Re: [Sursound] Soundfield-type mics: inverting or not?
Le 11-10-07 17:40, Sampo Syreeni a �crit : On 2011-09-30, Daniel Courville wrote: I think we should try to establish some sort of official database of what SoundField (and TetraMic) models are polarity inverting at the B-Format output. In that case we first need a datal model. Based on what you're talking about in below, it has one relation. The key is canonical mic name, and its dependent attributes are inverting and stereo. Some of the values are unknown, which suggests a bit of further normalization. Hum... I not sure I understand. What I'm suggesting is a simple database (a CSV file would be fine, even a Web page) where we have, per mic model, whether it's inverting or not at the B-Format output and at the stereo output. For A-Format mic (TetraMic, SPS200), it would be at the output of the software used to make A to B conversion. OK, to answer that one: for TetraProc: -it allows inversion, or not, at the user's choice (it actually allows it on a per channel (per mic capsule) basis -it also allows ... to complicate your task ... 'Endfire' (that is with the mic's 'top' pointed towards the soundstage, rather than the classic mic in a vertical position: with 'endfire' the 'handle' and the cabling point horizontally away from the soundstage). A word of caution though: If my memory is correct then TetraMic phantom power converters (or some of them) invert, before the signal reaches any software (see previous post). Am I saying the same thing as you (but with different words)? Maybe I should have said a list? Mmm a database seems 'a sledgehammer to crack a nut' ... but equally too many projects are not designed to allow for growth. In this case, though, a webpage might be the best start, as there do seem so many potential 'footnotes'/caveats that make the data set rather unclean. Michael - Daniel ___ 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
Re: [Sursound] Soundfield-type mics: inverting or not?
On Sun, Oct 09, 2011 at 08:24:02AM -, Michael Chapman wrote: for TetraProc: -it allows inversion, or not, at the user's choice (it actually allows it on a per channel (per mic capsule) basis -it also allows ... to complicate your task ... 'Endfire' Not really exact. Tetraproc allows to invert any combination of X,Y,Z and the Endifire options which swaps X and Z and inverts one of them. All of these operate on the B-format signals. There are no UI controls to invert the capsule signals. It can be done of course by editing the A-B matrix. Ciao, -- FA ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] Soundfield-type mics: inverting or not?
On Sun, Oct 09, 2011 at 08:24:02AM -, Michael Chapman wrote: for TetraProc: -it allows inversion, or not, at the user's choice (it actually allows it on a per channel (per mic capsule) basis -it also allows ... to complicate your task ... 'Endfire' Not really exact. Tetraproc allows to invert any combination of X,Y,Z and the Endifire options which swaps X and Z and inverts one of them. All of these operate on the B-format signals. There are no UI controls to invert the capsule signals. It can be done of course by editing the A-B matrix. Not exact at all ;-( I'd just got out of bed ... a poor excuse. Thanks the correction, Fons. Michael ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] Soundfield-type mics: inverting or not?
Hi folks, A wet Sunday morning and I haven't been up that long (only on first cup of coffee) so I hope this will make sense! Surely all that is actually needed, at least as far as B format is concerned, is whether the W signal goes positive for a pressure increase? Everything else is given by the B format definition wrt this. Of course, it would still be useful to know about other things (such as those given in the earlier messages below) but not essential. That said, knowing about the mic only really helps if you also know the polarity of the whole signal chain. If you want the information about this to persist, the only (near) reliable approach is to record an acoustic test signal at the start of each recording. Does anyone know, of the top of their heads, if a film set type clapper board reliably provides a positive going leading edge to it's impulse? I can't see it not, but I'd prefer that to be confirmed by repeatable experiments. Dave On Oct 9 2011, Michael Chapman wrote: On Sun, Oct 09, 2011 at 08:24:02AM -, Michael Chapman wrote: for TetraProc: -it allows inversion, or not, at the user's choice (it actually allows it on a per channel (per mic capsule) basis -it also allows ... to complicate your task ... 'Endfire' Not really exact. Tetraproc allows to invert any combination of X,Y,Z and the Endifire options which swaps X and Z and inverts one of them. All of these operate on the B-format signals. There are no UI controls to invert the capsule signals. It can be done of course by editing the A-B matrix. Not exact at all ;-( I'd just got out of bed ... a poor excuse. Thanks the correction, Fons. Michael ___ 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
Re: [Sursound] Soundfield-type mics: inverting or not?
