Ethan Winer Builds a Wire Null Tester

[watchnerd]

Too late: https://www.bursonaudio.com/products/cable-plus-pro/

I got a free pair of those from Burson and reviewed them for head fi.

 

[watchnerd]

What I am curious about though is that "hum" is there any concrete is measuring how much of it a cable resists? We saw how being near certain components introduced a LOT of hum and being moved away from such components removed said introduced hum. Are the cables in existence that can and do block the introduction of this hum when near said components?

Fully balanced cables are the usual better option for reducing interference.

Which is also ironic....if audiophile vendors wanted to make "better" cables, if only from a noise rejection POV, they should have switched balanced decades ago.

Why they didn't, I don't know....

 

[Johnny2Bad]

We are talking about cables transmitting analogue signals here?
What about cables that transmit digital signals, like usb cables, coax/AES/EUB, I2s etc.... ?

There is no such thing as "digital signals"; all digital interconnects transmit analog signals that *represent* digital data.

So, given the same digital source data, you should be able to compare two cables using an analog null system.

I like to use a calibrated microphone, one loudspeaker of a stereo pair playing, and compare reproduction using null software. The location of the speaker and microphone remain static during the test.
The advantages are:
Relatively simple measurement equipment required
The entire system is measured from source to speaker & room, which takes care of how the DUT affects other components (if it does).

 

[Blumlein 88]

Fully balanced cables are the usual better option for reducing interference.

Which is also ironic....if audiophile vendors wanted to make "better" cables, if only from a noise rejection POV, they should have switched balanced decades ago.

Why they didn't, I don't know....

The idea has been fed that balanced gear requires twice the components and is inherently unmatchable. So quality single ended circuits are inherently better, more musical, and closer to theoretical perfection (no matter how much noise they pick up). Yes I know the various things wrong with the idea, but that is the idea nurtured in some high end circles.

 

[Blumlein 88]

We are talking about cables transmitting analogue signals here?
What about cables that transmit digital signals, like usb cables, coax/AES/EUB, I2s etc.... ?

AES/EBU, and USB are balanced.

 

[Blumlein 88]

There is no such thing as "digital signals"; all digital interconnects transmit analog signals that *represent* digital data.

So, given the same digital source data, you should be able to compare two cables using an analog null system.

I like to use a calibrated microphone, one loudspeaker of a stereo pair playing, and compare reproduction using null software. The location of the speaker and microphone remain static during the test.
The advantages are:
Relatively simple measurement equipment required
The entire system is measured from source to speaker & room, which takes care of how the DUT affects other components (if it does).

Firstly I don't agree that there are no digital signals they are all analog. The analog quality can be horribly degraded and work as a digital transmission.

A null test of digital signal cables would work, but unlike analog audio cables, the bandwidth would need to be well into the megahertz region. Further you could have digital cables that will not null at all well. While the digitally retrieved signal fed into a DAC could put out near theoretically perfect results with both resulting analog reconstructions within the limits of thermal noise.

While using a microphone and the whole system over a speaker can have its uses (Ray does this often) it has its limits as well. Ambient noise various background sounds not being constant (passing traffic, fridges, HVAC) and keeping everything placed exactly even when you don't move anything will mean a null possible here is much less good than will be possible for signals leading up to the speaker. If you wish to null the whole system, the most precise way would be using the signal at the speaker connectors. Any change here would be seen and will be reproduced by the speakers even when it is far too small to be detected as sound in the room.

 

[restorer-john]

I think we've all tried this for ourselves, many of us, years ago.

I remember having a 'eureka' moment when I was about 22yo, thinking I could put the speaker leads (via a feed from the terminals) in the feedback loop to cancel out their contribution to damping factor. Then I found out it was all done before.

The same with direct distortion cancelling circuits.

Then negative impedance drive. That was done too.

 

[Sal1950]

Umm, when one clearly sets themselves apart as a antagonist you can expect a reaction. In this regard Winer often clips his own wings with a unnecessarily belligerent attitude at times which is a real shame as he’s done a great service to the hobby imo and continues to do so as well as being quite amusing at times.

After dealing with the crap the believers deal out, day after day, year after year, it's no wonder he sometime behaves in the manner he does. I've encouraged him to be more active here at ASR, he's a greatly valued member of the scientific audio community.
I've been asked a number of times why I often reply to the phools with biting sarcasm and have said, "when discussion using science, hard facts, and common sense fail, all that's left is ridicule.

Bah, he's a rank amateur, now Peter Aczel in his prime, there was a guy who really could antagonise when the mood took him!

A J Southfield deserves a gold star for his sparky tongue.
In a battle of wit, most have come unarmed.

 

[Sal1950]

I do think Headphone cables make an impact

Like all analog cables, if the LCR combine with the source or load impedance to alter response, that can be easily measured and determined.
Otherwise is a sighted bias.

 

[Johnny2Bad]

qa

Firstly I don't agree that there are no digital signals they are all analog. The analog quality can be horribly degraded and work as a digital transmission.

A null test of digital signal cables would work, but unlike analog audio cables, the bandwidth would need to be well into the megahertz region. Further you could have digital cables that will not null at all well. While the digitally retrieved signal fed into a DAC could put out near theoretically perfect results with both resulting analog reconstructions within the limits of thermal noise.

While using a microphone and the whole system over a speaker can have its uses (Ray does this often) it has its limits as well. Ambient noise various background sounds not being constant (passing traffic, fridges, HVAC) and keeping everything placed exactly even when you don't move anything will mean a null possible here is much less good than will be possible for signals leading up to the speaker. If you wish to null the whole system, the most precise way would be using the signal at the speaker connectors. Any change here would be seen and will be reproduced by the speakers even when it is far too small to be detected as sound in the room.

