wasn't the original conception for stereo = 90 degrees, but 'hole in the middle' effects led to standardising on the narrower figure? Dr. Peter Lennox Senior Fellow of the Higher Education Academy Senior Lecturer in Perception College of Arts University of Derby
Tel: 01332 593155 ________________________________________ From: Sursound [sursound-boun...@music.vt.edu] On Behalf Of Dave Hunt [davehuntau...@btinternet.com] Sent: 29 March 2016 19:02 To: sursound@music.vt.edu Subject: Re: [Sursound] OT Stereo stage width - Was: Static stereo source in rotating soundfield, possible? Hi Stefan, The "stereo triangle" page you pointed to says, "By making the distance between the speakers and each speaker to you (the center listening point) the same, you have made an equilateral triangle. This stereo set up ensures that the sound from each speaker has the exact same distance to travel to reach you." The first sentence is true. However an equilateral triangle is not necessary to ensure that each speaker is at the same distance to a laterally central listener. For an equilateral triangle the sound would travel the same distance from one speaker to another as it does to travel to the listener. I don't see that this is of any importance. OK some sound from each speaker would be reflected by the other, but this would be off axis from the source speaker and reflected backwards due to the speakers being angled inwards towards the listener. I would suggest that this would be barely audible in comparison with other acoustic room effects. The -3dB central panning level is a result of the sine/cosine panning law. One speaker is at zero degrees, the other at 90 degrees. When fed a mono signal an angle of 0 results in a gain of one to one speaker and zero to the other. 90 degrees reverses the result. 45 degrees gives a gain to each speaker of 0.707, or -3dB. This appears to result in a good phantom central image. With a linear panning law the gain to each speaker would be 0.5 or -6dB, which appears to result in a "hole in the middle". Why plus and minus 30 degree separation for "normal stereo" is still a mystery to me. Ciao, Dave Hunt > From: Stefan Schreiber <st...@mail.telepac.pt> > Date: 28 March 2016 19:07:14 BDT > To: eero....@dlc.fi, Surround Sound discussion group > <sursound@music.vt.edu> > Subject: Re: [Sursound] OT Stereo stage width - Was: Static stereo > source in rotating soundfield, possible? > > > Eero Aro wrote: > >> Hi Dave >> >> I have a feeling that this subject has been discussed in Sursound >> many times >> before. >> >> The point in my reply was that when you use two channel stereo in the >> surround sound field, a wide angle between the virtual >> loudspeakers doesn't >> work too well. >> >> I don't know where the 60 degrees angle between the stereo >> speakers originally >> came from. Blumlein used a 30...35 degrees angle between the >> speakers. >> When I started to work in broadcasting in 1977, all control rooms >> were equipped >> with a stereo listening setup. The speakers were arranged so that >> they were in a >> 60 degrees angle from the mixer's seat. >> >> I have noticed with students, that there is a wide spectrum of >> people, most do >> can integrate a stereo sound image between the loudpeakers with 60 >> degrees. >> I have met people, who tell that they cannot hear any kind of a >> stereo image >> between the loudspeakers, whatever the angle. They hear sound from >> two speakers. >> At the other end are people, who can hear an integrated stereo >> image with 90 >> degrees. >> >> I don't know. Anyway, in music industry and boradcasting, you need >> to have some >> standard. The broadcasting house I worked in, had then 250 radio >> studios. The >> listening conditions needed to be at least somewhat similar >> between control rooms, >> so that you could continue the work in another studio another day. >> Why 60 degrees >> was chosen, I don't know. >> >> Eero >> > Because of the < stereo triangle > concept? > > http://www.centerpointaudio.com/SpeakerPlacementAndPositioning.aspx > > "Equilateral", bla bla bla... the angle is 60ยบ in the equilateral > bla bla bla .... > Best, > > Stefan > > > > > From: David Pickett <d...@fugato.com> > Date: 28 March 2016 19:33:08 BDT > To: Surround Sound discussion group <sursound@music.vt.edu> > Subject: Re: [Sursound] OT Stereo stage width - Was: Static stereo > source in rotating soundfield, possible? > > > The problem with speakers at +/- 45 degrees is that one needs a > wide room if one is to sit at a decent distance from them. > However, it can be impressive. I have found the effect even better > if a centre speaker of the same typeis added. Gerzon gave the > ratios necessary for matrixing 2 channel stereo into this 3 channel > format. It is not simply a question of feeding the centre speaker > with a -3dB sum, but quite easy to implement. > > David > -------------- next part -------------- An HTML attachment was scrubbed... URL: <https://mail.music.vt.edu/mailman/private/sursound/attachments/20160329/e82cf2f4/attachment.html> _______________________________________________ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound - unsubscribe here, edit account or options, view archives and so on. The University of Derby has a published policy regarding email and reserves the right to monitor email traffic. If you believe this was sent to you in error, please select unsubscribe. Unsubscribe and Security information contact: info...@derby.ac.uk For all FOI requests please contact: f...@derby.ac.uk All other Contacts are at http://www.derby.ac.uk/its/contacts/ _______________________________________________ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound - unsubscribe here, edit account or options, view archives and so on.
