Telos Quantum Active Cable - Snake Oil?

[Arpiben]

13 hours ago, CG said:

 

Umm, much of the PIM problems with RF fall into the band as well - like the cellular bands.  I'm not sure that's what you meant to say.

 

But, let's use your numbers.

 

You describe a dynamic range of roughly 120 dB.  I'm not sure if the -100 dBm level is the effective noise floor for the receiver or whether that's the minimum receive level for successful operation, and I'm too lazy to look that up this late at night.  So, I'll stick with 120 dB for the moment.

 

Second order distortion goes up by 2 dB for every dB of fundamental power.  Third order by 3 dB, and so on.  Typical audio power levels from a power amplifier are probably between 30 dBm (1 watt for folks reading) and maybe as much as 40 dBm.  At 30 dBm, that would raise the second order IMD level by 20 dB compared to your referenced 20 dBm.  That puts the dynamic range for second order IMD at 100 dB.  It gets worse as you go up in order.  So, maybe it's not so insignificant after all.  Maybe.  Dunno!

 

My point is, this stuff doesn't get measured or evaluated.  It either is blown off as being "obviously insignificant" or dismissed because "nobody can hear that."  Or, worse.  You don't need to search very far to find these kinds of arguments.  

 

That is decidedly different from, "we measured 20 tone IMD and looked at the IMD levels for 31 different kinds of connectors and found that the highest distortion levels were found to be at a level that would be equivalent to 30 dB below a very quiet room's ambient noise level when the audio system is operated at normal listening levels.  The tones were spectrally shaped in amplitude to approach the typical spectral distribution of energy for various forms of music as well as spoken voice.  In addition, a weighting filter was applied to simulate the human aural sensitivity curve.  Finally, out of band signals were also measured to be sure that nothing untoward was found there, in order to be thorough.  The spectra were measured using not only an averaging scheme to minimize the effects of thermal noise in the system, but also using a peak hold function over time so that the relative phase alignment of the test tones and subsequent signal crests of the distortion products were captured as well.  We also found cases where dirty connectors caused much higher levels of distortion that is likely to be audible.  More work is required in that area."

 

One is scientific investigation, while the other is a dorm room argument.  This is the world we live in today.  People need to be persuaded and often the threshold of persuasion is insurmountable based upon forces other than reason.  

 

"Still a man hears what he wants to hear 
"And disregards the rest" - P. Simon, 1968

 

Typical RF Microwave Channel Spacing  C.S. & bandwidth are: 7/14/28/40/56/112 MHz ETSI  10/20/30/40/50 MHz etc ANSI

Typical RF Microwave Transmit Power from 0 dBm to +35 dBm

Typical RF Microwave Receiver Noise Floor - 100 dBm @ CS = 7 MHz & Frequency below 7GHz  

 

PIM is out of concern when you carry only one channel whatever bandwidth since the non linearities order 3/5/7 will never fall down in the Receiver frequency range.

In RF microwave transmission for example TX and Rx frequencies are spaced by a few hundred MHz (shifter).

In RF microwave Tx & Rx frequencies (bands) are spaced by an integer n*CS

In RF microwave Tx & Rx signals share the same path. Non linearities are usually generated by defective circulators ( feromagnetics).

In case of no non linearities there is a margin of around 150 dB.

 

Forgetting RF microwave transmission, as far as I know, in consumer usage nobody is transmitting multi audio channels CS=44/48/88/96/ etc kHz and simultaneously receiving them at the same point with hundreds dB less!

Let's compare apples with apples before providing analogies.

 

[jabbr]

The way I see it is that all too often only a very limited set of "standard" measurements are done, e.g. a single tone into an AP analyzer, or THD, before two components are declared to "measure the same". Folks who hear differences between the two come to the conclusion that measurements don't tell the whole truth and that there are SQ factors that are "immeasurable" and this leaves open the marketing of "advanced" factors such as quantum ... when in reality there are vast amounts of measurements that haven't been done.

 

The real answer is that no real scientist nor engineer cares why you hear a SQ difference when swapping AC power cables to your network switch, yet all the same, if there were a real SQ difference, the difference would be measurable.

[alfe]

28 minutes ago, jabbr said:

The way I see it is that all too often only a very limited set of "standard" measurements are done, e.g. a single tone into an AP analyzer, or THD, before two components are declared to "measure the same". Folks who hear differences between the two come to the conclusion that measurements don't tell the whole truth and that there are SQ factors that are "immeasurable" and this leaves open the marketing of "advanced" factors such as quantum ... when in reality there are vast amounts of measurements that haven't been done.

 

The real answer is that no real scientist nor engineer cares why you hear a SQ difference when swapping AC power cables to your network switch, yet all the same, if there were a real SQ difference, the difference would be measurable.

