Preferred aes/ebu 110 ohm digital cable you have tried

[ar-t]

Is it possible to take this measurement stuff to another thread? While semi-interesting, it really is off-topic.

I have no problem in moving this. It probably does deserve its own thread. Especially since members are sending a total of 6 cables for measurement. *

Of course, they all had to tell me what the cables are. (I really do not care.) I can say it is an interesting mix of expensive brands and generic ones, that make no effort to conceal what the wire source is. Brands we will all know, some I have never heard of. But, since I am not a consumer of high-end cables, no surprise I have no idea who half of them are.

* = As of the time of this post.

 

[ar-t]

The article you refer adds weight to what Orb and I have been saying - you have to look at the properties of the sender and the receiver to analyze the problem.

I have been preaching this for over 20 years. Equipment manufacturers commit much more egregious errors than the average cable manufacturer. Neither deserve a pass.

One told me the reason they used 100 ohms, instead of 75 ohms, is because that is what they had that day. His excuse was that I should not be concerned, since back in those days, it was common to see SPDIF inputs that were unterminated. A rho (reflection coefficient) of 20% was lot better than 100%, so why was I upset? (Everyone knows this company, although no one would nominate them for best of anything.)

And then there was the company that lots of folks would say is a nominee...............

They had a 7-pole filter on the input of their DAC. That model somehow didn't last long. I wonder why.

 

[ar-t]

micro said and Gary also asked about verification with listening tests... I have found that the best way to demonstrate the effect of digital cable impedance is by using a cable with variable such impedance. And that cable is the MIT MA-X; if you measure the *DC* resistance of its hot and return wires you will notice significant variations - in my 1m, it ranges from 11.5 to 15.6 ohms per wire (i.e. double for the entire path), and their network is clearly in-series with the wires (not only because of this, but also because there are pauses as you switch from setting to setting). Said DC resistance will certainly have an effect on the cable's overall impedance at the operating frequencies, and I just don't know where the 110ohm value is - that would be a good cable for Pat to measure.

Uh.............not necessarily.

At low frequencies, you know, the ones Microstrip seems to be interested in discussing, this is true. But, we are not looking at signals in the 100-400 kHz range. Which is where the transition to transmission lines takes effect.

But, it is generally accepted, that at the frequencies where a wire acts as a transmission line, the resistance and (insulator) conductance are no longer part of the equation. At this point, Z = sqrt(L/C). That is what makes a transmission line a transmission line.

(I brought this very subject up with "Perry Mason". I gave a brief explanation how OCOS cable works. Even though they stopped making it............I dunno.........a few years back, I probably signed a NDA. I'll leave it at that. But, that was the point. To make a cable that would act as a transmission line, at very low frequencies. You had to factor in resistance and conductance, into a messy equation.)

I have no idea what MIT does, and again, not really interested. I do know they employ some sort of network, on their cables. Based on my experience, I bet their network is nothing more than an attenuator. Attenuators do attenuate reflections (along with the desired signal), and the use of them, in these sort of applications is nothing new. (I wonder who has been also preaching this, for over 20 years.)

Adding an attenuator would easily explain a change in resistance, depending on how it is done. There are ways to measure all of this.

However, as Orb said, there are also the transmitter and receiver chips in the transport and DAC - therefore, what makes this cable really good is that you can adjust its impedance to match the equipment you have.

So they claim.

Unless you buy already matched components with a matched cable to go - e.g. dCS - the other option is to adjust the impedance by ear, or hire someone competent to measure your equipment and adjust the cable. What also doesn't work well is buying fixed "matched" digital cables utilizing networks from companies that _think_ they know what the impedance characteristics of the transport and DAC you are connecting are, as if they have measured everything out there.

We don't know what sort of mismatch will occur, which is why.................

