Re: [Sursound] Another query..
Eero Aro wrote: > Dave Malham wrote: >> the Ambisonic demo bug was striking even then... > > Yes, I noticed that too. > > Makes me wonder if the reason for the slow adaptation of > Ambisonics have just been unlucky demonstrations? > > :-) Instead, it made me think that first-order Ambisonics (particularly with four speakers) is on the border of stability. In one sense this is an indication of its merit. It is very difficult to screw up a demonstration of 5.1, but then how do you screw up something that is already broken? Regards, Martin -- Martin J Leese E-mail: martin.leese stanfordalumni.org Web: http://members.tripod.com/martin_leese/ ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
[Sursound] Giving Precedence to Ambisonics
Greetings All, I have a friend who's an advocate of the Decca Tree mic arrangement. Many of his recordings (a lot of choir and guitar) sound quite nice, so I looked into aspects of the Decca Tree technique. For those who may not be familiar, the *traditional* Decca Tree arrangement is comprised of three spaced omnidirectional mics. A center microphone is spaced slightly forward. From what I've read thus far (Spatial Audio by Francis Rumsey, Focal Press; and selected articles in the AES Stereophonic Techniques Anthology), the slightly advanced time-of-arrival for the center mic stabilizes the central image due the precedence effect. However, the existence of the third (center) mic can result in exacerbated comb-filtering effects that can arise with spaced pairs. So, to avoid these filtering effects, bring on a Soundfield / Ambisonic mic...?? As I understand, Ambisonics already takes into consideration known psychoacoustical principles, and is why shelving is used to *optimize* ILDs and ITDs above and below 700 Hz, respectively. But as many readers may know, there are some nearly unpredictable ILD/ITD effects at approx. 1.7 kHz (for example, see Mills, 1972, Foundations of Modern Auditory Theory). Creating a virtual Decca Tree seems straightforward. To move the center channel, or a virtual mic *forward* would require little more than offline processing. I wonder whether anybody has tried the following: Slightly delay all channels except the signal (or feeds) that make up the forward-most (central) channel. Using an Ambisonic mic would eliminate combing effects. I realize a number of Ambisonic plug-ins have built-in crossed-cardiod, Blumlein, and spaced omni functions, but not sure I've seen any of them give *precedence* to the precedence effect or Decca Tree arrangement. Two-channel playback (both convention and binaural) is here to stay for a while, so optimizing Ambisonics for stereo is desirable to me. In fact, one of my favorite recordings from the late 80s was made with the band (The Cowboy Junkies) circled around a Calrec Soundfield mic. I've never heard whether the Trinity Session recording was released in a surround format, or if the mic's hardware decoder converted straight to stereo from the get go. That particular recording made me aware of the Soundfield mic, though surround sound wasn't an interest for me at that time. If anybody I had attempted the Decca Tree using an Ambisonic mic (even with addition of a separate and forward omni mic), I'd be interested in knowing what your experiences were. Many thanks for your time. Best, Eric C. (the C continues to remind readers that this post submitted by the *off-the-cuff* Eric) -- next part -- An HTML attachment was scrubbed... URL: <https://mail.music.vt.edu/mailman/private/sursound/attachments/20130626/535efc06/attachment.html> ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] Giving Precedence to Ambisonics
Eric Carmichel wrote: ... >> Two-channel playback (both convention and binaural) is here to stay for a >> while, so optimizing Ambisonics for stereo is desirable to me. In fact, one >> of my favorite recordings from the late 80s was made with the band (The >> Cowboy Junkies) circled around a Calrec Soundfield mic. I've never heard >> whether the Trinity Session recording was released in a surround format, or >> if the mic's hardware decoder converted straight to stereo from the get go. The Trinity Session is CD UHJ encoded, so can be decoded to surround sound using an Ambisonic UHJ decoder. However, when you do this, the performers are (correctly) located in strange places. This suggests that the UHJ was not intended to be decoded. Instead, decode it using the Super Stereo mode. This keeps the performers at the front where they "belong", while still surrounding the listener with the ambience of the Trinity Church. >From memory, the recording engineer has said that the output from the Soundfield mic went straight into a UHJ encoder, and only two channels were recorded. If true, this means that the recording can not exist in B-Format. Regards, Martin -- Martin J Leese E-mail: martin.leese stanfordalumni.org Web: http://members.tripod.com/martin_leese/ ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] Giving Precedence to Ambisonics
