JQ Adams wrote: > Trifield is new to me. Thanks for this. > > I'm not entirely certain what is said in this article...: > >> Each filtered signal then passes to a sine/cosine potential divider, which >> is set differently for each frequency band. Only with this arrangement, >> Gerzon found, could a wide stereo image and sharpened central focus be >> traded off effectively against one another across the entire audible >> spectrum.[image: Inline image 1]* > > This seems to be saying that different weightings of energy gets sent to > the middle versus side speakers. I would presume the center channel would > receive the greater proportion of low frequency content, but it's not said > here, directly.
With Trifield, the transition frequency for the shelf filters is 5 kHz. So, the low frequencies are not that low. Marc Lavall?e wrote: > I made a Trifield decoder a few months ago (with the help of Aaron > Heller, to understand how to use Faust), and it works surprisingly > well! The distances can be adjusted, so it would work with 3 speakers > on a plane. The only problem is the patent... So I'm not sure I can > distribute it. One way around the patent is to buy a Meridian Surround Processor. These all have Trifield, and a used 561 or 565 is going on eBay for under US$500. (Not sure whether the Meridian 541, which was analogue, has Trifield but the rest do.) David Pickett wrote: > I found the other article. It is "Optimal Reproduction Matrices for > Multispeaker Stereo", AES Preprint 3180 (91st Convention, NY 4-8 Oct. > 1991). Figure 16 is identical with that in the Stereophile article > given above. This is a more sophisticated approach, which I have not > tried, though I found that matrixing without "frequency compensation" > was pretty impressive on some recordings. This preprint describing Trifield was published as the journal article: M.A. Gerzon, "Optimum Reproduction Matrices for Multispeaker Stereo", J. Audio Engineering Society, vol. 40 no. 7/8, pp. 571-589 (1992 July/Aug.) Regards, Martin -- Martin J Leese E-mail: martin.leese stanfordalumni.org Web: http://members.tripod.com/martin_leese/ _______________________________________________ Sursound mailing list [email protected] https://mail.music.vt.edu/mailman/listinfo/sursound
