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Old 7th November 2011, 11:46 PM   #11
Elias is offline Elias  Finland
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Quote:
Originally Posted by weltersys View Post
Elias,
What is "parameter x", and how is "parameter x" varied between 0 and 1 ?
A wiring diagram would be helpful for others to do the recommended experimenting ...
The x is a gain factor, x = 0 means no signal (for given input) and x = 1 means signal is passed unmodified.

If x is to be made continously variable, it may be best done using active circuit or controller for example Behringer DCX or similar.

However, x = 0.5 can be done passively !
This schematic allows comparison between x = 0 (Stereolith) and x = 0.5 (vector steering) by a single switch ! (x = 0 means switch is closed)

Click the image to open in full size.


Using the switch while listening is enlightening !


- Elias
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Dipole Bass vs Monopole Bass Stereophonic Sound from a Single Loudspeaker 3 Speaker Linear Stereo Matrix Wavelets
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Old 8th November 2011, 12:06 AM   #12
optic is offline optic  New Zealand
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Hi Elias,

Something more complex for ya... Works well for me. Slight variation to yours is i angled the left / right speakers about 30deg forward.... Not sure if this matters as i did this from the start without to much thought.

Below is my simple version.

My enhanced version splits s0,s1 into above 5k and below 5k frequency ranges with a 6db per octave hp/lp. Different degree setting to angle (35.26) below 5k and angle (54.74) above 5k. It also delays OutCC.

Simple Version......

s0 = left input
s1 = right input
width = 0.5 to 1
degree = 35.26 * 0.017453; 1st number is angle.


OutL = (0.5*sin(degree))*(s0+s1)+0.5*width*(s0-s1);
OutR = (0.5*sin(degree))*(s0+s1)-0.5*width*(s0-s1);
OutCC = (0.70710678*cos(degree))*(s0+s1);

I do this in dsp.... You can do this with opamps etc... Just dont know how

btw the above keeps equal power to all 3 speakers (Very close to it) i.e L + R = L + C + R

Cheers

Optic
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Old 8th November 2011, 12:39 AM   #13
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This is somewhat like a stereo microphone with sum and difference processing. You can use it to vary the pattern and send left and right energy off in their respective directions to varying degrees. The question is whether energy to the left and energy to the right is effective stereo. Perhaps with left and right reflecting surfaces it might be. Without reflections to create a physical separation I don't think it is.

Look up the Jensen precedents. They had a sum and difference system in a single cabinet.

David S.
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Old 8th November 2011, 05:43 AM   #14
CLS is offline CLS  Taiwan
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That looks familiar.
Making 3 front channels out of stereo signal


The 'only' difference is I use it on 3 separate DML panels. I may (soon) try it on a single panel, as the descriptions mentioned in the thread of Bessel array:
The Bessel Array

Last edited by CLS; 8th November 2011 at 05:49 AM.
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Old 8th November 2011, 07:27 AM   #15
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Quote:
Originally Posted by speaker dave View Post
This is somewhat like a stereo microphone with sum and difference processing. You can use it to vary the pattern and send left and right energy off in their respective directions to varying degrees. The question is whether energy to the left and energy to the right is effective stereo. Perhaps with left and right reflecting surfaces it might be. Without reflections to create a physical separation I don't think it is.

Look up the Jensen precedents. They had a sum and difference system in a single cabinet.

David S.
Yes, reflectors to the left and the right are crucial, so is the level (and angle) of the resulting reflections.
I've sketched a prototype with larger full range drivers for L and R some time ago but haven't had the time to actually build it.
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Old 8th November 2011, 10:12 AM   #16
Elias is offline Elias  Finland
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Quote:
Originally Posted by optic View Post
Hi Elias,

Something more complex for ya... Works well for me. Slight variation to yours is i angled the left / right speakers about 30deg forward.... Not sure if this matters as i did this from the start without to much thought.

Below is my simple version.

My enhanced version splits s0,s1 into above 5k and below 5k frequency ranges with a 6db per octave hp/lp. Different degree setting to angle (35.26) below 5k and angle (54.74) above 5k. It also delays OutCC.

Simple Version......

s0 = left input
s1 = right input
width = 0.5 to 1
degree = 35.26 * 0.017453; 1st number is angle.


OutL = (0.5*sin(degree))*(s0+s1)+0.5*width*(s0-s1);
OutR = (0.5*sin(degree))*(s0+s1)-0.5*width*(s0-s1);
OutCC = (0.70710678*cos(degree))*(s0+s1);

I do this in dsp.... You can do this with opamps etc... Just dont know how

btw the above keeps equal power to all 3 speakers (Very close to it) i.e L + R = L + C + R

Cheers

Optic

Those coefficients have so many decimals it must be based on academic research Any references ? Gerzon ?

So your three speakers, are they integrated as one, or spread in front in conventional triangle ?


- Elias
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Dipole Bass vs Monopole Bass Stereophonic Sound from a Single Loudspeaker 3 Speaker Linear Stereo Matrix Wavelets
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Old 8th November 2011, 10:18 AM   #17
Elias is offline Elias  Finland
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Quote:
Originally Posted by speaker dave View Post
The question is whether energy to the left and energy to the right is effective stereo. Perhaps with left and right reflecting surfaces it might be. Without reflections to create a physical separation I don't think it is.

Sure, this kind of speaker must operate in harmony with the room ! It will not work in anechoic conditions. Also it may not work in arena or large auditorium, the side reflections may be too weak.

However normal living rooms have what it takes for this to work, relatively close side walls ! In my 25 m2 room it works very well ! This is a living room speaker


- Elias
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Dipole Bass vs Monopole Bass Stereophonic Sound from a Single Loudspeaker 3 Speaker Linear Stereo Matrix Wavelets
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Old 8th November 2011, 11:43 AM   #18
graaf is offline graaf  Poland
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have You considered/measured the effect of the back wave of one speaker superimposed on the output of other two speakers and of the output of each speaker diffracting around the box?
for me it looks like that for frequencies below about 700<1000 Hz the output from each of the speakers is equally all around just with little relative SPL differences plus small time delays
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Old 8th November 2011, 11:53 AM   #19
Elias is offline Elias  Finland
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Quote:
Originally Posted by CLS View Post
Yeah ! Now all you need to do is integrate your speakers as a single entity !


Quote:
Originally Posted by CLS View Post
...
on a single panel, as the descriptions mentioned in the thread of Bessel array:
The Bessel Array
http://www.angelfire.com/sd/paulkemble/soundf.html
Click the image to open in full size.

This is a same principle ! Elements B and D form a dipole for the difference signal, and elements A, C and E form a monopole for the sum signal. However, the reason for having three elements for the monopole is not immediately obvious, maybe it's just a forced fit into Bessel array format(?).


- Elias
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Liberate yourself from the illusion of two speaker stereo triangle
Dipole Bass vs Monopole Bass Stereophonic Sound from a Single Loudspeaker 3 Speaker Linear Stereo Matrix Wavelets
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Old 8th November 2011, 12:14 PM   #20
graaf is offline graaf  Poland
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Quote:
Originally Posted by Elias View Post
This is a same principle ! Elements B and D form a dipole for the difference signal, and elements A, C and E form a monopole for the sum signal.
yes, looks the same
Click the image to open in full size.

the wheel reinvented once again?

Quote:
Originally Posted by Elias View Post
However, the reason for having three elements for the monopole is not immediately obvious, maybe it's just a forced fit into Bessel array format(?).
- Elias
it can be made purely by wiring this way, without even any passive filtering
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