I've simulated the diffuse field response for the Velan design using the A-to-B matrix I gave earlier. The analysis and graph are at
http://www.ai.sri.com/ajh/ambisonics/velan_sim_dfr.html Note that in practice these simulations are only a starting point for EQ. Real capsules deviate significantly from the idealized math models used here. In addition, the capsules shadow each other and the space in the middle acts as a resonant cavity. So you really have to measure the finished array and then design the EQ. -- Aaron Heller (hel...@ai.sri.com) Menlo Park, CA US On Sun, May 27, 2012 at 7:38 PM, umashankar mantravadi <umasha...@hotmail.com> wrote: > > dear aaron thank you umashankar > > i have published my poems. read (or buy) at http://stores.lulu.com/umashankar > > Date: Sat, 26 May 2012 14:09:28 -0700 >> From: hel...@ai.sri.com >> To: sursound@music.vt.edu >> Subject: Re: [Sursound] microphone epiphany ? >> >> One set of gains that works is >> >> 0.2357 0.2357 0.2357 0.2357 0.2357 0.2357 >> 1.0000 -1.0000 0.0000 0.0000 0.0000 0.0000 >> 0.0000 0.0000 1.0000 -1.0000 0.0000 0.0000 >> 0 0 0 0 1.0000 -1.0000 >> >> I put a write up on how to derive those at: >> >> http://www.ai.sri.com/ajh/ambisonics/umashankar_velan.html >> >> -- >> Aaron (hel...@ai.sri.com) >> Menlo Park, CA US >> >> >> On Sat, May 26, 2012 at 12:41 PM, umashankar mantravadi >> <umasha...@hotmail.com> wrote: >> > >> > assuming all six capsules have same gain, and all are contributing to W, >> > how much should be the attenuation? umashankar >> > >> > i have published my poems. read (or buy) at >> > http://stores.lulu.com/umashankar >> > > Date: Sat, 26 May 2012 18:25:04 +0200 >> >> From: netti...@stackingdwarves.net >> >> To: sursound@music.vt.edu >> >> Subject: Re: [Sursound] microphone epiphany ? >> >> >> >> On 05/26/2012 04:51 PM, Augustine Leudar wrote: >> >> >> Hi Michael, >> >> >> thanks for the reply - there is no doubt Ive missed something ! >> >> >> I am aware of the need for W coordinate and have included it in my >> >> >> encoder >> >> >> as instructed although I have to admit I am still not clear on its >> >> >> function - but my question specifically relates to the information >> >> >> gained >> >> >> from the 3 fig of eight patterns gained form a mic design such as this >> >> >> one : >> >> >> >> >> >> http://www.shapeways.com/model/143678/velan-140-internals.html >> >> >> >> >> >> Am I right in thinking the W component gives you enhanced distance >> >> >> information for a given sound source ? >> >> >> >> we cannot hear absolute phase, so if you are listening to a figure of >> >> eight microphone, there is no way to tell whether the sound you're >> >> hearing was coming into the (positive) frontal lobe or the (inverted) >> >> rear lobe. hence, the only information we can get from a lonely fig8 is >> >> "it's obviously not coming from the side". >> >> >> >> now if you add an omni to the equation, all of a sudden you have the >> >> possibilty to discern between the two lobes of the fig8: one is in-phase >> >> with the omni, the other isn't. >> >> >> >> thus, the 0th order component helps you resolve the ambiguities of all >> >> the 1st order signals. >> >> >> >> btw, if you move to second order, the situation is the same: with a >> >> cloverleaf directivity, you only know "it's either coming from >> >> front-or-back, or from left-or-right". only with the first-order >> >> information, the ambiguity can be resolved. >> >> >> >> W also has a subtle role in distance coding, but its main job is really >> >> to help us make sense of the fig8s. >> >> >> >> >> >> to wrap up, three real fig8s won't ever give you ambisonics. but if you >> >> obtain the fig8s by subtracting two back-to-back cardioids, you can also >> >> add them, which then gives you a nice omnidirectional component. note >> >> that you will have to attenuate the resulting omni signal according to >> >> the number of capsules you used. >> >> >> >> >> >> best, >> >> >> >> >> >> jörn >> >> >> >> >> >> >> >> -- >> >> Jörn Nettingsmeier >> >> Lortzingstr. 11, 45128 Essen, Tel. +49 177 7937487 >> >> >> >> Meister für Veranstaltungstechnik (Bühne/Studio) >> >> Tonmeister VDT >> >> >> >> http://stackingdwarves.net >> >> >> >> _______________________________________________ >> >> Sursound mailing list >> >> Sursound@music.vt.edu >> >> https://mail.music.vt.edu/mailman/listinfo/sursound >> > >> > -------------- next part -------------- >> > An HTML attachment was scrubbed... >> > URL: >> > <https://mail.music.vt.edu/mailman/private/sursound/attachments/20120527/db077b8f/attachment.html> >> > _______________________________________________ >> > Sursound mailing list >> > Sursound@music.vt.edu >> > https://mail.music.vt.edu/mailman/listinfo/sursound >> _______________________________________________ >> Sursound mailing list >> Sursound@music.vt.edu >> https://mail.music.vt.edu/mailman/listinfo/sursound > > -------------- next part -------------- > An HTML attachment was scrubbed... > URL: > <https://mail.music.vt.edu/mailman/private/sursound/attachments/20120528/a87d2ddb/attachment.html> > _______________________________________________ > Sursound mailing list > Sursound@music.vt.edu > https://mail.music.vt.edu/mailman/listinfo/sursound _______________________________________________ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
