Re: [Sursound] Waveplayer - 16 chnl SD-card audio device
Hi Marc I've certainly thought about doing that, but not initially since it means that (a) you would be limited to passive speakers (b) the specs aren't as good as the Analog Devices ADAU1966, the evaluation board for which is sitting next to me :-) (c) serious levels of hardware design needed for the power amps stages on the other hand, the TAS5508C has a "Full 8×8 Input Crossbar Mixer. Each Signal-Processing Channel Input Can Be Any Ratio of the Eight Input Channels." and "Mixer gain operations are implemented by multiplying a 48-bit, signed data value by a 28-bit, signed gain coefficient" so 8 speaker digital decoder, anyone? Only problem is, no way to implement shelf filtering :-( Dave On 10/07/2012 02:20, Marc Lavallée wrote: Dave, It's possible to skip the A/D conversion by using amplifiers with digital inputs. Texas Instruments have a 8 channels digital to PWM converter that can drive D-class amps with PWM inputs; that means only one A/D conversion, done by the speaker... http://www.ti.com/product/TAS5508C Marc Wed, 25 Apr 2012 15:51:02 +0100, Dave Malham a écrit : Hi Marc, True, I'm sure you could use a usb interface, but even a low cost multichannel unit would be quite a lot more expensive (and, probably, power hungry) than the PI whereas Analog Devices (for instance) do a 16 channel, 24 bit, 192kHz DASC IC for around 10 ukp (ADAU1966) which would probably need around another 20 quid's worth of op-amps and other bits to get going properly. Much more in the maker tradition - and a possible product. Dave PS total number of pre-orders for PI's have reach 350,000! PPS I'm not connected with them at all, I've not even ordered one! On 24/04/2012 18:33, Marc Lavallée wrote: The snd_bcm2835 driver is for the integrated stereo sound module. For more channels, a cheap 8 channels USB sound module would probably work, and ALSA drivers for many sound modules are stable. Martin Leese a écrit : Dave Malham wrote: The Raspberry PI is really cheap and runs Linux, so it does provide some real possibilities, though it is, in some ways, quite limited - max 256m ram at present, for instance - ... it seems that the SPI pins are available on a standard header so shouldn't be too difficult physically to add DAC's or ADC's (since most use that interface), though how easy it would be to write the drivers, I don't know. The Arch Linux ARM image (operating system) contains an ALSA driver. However, it states: "The alpha-quality ALSA driver included in this release is disabled by default. Type modprobe snd_bcm2835 to enable it." Regards, Martin ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound -- These are my own views and may or may not be shared by my employer /*/ /* Dave Malham http://music.york.ac.uk/staff/research/dave-malham/ */ /* Music Research Centre */ /* Department of Music"http://music.york.ac.uk/"; */ /* The University of York Phone 01904 322448*/ /* Heslington Fax 01904 322450*/ /* York YO10 5DD */ /* UK 'Ambisonics - Component Imaging for Audio' */ /*"http://www.york.ac.uk/inst/mustech/3d_audio/"; */ /*/ ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] Waveplayer - 16 chnl SD-card audio device
Thought you just might have meant that :-) Dave On 10/07/2012 02:24, Marc Lavallée wrote: I meant: "one D/A conversion" I wrote: It's possible to skip the A/D conversion by using amplifiers with digital inputs. Texas Instruments have a 8 channels digital to PWM converter that can drive D-class amps with PWM inputs; that means only one A/D conversion, done by the speaker... http://www.ti.com/product/TAS5508C Marc Wed, 25 Apr 2012 15:51:02 +0100, Dave Malham a écrit : Hi Marc, True, I'm sure you could use a usb interface, but even a low cost multichannel unit would be quite a lot more expensive (and, probably, power hungry) than the PI whereas Analog Devices (for instance) do a 16 channel, 24 bit, 192kHz DASC IC for around 10 ukp (ADAU1966) which would probably need around another 20 quid's worth of op-amps and other bits to get going properly. Much more in the maker tradition - and a possible product. Dave PS total number of pre-orders for PI's have reach 350,000! PPS I'm not connected with them at all, I've not even ordered one! On 24/04/2012 18:33, Marc Lavallée wrote: The snd_bcm2835 driver is for the integrated stereo sound module. For more channels, a cheap 8 channels USB sound module would probably work, and ALSA drivers for many sound modules are stable. Martin Leese a écrit : Dave Malham wrote: The Raspberry PI is really cheap and runs Linux, so it does provide some real possibilities, though it is, in some ways, quite limited - max 256m ram at present, for instance - ... it seems that the SPI pins are available on a standard header so shouldn't be too difficult physically to add DAC's or ADC's (since most use that interface), though how easy it