Channel level vs Channel distance - AVS Forum
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post #1 of 9 Old 12-23-2013, 06:10 AM - Thread Starter
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Hi,

I just needed to solve a problem that kind of got me thinking i don't understand something and since its about audio theory this is the place to ask. Over the last few weeks i was bothered by my soundstage pulling to one side. Voices that should be in the middle clearly moved about 50cm. To 'pull' it to the middle i had to add 4dB to one of the main channels. This bothered me since i had a channel go bad on me last year (slowly loosing volume, turned out to be a digital card) so i debugged it. Gave it mono signal to confirm, flipped channels on the poweramp (the sides flipped) so i knew it was not my input signal and/or my speakers. Long story short turns out my pre/pro keeps distances in pure-direct mode and has a special menu for it. In here the distance was wrong by 15cm (6"). Fixing that made the sound image move back to the middle.

Clearly my setup and ears are more sensitive to the delay (must be small) of sound hitting my ears than the volume. Adding 4dB/5dB ( that a lot ) solved the problem too but once i removed 6" from the distance i could remove the 4dB/5dB and the image stayed locked in the middle.

Can someone confirm/explain how this works, are ears much more sensitive to the sound arrival than volume ? and is there a good guideline for this. I was kinda shocked about the differences a few " makes (no jokes please smile.gif ).

Happy i revolved my problem but want to know more.

System used :

pre-pro : denon avp a1hd-ci-3d
poweramp : denon poa (bridged into the fronts).
speakers : B&W 802d2 (in triangle toe-in).

Daniel.

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post #2 of 9 Old 12-23-2013, 06:34 AM
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Originally Posted by danielo View Post

Can someone confirm/explain how this works, are ears much more sensitive to the sound arrival than volume ? and is there a good guideline for this. I was kinda shocked about the differences a few " makes (no jokes please smile.gif ).

I don't know about more sensitive, but our ears/brains are very sensitive to the time domain in the process of hearing. There is a very important evolutionary reason for this, as a little thought can demonstrate. Your sensitivity to minute differences in the arrival of sound varying by mere inches is what allows you to locate objects emitting sound waves in three-dimensional space.

If you were hunting for a meal and lying in wait for your prey, you would rely not only on your eyes, but also your ears for the sound of prey approaching. The slight delay you can detect unconsciously between when the sound the prey makes arrives at your left ear versus your right allows you to pinpoint where the sound is coming from. You turn your head towards the sound and look to verify its location. We humans are very good at this sort of location by time delay.

The sound image being off-center is a side effect of our ability to locate objects by observing that time delay.
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post #3 of 9 Old 12-23-2013, 06:44 AM - Thread Starter
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Originally Posted by Will2007 View Post

I don't know about more sensitive, but our ears/brains are very sensitive to the time domain in the process of hearing. There is a very important evolutionary reason for this, as a little thought can demonstrate. Your sensitivity to minute differences in the arrival of sound varying by mere inches is what allows you to locate objects emitting sound waves in three-dimensional space.

If you were hunting for a meal and lying in wait for your prey, you would rely not only on your eyes, but also your ears for the sound of prey approaching. The slight delay you can detect unconsciously between when the sound the prey makes arrives at your left ear versus your right allows you to pinpoint where the sound is coming from. You turn your head towards the sound and look to verify its location. We humans are very good at this sort of location by time delay.

The sound image being off-center is a side effect of our ability to locate objects by observing that time delay.

I guess that makes perfect sense, i still wonder what the relation is between level and delay. Also its kind of weird that evolution made it easer for us to pick up the direction of higher freq. vs lower freq. Seems to me that bears, lions and other stuff to avoid growl in a low pitch smile.gif. But i guess we use the higher freq to detect movement in your logic.

Hope to find more on this but your thought experiment makes perfect sense to me, This had me freaked out until i found the special menu for settings in 2 channel mode smile.gif. I almost started moving speakers and objects in the room smile.gif.

On the positive side if singers attack me now at least i can detect where they are coming from again smile.gif

Daniel.

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post #4 of 9 Old 12-23-2013, 07:56 AM
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Quote:
Originally Posted by Will2007 View Post

Quote:
Originally Posted by danielo View Post

Can someone confirm/explain how this works, are ears much more sensitive to the sound arrival than volume ? and is there a good guideline for this. I was kinda shocked about the differences a few " makes (no jokes please smile.gif ).

I don't know about more sensitive, but our ears/brains are very sensitive to the time domain in the process of hearing. There is a very important evolutionary reason for this, as a little thought can demonstrate. Your sensitivity to minute differences in the arrival of sound varying by mere inches is what allows you to locate objects emitting sound waves in three-dimensional space.

If you were hunting for a meal and lying in wait for your prey, you would rely not only on your eyes, but also your ears for the sound of prey approaching. The slight delay you can detect unconsciously between when the sound the prey makes arrives at your left ear versus your right allows you to pinpoint where the sound is coming from. You turn your head towards the sound and look to verify its location. We humans are very good at this sort of location by time delay.

The sound image being off-center is a side effect of our ability to locate objects by observing that time delay.

In fact we have at least three different listening experiences that give strong directional cues. Yes, time delays matter, but hearing the effects of azimuth positions and changes is not about just time.

(1) Time delay matters-the arrival time of the sound at each ear changes with azimuth.

