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Channel Separation?

SIY

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My assumption here is that if low power, high finesse devices like HP amps can have it that bad, it must be much worse with power amps.
Usually the opposite. "Finesse," whatever that means, is irrelevant. Most crosstalk happens at source switches, volume controls, and coupling because of channel proximity.

A quick look at the last power amp tested here showed a crosstalk rating of "very poor." And at 1kHz, it was -60dB (because coupling is usually capacitive, the crosstalk will be even lower at lower frequencies). I think you're worried about nothing.
 

Cbdb2

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I've read a review once, of two amps by the same brand. The 1st had 80dB channel separation, the 2nd 90dB. It was almost the only difference between them, according to the specs.
The reviewer said that the soundstage of the 1st one wasn't wide enough, but that the soundstage of the 2nd one was great.
I don't know if he said that because he tried both of them at the same SPL or because the reading of the specs made it state so.
Another review based on imagination. Unplug the source right input. Put some music on at a decent level. How much music do you hear coming out the right speaker? How much is that barely audible signal (if at all) going to change anything.
 

Mihalis

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This all goes against intuition. Stereo signal separates right and left in a way that confuses us nd we think we hear real space. My xtc filter doesn’t want the two mixed up. So why is channel sepration enough at 50 or even less db? If we had zero would we not be listening to mono? I appreciate my intuition is not maybe correct here (I have read correlations aren’t high in sense of imaging and Low crosstalk, but surely mixing up signals and differently at different hz must have effect?
 

Blumlein 88

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This all goes against intuition. Stereo signal separates right and left in a way that confuses us nd we think we hear real space. My xtc filter doesn’t want the two mixed up. So why is channel sepration enough at 50 or even less db? If we had zero would we not be listening to mono? I appreciate my intuition is not maybe correct here (I have read correlations aren’t high in sense of imaging and Low crosstalk, but surely mixing up signals and differently at different hz must have effect?
Because you won't hear a difference past about 18 db channel separation and 118 db of channel separation. That is how our hearing works. Has a lot to do with how much blending an off axis source has between one ear and the other. Our hearing makes use of timing at lower frequencies, and intensity at higher frequencies with a mix of the two in between. 25 db is plenty of channel separation for perception of stereo.
 

abm0

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Unplug the source right input. Put some music on at a decent level. How much music do you hear coming out the right speaker? How much is that barely audible signal (if at all) going to change anything.
Sounds like a sloppy test I would expect to hear recommended by subjectivists. Even for THD+N the most lenient threshold considered acceptable by most people who evaluate audio gear based on science and measurements is -85 dB. It's completely ridiculous to me that there are still people on here expecting to be taken seriously claiming that bleeding of opposite-channel information should have no discernible effect even up to levels higher by several orders of magnitude.

If you like subjectivist arguments, I'll give you my subjective experience from the Verum 1 when used with the stock vs. a quality 4-wire cable, where the crosstalk owed purely to the cable structure goes from -20 to -40 dB, and was effortlessly detectable and made me never want to use the "tunnel-like" sounding Y-shaped cable ever again. So from my experience, any "no-worries" threshold has to be at least -40 dB, quite some doublings closer to the NwAvGuy recommendation of -60 dB (and mind you, that's a whole-system number as opposed to my estimated -40 which is just from the voltage divider formed by the amp Z-out + connectors + cable + headphone driver).

And then with subjectivist arguments there's always the issue of taste as well: some people may simply not care as much as I do about how far from center the sounds go when listened to with this setup or that setup, as long as they go "far enough" to be considered stereo. I'm reminded of the fact that Garuspik purposely designed the Verum 1 to sound as much "like speakers" as possible - well unless the way he was A/B-ing to determine that involved putting his head right between 2 speakers firing directly at eachother, he was probably looking for not-a-lot of separation, maybe +30 & -30 degrees in front of the head. Myself, I would find that pathetic if that was all that a headphone-terminated system was able to do for me.
 

Dimitri

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Even for THD+N the most lenient threshold considered acceptable by most people who evaluate audio gear based on science and measurements is -85 dB. It's completely ridiculous to me that there are still people on here expecting to be taken seriously claiming that bleeding of opposite-channel information should have no discernible effect even up to levels higher by several orders of magnitude.
Give some thought to how much separation is present in the source material in the first place; then it will not be as "ridicilous".
 

Blumlein 88

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You can still download these files and try for yourself. Notice several responders saying they couldn't hear past 20 db vs better separation.


Or maybe look at the reel to reel machines. I don't think I've seen one claiming more than 50 db separation. Most are 40 to 45 db. And I'm referring to things like a Studer A800, or Ampex ATR 100 or 102. Some of the best machines made, and used by big recording studios.
 

abm0

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Give some thought to how much separation is present in the source material in the first place; then it will not be as "ridicilous".
Since electronic music exists that is under no obligation to reproduce or simulate instruments as if playing in a physical space, captured with 2 microphones, leading to inherent crosstalk etc. etc., there is always an expectation that arbitrary numbers of samples per track could be 100% L-R separated, and a good reproduction system should maintain that to the very limit of human capabilities to detect.

