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FWIW I pretty much agree with what Tom Fine says. In addition I sent these remarks over to old friend Tony Lauck, who independently has been researching this topic. He returned with: EQ can be fixed in the digital domain if it was done incorrectly, but results won't be as good as if correct equalization had been used prior to digitization. Ticks and pops must be removed by hand. It can be an artistic judgment whether they belong in or out, e.g. bows striking music stands. I use iZotope RX 2. On really bad disks automatic click reduction can be used on a conservative setting to get rid of the worst half of the noises, leaving less manual work. (On the worst recordings it can take an hour's work to clean up a minute of music.) This software can also fake tape dropouts, sometimes up to 1/4 second. It can even fake glissando and vibrato that are missing, but this doesn't always work correctly. Digital noise reduction can be used to remove constant noise, which includes tape hiss, constant room machinery and hum. Good noise reduction software (iZotope RX 2 mode C) doesn't degrade the musical sound despite stripping the noise, but there will be a noticeable loss of ambiance if much noise reduction is used. Whether this is advantageous or not will very much depend on the particular recording. Unfortunately, this style of psycho-acoustic noise reduction doesn't work with periodic noises, which include ignition noise or 78 RPM swoosh, because the algorithm use a noise "profile" to define what is noise and what is signal. If the profile is set on the quiet portion of the swoosh it will leave the loud noise in. If the profile is set on the noisy portion of the swoosh it will scrape away some of the music. (Perhaps some software can be developed to deal with this situation, but I've not seen it.) It might seem that one could tackle a recording one second at a time, but it turns out this strategy doesn't always work. If there are many problems in a transfer that get "fixed" the net result can be weird even though each individual change seems like a good one. It may be that listening to 10 seconds sounds good, but if one listens for minutes one gets a strange feeling that something is very wrong. This is particularly true when removing acoustic noises. (Example: a lecture where there were many people coughing. It was possible to remove coughs between the speaker's syllables, but the coughs that overlapped were left in. Any short period sounded natural, but after listening for more than about 30 seconds it became obvious that the audience only coughed when the speaker was vocalizing. Weird.) _________________________ TOTALLY agree with that observation. clark On Tue, Apr 10, 2012 at 8:49 AM, Tom Fine <[log in to unmask]>wrote: > Read the article, it was in the ARSC Journal a while back, maybe a year or > two. Too technical to summarize here, at least for this non-EE. > > ----- Original Message ----- From: "Andrew Hamilton" <[log in to unmask]> > To: <[log in to unmask]> > Sent: Tuesday, April 10, 2012 8:39 AM > Subject: Re: [ARSCLIST] Recording_78rpm_records > > > Gary has also written for ARSC Journal advocating analog playback and EQ >>>>> of >>>>> grooved media, rather >>>>> than "flat playback" and software EQ, and has specified the technical >>>>> reasons why analog EQ works >>>>> differently from DSP EQ. >>>>> >>>> >> >> >> What is it about minimum phase digital audio equalization, such as that >> found in a de-RIAA or RIAA plugin, that Mr. Galo feels is not up to snuff? >> >> >> >> >> >> Andrew >> >>