Second cup of coffee has now penetrated and I realise I forgot about the stereo - still, essentially the same, except we say that it's non-inverting if a due front pressure increase produces a positive signal in both channels. Dave On Oct 9 2011, dave.mal...@york.ac.uk wrote: Hi folks, A wet Sunday morning and I haven't been up that long (only on first cup of coffee) so I hope this will make sense! Surely all that is actually needed, at least as far as B format is concerned, is whether the W signal goes positive for a pressure increase? Everything else is given by the B format definition wrt this. Of course, it would still be useful to know about other things (such as those given in the earlier messages below) but not essential. That said, knowing about the mic only really helps if you also know the polarity of the whole signal chain. If you want the information about this to persist, the only (near) reliable approach is to record an acoustic test signal at the start of each recording. Does anyone know, of the top of their heads, if a film set type clapper board reliably provides a positive going leading edge to it's impulse? I can't see it not, but I'd prefer that to be confirmed by repeatable experiments. Dave On Oct 9 2011, Michael Chapman wrote: On Sun, Oct 09, 2011 at 08:24:02AM -, Michael Chapman wrote: for TetraProc: -it allows inversion, or not, at the user's choice (it actually allows it on a per channel (per mic capsule) basis -it also allows ... to complicate your task ... 'Endfire' Not really exact. Tetraproc allows to invert any combination of X,Y,Z and the Endifire options which swaps X and Z and inverts one of them. All of these operate on the B-format signals. There are no UI controls to invert the capsule signals. It can be done of course by editing the A-B matrix. Not exact at all ;-( I'd just got out of bed ... a poor excuse. Thanks the correction, Fons. Michael ___ 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 ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] Soundfield-type mics: inverting or not?
On Sun, Oct 09, 2011 at 10:16:22AM +0100, dave.mal...@york.ac.uk wrote: Does anyone know, of the top of their heads, if a film set type clapper board reliably provides a positive going leading edge to it's impulse? I can't see it not, but I'd prefer that to be confirmed by repeatable experiments. I wouldn't rely in it. There's some air being squeezed out, but that would be a low-F thing. The real 'clap' is the sound of two pieces of wood hitting each other - I wouldn't make any guess as to the polarity of that wavefront. If you have a piece of bubble plastic around, making on of the bubbles burst should produce a 'positive' pulse... Ciao, -- FA ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] Soundfield-type mics: inverting or not?
Daniel Courville wrote: I think we should try to establish some sort of official database of what SoundField (and TetraMic) models are polarity inverting at the B-Format output. Using the original cylindrical PPA, TetraMic's A-format outputs were inverting. Using the current PPA2, its A-format outputs are non-inverting. Len Moskowitz (mosko...@core-sound.com) Core Sound LLC www.core-sound.com Home of TetraMic ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] Soundfield-type mics: inverting or not?
At 04:16 09/10/2011, dave.mal...@york.ac.uk wrote: Does anyone know, of the top of their heads, if a film set type clapper board reliably provides a positive going leading edge to it's impulse? I can't see it not, but I'd prefer that to be confirmed by repeatable experiments. It surely has to, since it is forcing air out of the gap: though it is a figure of eight device! David ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] Soundfield-type mics: inverting or not?
On 10/09/2011 09:01 PM, David Pickett wrote: At 04:39 09/10/2011, Fons Adriaensen wrote: On Sun, Oct 09, 2011 at 10:16:22AM +0100, dave.mal...@york.ac.uk wrote: Does anyone know, of the top of their heads, if a film set type clapper board reliably provides a positive going leading edge to it's impulse? I can't see it not, but I'd prefer that to be confirmed by repeatable experiments. I wouldn't rely in it. There's some air being squeezed out, but that would be a low-F thing. The real 'clap' is the sound of two pieces of wood hitting each other - I wouldn't make any guess as to the polarity of that wavefront. There would be a progressive increase in pressure as the angle between two pieces of wood decreases, but do the pieces of wood themselves really make a sound as they hit each other, other than the sound of air being squeezed out? if a clapper board claps in a forest and no one is around to hear it, does its sound pressure have defined polarity? that reminds me, i need to perceive my bed back into existence, urgently. and peek into the linen to collapse the wavefunction of my pillow into something soft and comfortable... btw, between yawns, i've always assumed a clap of some kind would start with a clearly defined positive flank, and i can't remember seeing anything else, but that's anecdotal evidence at best. -- 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
Re: [Sursound] Soundfield-type mics: inverting or not?
On Sun, Oct 09, 2011 at 02:01:50PM -0500, David Pickett wrote: At 04:39 09/10/2011, Fons Adriaensen wrote: On Sun, Oct 09, 2011 at 10:16:22AM +0100, dave.mal...@york.ac.uk wrote: Does anyone know, of the top of their heads, if a film set type clapper board reliably provides a positive going leading edge to it's impulse? I can't see it not, but I'd prefer that to be confirmed by repeatable experiments. I wouldn't rely in it. There's some air being squeezed out, but that would be a low-F thing. The real 'clap' is the sound of two pieces of wood hitting each other - I wouldn't make any guess as to the polarity of that wavefront. There would be a progressive increase in pressure as the angle between two pieces of wood decreases, but do the pieces of wood themselves really make a sound as they hit each other, other than the sound of air being squeezed out? Is this any different from clapping or bursting a paper bag? There is a difference. With the paper bag you have an overpressure inside the bag which is suddenly released. A similar thing happens when clapping your hands - try doing it such that there is no closed volume between the hands, it doesn't make much noise. A clapper doesn't have a closed volume. Ciao, -- FA ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
