Yes, there are lots of interesting things that can be done with frequency shifting. Feedback suppression in a PA system by frequency shifting was suggested by Manfred Schroeder a long time ago. I have occasionally found it to be useful to broaden a mono signal by feeding it through a hilbert transform pair, or actually any pair of allpass filters. Very small frequency shifts produce slowly moving stereo images. I have collected some sound examples (mostly using an analog frequency shifter) here:
http://ristoid.net/modular/freqshift.html The theoretical exposition is not aimed at readers on this list, but maybe you can spot some errors. Risto Den 2017-02-07 kl. 18:35, skrev STEFFAN DIEDRICHSEN: > A nice thing are the endless phase shifts, if you feed back a > frequency shifter. It’s like a Shepard tone. > If you have Logic Pro or MainStage, try the RingShifter, it can do > such tricks. It has 2x6 Allpass filters for the constant phase shift > and a quadrature oscillator with FM and a delay. > > Steffan > > > >> On 07.02.2017|KW6, at 18:25, Eric Brombaugh <ebrombau...@cox.net >> <mailto:ebrombau...@cox.net>> wrote: >> >> That's the right idea. In fact if you multiply by e^iw you can get >> arbitrary phase shifts to move the stereo image around subtly. For >> this reason, most of the frequency shifters I've worked on have a >> nonlinear response in the mapping of control voltage that gives fine >> resolution near DC shift frequency so that you can dial in small >> offsets for subtle phasing effects. >> >> Eric > > > > _______________________________________________ > dupswapdrop: music-dsp mailing list > music-dsp@music.columbia.edu > https://lists.columbia.edu/mailman/listinfo/music-dsp
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