[acs236]

I don't know if this is in the right forum, so if a mod wants to move it, I won't be insulted. I may, however, hold a subconcious grudge that could later manifest itself in a flurry of unending rage.

So... What is the desired level of crossfeed -- how much is needed to "fix" the unnatural sound of headphones?

I have tried a couple different crossfeeds - (1) on the Airhead, (2) Cmoy Hansen from JMT, and (3) a modified Linkwitz courtesy of Tangent. All of them have been fairly settle, to my ears, in the blending of the two channels.

When I listen to my speakers in stereo, the amount my right ear can hear the left channel (and left ear can hear the right) seems to be much much more substantial than any crossfeed I have tried.

I assume that those who have developed crossfeed have some reason for designing crossfeeds at the levels of the ones I have tried (see above). My questio is: What's the theory behind it?

 

[acs236]

Someone should have an opinion on this.

 

[slindeman]

Quote:

So... What is the desired level of crossfeed -- how much is needed to "fix" the unnatural sound of headphones?

I don't believe that headphones need to be fixed that much. You can do a lot with your own mind to imagine a real soundstage with headphones. Besides, I've heard expensive speakers setup in reference rooms and I didn't find them to sound like a live performance either, so I'm not too concerned if my headphones don't have a soundstage like speakers.

My goal with crossfeed is not necessarily to reproduce the sound of speakers so much as to reduce the annoyance when listening to those recordings that have instruments solely in one channel. I've also noticed that how much this bothers me depends on the headphones. HD600 seems to really benefit from crossfeed, whereas my Stax headphones don't seem to need it at all. I've heard the Headroom crossfeed, the Meier, and the Linkwitz; of those I prefer the Linkwitz.

 

[PinkFloyd]

Hi acs236
That's a kind of hard question to answer as you really cannot define crossfeed on a scale of 1 - 10. The "desired" level of crossfeed should, ideally, not interfere with the sound quality at all but should "present" the music realistically.

When you listen to speakers your left ear can hear the music from the right speaker and your right ear can hear the music from the left speaker (try playing music through only the left speaker and you'll notice that you can hear it through both ears).

With headphones this is totally different. If you listen to only the left channel through your headphones only your left ear will hear the sound, if listening to only the right channel then only your right ear can hear the sound.

This is totally unnatural as we are accustomed to hearing natural sounds through both ears and listening to music through headphones leads to fatigue as your mind can't focus on the artificial presentation of the music and it spends it's time trying to figure out what goes where.

Crossfeed basically feeds a small part of one channel to the other, and vice versa which presents your ears with the small amount of natural time delay that they are used to hearing in everyday life. Just think of it this way, if you were mean't to only hear a person in your right ear when he / she was speaking to you from the right then our ears would have been designed that way.

listening to headphones portrays an unnatural sound presentation, next time when somebody is talking into your right ear stick a cork in your left ear and you'll see exactly what I mean.
Sorry if this is not a complex enough answer but I've had a real bitch of a week, I hope it gives you the general idea though.

 

[john_jcb]

I have found that the degree of crossfeed is recording Dependant as well. For instance some of the early rock recordings sound completely unnatural as they bounce back and forth between the left and right channel. Jan Meier's new crossfeed box lets you select from 3 levels when the crossfeed is engaged as well as adjustments for the input and headphone impedance.

 

[wordsworth]

acs236

Not sure if this is of any help but on headwize Xin (designer of the supermini amp) talks about his crossfeed (XinFeed) and what levels he uses and what he considers too strong.

http://headwize2.powerpill.org/ubb/s...=4106&fdays=20

Wordsworth

 

[acs236]

Thanks for the info guys. This thread was motivated by my thought that, in order to approximate the way we hear naturally, the channel-mixing/crossfeed should be greater than most crossfeeds on amps provide.

Does anyone disagree that the typical crossfeeds on amps do not approximate this level? Would more crossfeed be better?

Or is this even the correct goal?

I'd be interested in getting Tyll's opinion on this.

 

[slindeman]

Quote:

Does anyone disagree that the typical crossfeeds on amps do not approximate this level? Would more crossfeed be better?

I don't think more would be better. I think the higher crossfeed levels make the sound much worse, not better. The reason is that simple crossfeed is not enough to create a true soundstage, so cranking up the amount of crossfeed does nothing but destroy instrument separation, air, and with some types of crossfeed, frequency response. Something like Dolby Headphone or even the Sennheiser DSP Pro does a much better job of recreating a real soundstage, and those involve more than simple delay, attenuation, and mixing of signals. Crossfeed has never fooled me into thinking there was a real soundstage in front of me as the DSP pro has done. Of course the DSP does many bad things to the signal, but in the faking of a real soundstage it does much better than crossfeed does.

