On Tue, Sep 20, 2011 at 12:02:56AM +0100, Paul Hodges wrote: >> It's not the same. The shuffler is designed to process signals >> that have no significant level differences in the frequency >> range it handles, just the phase differences. > > But Blumlein also considered shuffling might be desirable with crossed > ribbons (Burns, The life and times of AD Blumlein, p133), and I > understood this was part of the EMI Stereosonic system (though I'm open > to correction on this).
This is a different form of shuffling, it amounts to a much gentler (0dB at LF, -3dB at HF) shelf filter applied to the difference channel (and ideally a corresponding phase compensation in the sum channel). This ensures that the LF and HF images of the same source coincide (except at the extreme L,R positions). It's quite similar to the shelf filters used in AMB decoding, and based on the same ideas. Stereosonic was developed after the death of Blumlein. According to this source <http://www.phaedrus-audio.com/shuphler.htm> the circuit was called 'a shuffler' in his honour by his former collegues. The software I presented only implements the 'original' Blumlein shuffler. This is quite different: it operates only on LF, and the high LF gain (-6 dB/oct) and 90 degrees phase shift of the difference channel filter are its essential features. Ciao, -- FA _______________________________________________ Sursound mailing list [email protected] https://mail.music.vt.edu/mailman/listinfo/sursound
