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Old 10th December 2011, 05:41 PM   #201
Elias is offline Elias  Finland
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SSS x = 0.5 Gerzonic psychoacoustic filter.

There was a question regarding the function of the filter:
Click the image to open in full size.

I found suitable values for Csp = 4.7uF and Rsp = 4.7 ohm with Visaton FRS8 elements. Other elements may require different values.

The filter has two purposes:
1) To steer the high frequency energy from the center element to the side elements. This help preventing localisation of the speaker.
2) To steer the high frequency energy from the non panned side to the panned side. This helps creating stronger side signal from the 'correct' side.


In the following plots is demonstrated the response curves of each individual elements (idealised).

For a center panned signal i.e. L = 0.7 and R = 0.7 the element responses are: (note: curves for Lo and Ro coincide). It is seen that center element signal Co is low pass shelved, and side element signals Lo and Ro are high pass shelved.
Click the image to open in full size.


For a hard left panned signal i.e. L = 1 and R = 0 the element responses are here: (note: now the curves for Co and Ro coincide). Now center element signal Co and right element signal is low pass shelved, and left element signal Lo is high pass shelved.
Click the image to open in full size.


The simulation schema as FYI: I'm using APLAC, the best engineering tool ever
Click the image to open in full size.


- Elias
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Old 11th December 2011, 01:04 AM   #202
CLS is offline CLS  Taiwan
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Quote:
Originally Posted by Elias View Post
...

I want to see DIY BWL, with a proven measurements achieving the claimed 'decorrelation' !
...
Pity, no measurement to prove anything.

The character of chaotic vibration on large area (break-up all the time) makes it difficult or nearly impossible to make proper and meaningful measurements by ordinary methods. Many have tried and reported the very poor connection with hearing in person. I'm not any better than they are in this regard so I don't bother trying.

But OTOH, we have ears and brains. The combination is the ultimate target to fool anyway. Er, I mean, to persuade.
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Old 11th December 2011, 10:05 AM   #203
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OK, if we want to measure "naturalness" of principal left/right and center
phantoms, why not simply measure anechoic FR at some defined positions
(listening in median plane vs. offset) with mono signal:

Full left panning, full right panning, centered.

Maybe a somewhat downsized stereo triangle
(and closer listening position) would be advantageous to
keep the room out above above say 300...500 Hz ?

So if we could agree on some configuration, we would have comparable
results in measuring "alternative" stereo setups.
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Last edited by LineArray; 11th December 2011 at 10:07 AM.
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Old 11th December 2011, 12:18 PM   #204
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Quote:
Originally Posted by Elias View Post

...
I want to see DIY BWL, with a proven measurements achieving the claimed 'decorrelation' !
...

- Elias
These raw phase plots (ungated) are from measurements i took about 2 years ago.

3 very different speakers in the same room, mic distance about 1m+ , but positions
of speakers are NOT the same, though comparable (no close side walls,
>1m distance from front wall ...)

"bwl" is an early "ancestor" of current "Model 2" bending wave loudspeaker
"d8" is "dipol08" line array
"rib" is a bookshelf speaker on a stand, having an isodynamic ("ribbon like") tweeter with XO somewhat below 1Khz

The upper cuttof of that early BWL was about 8Khz, so the phase plot is truncated
at the upper end when compared to the other speakers.

The bwl shows an increasing phase decorrelation >1Khz. The other speakers do not show this
behaviour consequently when looking at >2Khz.

Of course here we have all mixed up: Phase decorrelation from the speaker itself plus room effects,
also arising from different directivity of the speakers.

Nevertheless the isodynamic tweeter of the bookshelf speaker is very wide radiating in the horizontal
plane, because its membrane is only about 10mm wide X 120mm in height, no waveguide or protruding
edges on the baffle ... In comparison Dipol 08 is the most directional design of the three.

Subjective descriprion due to imageing and "disappearance":

The bookshelf speaker disappears with appropriate recordings, in the way any
good bookshelf speaker does it ... but with critical material (bad recordings e.g.)
it is localizeable as a sound source.