So back to the listening tests: with the MA-X in my system you can fairly easily tell the difference between settings (which affect jitter as a result of reflections caused by the various impedance selections) by listening to strings - at one setting they gain all the bite and focus they really have, others give a rather hazy, softer sound. Finally, see this http://www.positive-feedback.com/Issue14/spdif.htm regarding reflections and how they affect jitter.

Some annoying little arrogant jerk, down in Texas, and all of his equally annoying and arrogant (but not so little) jerk telecom-refugee cohorts came up with this idea back in '92. Along with the idea of stick a pad in there somewhere.

 

[ack]

You are right about z=sqrt(L/C), the article I posted also mentions this. Since the MIT is sold as an impedance matching cable it's still worth testing - I measure no capacitance change between settings and don't know about inductance; it is likely it varies inductance as well as resistance

 

[ar-t]

One can argue that a pad is an impedance matching device. I gave "PM" a detailed demonstration of how attenuators reduce reflections. I suggested we tape that, as well. He felt it was too technical. I'm still up for doing it. Maybe we can change his mind.

 

[ack]

You should. Perhaps what I am measuring is DC resistance of inductors in the network box

 

[ar-t]

That would show up on the TDR or VNA. Worth looking at.

 

[microstrip]

We debated the Ocos case sometime ago in WBF - the equation is quite simple. http://www.whatsbestforum.com/showthread.php?3759-RF-Speaker-Cables&p=59966&viewfull=1#post59966

 

[ar-t]

From that thread (and not posted by anyone that I know):

The cable formulas get rather tricky at audio frequencies.

I did not see your high school debate team techniques employed on that poster. Are you making a point, or merely trying to run me off? I'll gladly leave if it will make you feel better.

 

[jap]

We debated the Ocos case sometime ago in WBF - the equation is quite simple. http://www.whatsbestforum.com/showthread.php?3759-RF-Speaker-Cables&p=59966&viewfull=1#post59966

Thought you were out of this thread:

I can see now that you are not playing any game worth reading. We have real and friendly audio experts in WBF from whom we learn and those that always have a brilliant reason to avoid answering. Bye. I should have understood when it was said you were not interested in listening.

 

[microstrip]

Thought you were out of this thread:

jap,

I was out of a particular topic, as I could see that nothing new could be obtained about it. Since there was a reference to Ocos - that as far as I know is not used as digital cable - in the thread I posted something I knew about it, also because I still own it in another system and enjoy its sound.

BTW1, unless instructed by WBF moderators I will post when I decide I should do it.
BTW2 this thread is entitled "Preferred aes/ebu 110 ohm digital cable you have tried". Soon I will post on the Transparent Audio XL I am listening to.

Are you pleased now, Sir?

 

[jap]

Jap,

I was out of a particular topic, as I could see that nothing new could be obtained about it. Since there was a reference to Ocos - that as far as I know is not used as digital cable - in the thread I posted something I knew about it, also because I still own it in another system and enjoy its sound.

BTW1, unless instructed by WBF moderators I will post when I decide I should do it.
BTW2 this thread is entitled "Preferred aes/ebu 110 ohm digital cable you have tried". Soon I will post on the Transparent Audio XL I am listening to.

Are you pleased now, Sir?

First, my username is jap, with a small j.

Nice to know there was something in one Pat's post that you knew something about.

 

[microstrip]

First, my username is jap, with a small j.

Nice to know there was something in one Pat's post that you knew something about.

Username corrected, my apologies. I hope that sometime in the future you will be able to see that there were a few things more I also knew about. Happily some others managed to understand it, but I will try to improve my communication skills.

 

[nexans]

As an old diy`er I`ve came upun some interesting alternatives. To those of you who has Access to the European marked; try to get tour hands on a piece of Vivanco KX-710 tv-coax and a pair of decent rca-plugs. This is the only digital coax I`ve ever heard outperform a optical AT&T

 

[Speedskater]

From that thread (and not posted by anyone that I know):

I did not see your high school debate team techniques employed on that poster. Are you making a point, or merely trying to run me off? I'll gladly leave if it will make you feel better.

