That is nearly 2 year old info, I found when reading one of the links.
I suspect there have been some Zylia product developement up to now.
Possibly also on the USB interface implementation.
If the MEMS noise level is acceptable and the stated MEMS advantages - long
term stability and very low difference between individual samples of MEMS
elements that they may have made an exellent choise of mic elements for a
ambisonic array.
But Listening to recording samples and mesurements will show the resulting
implementation quality, MEMS seems to be Electret microphones implemented
with a semiconductor process.
I found this very interesting, at least some MEMS have mechanical membrance
resonances at around 15 kHz. Older mems implentations referenced here
https://nepp.nasa.gov/docuploads/3832EB0E-2297-4CF5-B58AC8FC54DF9705/Seattle%20Presentation.ppt
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4032405/
MEMS can be constructed using optical readout of data, then getting below
23dBA self noise - Electrostatic MEMS have appearently higher values, I
have not found how much.... And dont know what MEMS Zylia uses.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4032405/
This indicate that SNR values around 64 to 65 dBA might be typical of a
conventional MEMS microphone.
https://www.ama-science.org/proceedings/getFile/ZwZ2Zt==
Here is aRECENT summer 2017 press release from Infineon about their 2017
MEMS mic elements. Seems there is a difference.
I am not a Mic designer so I do not know what a 70dB SNR ratio means in the
real world for performance.
https://www.infineon.com/cms/en/about-infineon/press/market-news/2017/INFPMM201707-064.html
extract below:
Current MEMS microphone technology uses a sound wave actuated membrane and
a static backplate.
Infineon’s dual backplate MEMS technology uses a membrane embedded within
two backplates thus generating a truly differential signal.
This allows improved high frequency immunity for better audio signal
processing and increases the acoustic overload point of 10 percent Total
Harmonic Distortion (THD) to 135 dB SPL.
The SNR of 70 dB is an improvement of 6 dB compared to a conventional MEMS
microphone.
This improvement is equivalent to doubling the distance from which a user
can give a voice command that is captured by the microphone.
Additionally, the analog and digital microphones have excellent
microphone-to-microphone matching (±1 dB sensitivity matching and ± 2°
phase matching) which is ideal for implementing in arrays.
Bo-Erik: I dont think this will be good enough for not having matched
elements in production if only a single standard A to B conversion is used?
Showing how to mount MEMS microphones for best performance!
https://www.infineon.com/dgdl/Infineon-AN557_MEMS_microphone_mechanical_and_acoustical_implementation-AN-v01_01-EN.pdf?fileId=5546d4626102d35a01612d1e3bf96add
Any comments for further speculation welcome :-)
Bo-Erik
2018-08-16 23:03 GMT+02:00 Wim <***@gmail.com>:
> I seem to remember the Zylia uses Primo electret capsules. And this post on
> the Prorecording list seems to confirm it:
> https://www.tapatalk.com/groups/prorecordingworkshop/
> zylia-microphone-t19409070.html
>
> And this AES publication confirms at least the electret part:
> http://www.aes.org/e-lib/browse.cfm?elib=17902
> "Zamojski, Jakub Affiliation: Zylia sp. z o.o ... a spherical microphone
> based on inexpensive electret capsules"
>
>
> Op do 16 aug. 2018 om 20:33 schreef Stefan Schreiber <
> ***@mail.telepac.pt
> >:
>
> > I don’t believe at all that they (Zylia) are using MEMS clusters...
> >
> > Otherwise very interesting thoughts in the cited mail below...
> >
> > I also believe that noise of different capsules doesn’t add up (so I
> > agree with Bo-Erik, at least at first sight), but we can’t get below
> > the noise floor of a single capsule. MEMS type or not...
> >
> > Typical specifications (High performance MEMS audio sensor):
> >
> > https://www.st.com/resource/en/datasheet/mp23ab01dh.pdf
> >
> > (SNR: 65dB)
> >
> > I personally would be very interested in a PRO version of the Zylia
> > ZM-1 microphone, especially since even the current version seems to be
> > (quite? very?) nice. According to various personal reports....
> >
> > Best regards
> >
> > Stefan
> >
> > - - - -
> >
> > Citando Bo-Erik Sandholm <***@gmail.com>:
> >
> > > I agree with Len, we have not seen any technical spec of self noise
> level
> > >
> > > of the MEMS (clusters?) that are used in Zylia.
> > >
> > >
> > >
> > > Only text saying that in normal musical recording situations self
> noise
> > is
> > >
> > > not disturbing :-).
> > >
> > >
> > >
> > > I have a personal theory that self noise of physical elements in an
> > >
> > > ambisonic mic array is not directly additive.
> > >
> > > The basis for my theory is that as we convert to B-format the noise
> from
> > >
> > > all the physical elements are distributed over a spherical surface,
> > >
> > > and the noise level for a virtual microphone in decoding do not have
> the
> > >
> > > full sum of the added microphone noise levels.
> > >
> > > Only coherent noise within the take up volume of the virtual
> microphone
> > is
> > >
> > > relevant in that directional microphones response.
> > >
> > >
> > >
> > > But I am can be totally wrong in this mental visualization of the
> > decoding
> > >
> > > process. I have not done any mathematical research of this...
> > >
> > >
> > >
> > > Bo-Erik Sandholm
> > >
> > > Stockholm
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