360 Degree, 4 Ch. Audio Panner
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From: Greg Hanson on 2 Jun 2010 07:40 Has anyone seen a circuit, or commercial product, that enables one to pan (rotate) a mono audio signal 360 degrees around 4 speakers arranged in a circle? Ideally, speed of rotation needs to be manually adjustable across the full range of 1-40Hz. There are plenty of 2 channel panners out there, but they do not suit this application. Greg Hanson
From: Dirk Bruere at NeoPax on 2 Jun 2010 16:00 On 02/06/2010 12:40, Greg Hanson wrote: > Has anyone seen a circuit, or commercial product, that enables one to > pan (rotate) a mono audio signal 360 degrees around 4 speakers > arranged in a circle? > > Ideally, speed of rotation needs to be manually adjustable across the > full range of 1-40Hz. > > There are plenty of 2 channel panners out there, but they do not suit > this application. > > Greg Hanson Suggest you post in one of the rec.audio NGs -- Dirk http://www.transcendence.me.uk/ - Transcendence UK http://www.blogtalkradio.com/onetribe - Occult Talk Show
From: Paul Keinanen on 2 Jun 2010 16:24 On Wed, 02 Jun 2010 11:40:39 GMT, greghanson(a)prograde.com (Greg Hanson) wrote: >Has anyone seen a circuit, or commercial product, that enables one to >pan (rotate) a mono audio signal 360 degrees around 4 speakers >arranged in a circle? > >Ideally, speed of rotation needs to be manually adjustable across the >full range of 1-40Hz. > >There are plenty of 2 channel panners out there, but they do not suit >this application. > >Greg Hanson What kind of hearing model are you assuming ? Just simple amplitude weighting ? Or perhaps correct phase and/or time delay relation ship between the channels ? The criticality also depends on frequency. You might get away with a simple model on some frequencies, but not on other. In human hearing, the shape of the external ear will modify the frequency response of sounds coming from different directions. How believable should the hearing experience be ?
From: whit3rd on 2 Jun 2010 17:16 On Jun 2, 4:40 am, greghan...(a)prograde.com (Greg Hanson) wrote: > Has anyone seen a circuit, or commercial product, that enables one to > pan (rotate) a mono audio signal 360 degrees around 4 speakers > arranged in a circle? > > Ideally, speed of rotation needs to be manually adjustable across the > full range of 1-40Hz. One could do the cheesy thing, put four speakers in an anechoic box with a rotating array of four microphones... Or you could drive four quadrants of a 360 degree potentiometer (this will have some amplitude variation). Scratchy potentiometers aren't recommended. Or, you can note that an interpolation rule can give the in-between signal in amplitude-independent form, Soutput(theta) = Sinput(0) *A+ Sinput(90) * B + Sinput(180) *C + Sinput(270) * D where A is zero unless theta is in the (270,,,90) range, or cos**2(theta) when it's in that range. B is zero unless theta is in the (0...180) range, otherwise sin**2(theta) C is zero unless theta is in the (90...270) range, otherwise cos**2(theta) D is zero unless theta is in the (180... 0) range, otherwise sin**2(theta) Four multiplying DACs and a oscillator/counter/lookup-table will do it (and maybe some logic to enforce the zero terms with an analog switch).
From: whit3rd on 2 Jun 2010 17:43
On Jun 2, 2:16 pm, whit3rd <whit...(a)gmail.com> wrote: > Or, you can note that an interpolation rule can give the in-between > signal in amplitude-independent form, > > Soutput(theta) = Sinput(0) *A+ Sinput(90) * B + Sinput(180) *C + > Sinput(270) * D > Four multiplying DACs and a oscillator/counter/lookup-table will do it > (and maybe some logic to enforce the zero terms with an analog > switch). OOPS. It's a mono signal? You'd only need two DACs, one for sin**2 and one for cos**2... still need analog switches to steer on a quadrant-by-quadrant basis, though. Multiplying converters are very useful, here; they take the AC signal as the reference, and output the product of that reference and the (nonnegative) digital value you feed them. |