would be to write the drivers, I don't know. The Arch Linux ARM image (operating system) contains an ALSA driver. However, it states: "The alpha-quality ALSA driver included in this release is disabled by default. Type modprobe snd_bcm2835 to enable it." Regards, Martin ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound -- These are my own views and may or may not be shared by my employer /*/ /* Dave Malham http://music.york.ac.uk/staff/research/dave-malham/ */ /* Music Research Centre */ /* Department of Music"http://music.york.ac.uk/"; */ /* The University of York Phone 01904 322448*/ /* Heslington Fax 01904 322450*/ /* York YO10 5DD */ /* UK 'Ambisonics - Component Imaging for Audio' */ /*"http://www.york.ac.uk/inst/mustech/3d_audio/"; */ /*/ ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] higher order ambisonics over 8 to 10 loudspeakers
It's implied, but not really explicitly given in 'Ambisonics Encoding of Other Audio Formats for Multiple Listening Conditions' by Daniel, Jérome; Rault, Jean-Bernard; Polack, Jean-Dominique AES Convention:105 (September 1998) Paper Number:4795. I think there's a corrected version on Jerome's website. Dave On 09/07/2012 22:11, Eric Benjamin wrote: Fons Adriaensen wrote: for anything based on energy> vectors the angle between the speakers can't be too big. Is there a good reference for that important point? Eric - Original Message From: Fons Adriaensen To: sursound@music.vt.edu Sent: Mon, July 9, 2012 6:48:40 AM Subject: Re: [Sursound] higher order ambisonics over 8 to 10 loudspeakers On Mon, Jul 09, 2012 at 11:13:04PM +1000, GP wrote: If the min is (N+1)². Surely for 3rd order that is (3+1)² = 16 speakers? The minimum is (M + 1)^2 for 3D, and (2 * M) + 1 for 2D, but - You better use at least on more, - For 3D, the minimum is 8, even for first order. That is because the the equations above assume a systematic decoder, but a decoder should be systematic only at LF, and for anything based on energy vectors the angle between the speakers can't be too big. Ciao, -- These are my own views and may or may not be shared by my employer /*/ /* Dave Malham http://music.york.ac.uk/staff/research/dave-malham/ */ /* Music Research Centre */ /* Department of Music"http://music.york.ac.uk/"; */ /* The University of York Phone 01904 322448*/ /* Heslington Fax 01904 322450*/ /* York YO10 5DD */ /* UK 'Ambisonics - Component Imaging for Audio' */ /*"http://www.york.ac.uk/inst/mustech/3d_audio/"; */ /*/ ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] Domestic Concert Hall
On 07/09/2012 06:15 PM, Simon Edmonds wrote: using first order for reverb is fine as the overall localisation is not critical. In the next incarnation of my system I will have a 3rd order mixer but still using a 1st order send and reverb i used to say the same, but i have found it's not true as you scale up to larger numbers of speakers. natural-sounding reverb needs a low IACC, and to ensure that, you want very high-resolution reverb. not for its localisation benefit (obviously), but to ensure very low crosstalk between neighboring speakers. using a first-order reverb on more than, say, twelve speakers periphonic will begin to add significant phasing artefacts as you move around even slightly, because neighboring speakers convey very similar signals. they will interfere in a nasty way without giving any benefit. on a 40-channel speaker system which i built last year for the ICSA conference, we used two decoders designed by fons, one dedicated third-order, the other first-order, for native soundfield signals and reverb. the first-order decoder used only a subset of the available speakers, which improved the perceived quality a lot. morale: low-order reverb doesn't scale. if you want to use it on massive systems, keep low-order content separate and pipe it through a dedicated decoder using fewer speakers. -- 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] higher order ambisonics over 8 to 10 loudspeakers
On 07/09/2012 03:17 PM, GP wrote: I did wonder about using Daniel Courville's plugins to do decoding for the height info separate to HARPEX. The HARPEX decoding does sound good ( how can I confirm it is 3rd order over 8 speakers?) and so if I could add height using another approach that would be good. I need to look at how to get height only from Daniel's plugs. well, if you have an upper front and an upper rear speaker, you can use UF = W + aX + bZ and UR = W - aX + bZ, with a and b chosen to taste. which is pretty much what a virtual mic would do. or you can use a periphonic decoder which matches the position of your upper speakers well, and leave everything except the upper speakers unconnected. -- 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] higher order ambisonics over 8 to 10 loudspeakers