(2) Intensity matters - off-axis sounds fall on each ear differently, giving additional azimuth cues.

(3) The shape of our heads further modify the intensity and timbre of sounds as they vary in azimuth.

Most sensations are not dependent on how our senses respond via just one path for sensing.

For example, put an ear plug in one ear, shut your eyes and have someone move around you while they are talking. You will still sense direction, even though 2 out of the 3 items above is null and you are receiving no visual cues.

Furthermore, both absolute azimuth and changes and azimuth are sensed separately. Generally, we are more sensitive to changes in azimuth than absolute azimuth.
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post #5 of 9 Old 12-23-2013, 10:48 AM
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Thanks for your excellent explanation, Arny.
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post #6 of 9 Old 12-23-2013, 11:09 AM
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Quote:
Originally Posted by danielo View Post

Hi,

I just needed to solve a problem that kind of got me thinking i don't understand something and since its about audio theory this is the place to ask. Over the last few weeks i was bothered by my soundstage pulling to one side. Voices that should be in the middle clearly moved about 50cm. To 'pull' it to the middle i had to add 4dB to one of the main channels. This bothered me since i had a channel go bad on me last year (slowly loosing volume, turned out to be a digital card) so i debugged it. Gave it mono signal to confirm, flipped channels on the poweramp (the sides flipped) so i knew it was not my input signal and/or my speakers. Long story short turns out my pre/pro keeps distances in pure-direct mode and has a special menu for it. In here the distance was wrong by 15cm (6"). Fixing that made the sound image move back to the middle.

Clearly my setup and ears are more sensitive to the delay (must be small) of sound hitting my ears than the volume. Adding 4dB/5dB ( that a lot ) solved the problem too but once i removed 6" from the distance i could remove the 4dB/5dB and the image stayed locked in the middle.

Can someone confirm/explain how this works, are ears much more sensitive to the sound arrival than volume ? and is there a good guideline for this. I was kinda shocked about the differences a few " makes (no jokes please smile.gif ).

Happy i revolved my problem but want to know more.

System used :

pre-pro : denon avp a1hd-ci-3d
poweramp : denon poa (bridged into the fronts).
speakers : B&W 802d2 (in triangle toe-in).

Daniel.
Do a search for Haas Effect or Precedence Effect.

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Perfection is not attainable, but if we chase perfection we can catch excellence."

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post #7 of 9 Old 12-23-2013, 11:22 AM - Thread Starter
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Hi,

Thanks for the feedback guys, i party posted because i was happy to find my problem but the extra info i can read is always fun. Maybe i was just shocked how so little change in the distance setting had such a clear effect.

back from reading : I am still a little confused, if my calc is correct the 15cm (6") only accounts for a delay of 0,5ms. It seems the Haas effect talks about 2ms or more are we saying that below that sounds don't get smeared into into one but it still effects the direction ? I like Will's explain in that i makes sense that we should have a system that is able to detect small delays in nature smile.gif I guess its a more complex system but we do agree i guess that having a 6" mistake in setup if detectable and in fact very distracting.

Daniel.

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post #8 of 9 Old 12-23-2013, 02:36 PM
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I have found the distance settings to be extremely crucial. This is why I prefer using AVRs instead of old analog 2ch preamps. Sure, in an ideal world with an old analog 2ch preamp you would want to make sure both speakers were the exact same distance away from you. (within 5mm difference)

Throw more speakers into the mix and trying to accommodate all of that in a functioning family lounge with the TV and everything and you can see the necessity for speaker distance settings on AVRs. The first AVRs came out with distance settings of near, medium, far. The next generation came with distance settings in steps of .5 of a metre. Then they came out with adjustments in 100mm increments. The latest Yamahas now come with 50mm adjustment steps and Denons can be adjusted in 10mm steps.

All of this has a very large influence on how a surround sound musical experience will sound as well. I can fully understand some people trying music in surround sound in the earlier days of AVRs and not having a very good experience with it.
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post #9 of 9 Old 12-23-2013, 04:05 PM - Thread Starter
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Originally Posted by kiwi2 View Post

I have found the distance settings to be extremely crucial. This is why I prefer using AVRs instead of old analog 2ch preamps. Sure, in an ideal world with an old analog 2ch preamp you would want to make sure both speakers were the exact same distance away from you. (within 5mm difference)

Throw more speakers into the mix and trying to accommodate all of that in a functioning family lounge with the TV and everything and you can see the necessity for speaker distance settings on AVRs. The first AVRs came out with distance settings of near, medium, far. The next generation came with distance settings in steps of .5 of a metre. Then they came out with adjustments in 100mm increments. The latest Yamahas now come with 50mm adjustment steps and Denons can be adjusted in 10mm steps.

All of this has a very large influence on how a surround sound musical experience will sound as well. I can fully understand some people trying music in surround sound in the earlier days of AVRs and not having a very good experience with it.

Thde denon avp is a pre-pro and allows me to set the distances within a 10mm range. I don't know if you know the avp but it has a lot of options so i missed that they have a special menu for just direct/pure-direct mode distances. Not sure why that is since its not like your 2 front speakers move when entering this mode. My guess it might have todo with them turning parts of the digital boards off in this mode but allowing like you stated to be able to time-align the speakers using a second circuit (if that makes sense). I am happy they build it in but if the settings somehow get confused its not easy to find.. its been bothering me for weeks until i excluded all other problems.

Daniel.

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