Crosstalk in cables

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akmh

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Crosstalk in cables
« on: 10 Aug 2019, 11:16 pm »
Has anyone taken the time to measure the crosstalk between interconnect cables and if different cables produce better measurements? I have spent some time measuring different (cheap and expensive) cables and the results are very interesting. Using certain geometry, dielectrics, and filter circuits, you can bring the crosstalk down about 12db and it noticeably sounds much better, more dynamic and more clear. Anyone else tried this?

Speedskater

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Re: Crosstalk in cables
« Reply #1 on: 11 Aug 2019, 03:02 pm »
There must be some uncontrolled variables in your test setup.

But in 100 meter long unshielded Cat3 balanced cables, crosstalk is about -96dB.
(if I remember correctly)

audioengr

Re: Crosstalk in cables
« Reply #2 on: 11 Aug 2019, 04:14 pm »
Are you certain that it is crosstalk you are hearing?  Are your IC's unshielded?  It's generally a non-issue IME.

gab

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Re: Crosstalk in cables
« Reply #3 on: 11 Aug 2019, 04:46 pm »
I quote Mr. Linkwitz (RIP) from his site (note this is speaker cable crosstalk related but still applicable):

"The way I test crosstalk is to terminate each of the two wire pairs with a resistor of 6 ohm or similar value to simulate the driver load. I would not use actual drivers because you might damage them when the sinewave signal level is too high and continuous.

Then I drive the first pair on its other end from a power amp of very low source impedance. The second pair is short circuited at its amplifier end to simulate a 0 ohm source.

Now I measure the voltage across each resistor at 10 kHz. The ratio of the two voltages is the crosstalk. The frequency could be swept and you want to see what happens around 5 kHz where the W22 has a resonance.

Crosstalk attenuation should be greater than 40 dB, especially at 5 kHz. This measurement is only necessary when you have a tightly wound multi-conductor speaker cable bundle or very long tightly wrapped cables.

This test accounts for magnetic field coupling, which is dominant, and also for any electric field coupling.

SL"

Speedskater

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Re: Crosstalk in cables
« Reply #4 on: 11 Aug 2019, 10:42 pm »
Multi-channel speaker cables are one thing and reasonable coax RCA interconnects are another.

akmh

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Re: Crosstalk in cables
« Reply #5 on: 12 Aug 2019, 06:47 pm »
There must be some uncontrolled variables in your test setup.

But in 100 meter long unshielded Cat3 balanced cables, crosstalk is about -96dB.
(if I remember correctly)

Wouldn't that of been measured for signal level of networking devices? Also I've never heard of using Cat3 for hifi interconnect wire. Seems like it wouldn't have enough copper to go more than a few feet without some serious cable effects.

To clarify, this was a 3.5mm stereo unbalanced cable. So I would send pink noise@line level+4dbu(.775v) into the tip(L) and then measure how much noise was being picked up by the ring(R). A standard monster 3.5mm cable measured like -80db. My special cable measured -92db with nothing changed other than the cables. I wish I would of taken pictures. I also tested a Audioquest Angel 3.5mm and it was only like -84db. Crazy thing is you can hear this in the cable as a sharper and more defined sound on almost anything its plugged into. Something it doesn't make a difference. And somethings its night and day. On a nice system it sounds absolutely glorious.

akmh

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Re: Crosstalk in cables
« Reply #6 on: 12 Aug 2019, 06:54 pm »
I quote Mr. Linkwitz (RIP) from his site (note this is speaker cable crosstalk related but still applicable):

"The way I test crosstalk is to terminate each of the two wire pairs with a resistor of 6 ohm or similar value to simulate the driver load. I would not use actual drivers because you might damage them when the sinewave signal level is too high and continuous.

Then I drive the first pair on its other end from a power amp of very low source impedance. The second pair is short circuited at its amplifier end to simulate a 0 ohm source.

Now I measure the voltage across each resistor at 10 kHz. The ratio of the two voltages is the crosstalk. The frequency could be swept and you want to see what happens around 5 kHz where the W22 has a resonance.

Crosstalk attenuation should be greater than 40 dB, especially at 5 kHz. This measurement is only necessary when you have a tightly wound multi-conductor speaker cable bundle or very long tightly wrapped cables.

This test accounts for magnetic field coupling, which is dominant, and also for any electric field coupling.

SL"


I've been taught that cross talk will be the weak link in dynamic response of audio equipment. If you have -40db of crosstalk rejection in a speaker crossover, you only 40db of effective dynamic range. You definitely need more for lifelike sound reproduction/recording.

Speedskater

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Re: Crosstalk in cables
« Reply #7 on: 12 Aug 2019, 10:08 pm »
I looked it up (in a 2002 book) and it was Cat5 used as a pro audio 4 channel XLR balanced interconnect. Using Cat cable is becoming more common in pro audio. Not so good for phantom powered microphone cables.

Speedskater

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Re: Crosstalk in cables
« Reply #8 on: 12 Aug 2019, 10:11 pm »
I've been taught that cross talk will be the weak link in dynamic response of audio equipment. If you have -40db of crosstalk rejection in a speaker crossover, you only 40db of effective dynamic range. You definitely need more for lifelike sound reproduction/recording.
That idea has no basis in fact. Your ears are only a few inches apart, they hear lots of cross talk.

Elizabeth

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Re: Crosstalk in cables
« Reply #9 on: 12 Aug 2019, 11:07 pm »
That idea has no basis in fact. Your ears are only a few inches apart, they hear lots of cross talk.
Just to mention the FACT: ear through the skull crosstalk is actually AT 40dB down. -40dB is the level you hear in the other ear, what is in the first one. This may vary slightly, depending how thick headed you are...  :thumb:

akmh

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Re: Crosstalk in cables
« Reply #10 on: 13 Aug 2019, 01:08 am »
That idea has no basis in fact. Your ears are only a few inches apart, they hear lots of cross talk.