ahh thanks Daniel I had not seen that. Would be cool if the speaker layout GUI could be rotated so one could see the 3D layout more clearly. So I guess as you suggest I could use one instance of Harpex for my main horizontal layout and then another instance with 2 or more shotguns raised in elevation to manage the height, depending on the available speakers Cheers, Garth Paine ga...@activatedspace.com On Jul 10, 2012, at 6:26 AM, Daniel Courville wrote: > Le 2012-07-09 09:17, GP a écrit : > >> I did wonder about using Daniel Courville's plugins to do decoding for >> the height info separate to HARPEX. The HARPEX decoding does sound good ( >> how can I confirm it is 3rd order over 8 speakers?) and so if I could add >> height using another approach that would be good. I need to look at how >> to get height only from Daniel's plugs. > > The Harpex-B has a shotgun output mode with three presets for 3D: > Octahedron, 3D 7.0 and Cube. You can use them or build your own 3D decoder > with virtual shotguns (eight maximum) to accommodate an ad hoc > installation. > > - Daniel > > > ___ > 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/20120710/cf5b59de/attachment.html> ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] Waveplayer - 16 chnl SD-card audio device
Hi Dave Dave Malham a écrit : > Hi Marc > > I've certainly thought about doing that, but not initially since it > means that > > (a) you would be limited to passive speakers This limitation is a feature: with less hardware the cost is lowered and the quality is raised. It would be a good choice to create small domestic systems or public installations. It would be adequate with 6 or more identical full range speakers. > (b) the specs aren't as good as the Analog Devices ADAU1966, the > evaluation board for which is sitting next to me :-) The better spec of the ADAU1966 is rarely matched by amps and speakers... I agree that for professional use it would be perfect. ;-) > (c) serious levels of hardware design needed for the power amps stages In the example application schematic the D-class amps with PWM inputs are connected directly to the PWM ouputs of the TAS5508C. How easier can it be? The final system could be made in the form of a PCM to PWM decoding board to connect amps with PWM inputs. > on the other hand, the TAS5508C has a "Full 8×8 Input Crossbar Mixer. > Each Signal-Processing Channel Input Can Be Any Ratio of the Eight > Input Channels." and "Mixer gain operations are implemented by > multiplying a 48-bit, signed data value by a 28-bit, signed gain > coefficient" so 8 speaker digital decoder, anyone? Only problem > is, no way to implement shelf filtering :-( Interesting! But its only job would be to interface PCM streams to PWM inputs. There's also stereo D-class amp chips with I2S inputs. Marc > > Dave > > On 10/07/2012 02:20, Marc Lavallée wrote: > > Dave, > > > > It's possible to skip the A/D conversion by using amplifiers with > > digital inputs. Texas Instruments have a 8 channels digital to PWM > > converter that can drive D-class amps with PWM inputs; that means > > only one A/D conversion, done by the speaker... > > > > http://www.ti.com/product/TAS5508C > > > > Marc > > > > > > Wed, 25 Apr 2012 15:51:02 +0100, > > Dave Malham a écrit : > > > >> Hi Marc, > >> True, I'm sure you could use a usb interface, but even a low > >> cost multichannel unit would be quite a lot more expensive (and, > >> probably, power hungry) than the PI whereas Analog Devices (for > >> instance) do a 16 channel, 24 bit, 192kHz DASC IC for around 10 ukp > >> (ADAU1966) which would probably need around another 20 quid's > >> worth of op-amps and other bits to get going properly. Much more > >> in the maker tradition - and a possible product. > >> > >> Dave > >> > >> PS total number of pre-orders for PI's have reach 350,000! > >> PPS I'm not connected with them at all, I've not even ordered one! > >> > >> On 24/04/2012 18:33, Marc Lavallée wrote: > >>> The snd_bcm2835 driver is for the integrated stereo sound module. > >>> For more channels, a cheap 8 channels USB sound module would > >>> probably work, and ALSA drivers for many sound modules are stable. > >>> > >>> Martin Leese a écrit : > >>> > Dave Malham wrote: > > > The Raspberry PI is really cheap and runs Linux, so it does > > provide some real possibilities, though > > it is, in some ways, quite limited - max 256m ram at present, > > for instance - > ... > > it seems that the SPI pins are available on a standard header so > > shouldn't be too difficult > > physically to add DAC's or ADC's (since most use that > > interface), though how easy it would be to > > write the drivers, I don't know. > The Arch Linux ARM image (operating system) > contains an ALSA driver. However, it states: > > "The alpha-quality ALSA driver included in this > release is disabled by default. Type > modprobe snd_bcm2835 > to enable it." > > Regards, > Martin > > > > ___ > > 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
