Bo-Erik Sandholm wrote:
http://www.williamsonic.com/DipoleMic/ as often I am too fast to post :-)
I found the article again on a practical differential microphone for DIY.
Regards
Bo-Erik
And we should not forget to point to some "intro" article, right? ;-)
http://audioxpress.com/files/williamson3063.pdf
Anyway, the Halliday array for (2D) Ambisonics has already been here.
Does it really help to simulate fig.-of-8 capsules/resonses via pairs of
omnidirectional capsules?
For a horizontal array we could use just 4 microphones :-)
vs.
"Since the components of first-order Ambisonics correspond to physical
microphone pickup patterns, it is entirely practical to record B-format
directly, with a collection of coincident microphones: an
omnidirectional capsule, one forward-facing and one left-facing
figure-of-eight, yielding the W, X and Y components"
"The primary difficulty inherent in this approach is that high-frequency
localisation and clarity relies on the diaphragms approaching true
coincidence. By stacking the capsules vertically, perfect coincidence
for horizontal sources is obtained. However, sound from above or below
will suffer from subtle comb filtering effects in the highest frequencies."
(Source: https://en.wikipedia.org/wiki/Ambisonics#Native_B-format_arrays)
I don't believe that anything of this relates to the microphone built
into the OZO camera...
Best,
Stefan
2015-12-04 20:46 GMT+01:00 Bo-Erik Sandholm <bosses...@gmail.com>:
I came to think about a software written by Angelo Farina a long time ago
http://pcfarina.eng.unipr.it/Public/B-format/Software/Crux7toBform.exe
this is for 7 omni mics, one in the center on a cross created by x y z
direction placed omni mic pairs placed the same distance from the center
element.
I once saw a working design to create a figure 8 mic by using 2 omni
electret elements side by side in the end of 2 ,
the priciple of Differential Microphone Arrays is described for example
here here https://www.spsc.tugraz.at/sites/default/files/Main.pdf
It should be workable to create a figure 8 mic signal by taking the
differential signal from 2 omni mics, the optimal operation frequency range
for this ofcource depends on the distance between the microphones.
the central omni mic can possibly be replaced by the sum of all the
mirophones?
I once speculated that it should be possible to modify this mic setup to
work withouth the 7th microphone in the center as this is a central omni -
maybe this signal can be created from the sum of all the others?
For a horizontal array we could use just 4 microphones :-)
I also had the idea that one could create a better working mic by using
several omni mics with different distances from the center to optimize the
responce for a number of frequenzy bands.
I do not know how relewant or workable this is but I think it might be a
workable solution if we can produce a software for this.
Any reflection on this? apperently it has alredy been done,,,
http://lcav.epfl.ch/research/topics/gradient_based_sndfield_acquisition.html
https://www.google.se/search?q=differential+microphone+array&biw=1192&bih=463&tbm=isch&tbo=u&source=univ&sa=X&ved=0ahUKEwj-ipr_-MLJAhVDJHIKHeJGA6kQsAQIUg#imgrc=LCpYmEPkSqx8-M%3A
Best Regards Bo-Erik
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