs. The "chipmunk" edge to dialogue sped up by 4% annoys me.)

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Of course, if the chip has to “work”, it produces more noise which can be injected right into system.

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Posted (edited)
4 hours ago, AussieMick said:

Of course, if the chip has to “work”, it produces more noise which can be injected right into system.

Not really. The buffering and reclocking algorithms remain active even if the incoming stream is pristine. 

 

As for noise, if you look at the specifications for standalone DACs on the market you'll find the analogue audio that emerges has a signal to noise ratio that is more than sufficient for the program material being carried by the digital stream.  I note that 16 bit CD sound has an inherent noise from using only 16 bits. However you'd only hear that at a very high gain setting.

 

As for 24 bit sound, that precision doesn't really exist for the least significant bits, as room noise and other noises in the recording process necessarily occupy the least significant bits.

Edited by MLXXX

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Posted (edited)
9 hours ago, AussieMick said:

Of course, if the chip has to “work”, it produces more noise which can be injected right into system.

Current draw you are quite correct is different for certain integrated circuits vs others, the

cheap fix usually seen, is a resistor to provide a modicum of separation between devices.

The better approach would be to supply from separate high impedance current regulated

supplies, to reduce adjacent noise between devices. 

 

Voltage regulators too factor into this, typified by the cheap 78xx and 79xx types,

The problem with these sharing circuits doing different functions,  is their low

impedance capability,  which even without a device being connected,  loads a circuit

constantly at 10ma of current between their output and ground. 

 

Seen as an attribute in lesser circuits  ,to in some cases relieve circuits of output capacitance, their widespread use in digital circuitry, is indicative of simple price cutting.      

Edited by stereo coffee

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