Transparent Audio Cable Network Boxes

Speedskater

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No, for a SP/DIF interconnect system, RCA connectors (at about ½ inch long) are orders of magnitude better than needed. Remember that SP/DIF in the digital world is very low frequency stuff. Now if we are talking about GHz signals then picoseconds and fractions of an inch are important, but that's another world. And for a 15/44.1 SP/DIF cable shorter than lets say 30 feet (or 10 meter) the 75 Ohm impedance tolerance is about 50 to 110 Ohms. However the newer, higher speed AES 3id spec has a 5% impedance tolerance.
 

Empirical Audio

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No, for a SP/DIF interconnect system, RCA connectors (at about ½ inch long) are orders of magnitude better than needed. Remember that SP/DIF in the digital world is very low frequency stuff. Now if we are talking about GHz signals then picoseconds and fractions of an inch are important, but that's another world. And for a 15/44.1 SP/DIF cable shorter than lets say 30 feet (or 10 meter) the 75 Ohm impedance tolerance is about 50 to 110 Ohms. However the newer, higher speed AES 3id spec has a 5% impedance tolerance.

We are talking about signals with GHz components, just not the fundamental. It still matters.

Steve N.
Empirical Audio
 

jkeny

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We are talking about signals with GHz components, just not the fundamental. It still matters.

Steve N.
Empirical Audio

Agreed, a squarewave needs many harmonics to be correctly characterised - it's not just a fundamental
 

DaveC

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There are a few 75 ohm RCAs, all are not created equal...
 

Empirical Audio

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There are a few 75 ohm RCAs, all are not created equal...

I have found that it's not the Char. Imp. of the connector, but how the cable is terminated to it that makes the difference. Certainly most RCA jacks are not 75 ohms. BNC jacks can be 75 ohms.

Steve N.
 

Sablon Audio

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Crimp / set screw terminations are better than solder and both jack & internal wiring needs to be 75ohm compliant for best results.
 

Speedskater

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Agreed, a squarewave needs many harmonics to be correctly characterised - it's not just a fundamental
While SP/DIF may sort of resemble a square wave, it's not a square wave nor does it need to be.
Remember it's Low Pass filtered. Digital logic doesn't need square waves.
 

Empirical Audio

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16/44.1 SP/DIF is Low Pass filtered at about 15 MHz.

Has nothing to do with the receiver that gets the S/PDIF signal. At what point that receiver detects the edge is exactly what determines the jitter that the D/A gets. Faster edge and lower jitter in the signal means less jitter to the D/A.

If you give a slower edge, this creates more uncertainty as to when the edge is detected, which results in higher jitter.

Steve N
Empirical Audio
 

BlueFox

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Has nothing to do with the receiver that gets the S/PDIF signal. At what point that receiver detects the edge is exactly what determines the jitter that the D/A gets. Faster edge and lower jitter in the signal means less jitter to the D/A.

If you give a slower edge, this creates more uncertainty as to when the edge is detected, which results in higher jitter.

Exactly, and this is why I think different Ethernet cables have the potential to sound different.
 

Empirical Audio

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Exactly, and this is why I think different Ethernet cables have the potential to sound different.

Ethernet is a different animal. Buffered packets. It should not be sensitive to edge-rates for that reason. It is sensitive to leakage though. This is kind of like the way common-mode noise affects USB. It's not a direct signal issue, but it does impact SQ.

Wired Ethernet in particular should be driven by a Router or Switch that has an earth-grounded LPS where the earth ground is tied to the DC common. This reduces leakage noise the best. Isolators can also help.

Steve N.
Empirical Audio
 

BlueFox

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Ethernet transmits an analog signal that represents digital values. If the cable degrades the signal then the rise/fall point can be shifted which could result in the analog to digital conversion having slight timing differences in the bits between the source and destination. Isn’t that jitter?
 

Empirical Audio

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Oct 12, 2017
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Ethernet transmits an analog signal that represents digital values. If the cable degrades the signal then the rise/fall point can be shifted which could result in the analog to digital conversion having slight timing differences in the bits between the source and destination. Isn’t that jitter?

If data errors occur because of timing, the packets are retransmitted. Timing variation should not impact SQ, unless it is so bad that drop-outs occur because of traffic or retries. Ethernet data needs to be reliable.

The main thing that impacts jitter is leakage through the transformer. Edge-rates may have an effect on this, but not sure about that.

Steve N.
Empirical Audio
 

jkeny

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Feb 9, 2012
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While SP/DIF may sort of resemble a square wave, it's not a square wave nor does it need to be.
Remember it's Low Pass filtered. Digital logic doesn't need square waves.

You are correct, it doesn't NEED square waves but the risetime slope is where the transition is sensed & this slope needs to be steep in order for accuracy in timing - if the slope is not steep then the timing of the transition crossing becomes much less accurately defined - signal correlated jitter, anyone?

Edit: I see Steve already gave you this answer!
 

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