You can still download these files and try for yourself. Notice several responders saying they couldn't hear past 20 db vs better separation.
I could, just out of curiosity, but notice also the limits of what that experiment can prove, according to the author themselves:
with this song at least, any unit providing 30dB channel separation, or more, should suffice, for me
No better than doing my own test with my own song, with a real-world (not synthetic) cable-change based alteration. And I detected differences that tell me -20 dB is far from sufficient, for me. But it's true that I only compared vs. -40 dB, since I only had the cables I had, and the difference I was hearing could have been realized anywhere in between. So it's not impossible that I have the same true threshold as the above author, that -30(?) dB happens to be enough for me as well, and that I was actually getting no extra benefit going from there to -40.

I imagine it would take a lot of work to set up a test to really clarify this - I would need to see what the frequency envelope of real-world crosstalk tends to be, if by any chance it isn't flat, then I'd have to set up some way to apply crosstalk with that envelope to as many songs from my collection as I wanted, while also being able to tweak the amount of crosstalk from, say, -20 to -50 dB. And then listen and compare and listen and compare 'til I'm blue in the face. :) Doesn't seem to be worth it, since all the gear I currently own is keeping me comfortably far away from -20 dB crosstalk, and if I ever think of getting any other ridiculously low-impedance headphones (or fall prey to the virus of IEMs) I will just take care to put them on a 4-wire SE cable at least (or better yet balanced), and that should have me covered. (Balanced is everywhere these days, so I don't expect a significant cost penalty for my insistence on having at most -40 dB crosstalk.)
 

Dimitri

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Since electronic music exists that is under no obligation to reproduce or simulate instruments as if playing in a physical space, captured with 2 microphones, leading to inherent crosstalk etc. etc., there is always an expectation that arbitrary numbers of samples per track could be 100% L-R separated, and a good reproduction system should maintain that to the very limit of human capabilities to detect.
sure, minus that pesky "human capabilities to detect".
I'm pretty sure when I cover my left ear the left channel doesn't "go away" "100%" .
 

Cbdb2

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Since electronic music exists that is under no obligation to reproduce or simulate instruments as if playing in a physical space, captured with 2 microphones, leading to inherent crosstalk etc. etc., there is always an expectation that arbitrary numbers of samples per track could be 100% L-R separated, and a good reproduction system should maintain that to the very limit of human capabilities to detect.


I could, just out of curiosity, but notice also the limits of what that experiment can prove, according to the author themselves:

No better than doing my own test with my own song, with a real-world (not synthetic) cable-change based alteration. And I detected differences that tell me -20 dB is far from sufficient, for me. But it's true that I only compared vs. -40 dB, since I only had the cables I had, and the difference I was hearing could have been realized anywhere in between. So it's not impossible that I have the same true threshold as the above author, that -30(?) dB happens to be enough for me as well, and that I was actually getting no extra benefit going from there to -40.

I imagine it would take a lot of work to set up a test to really clarify this - I would need to see what the frequency envelope of real-world crosstalk tends to be, if by any chance it isn't flat, then I'd have to set up some way to apply crosstalk with that envelope to as many songs from my collection as I wanted, while also being able to tweak the amount of crosstalk from, say, -20 to -50 dB. And then listen and compare and listen and compare 'til I'm blue in the face. :) Doesn't seem to be worth it, since all the gear I currently own is keeping me comfortably far away from -20 dB crosstalk, and if I ever think of getting any other ridiculously low-impedance headphones (or fall prey to the virus of IEMs) I will just take care to put them on a 4-wire SE cable at least (or better yet balanced), and that should have me covered. (Balanced is everywhere these days, so I don't expect a significant cost penalty for my insistence on having at most -40 dB crosstalk.)
So where in modern equipment is the crosstalk worst than -40db? This is a non issue.
 

SIY

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I could, just out of curiosity, but
...won't bother and continue to assert dubious stuff for which I have no evidence."

The experiment is there, the work has already been done. Don't make excuses.
 

abm0

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So where in modern equipment is the crosstalk worst than -40db? This is a non issue.
It's like I'm just talking to myself here. Didn't I just link you to the example of the Verum 1? With the stock cable those have crosstalk at -20 dB due to their very low impedance drivers, high impedance wires (1.8 ohm round-trip) and long common return wire. The voltage divider that forms there creates comical amounts of crosstalk.

The experiment is there, the work has already been done.
Correct. My experiment, which is as subjectivity influenced and as conclusive as his, possibly more because my alteration wasn't synthetic. The work has been done and I have my conclusion, which I can oppose to anyone else's subjectivity influenced conclusion from their test of "that one arbitrary special song I happened to choose that day". Talking about that test like it's God's Standard for Separation, brought down to us on stone tablets from the mountain, is quite funny to see in a science-focused forum.
 
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SIY

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My experiment, which is as subjectivity influenced and as conclusive as his
That's delusional, to put it mildly. As is your claim absent any evidence. Try using your ears and not peeking. It's easy to make two files of whatever music you like, add crosstalk to one, then ABX them. Do it. Or not, and remain the guy claiming he can levitate 20 feet in the air, but you'll just have to take my word for it.
 
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