Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!utgpu!water!watmath!clyde!cbosgd!ihnp4!ptsfa!ames!ll-xn!husc6!seismo!rochester!pt!speech1.cs.cmu.edu!phd From: phd@speech1.cs.cmu.edu.UUCP Newsgroups: sci.electronics Subject: Re: 3800 Hz notch filter [will] be used on CD masters Message-ID: <1003@speech1.cs.cmu.edu> Date: Thu, 9-Jul-87 04:42:02 EDT Article-I.D.: speech1.1003 Posted: Thu Jul 9 04:42:02 1987 Date-Received: Sat, 11-Jul-87 17:53:05 EDT References: <598@neoucom.UUCP> <67@sdeggo.UUCP> <1597@ihuxi.ATT.COM> <268@uvicctr.UUCP> Organization: Carnegie-Mellon University, CS/RI Lines: 35 Summary: Adding Harmonics MIGHT improve the sound quality... In article <268@uvicctr.UUCP>, collinge@uvicctr.UUCP (Doug Collinge) writes: > I suggest that, since 3800 Hz energy in music will be mostly harmonics of > lower frequency tones, the thing to do is to put the music through a > fuzzbox then filter out the 3800 Hz energy of the generated harmonics and > intermodulation products. This has the advantage of correlating the > synthetic stuff with the music that is already present - something the ear > is extremely sensitive to. This is a very interesting proposal! It is based upon the assumption that most instruments generate harmonic partials in a fairly smooth fashion. This is quite reasonable for certain instruments, for instance, the brasses. However, some instruments have enharmonic partials (bells come to mind), and some have very pronounced gaps (like the clarinet) which give rise to the characteristic timbre. These might sound a little strange when a hole that was there before suddenly gets filled when running up a scale. Still, this is the sanest idea I've heard yet, and might be well worth the effort. (Of course, this is only for the real purists: I doubt most people will be able to notice the difference without an A/B comparison anyway!) I don't really know what a fuzzbox does (feel free to send me mail...), but I assume it's some sort of time invariant, non-linearity. For experimentation purposes, a saturating non-linearity might be reasonable (i.e. a comparator), but I suspect that it is not optimal. Out of curiosity, does anybody out there in netland know of any literature on the the spectral properties of various non-linearities? (i.e. things like exponentials, generic polynomials, and trigonometric functions...) Paul H. Dietz, Graduate Slave Laborer in Trumpet Acoustics phd@speech1.cs.cmu.edu on ARPA Dept. of Electrical and Computer Engineering Caregie Mellon University Disclaimer: I ASSUMED that the University was aware of my actions. However, they patently deny that they were ever informed...