Obviously there is no reason not to use subwoofers with RACE, Wareing, or Choueiri. I think we are splitting hairs here. It is incontroverible that the human ability to localize declines with frequency. Based on the Bose experiments and other AES papers written too long ago to remember, 90 Hz is where localization begins to become difficult. This is very hard to verify because all subwoofers have harmonic distortion and one localizes to that. Also in the early days, and even now apparently, the crossovers were not steep enough to prevent some energy over 90 Hz from reaching the subwoofers. I am sure somebody did it before Bose, but as far as I know he was the first to make a completly passive crossover network steep enough to allow the subwoofers to remain unlocalizable to anybody except Fons. (See earlier posting.) Yes, there are bass issues apart from localization like envelopment and the advantages of stereo subwoofers, but these should not be confused with the basic issue of pure low bass localization and its relevance to crosstalk cancellation. But if anybody thinks having the bass, largely uncrosstalk cancelled, as in RACE and others, and thus coming from the main frontal speakers is inadequate, then by all means use subwoofers placed where they work well in the room as per Toole and Griesinger. The same applies to stereo reproduction where if the main speaker woofers at 30 degrees don't do the job you get subwoofers and place them as you like. I use subwoofers in two of my Ambio systems. Incidentally Choueiri does not have subwoofers in his Princeton demo and the bass sounds fine to me. Choueiri's new BACCH method uses the same speaker arrangement as RACE and like RACE, can play recordings made with coincident mics, spaced mics, ORTF, Soundfield, or dummy head mics. RACE and BACCH simply eliminate crosstalk (BACCH up to 20DB) so whatever ITD or ILD is on the recording gets to the ears reaonably well depending on the precision of the crosstalk algorthim, the balance of the speakers, etc. I find room acoustics to be less of a problem in Ambio compared to stereo, but more research needs to be done. Yes, as in stereo, recodings, without ITD or without ILD or with both, will reproduce differently in Ambio or similar. That is why in stereo there are so many arguments as to whether Blumlein or spaced Omnis sound better. I, of course, play all kinds of mic'ed classical music recordings without a problem. Both Choueiri and I can get more consistent psychoacoustic results if we make recordings using an array like the Ambiophone or in Choueiri's case a dummy head, so we are both sure of getting both ITD and ILD in abundance. Finally, there is no reason why you cannot divide RACE up into frequency bands, and use attenuation and delay (or even bypass) for each band to get a better result and this is what is done in BACCH among other advantages over minimalist RACE. I am sure this has been done already earlier by many others. Or you can make the RACE parameters a continuous function of frequency and avoid all compromises. Ralph Glasgal
From: Marc Lavallée <m...@hacklava.net> To: Surround Sound discussion group <sursound@music.vt.edu> Sent: Wednesday, June 1, 2011 8:00 PM Subject: Re: [Sursound] Bass Problem in crosstalk cancellation Le Wed, 1 Jun 2011 19:38:10 +0000, Fons Adriaensen <f...@linuxaudio.org> a écrit : > Ambiophonics makes a mess of it. Unless you use separate widely > spaced speakers for LF (driven by intensity-based stereo), as > some researchers have already recommended. I jut tried using 2 satellites at +-7.5 degrees (with the new XTC filter from DW) and 2 subs at +-30 degrees with no treatment (direct stereo), crossed at ~130hz. This configuration is very enjoyable; the bass seems more defined and localizable. -- Marc _______________________________________________ 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/20110602/294e6572/attachment.html> _______________________________________________ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
