On 10 April 2018 at 16:49, jack reynolds <jackreynolds...@gmail.com> wrote:
Fernando - is your A2B matrix for the octathingy first order?
On 04/10/2018 08:54 AM, jack reynolds wrote:
I've just noticed the second order function in A2B_matrix.m!
There is some preliminary 2nd order support in the current git (WXYZUV).
I have quite a bit more that I have not checked in yet (bad programmer,
I should do that more often!). Currently it derives WXYZSTUV, but of
course that depends on having calibration measurements above and below
the horizontal plane. A 1st order mic, because of its symmetry, can be
calibrated with just horizontal plane measurements (much easier).
The current code is similar to what the 1st order calibration does, that
is, it assumes coincident capsules and derives a static A to B matrix in
a frequency range where the microphone array is well behaved, and then
creates FIR filters for each component that try to compensate for the
spacing of the capsules (same as Gerzon did a long time ago).
I actually should go back to my original approach (more complicated) for
1st order, which was to derive a 4x4 matrix of filters (which would be
8x8 for the 2nd order mic). The whole calibration software method needs
a new/better approach, I think, this is hack I thought would not work at
all :-)
In any case I'm working on the calibration for my second prototype. I
really need a better calibration rig so that more stuff can be
automated... I did a run on Friday but I did not notice the recorded
levels were too low, stuff that happens when you are in a hurry...
-- Fernando
On 10 April 2018 at 06:37, Fernando Lopez-Lezcano <
na...@ccrma.stanford.edu> wrote:
On 04/09/2018 01:49 PM, Augustine Leudar wrote:
My guess would be the AD converters are not great - DA converters are
generally flat as a pankake these days but AD converters are not always
on
cheaper stuff. I tried it with various different microphones and was
never
happy - several other sI know found the same. Of course they dont have
phantom power either ...
But the internal capsules do have phantom power! Which can lead to SpHEAR
Franken-Microphones like the one in the attached picture[*] :-) That was
the first prototype, works fine (too bad the H2N does not store four
channel recordings in "native" format, makes things more difficult). One
hole on one the side and the right connectors and you are in (and a lot of
work, mind you). I have yet to finish assembling the second. Only so many
hours in a day (24, last time I checked, too few).
-- Fernando
[*] part of the SpHEAR project:
https://cm-gitlab.stanford.edu/ambisonics/SpHEAR/
On 9 April 2018 at 21:43, David Pickett <d...@fugato.com> wrote:
At 22:36 09-04-18, Augustine Leudar wrote:
PS thats with the onboard capsules though - the AD converter is a mini
jack
in and terrible quality.....
Why is this? It is counter-intuitive. I mean, the actual input level and
impedance may be non-standard and need some accommodation, but having
taken
care of that, why should the quality be worse than using the microphione
mounted on the side?
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