Ron Streicher has written about using a Soundfield as the middle mic in a Decca tree http://www.wesdooley.com/pdf/Surround_Sound_Decca_Tree-urtext.pdf and Tom Chen has a system he calls B+ Format, which augments first-order B-format from a Soundfield mic with a forward ORTF pair. I've heard it on orchestral recordings at his studio in Stockton and it sharpens up the orchestra image nicely. Aaron Heller (hel...@ai.sri.com) Menlo Park, CA US On Wed, Jun 26, 2013 at 10:02 AM, Eric Carmichel wrote: > Greetings All, > I have a friend who's an advocate of the Decca Tree mic arrangement. Many > of his recordings (a lot of choir and guitar) sound quite nice, so I looked > into aspects of the Decca Tree technique. For those who may not be > familiar, the *traditional* Decca Tree arrangement is comprised of three > spaced omnidirectional mics. A center microphone is spaced slightly > forward. From what I've read thus far (Spatial Audio by Francis Rumsey, > Focal > Press; and selected articles in the AES Stereophonic Techniques > Anthology), the slightly advanced time-of-arrival for the center mic > stabilizes the central image due the precedence effect. However, the > existence of the third (center) mic can result in exacerbated > comb-filtering effects that can arise with spaced pairs. So, to avoid these > filtering effects, bring on a Soundfield / Ambisonic mic...?? > As I understand, Ambisonics already takes into consideration known > psychoacoustical principles, and is why shelving is used to *optimize* ILDs > and ITDs above and below 700 Hz, respectively. But as many readers may > know, there are some nearly unpredictable ILD/ITD effects at approx. 1.7 > kHz (for example, see Mills, 1972, Foundations of Modern Auditory Theory). > Creating a virtual Decca Tree seems straightforward. To move the center > channel, or a virtual mic *forward* would require little more than offline > processing. I wonder whether anybody has tried the following: Slightly > delay all channels except the signal (or feeds) that make up the > forward-most (central) channel. Using an Ambisonic mic would eliminate > combing effects. I realize a number of Ambisonic plug-ins have built-in > crossed-cardiod, Blumlein, and spaced omni functions, but not sure I've > seen any of them give *precedence* to the precedence effect or Decca Tree > arrangement. > Two-channel playback (both convention and binaural) is here to stay for a > while, so optimizing Ambisonics for stereo is desirable to me. In fact, one > of my favorite recordings from the late 80s was made with the band (The > Cowboy Junkies) circled around a Calrec Soundfield mic. I've never heard > whether the Trinity Session recording was released in a surround format, or > if the mic's hardware decoder converted straight to stereo from the get go. > That particular recording made me aware of the Soundfield mic, though > surround sound wasn't an interest for me at that time. > If anybody I had attempted the Decca Tree using an Ambisonic mic (even > with addition of a separate and forward omni mic), I'd be interested in > knowing what your experiences were. > Many thanks for your time. > Best, > Eric C. (the C continues to remind readers that this post submitted by the > *off-the-cuff* Eric) > -- next part -- > An HTML attachment was scrubbed... > URL: < > https://mail.music.vt.edu/mailman/private/sursound/attachments/20130626/535efc06/attachment.html > > > ___ > 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/20130626/1de5eaf1/attachment.html> ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] Giving Precedence to Ambisonics
ther the >Trinity Session recording was released in a surround format, or if the mic's >hardware decoder converted straight to stereo from the get go. That particular >recording made me aware of the Soundfield mic, though surround sound wasn't an >interest for me at that time. >If anybody I had attempted the Decca Tree using an Ambisonic mic (even with >addition of a separate and forward omni mic), I'd be interested in knowing >what your experiences were. >Many thanks for your time. >Best, >Eric C. (the C continues to remind readers that this post submitted by the >*off-the-cuff* Eric) >-- next part -- >An HTML attachment was scrubbed... >URL: ><https://mail.music.vt.edu/mailman/private/sursound/attachments/20130626/535efc06/attachment.html> >___ >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/20130626/ef2e8691/attachment.html> ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
