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John Swenson tutoring paper: "Considerations regarding usage of external reference clocks" (EtherREGEN and other): Sine vs. square, impedance, cables—and a money saving surprise at the end.


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Thank you for the pointed white paper. 99% clear.

 

Since I use a quality Ref10 clock, I'm left  wondering about my cables.

 

How much does attenuation plays a rule in a 1.5 cable? Professional companies gives  their specs @ 100m runs. 

For example, the attenuation of Canare LV-77S @ 100' is 1.0. Can things get any lower? LV-61S @ 100' is 1.3.

 

 

Secondly, if performance can be improved, can anyone recommend a low attenuation 75ohm cable?  By the meter or feet is better, as I solder my BNC cables myself.

Stereo

[Genelec 1032C x 2 + 7360 x 2] <== [MC3+USB x 3 <-- REF10 SE120] <== [AERIS G2] <== [EtherRegen x 3]
Chain switchable to [Genelec 8331 x 2 + 7350]


Surround

[Genelec 1032C x 3 + 8431 x 2  + 7360 x 2] <== [MiniDSP U-DIO8] <== [Mac Mini] 

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18 minutes ago, JohnSwenson said:

Raw attenuation doesn't matter, it is how the attenuation changes with frequency that matters. So the numbers you quoted don't make any difference, what you need is the attenuation vs frequency graph. The flatter the graph below 1GHz the better. The problem is you cannot compare graphs from different companies since the scales are almost always different. Even within the same company the scales are frequently different.

 

The Canare LV-77S spec sheet has a table for this with several of their models. You can tell by looking at this table that the LV-77S has significantly less change with frequency than the others do. This is the information you need to look at to compare cables.

 

Note this is only if you are using square wave output, if you are using sine wave it doesn't matter.

 

John S.

 

Very helpful, John!

 

And yes, I can see how the increments on the LV-77S is lower than the other cables.

Guess I've just pointed me at the right direction...

Stereo

[Genelec 1032C x 2 + 7360 x 2] <== [MC3+USB x 3 <-- REF10 SE120] <== [AERIS G2] <== [EtherRegen x 3]
Chain switchable to [Genelec 8331 x 2 + 7350]


Surround

[Genelec 1032C x 3 + 8431 x 2  + 7360 x 2] <== [MiniDSP U-DIO8] <== [Mac Mini] 

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2 hours ago, James Stephens said:

 

Hi there,

 

Canare LV-77S does have the lowest attenuation with frequency of the listed cables here:

http://www.canare.com/ProductItemDisplay.aspx?productItemID=74

 

I have been using this up to now for a square wave cable.

 

Of course the info shared today changes things .. lol I might just be buying an AfterDark sine wave clock now!

 

Will read and re-read a few more times first though ....

 

For square wave cable hunters though, Belden 1694A does look to be even better (lower) by the metric of attenuation vs frequency:

 

https://catalog.belden.com/techdata/EN/1694A_techdata.pdf

 

Best,

James

 

Excellent tip, James.

 

Regrettably, the Canare and the  Belden measurements don't fully overlap, but where the do, the 1694A does measure better. 

I have a small spool of Furutech FP-62 on hand, but the company doesn't publish any numbers, so I'm reluctant to use it.

I guess Belden it is.

Stereo

[Genelec 1032C x 2 + 7360 x 2] <== [MC3+USB x 3 <-- REF10 SE120] <== [AERIS G2] <== [EtherRegen x 3]
Chain switchable to [Genelec 8331 x 2 + 7350]


Surround

[Genelec 1032C x 3 + 8431 x 2  + 7360 x 2] <== [MiniDSP U-DIO8] <== [Mac Mini] 

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1 hour ago, MartinT said:

 

But the Canare LV-77S sounds better!  Trust your ears, it's not just about measurements.

 

I haven't used either, but I doubt I'll be able to hear any difference in a ref clock application. (Hell, I had to temporarily replaced a home-brewed Furutech cable with a $2 BNC/BNC and I couldn't detect anything different). 

 

Still, I believe a solid core is less prone to skin effect than a stranded core, which might explain why Belden measures better than the Canare. 

