Crosstalk Cancellation?

Crosstalk cancellation was invented by Atal and Schroeder at Bell Labs. It was invented to allow binaural recordings (those made with mics in the ears and intended for headphones) to play back over speakers. With headphones each driver talks to each ear separately. With speakers, however, each speaker talks to both ears and destroys the desired effect of the binaural recording.

Crosstalk cancellation methods take a little of the left signal and feed it to the right speaker with the right delay (and phase) to have it combine with the actual right speaker signal and cancel the part that goes to the left ear. Similarly for the other side. However... cancellation depends greatly on the position of the head. A few cm movement destroys the conditions for cancellation and artifacts start to kick in.

It's basically why all these so-called 3d audio systems don't work for more than one person. And even for that one listener, they only work if they don't move their head at all.

As far as measurements are concerned, if you have the two speakers connected to each other with this crossfeed cable then you are asking for trouble. When MultEQ measures the left speaker there is signal coming out of the right speaker as well with some phase change and delay. As you move the mic around these differences will vary and the result will be measurements that are corrupted by these artifacts. Not recommended...

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17 Comments

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    Robert Charron

    Hi Chris,

    Audyssey with 2-channel stereo is not imaging at all properly!!! The vocals are coming from way far to the left and to the right, nothing in between those two speakers!!! What's going on? If I disengage Aydyssey, my imaging is perfect. I need help big time please?

    Robert

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    Robert Charron

    I think that I just discovered a major flaw, and today is a very sad day indeed.

    Because you simply cannot take two Auddyssey measurement (one for two-channel stereo music and the other one for multichannel separately); and that the one that is taken with all your speakers active from an Onkyo/Integra pre/pro or receiver made in 2007, simply cannot correct the anomalies that are totally unacceptable in two-channel stereo music listening with Audyssey engaged! We have been made by many people from this industry and it is very and deeply sad. Shame on many of them for havong preach benefits that were NOT.

    Chris, I'm simply asking you as a man and honestly if you can speak from your heart and not like a businessman. Am I right or wrong about this major flaw?

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    Robert Charron

    Seems to me that you do help a lot of people, but is it good enough?

    How come we are still kept in the darkness? Is is the way we really want to live our life in our planet?

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    Chris Kyriakakis

    Hi Robert,

    There is no need to take separate measurements for 2-ch stereo and multichannel.  MultEQ corrects the acoustical problems of each speaker individually.  It doesn't care how many speakers are connected.  It simply measures the performance of each one and then creates a filter to undo the problems it finds.

    One reason for the imaging problems could be the placement of the microphone.  The first mic position has to be in the center of the listening area because that is where the distances and levels are calculated from.  The measurement pattern after that first position can be found here.

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    Robert Charron

    It was done very professionally Chris, very methodically.

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    Chris Kyriakakis

    What kind of front L and R speakers do you have?

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    Robert Charron

    I've been following you for years and know a lot about Audyssey.

    But it is only recently that I discovered this, and if you'll be at my place you'd be in total deception. My mic positions were all taken prcisely, in particular the very first one.

    What can I do? Start all over again?

    I am talking with few people at this moment and another fellow have the same ecact problem from is Onkyo PR-SC885P pre/pro; imaging that is totally lost in 2-ch stereo music listening with Audyssey engaged (both from the digital and analog connections).

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    Chris Kyriakakis

    Hi Robert, we are not deceiving anyone.  Thousands of people are enjoying there 2-ch systems with Audyssey.  If there is a problem with imaging then it must have to do with something that happened in the measurements.  What model # are your front speakers?

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    Robert Charron

    They are Image Concept 200, made in 1987-88. Very hard to find any info, but they are good.

    You just gave me a great idea though, I can try with some other inferior speakers just to hear.

    But then Chris, those actualo speakers (concept 200) they imaged superbly without Audyssey engaged. Are you saying that Audyssey is powerful enough to decipher their most secret deficiencies? I would tend to beliebe you, but I'm doing also my own investigation by asking other people to verify that, and taking into account from which product having Audyssey.

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    Chris Kyriakakis

    Yes, those are good speakers.  I don't think they have secret deficiencies.  However, consider this:What you are hearing as "imaging" with Audyssey off may not be correct.  This happened to us recently when visiting a music mixing studio.  The mixer's first reaction was: "the imaging is better with Audyssey off".  But, after listening for about 1 hour he had a revelation.  With Audyssey off everything was more mono and collapsed to the center.  That was giving him a false impression that this is better imaging.  Once he started playing all different types of music he started to realize that the instruments were better spread out and more clearly placed in the soundstage.  

    Audyssey creates filters that match the speakers to each other much better.  This is one of the most important perceptual cues that help with imaging.  So, I would urge you to listen to some content for a while and not just judge what is in the very center.  Listen to the presentation of the instruments and voices and see if you can hear them placed on the stage more accurately.  They should cover a wider area than just a narrow spot in the middle.

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    Robert Charron

    Man! Now it's my speakers that I love that are wrong, but it can happen, I believe that. They work just so lovely without Audyssey (stereo).

    Just need to buy other speakers that Audyssey like that's all!

    Again Chris, Image Concept 200, made in Canada by API, and designed by Ian Paisly in 1987.

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    Chris Kyriakakis

    I don't think it's the speakers.  Please read my note above.

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    Robert Charron

    Lol Chris, were taliking Diana Krall all over the place here. With Audyssey she's way out there to the left and way out there to the right!

    Without Audyssey she's right there in front of you where she belongs and the other members of her band are right there where they belong too, to the right and to the left; my soundtage is simply fabulous.

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    Robert Charron

    I am quite surprised by that extension of the soundstage, it just don't gel right at all. You are inviting me with new notions from 45 years (me) of listening to good music (I'm also a musician; guitars, flutes, harmonicas...).

    I feel quite happy with Movies (no problem there to the contrary, great bass with much improvement). The problem is with stereo, the vocals are no longer centered, they are lost behind the curtains, and I know for a fact that it ain't what was originally recorded.

     

    P.S. How come the typing on your blog is so small, I'm just making a bunch more of typos lol.

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    Chris Kyriakakis

    OK. I am just trying to cover all possibilities.  This is not an issue that we have seen in any of our tests over the past 8 years...

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    Robert Charron

    This is from an onkyo 886, and my neibor friend has an onkyo 805 with the same issue with his evergy veritas 2.8 speakers!

    And another member from an audio site also have this same issue with his 885 pre/pro!

    I am investigating further...

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    Robert Charron

    Chris, let's leave it here for now (we are both busy), and when I found some more I will let you know right here. Meanwhile do the same and enjoy your day.

    Cheers,

    Robert

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