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Old 18th November 2011, 09:46 AM   #121
sbe4kdr is offline sbe4kdr  Belgium
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3 channel audio player.

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Old 18th November 2011, 12:29 PM   #122
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Another observation: the presentation becomes very spacious and high frequency sounds span from side wall to side wall when the center driver is switched off or a thick absorber in front of the speaker blocks direct high frequencies.

Here's the ETC (left channel):

Click the image to open in full size.
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Old 18th November 2011, 12:58 PM   #123
Elias is offline Elias  Finland
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Quote:
Originally Posted by markus76 View Post
Left channel goes to the left firing driver, right channel to the right driver and L+R is routed to the front driver.
...
The front firing driver is high passed at 1.6kHz
This signalling scheme seems to be similar with Stereolith.


But the problem as:

Quote:
Originally Posted by markus76 View Post
The image is very centered with most sounds localized at the speaker. Only certain sounds become spacious.

Is partly solved by:

Quote:
Originally Posted by markus76 View Post
the presentation becomes very spacious and high frequency sounds span from side wall to side wall when ... a thick absorber in front of the speaker blocks direct high frequencies.

You have reinvented the pillow trick !


- Elias
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Old 18th November 2011, 12:58 PM   #124
Rudolf is offline Rudolf  Germany
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Quote:
Originally Posted by markus76 View Post
Another observation: the presentation becomes very spacious and high frequency sounds span from side wall to side wall when the center driver is switched off or a thick absorber in front of the speaker blocks direct high frequencies.

Here's the ETC (left channel):

Click the image to open in full size.
10 dB more for 10 ms later - isn't this almost what "Trading" would suggest:

Click the image to open in full size.
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Old 18th November 2011, 01:45 PM   #125
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Quote:
Originally Posted by Elias View Post
You have reinvented the pillow trick !


- Elias
No re-invention just a confirmation of what we had found weeks ago. Obviously precedence is very strong for high frequency localization cues. The problem with a single stereo speaker is that center sounds fall apart into two or more components: lower frequencies coming from the center and delayed high frequency parts from the side reflections.

Could you post the impulse responses of your matrixed speaker? I'm wondering what the ETC looks like.
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Old 18th November 2011, 02:07 PM   #126
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10 dB more for 10 ms later - isn't this almost what "Trading" would suggest:
That's probably the short and simple truth. Strong reflections simply act as virtual loudspeakers. No other magic involved.
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Old 18th November 2011, 04:23 PM   #127
ScottG is offline ScottG  United States
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Quote:
Originally Posted by markus76 View Post
That's probably the short and simple truth. Strong reflections simply act as virtual loudspeakers. No other magic involved.
The reflection is different than a loudspeaker - or at least than a normal speaker (..unless the loudspeaker itself is extremely directive - like 5 degrees). (..it is after all a multiplicity of reflections spread over a much larger area.)

Also, you have to overcome the listener's dominance to the direct sound - simply a "strong" reflection(s) is generally not going to be enough.


Still, I'd agree that it conforms to a short and simple truth.


You can also make a design that goes the "other way".

Diffusivity/expansion/envelopment can also be accomplished by the angle vs. freq. (..where the angle relates to the listener's head). In other words you can move higher freq. reproduction further apart so that it's moving closer to the listener's 90 degree positions. Of course we aren't talking about a single-box solution at that point.
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Old 18th November 2011, 04:37 PM   #128
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Elias, how do you perceive my high pass filtered noise examples with your box?

http://dl.dropbox.com/u/21936387/pin...ation_test.zip
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Old 18th November 2011, 06:40 PM   #129
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Also, you have to overcome the listener's dominance to the direct sound - simply a "strong" reflection(s) is generally not going to be enough.
Well, 10dB is strong More side firing drivers might help. Something like this with a lower number of direct firing tweeters:

Click the image to open in full size.
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Old 18th November 2011, 08:18 PM   #130
Elias is offline Elias  Finland
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First directivity measurements !

I measured impulse responses of the SSS x = 0.5 to the angles shown here at 1 m distance using omni mic. Left and right side angles must be treated separately because the whole principle of the SSS is based on vector steered directional pattern and is different for left and right sides and it depends on the stereo signal panning.

Click the image to open in full size.


These measurements are done for hard Left side stereo panning i.e. L = 1 and R = 0. According to the theory of SSS operation, in this case left side signal should be higher than direct signal and right side signal.

In the following wavelet plots time t = 0 is the arrival of the impulse.


Here is Bark wavelet spektrogram at 0 degrees angle:
Click the image to open in full size.


Here is Bark wavelet spektrogram at 45 degrees angle Right:
Click the image to open in full size.


Here is Bark wavelet spektrogram at 45 degrees angle Left:
Click the image to open in full size.


And here is the frequency responses derived from the above wavelet plots at the time t = 0:

blue = 0 deg
green = 45 deg Left
red = 45 deg Right

Click the image to open in full size.


Heureka ! It is seen that directivity can be steered over the full audio spectrum

This is the new revolution of home audio reproduction !


- Elias
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