Stereo

[Genelec 1032C x 2 + 7360 x 2] <== [MC3+USB x 3 <-- REF10 SE120] <== [AERIS G2] <== [EtherRegen x 3]
Chain switchable to [Genelec 8331 x 2 + 7350]


Surround

[Genelec 1032C x 3 + 8431 x 2  + 7360 x 2] <== [MiniDSP U-DIO8] <== [Mac Mini] 

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I have a question fo my own here to John. Given we have the figures for both the Bedlen 1694A and Canare LV-77S, which of the two would he recommend over the other? Going by the numbers alone, the Bedlen is superior, but some people here claim that the Canare "sound" better. Kind of a contradiction, so I hope he could weigh in. 

Stereo

[Genelec 1032C x 2 + 7360 x 2] <== [MC3+USB x 3 <-- REF10 SE120] <== [AERIS G2] <== [EtherRegen x 3]
Chain switchable to [Genelec 8331 x 2 + 7350]


Surround

[Genelec 1032C x 3 + 8431 x 2  + 7360 x 2] <== [MiniDSP U-DIO8] <== [Mac Mini] 

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9 minutes ago, MartinT said:

 

It's really the Belden 4694R that should be compared with the Canare LV-77S.  And they sound really close albeit slightly different in character.

 

1694A is a lesser cable and sounds inferior.

 

Thanks for the guidance, Martin. 

 

Indeed, the 4694R measures better than the 1694A. 

How flexible is the 4694R? The 1694A is rather stiff, whereas the Canare very pliable. 

Stereo

[Genelec 1032C x 2 + 7360 x 2] <== [MC3+USB x 3 <-- REF10 SE120] <== [AERIS G2] <== [EtherRegen x 3]
Chain switchable to [Genelec 8331 x 2 + 7350]


Surround

[Genelec 1032C x 3 + 8431 x 2  + 7360 x 2] <== [MiniDSP U-DIO8] <== [Mac Mini] 

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1 hour ago, LEO SOUND said:

If square wave outputs are to be avoided, why the etherregen is "square wave" and therefore you have to buy a sin wave clock with a filter to be sure to have a good signal.
I'm interested in a Square Wave from AfterDark that claims it's special for etherregen on their website.

@AfterDark.Can you provide details on this clock as it looks like it was produced in collaboration with Uptone Audio.
But from the white booklet, we just have the impression that we need Sine Wave because almost no clock does a good Square Wave except the very expensive watches and out of budget for me.

Sotm is sine wave I think.

 

It's not true that a square wave is to be shunned. Here's what the paper says:

 

"Just remember that the best possible result is still going to be using a square wave clock box with a REALLY good sine to square converter, everything being just right inside the box—AND you use a really low-attenuation-with-frequency cable."

Stereo

[Genelec 1032C x 2 + 7360 x 2] <== [MC3+USB x 3 <-- REF10 SE120] <== [AERIS G2] <== [EtherRegen x 3]
Chain switchable to [Genelec 8331 x 2 + 7350]


Surround

[Genelec 1032C x 3 + 8431 x 2  + 7360 x 2] <== [MiniDSP U-DIO8] <== [Mac Mini] 

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  • 4 weeks later...
32 minutes ago, LewinskiH01 said:

 

Thank you!

 

That Prosig cable is the same one that displayed best behavior from the three cables you posted on April 2. I wonder what the magic sauce is in it?

 

 

Built to spec. 

 

A lot of the exotic cables don't meet the spec, and aren't property tested. 

 

Stereo

[Genelec 1032C x 2 + 7360 x 2] <== [MC3+USB x 3 <-- REF10 SE120] <== [AERIS G2] <== [EtherRegen x 3]
Chain switchable to [Genelec 8331 x 2 + 7350]


Surround

[Genelec 1032C x 3 + 8431 x 2  + 7360 x 2] <== [MiniDSP U-DIO8] <== [Mac Mini] 

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35 minutes ago, DarqueKnight said:

No. I prefer neutral sounding gear. I do not own any tube gear.  The Prosig cable had the least clarity and detail.

 

You make me scratch my head.

 

Those cables don't transmit sound, merely an analog wave that triggers a gate on the receiving end, which is in turn controls the receiver's timing.  The less jitter and noise phase arriving over that analog wave, the more accurate the timing.  So why would a more jittery signal--e.g., Audio Labs, as per your tests--sound better than a cleaner signal?   