The dynamic range of recording is 96db for 16 bit audio. Crosstalk can happen at any point in the chain and cause an number of different effects. Sometimes it will sound like its literally been compressed through a dynamic range limiter. All I'm saying is if you maintain -96db crosstalk threw your whole signal path, you have one less thing to worry about for amazing sound reproduction. 

Im kinda confused by the 40db number. The crosstalk between your ears does not effect your brains ability to precisely decipher between the sound captured by the left and the right ear. Im mean...Our lives depend on it. Thats why we can pin point the source of a sound or something behind us.

Elizabeth

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Re: Crosstalk in cables
« Reply #11 on: 13 Aug 2019, 01:19 am »
Did not say it mattered a whole lot. If a sound is at say 50dB in the other ear it will come in as 10dB etc... You are not very affected by it. But is is there...And if the sound is 110dB do you think you would notice the crosstalk ar 70dB with a 110dB blasting already, directly?
Whre one might be able to hear it is wearing say musicians sealed earpieces and one goes dead.. You are gonna then hear the crosstalk transmitted via your skull.. bone conduction....

akmh

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Re: Crosstalk in cables
« Reply #12 on: 13 Aug 2019, 05:27 pm »
I was really hoping to have some sort of constructive discussion but this is just people telling me I'm wrong! :( You really think conduction of SPL threw our skulls is the pertinent value to understanding not only how we hear, but how audio may or may not change when passing threw and electronic circuit?  All my years of study, no speaker expert has ever mentioned it as something to keep in mind.

Is it crazy to think you people don't know everything? Or maybe their are 1000s of different ways to do something and your way isn't the only way? You're not even curious to whats going on with my cables? Do you think I don't know what I'm hearing or I don't know how to do a A/B test? I would assume if someone took the time to sign up for a forum like this and put the effort to become a member, they would at least be given the time of day to discuss the possibilities.

I would really appreciate if someone who also has real-world experience testing with different cables(not just reading in books about it or anatomy theory) could chime in....

Elizabeth

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Re: Crosstalk in cables
« Reply #13 on: 13 Aug 2019, 09:27 pm »
In your initial post you say you can do something (bring crosstalk down 15%) and then fail to show any of the actual evidence.
You at least know no one has discussed such a thing, but you ask anyway hoping. You need to define what you are writing when you use the term crosstalk.
If you would have written out your methodology, and exactly what differences you achieved with what changes. Maybe you would get some response other than the ones you got.
So write out what you were actually measuring and how you measured it. How you changed what, and show us. Instead of complaining we can't read your mind.   :thumb:

WGH

Re: Crosstalk in cables
« Reply #14 on: 14 Aug 2019, 12:15 am »
My special cable measured -92db with nothing changed other than the cables.

Sounds like you discovered something very important. What cables, wire and plugs are you using? Not everyone makes their own cables, it costs just as much or more to make an excellent cable and not very many people have the equipment or knowledge to test it.

I like Zenwave but buying the Furutech FP-108(R) UPOCC copper center pin, rhodium plating; Neotech 26 gauge UPOCC silver/gold alloy with teflon insulation; and Neotech 24 gauge UPOCC copper with teflon insulation costs as much as buying one.

Kimber Kable has crosstalk measurements (which I don't understand, 92kHz is higher than I can hear), what you have achieved compared to their measurements is amazing. Do you also measure capacitance, series inductance, dc loop resistance and reactance?
 
GQ - Mini Cu: Crosstalk @ -60dB - 92kHz
       (Cp) parallel capacitance: 61.0 pF @ 20 kHz
       (Ls) series inductance: 0.84 μH @ 20 kHz
       (Rdc) dc loop resistance: 0.089 ohm
       (Xt) total reactance: 0.104 ohm @ 20 kHz
       Frequency response ±0.5 dB dc - 5Mhz

TAK Cu phono interconnect: Crosstalk @ -60dB - 92.0 kHz
                                            (Cp) parallel capacitance: 47.10 pF @ 20 kHz
                                            (Ls) series inductance: 1.31 μH @ 20 kHz
                                            (Rdc) dc loop resistance: 0.119 ohm
                                            Ground/Shield: R: 0.065 ohm X: 0.359
                                            (Xt) total reactance: 0.162 ohm @ 20 kHz
                                            Frequency response ±0.5 dB dc @ 5 MHz

Looking forward to hearing more about your cables.

akmh

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Re: Crosstalk in cables
« Reply #15 on: 14 Aug 2019, 06:26 am »
deleted.
« Last Edit: 20 Aug 2019, 07:09 pm by akmh »

Letitroll98

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Re: Crosstalk in cables
« Reply #16 on: 14 Aug 2019, 09:19 am »
How can one aquire these cables?  Do you have to make them yourself, or are they available for sale someplace?

Elizabeth

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Re: Crosstalk in cables
« Reply #17 on: 14 Aug 2019, 01:18 pm »
After reading the new attempt at explaining what the op discovered and did ... Makes a whole lot of sense. thanks for not just walking away. 
Not my thing there, but certainly something for folks interested to investigate further.  :thumb:

akmh

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Re: Crosstalk in cables
« Reply #18 on: 14 Aug 2019, 04:44 pm »
deleted
« Last Edit: 20 Aug 2019, 07:09 pm by akmh »

akmh

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Re: Crosstalk in cables
« Reply #19 on: 14 Aug 2019, 05:14 pm »
After reading the new attempt at explaining what the op discovered and did ... Makes a whole lot of sense. thanks for not just walking away. 
Not my thing there, but certainly something for folks interested to investigate further.  :thumb:

Thanks for giving me a chance!