Hi everyone,
On this page you have some information regarding the capsules (and frequency response), DSP, and the currently available software applications (ZYLIA Studio, Studio Pro and ambisonics converter). http://www.zylia.co/white-paper.html <http://www.zylia.co/white-paper.html> ______ Eduardo > On Aug 17, 2018, at 5:14 AM, umashankar manthravadi <umasha...@hotmail.com> > wrote: > > zyla is made of mems. We are now getting low noise and high sensitivity mems, > but they are still omni. > > Omni mounted on the surface of a sphere has some directional characteristics. > Later today I am going to measure a single mems loaded with a 16 mm square > horn (mouth flush on a 40 mm sphere) to see what kind of directivity pattern > I will get. > > umashankar > ________________________________ > From: Sursound <sursound-boun...@music.vt.edu > <mailto:sursound-boun...@music.vt.edu>> on behalf of Fernando Lopez-Lezcano > <na...@ccrma.stanford.edu <mailto:na...@ccrma.stanford.edu>> > Sent: Friday, August 17, 2018 12:05 AM > To: Surround Sound discussion group; Len Moskowitz > Cc: Justin Bennett > Subject: Re: [Sursound] Looking for mic advice (Zylia) > > On 08/16/2018 10:22 AM, Bo-Erik Sandholm wrote: >> 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. > > I think the noise we are talking about is that of the difference > microphones. In an open array built with cardioids that would be for > order 2 or higher, in a rigid sphere array with omnidirectional capsules > that would be for order 1 or higher. > > Those components drop in level at low frequencies at a rate of n x > 6dB/octave (starting at high frequencies). For the second order > components of a microphone made of cardioids n = 1 (6dB/oct), add > 6dB/oct per order increase for higher orders. > > As the component drops in amplitude towards the low frequencies you need > a filter that compensates for the drop, and of course it amplifies the > sef-noise of the capsules as well. At some point you have to give up or > the noise becomes a problem (where exactly depends on the self-noise of > the capsules and what kind of materials you are recording). > > In the second order microphones I'm building for the SpHEAR project I > can use the second order components down to about 400-500Hz ("unity > gain" for them is at around 9KHz). Even then the noise is objectionable > (but not necessarily "disturbing" :-) for recordings that have wide > dynamic range (my encoder uses an expander on those components to try to > minimize that effect). You can definitely hear the noise if there is a > silence in the recording. Of course it disappears if you mute the second > order components :-) > > A third order microphone (made of cardioids - I don't think there is > one) would be worse, the drop would be 12dB/oct for the third order > components. So you would have to limit the low end of the frequency > response at a higher frequency. > > AFAIK nobody specifies the noise specs for _those_ components in an > Ambisonics microphone. In a first order microphone made of cardioids > that is not a problem, as is the case for the first order components of > a second order microphone made of cardioids. > > (as a reference, the open source octofile software released for the > OctoMic shows that their calibration has three choices for the low > frequency cut off for the second order components, 500Hz, 900Hz and > 1.5KHz). > > -- Fernando > > _______________________________________________ > Sursound mailing list > Sursound@music.vt.edu > https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fmail.music.vt.edu%2Fmailman%2Flistinfo%2Fsursound&data=02%7C01%7C%7C880a958762324ad22ac808d603a71cca%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C636700413605498803&sdata=XyLmjx2mOOdApTO%2FBIrFR0Mzo%2FYnFvCW4Pes6Do7U3w%3D&reserved=0 > > <https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fmail.music.vt.edu%2Fmailman%2Flistinfo%2Fsursound&data=02%7C01%7C%7C880a958762324ad22ac808d603a71cca%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C636700413605498803&sdata=XyLmjx2mOOdApTO%2FBIrFR0Mzo%2FYnFvCW4Pes6Do7U3w%3D&reserved=0> > - unsubscribe here, edit account or options, view archives and so on. > -------------- next part -------------- > An HTML attachment was scrubbed... > URL: > <https://mail.music.vt.edu/mailman/private/sursound/attachments/20180817/2db3da37/attachment.html > > <https://mail.music.vt.edu/mailman/private/sursound/attachments/20180817/2db3da37/attachment.html>> > _______________________________________________ > Sursound mailing list > Sursound@music.vt.edu <mailto:Sursound@music.vt.edu> > https://mail.music.vt.edu/mailman/listinfo/sursound > <https://mail.music.vt.edu/mailman/listinfo/sursound> - unsubscribe here, > edit account or options, view archives and so on. -------------- next part -------------- An HTML attachment was scrubbed... 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