Stereo

[Genelec 1032C x 2 + 7360 x 2] <== [MC3+USB x 3 <-- REF10 SE120] <== [AERIS G2] <== [EtherRegen x 3]
Chain switchable to [Genelec 8331 x 2 + 7350]


Surround

[Genelec 1032C x 3 + 8431 x 2  + 7360 x 2] <== [MiniDSP U-DIO8] <== [Mac Mini] 

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46 minutes ago, DarqueKnight said:

I did not measure jitter and phase noise among the cables. I just looked at time domain plots on an oscilloscope.

 

If I understand you correctly, you are saying that the only electrical noise that affects sound quality at a DAC's output is jitter and phase noise? Why wouldn't an analog timing signal be subject to the same types of noise degradation as any other analog signal?

 

My digital music playback chain is as follows: NAS--(Ethernet)-->EtherREGEN--(Ethernet)-->Digital Music Player--(USB)-->Word Clock--(SPDIF)-->DAC.

 

Here is what I’m saying:

 

As far as I understand, if the shape is not a perfect square, the triggering interval is flawed, thus jitter is introduced into the DAC.

 

Now, it could be that shielding on that cable is so terrible that it picks up noise, which countervails the nearly perfect square to a point where the overall sound is degraded. 

 

A bit off tangent, but somewhat related: money doesn’t necessarily buy quality in this game. I inquired with Furutech about the attenuation on some of their coax cables, and the figures sent back to me were pretty dismal; considerably worse than the more affordable Canare LV-77S. 

 

Stereo

[Genelec 1032C x 2 + 7360 x 2] <== [MC3+USB x 3 <-- REF10 SE120] <== [AERIS G2] <== [EtherRegen x 3]
Chain switchable to [Genelec 8331 x 2 + 7350]


Surround

[Genelec 1032C x 3 + 8431 x 2  + 7360 x 2] <== [MiniDSP U-DIO8] <== [Mac Mini] 

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27 minutes ago, DarqueKnight said:

Sine waves aren't perfect square waves, and they make very good clock signals. A clock pulse can be any shape (square, sinusoidal, sawtooth, etc.) as long as it is periodic.

 

Matching the wave shape of the clock and the receiver will yield the best results, given the clocks in questions are of the same quality (that is, if you're comparing clocks), while a mismatch can introduce jitter into the receiver.  (In the case of the ER, the filter is here to address it) I believe the reason has to to do with the gate mechanism.  In your case, the cheap cable with the nearly perfect square should've produced the best sound, with the exception I'm making below. 

 

27 minutes ago, DarqueKnight said:

I am not sure if you are making a general comment or if you are referring to a specific cable.

 

I was referring to that stock cable, the less costly one, you tested with the square wave. One explanation I can come up with -- other than expectation bias, of course -- is that it picks up so much noise, that the benefits of the square wave are vitiated.  

 

Stereo

[Genelec 1032C x 2 + 7360 x 2] <== [MC3+USB x 3 <-- REF10 SE120] <== [AERIS G2] <== [EtherRegen x 3]
Chain switchable to [Genelec 8331 x 2 + 7350]


Surround

[Genelec 1032C x 3 + 8431 x 2  + 7360 x 2] <== [MiniDSP U-DIO8] <== [Mac Mini] 

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1 hour ago, flkin said:

In a nutshell, would it be fair to say then that using the filter makes the Sine wave clock work as well as the best square wave this particular sine wave clock can ever be? 

 

 

That's from the bottom of the white paper:

 

"Just remember that the best possible result is still going to be using a square wave clock box with a REALLY good sine to square convertor, everything being just right inside the box—and you use a really low-attenuation-with-frequency cable."

Stereo

[Genelec 1032C x 2 + 7360 x 2] <== [MC3+USB x 3 <-- REF10 SE120] <== [AERIS G2] <== [EtherRegen x 3]
Chain switchable to [Genelec 8331 x 2 + 7350]


Surround

[Genelec 1032C x 3 + 8431 x 2  + 7360 x 2] <== [MiniDSP U-DIO8] <== [Mac Mini] 

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