The benefit of a good crossfeed to me is the reduced fatigue for the recordings and headphones which benefit from it, with as minimal impact to the signal as possible. I have many recordings which sound essentially identical with or without crossfeed, and others which benefit greatly. I wouldn't have a crossfeed in my system that couldn't easily be bypassed with a switch or knob. And as I said before, the Stax's seem much less plagued by the problem than some other headphones.

 

[PinkFloyd]

Quote:

Originally posted by slindeman I don't think more would be better. I think the higher crossfeed levels make the sound much worse, not better. The reason is that simple crossfeed is not enough to create a true soundstage, so cranking up the amount of crossfeed does nothing but destroy instrument separation, air, and with some types of crossfeed, frequency response. Something like Dolby Headphone or even the Sennheiser DSP Pro does a much better job of recreating a real soundstage, and those involve more than simple delay, attenuation, and mixing of signals. Crossfeed has never fooled me into thinking there was a real soundstage in front of me as the DSP pro has done. Of course the DSP does many bad things to the signal, but in the faking of a real soundstage it does much better than crossfeed does. The benefit of a good crossfeed to me is the reduced fatigue for the recordings and headphones which benefit from it, with as minimal impact to the signal as possible. I have many recordings which sound essentially identical with or without crossfeed, and others which benefit greatly. I wouldn't have a crossfeed in my system that couldn't easily be bypassed with a switch or knob. And as I said before, the Stax's seem much less plagued by the problem than some other headphones.

Keep it subtle, keep it simple is the principle I adopt.

 

[edstrelow]

If crossfeed works for you, fine, but I am always amazed at the rationale sometimes stated for crossfeed that speaker sound is more natural than headpones. Rather, speakers unnaturally create "phantom channels" which muddy the sound.

Think of it this way, if you are in a room of real musicians playing, as far as your ears are concerned, there are two signals, one to the right ear and one to the left. This is also what two microphones will pick up. When you listen to the resulting recording from these mics through phones you will hear two channels, pretty much as if you had been there yourself (ignoring such factors as channel separation and time differences between the mikes which may not match the time delays between your ears.)

However, if the sound recorded by the mics is played through two speakers, you now have 4 channels of music, not two, because the left speaker now feeds both the left and right ear and similarly for the right speaker. The left speaker to right ear and right speaker to left ear are termed phantom channels, they are slightly delayed in time compared to the real left and right signals and they have no correspondance with what is recorded.

Some time back, Polk made speakers designed to supress the phantoms and I have happily had a pair for almost 20 years now. And, guess what? They sound more like headphones.

I had a crossfeed circuit in a preamp some years ago and almost never used it, after all, why reduce channel separation that the engineers have worked so hard to achieve. I guess if I had a lot of music with unbalanced stereo images, or sounds wholely on the left or right I might feel a need for some means of re-mixing the sound by crossfeed.

However I agree that spatial virtualizers, e.g Dolby Headphone, etc. are worthwhile, at least with movies. I nearly always use a Sennheisser 360 with my portable dvd player, although I would have to say, that basic stereo still sounds pretty good, at least through my Stax SR003's.

 

[john_jcb]

One of the problems you have when evaluating crossfeed is that the changes are fairly subtle I think in large part due to the work your brain does in processing the sound. Keep the level low and the effect is more natural and relaxing. Increase the crossfeed and the brain needs to work harder to process the information hence the fatigue starts to increase. All my opinion not based on any scientific evidence.

 

[acs236]

edstrelo --

I understand what you're saying in the situation that you describe -- recording live musicians with two microphones. In that case cross-feed would be undesirable. This sounds close to a binaural recording. However, much music is not recorded this way. In the process of studio recording, recording engineers, products, whoever, can do some strange things with the sound, as I'm sure you're well aware.

For example, there might be a segment of a song where the guitaro only comes out of the left channel. When listening to speakers, this is not a problem because both ears can hear the sound coming from the left channel. With headphones, obviously the right ear cannot hear the left channel at all. With recordings such as this, crossfeed makes sense. That being said, it would seem to me that the level of crossfeed provided by most amps w/ crossfeed is far less than what the ear would hear from a speaker set-up in this situation.

 

[slindeman]

Quote:

That being said, it would seem to me that the level of crossfeed provided by most amps w/ crossfeed is far less than what the ear would hear from a speaker set-up in this situation.

True, but more crossfeed does not make headphones sound more like speakers -- at least not with the two adjustable crossfeeds I've experimented with, the meier and linkwitz. To make headphones sound more like speakers requires a virtualizer like the DSP pro or Dolby headphone offers. And as edstrelow has so well stated, do we want our headphones to sound like speakers? Not usually, I suppose, unless we listen mainly to music that has been mixed specifically for speakers.

All I want is for my headphones to capture the essence of the original performance (if there was one). In addition to that, I want them to be less fatiguing. If crossfeed helps me achieve those two goals with a recording/headphone combination I'll use it, if not I won't.