Dipol 08 is less localizeable, but with some recordings that have deficient spatial
cues you can't deny there are two "speaker clouds", which remind you sitting in
front of a loudspeaker, especially if you have speakers for comparison which are
"better" due to that respect:

The bending wave speaker (about 0.5 sqm planar design) disappears very well,
produces more depth in soundstage which depends on the recording and less on how
close you sit to the speakers. It has believable and stable center images even when
listening offset to the median plane. And no, it does not have that smeared
imaging that comes with many bending wave designs. Phase is comparably or even more
stable than in the 2 other designs below 1Khz, as you may notice.

The bwl is simply the most accurate or at least "believable" speaker of that 3 especially
regarding imaging.

But can you localize the tweeters ?
Which tweeters ... they are not there, you cannot even localize them
sharply with hard panned test clicks. Which is why i can imagine, you would like it too.
Attached Images
File Type: jpg bwl_phase_raw.JPG (181.6 KB, 149 views)
File Type: jpg d8_phase_raw.JPG (167.5 KB, 14 views)
File Type: jpg rib_phase_raw.JPG (165.3 KB, 15 views)
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Last edited by LineArray; 11th December 2011 at 12:47 PM.
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Old 11th December 2011, 12:52 PM   #205
Elias is offline Elias  Finland
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Quote:
Originally Posted by LineArray View Post
OK, if we want to measure "naturalness" of principal left/right and center
phantoms, why not simply measure anechoic FR at some defined positions
(listening in median plane vs. offset) with mono signal:

Full left panning, full right panning, centered.

Maybe a somewhat downsized stereo triangle
(and closer listening position) would be advantageous to
keep the room out above above say 300...500 Hz ?

So if we could agree on some configuration, we would have comparable
results in measuring "alternative" stereo setups.

The principle of the SSS is to work in harmony with the listening room ! It does not work as intended without side wall reflections. How I should prove naturalness of the phantoms in anechoic conditions ?


- 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 11th December 2011, 12:54 PM   #206
Elias is offline Elias  Finland
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Quote:
Originally Posted by LineArray View Post
The bwl shows an increasing phase decorrelation >1Khz.

Is it able to reproduce an arbitrary high frequency waveform, or just an energy envelope with some time-freq resolution ?


- 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 11th December 2011, 12:57 PM   #207
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Sorry, posted the bookshelves phase twice ...

now i have got them right: bwl, dipol 08, bookshelf
Attached Images
File Type: jpg bwl_phase_raw.JPG (181.6 KB, 14 views)
File Type: jpg d8_phase_raw.JPG (177.9 KB, 8 views)
File Type: jpg rib_phase_raw.JPG (165.3 KB, 7 views)
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www.dipol-audio.de

Last edited by LineArray; 11th December 2011 at 01:01 PM.
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Old 11th December 2011, 01:06 PM   #208
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Quote:
Originally Posted by Elias View Post
The principle of the SSS is to work in harmony with the listening room ! It does not work as intended without side wall reflections. How I should prove naturalness of the phantoms in anechoic conditions ?


- Elias
Yes i know, sorry that would only work comparing "triangular stereophonic"
configurations. What would you suggest ?
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Old 11th December 2011, 01:27 PM   #209
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Quote:
Originally Posted by Elias View Post
Is it able to reproduce an arbitrary high frequency waveform, or just an energy envelope with some time-freq resolution ?


- Elias

Pics below are not current "state of the art" and naturally a step response
e.g. looks a bit different depending on angle, but it produces waveforms
quite well.

In the current model i already approached that ringing around 5Khz and it
also has "fullrange response" to the upper end now.

It will take some weeks until there are new measurements, as i am
building a new listening room right now before christmas.
Attached Images
File Type: jpg Proto_IV_FR_02.JPG (263.3 KB, 12 views)
File Type: jpg Proto_IV_STEP_FR.JPG (19.8 KB, 14 views)
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Old 11th December 2011, 01:37 PM   #210
Elias is offline Elias  Finland
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Quote:
Originally Posted by CLS View Post
ps. I'm going to try SSS on a sigle panel.
Brave decision

Which drivers would you be using ?


- Elias
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