As far as you know where you are...😀

[jabbr]

5 minutes ago, alfe said:

As far as you know where you are...😀

Maybe not where I am but I'll come to Cessy 😀

[CG]

22 hours ago, Arpiben said:

Forgetting RF microwave transmission, as far as I know, in consumer usage nobody is transmitting multi audio channels CS=44/48/88/96/ etc kHz and simultaneously receiving them at the same point with hundreds dB less!

Let's compare apples with apples before providing analogies.

 

Has nothing to do with that.

 

IMD is IMD, whether it's two tones at 10 KHz and 1 KHz (arbitrary choices) or whether it's a channel lineup of complex modulation schemes at microwave frequencies.  The very same mathematics apply, right?  That's comparing apples to apples.

 

The actual question is whether PIM is a condition that exists at lower frequencies such as audio.  And, if so, what levels are these IMD products at the typical power levels used in an audio system.  That's it!

[CG]

1 hour ago, jabbr said:

The real answer is that no real scientist nor engineer cares why you hear a SQ difference when swapping AC power cables to your network switch, yet all the same, if there were a real SQ difference, the difference would be measurable.

 

If they had an idea of what to look for and there was test gear available for looking.  (And, it was funded...)

 

In regard to the cable changes, at a basic level these kinds of questions are based on ideas usually covered in the very first EE course at the college level.  All that mesh and nodal analysis, Norton and Thevenin equivalents, and so on.  That's for direct "hard" coupling between the current loops.  Electromagnetic coupling is covered in an early physics course at the college level.

 

Personally, I would not expect somebody who majored in history, art, accounting, or any of those subjects in college to be familiar with these concepts.  That's not fair.  Same for folks who didn't go to college.  Presumably, people who design electronics systems like home audio would understand these subjects.  If not, why not?

[Arpiben]

5 hours ago, CG said:

 

Has nothing to do with that.

 

IMD is IMD, whether it's two tones at 10 KHz and 1 KHz (arbitrary choices) or whether it's a channel lineup of complex modulation schemes at microwave frequencies.  The very same mathematics apply, right?  That's comparing apples to apples.

 

The actual question is whether PIM is a condition that exists at lower frequencies such as audio.  And, if so, what levels are these IMD products at the typical power levels used in an audio system.  That's it!

 

Whatever power you are sending your arbitrary tones do you think that you have chance to listen to eventual PIM - 150 dB under ?

Amphenol RF connectors  aren't use in audio applications or frequency range are they?

Just hoping that no audio cable companies will provide any white paper without measurement claiming that they solve PIM issues 😉

[CG]

26 minutes ago, Arpiben said:

 

Whatever power you are sending your arbitrary tones do you think that you have chance to listen to eventual PIM - 150 dB under ?

Amphenol RF connectors  aren't use in audio applications or frequency range are they?

Just hoping that no audio cable companies will provide any white paper without measurement claiming that they solve PIM issues 😉

 

I don't know.  

 

Are the mechanisms the same at audio as at microwaves?  What is the distortion level at audio?  I don't know.  Maybe you can tell me and everybody else.  If the distortion is at the -120 dB level at 0.1 Watts at microwaves, would it not be greater than -100 dB at audio, assuming things are the same at both frequencies?  An awful lot of Internet forum characters (ink equivalent) are thrown around over DAC distortions at that approximate level.

 

My point is that I haven't seen any measurements or even theoretical analysis.  (Somebody, please point to it!)  There sure is a lot of "That doesn't matter, you idiot a**hole!" type rhetoric, though.

 

Not directed at you, Arpiben, but it sure seems to me that objective thought is awfully selective with regard to audio.  

[Arpiben]

12 hours ago, CG said:

 

I don't know.  

 

Are the mechanisms the same at audio as at microwaves?  What is the distortion level at audio?  I don't know.  Maybe you can tell me and everybody else.  If the distortion is at the -120 dB level at 0.1 Watts at microwaves, would it not be greater than -100 dB at audio, assuming things are the same at both frequencies?  An awful lot of Internet forum characters (ink equivalent) are thrown around over DAC distortions at that approximate level.

 

My point is that I haven't seen any measurements or even theoretical analysis.  (Somebody, please point to it!)  There sure is a lot of "That doesn't matter, you idiot a**hole!" type rhetoric, though.

 

Not directed at you, Arpiben, but it sure seems to me that objective thought is awfully selective with regard to audio.  

 

Hi CG,

 

Nothing directed at you either. No answer from my side since I have better experience in microwave vs audio.

It is not first time people do evoke PIM possibility for audio signals and link to those RF papers only.

Unfortunately I am not aware of any further analysis dealing with it at audio frequencies. 

Audio signals along a cable/connector do not share the same characteristics as RF (above 1 GHz) electromagnetic modes inside coaxial  or waveguides, difficult to compare.  In microwave PIM levels are extremely low unless any defective part,corrosion or mounting.

Rgds.