That was I. And it was only directed at people who try to use the radio frequency formula at audio frequencies.
One of the Ocos cables made an attemp, but it's a moving target.
Cyril Bateman in his "Measuring Speaker Cables" showed just how much work it is to measure Characteristic Impedance at audio frequencies. You have to measure all the parameters at each frequency of interest.

Cyril Bateman Articles
Electronics World Magazine

Measuring Speaker Cables: 1 Cyril Bateman Dec 1996 p925
Measuring Speaker Cables: 2 Cyril Bateman Jan 1997 p52
Measuring Speaker Cables: 3 Cyril Bateman Feb 1997 p119
Capacitor Distortion: Part 1 Cyril Bateman July 2002 p12 S
Capacitor Distortion: Part 2 Cyril Bateman Sept 2002 p16 S
Capacitor Distortion: Part 3 Cyril Bateman Oct 2002 p12 S
Capacitor Distortion: Part 4 Cyril Bateman Nov 2002 p40 S
Capacitor Distortion: Part 5 Cyril Bateman Dec 2002 p44 S
Capacitor Distortion: Part 6 Cyril Bateman Jan 2003 p44 S
Capacitor Sounds II: Part 1
Real-Time Hardware Cyril Bateman July 2003 p36 S
Capacitor Sounds II: Part 2
Distortion v Time v Bias Cyril Bateman Aug 2003 p46 S
Capacitor Sounds II: Part 3
Distortion Meter Cyril Bateman Sept 2003 p46 S
Capacitor and Amplifier Distortions Cyril Bateman Nov 2003 p44 S
Simulating Power MOSFETs: Part 1 Cyril Bateman Oct 2004 p22 S
Simulating Power MOSFETs: Part 2 Cyril Bateman Nov 2004 p26 S
Simulating Power MOSFETs: Part 3 Cyril Bateman Dec 2004 p10 S
Simulating Power MOSFETs: Part 4 Cyril Bateman Jan 2005 p34 S

 

[Orb]

Great post Speedskater, forgot about Cyril and his work beyond capacitor design-testing.
Cheers
Orb

 

[Rufus McDufus]

Am I missing something? AES/EBU protocol doesn't operate at audio frequencies, surely?

 

[Orb]

Am I missing something? AES/EBU protocol doesn't operate at audio frequencies, surely?

Not sure I quite follow Rufus.
SPDIF and AES/EBU (both are very similar and identical in other ways) are specification and transmission protocol as you say.
Does HDMI operate at audio frequencies or USB..... nope but they still can affect visual/audio.
Or what about I2S (although not technically a standard for data transmission) that is sometimes compared to SPDIF and sound quality.

Cheers
Orb

 

[Orb]

From a technical side (and tbh it does not really help much either side of the debate IMO but interesting from a technical framework-working perspective or those who work with protocols-specifications and interest in this type of thing or also into audio), here is the EBU guideline that is relevant to this discussion on AES/EBU spec: https://tech.ebu.ch/docs/other/aes-ebu-eg.pdf

Cheers
Orb

 

[microstrip]

Great post Speedskater, forgot about Cyril and his work beyond capacitor design-testing.
Cheers
Orb

The centenary British magazine Wireless World, re-named Electronics and Wireless World and now Electronics World was filled with excellent articles and energetic debates in audio. We can know find many of them in the net - the C. Bateman capacitor articles are available at Scribd http://www.scribd.com/doc/2610442/Capacitor-Sound.

Still as a student I spent long evenings reading its articles, and I built my first transmission line speaker from a project on Bayley on Wireless World .http://documents.jordan-usa.com/Famous-Articles/Bailey-1972-Transmission-Line-Loudspeaker-Enclosure.pdf. I remember that the more time consuming part was getting the long fiber natural wool - a critical part of the project!