Like all facts, it's not an opinion, so there is no "agree" or "disagree".

Everything digital occours completely in the analog domain. Even the CPU in a computer does it's processing via capacitors, resistors, and transistors. Early digital data was stored on vinyl records, and recovered via a phono cartridge. You must grasp the concept that digital data and digital storage, processing and transmission are different things. There is digital diata but in every case require analog representations of the digital data to manipulate, store, or transmit said data.

 

[andymok]

So we know differences between cables in frequency domain are insignificant. How about in time domain?

 

[SIY]

Unless you deliberately build in a delay line, wires are minimum phase.

 

[Blumlein 88]

So we know differences between cables in frequency domain are insignificant. How about in time domain?

Time and frequency domains are mirror images.

 

[solderdude]

So we know differences between cables in frequency domain are insignificant. How about in time domain?

The fun part of nulling is that both time and amplitude generate a difference in amplitude. This means time domain is included in the test.
This becomes a 'problem' when trying to null longer analog lines as the transmission speed makes a difference.

For that reason 'digital signal' nulls don't work either as the frequency and speed of electricity through copper are not negligible any more (about 5ns/meter).
One would need a nulling amp that goes in the GHz range (due to sharp edges) and need to have some sort of delay line in the reference branch that is not bandwidth limited.
Even then considerable differences will exist and result in nulls that only differ in shape but not amplitude yet there may (will) be no difference in the digital signal transport.

 

[solderdude]

Everything digital occours completely in the analog domain. Even the CPU in a computer does it's processing via capacitors, resistors, and transistors. Early digital data was stored on vinyl records, and recovered via a phono cartridge. You must grasp the concept that digital data and digital storage, processing and transmission are different things. There is digital diata but in every case require analog representations of the digital data to manipulate, store, or transmit said data.

I don't think Blumlein disagrees with you.
Even though technically speaking you are right, in the sense that any digital real world signal is represented by an analog value of some sort (voltage/charge/magnetic field/current/light level or whatever other possible way) it is still digital.

In analog world the actual value represents an analog value.
In digital signals there is a certain 'band' in which something is '0' and '1' where this is not the case with analog.

This means that in the case of an analog signal the value is of direct consequence to the signal where for instance in a 5V digital signal both 4V and 5V and everything in between is always a '1' (unless deteremined to be '0').

So.. while all digital levels are represented by a certain analog value it does not behave like analog signals (as it has ranges of values) but is bound to the same physics in the analog plane.

Yes, digital signals in real world applications are represented by some analog value but are not the same as an analog signal value.

 

[Killingbeans]

Everything digital occours completely in the analog domain. Even the CPU in a computer does it's processing via capacitors, resistors, and transistors.

Yes, but any CPU would be horribly crippled by the slightest amount of noise if it didn't have a rather broad definition of ones and zeros. For instance, a 5v CMOS input accepts anything from 3.5v to 5v as '1' and anything from 0v to 1.5v as '0'. An analog null test wouldn't really be of much help, unless it shows noise violent enough to push ones and zeros into the no man's land (not very likely). Digital audio signals are closer to RF territory though. So, proper impedance matching is way more important than noise

Edit: solderdude beat me to it

 

[RayDunzl]

What happen if we start producing some active cables, with some kind of mild amplification into it?

If optical, maybe some little dongles with a section of erbium doped raman amplified dispersion correcting glass fiber for the couple of feet between boxes in the rack.

It was good for 60 miles (600 or so when daisy chained) for me 20 years ago back at Nortel.

As for copper cables, worked with basketball court sized Central Office Switches, clock distributed from a master, data cables (like 48 conductors) up to 100 meters from the line/trunk frames to the switch matrix. Don't remember any digital cable problems unless a cable was broken/cut or terminated to the wrong connector.

Early on in the digital age, the telcos prohibited taking a picture with electronic flash in the switchroom, because somebody crashed a machine after saying "Smile!"

The old NEC Neax61 Star Trek style operation console, 1980 or so:

The actor is pretending to set some registers on the CPU to get things started. The frame to the right of that had a meg or two of memory.

 

[Cosmik]

Yes, digital signals in real world applications are represented by some analog value but are not the same as an analog signal value.

You can resolve any such question these days by sending the information to one of the anti-fake news fact-checking services.

You could ask: "Are all digital signals really analog?". They would have to come back with the right answer ('yes' or 'no') and all would be well.

Or maybe not all questions can be reduced to simple facts, and you need to understand what's going on as you do @solderdude. Yes, all digital cables are passing analogue signals, with distortion, noise, jitter, etc. but it doesn't follow that the resulting music has been affected by *any* analogue issues *whatsoever*. Soundbites like "All digital signals are analogue" are meaningless, but people ascribe meaning to them anyway, and it is how myths spread.

 

[solderdude]

who checks the anti-fake news fact-checking services whether or not their assumed facts are actual facts ?

Indeed, it isn't as simple as stating digital is a different form of analog. It's very, very misleading even though it has some truth to it.

Digital signals pass through analog cables using different voltage level ranges for '0' or '1' or by indicating a transition from low-to-high or high-to-low within specified time frames.

Still the signals are digital even though being represented by voltage levels.
They are not analog signals even though these too are varying voltage levels.

 

[watchnerd]

So we know differences between cables in frequency domain are insignificant. How about in time domain?

Is it regular sound or "deblurred" MQA going through those cables?