Sound issue
in [UK Mac]
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From: Rowland McDonnell on 29 Dec 2009 04:57 Adrian Tuddenham <adrian(a)poppyrecords.invalid.invalid> wrote: > Rob <patchoulianREMOVE(a)gmail.com> wrote: > > > Rowland McDonnell wrote: > > > > > > > > It is a technical error, these days, to mix the typical audio recording > > > in a fashion optimized for vinyl discs, > > > > In what way is audio recording optimised for vinyl? Do you mean mixing, > > or some form of filter? I only ask as someone interested in recording > > *from* vinyl, and asithappens, listening to LPs. > > Grooved media have a lot of limitations due to the geometry of the > system; the cutting was done with a sharp-edged tool, but the playback > tool is rounded and cannot follow exactly the same path. This becomes > significant when the dimensions of the modulation become comparable with > the dimensions of the groove (high frequencies and/or low surface speed > at the centre of the disc). Truncated elliptical styli can reduce this > effect - but they show-up other problems and are noisier with worn > records. `Truncated' - erm? Not sure what you mean by that - could you elucidate? > At high frequencies, the curvature of the modulation waveform can > approach the radius of the stylus tip, so waveform distortion occurs on > playback. Surely that distortion can be engineered out with a suitable approach to cutting, if one assumes a particular stylus tip profile? [snip] > With a truncated elliptical stylus, parallel tracking is particularly > important. A large angular error can give a comb-filtering effect on > the mono signal because the stylus tip is picking up the waveform at two > displaced points on the two groove walls - so cancellation occurs. Oh! Yes. I'd never thought of that. Coo. Hmm.... [snip] > A huge amount of information on the correct playback of discs is > contained in Chapters 3,4 & 5 of Peter Copeland's book: > http://www.bl.uk/reshelp/findhelprestype/sound/anaudio/analoguesoundrest > oration.pdf I got no such page when I followed that link. So I did a search and got this link, which did work: http://www.bl.uk/reshelp/findhelprestype/sound/anaudio/analoguesoundrest oration.pdf except it's the same url. Can anyone explain that strangeness? Firefox latest version, MacOS X 10.6.2. > ...this is an absolute 'must read' for anyone who transfers discs to > digital and wants to understand what they are doing. I can't help feeling that almost everyone who's done that has failed to do it properly. [snip] Rowland. -- Remove the animal for email address: rowland.mcdonnell(a)dog.physics.org Sorry - the spam got to me http://www.mag-uk.org http://www.bmf.co.uk UK biker? Join MAG and the BMF and stop the Eurocrats banning biking
From: Rowland McDonnell on 29 Dec 2009 04:57 J. J. Lodder <nospam(a)de-ster.demon.nl> wrote: > Adrian Tuddenham <adrian(a)poppyrecords.invalid.invalid> wrote: > > > J. J. Lodder <nospam(a)de-ster.demon.nl> wrote: > > > > > Adrian Tuddenham <adrian(a)poppyrecords.invalid.invalid> wrote: > > > > > > > J. J. Lodder <nospam(a)de-ster.demon.nl> wrote: > > > > > > > > > Rowland McDonnell <real-address-in-sig(a)flur.bltigibbet.invalid> wrote: > > > > > > > > > > A listen to a classic Decca recording will show the fallacy of all > > > > > > those assumptions. > > > > > > > > > > Try feeding the signals through a low-pass filter, > > > > > and see how much S-component you've got left. > > > > > But you cleary never tried it. > > > > > The pick up elements of those days > > > > > just can't handle the large vertical amplitudes. > > > > > > > > > > BTW, you can even see it with a magifying glass. > > > > > The long wavelength wiggles are purely horizontal, > > > > > > > > During the era of changeover from mono to stereo when both types of > > > > record were on sale, Decca produced two completely independent mixes for > > > > the two issues. > > > > > > Yes. Why wouldn't they? > > > > Some record companies just combined the two channels, with or without > > filtering, to produce their mono versions, it was a lot cheaper and > > less time-consuming. The proportion of reverberation has to be > > different wth mono and that can't be properly controlled by just > > knocking the 'S' signal out of a stereo recording, which was why Decca > > took the extra trouble to get it right. > > It was said at the time that there was a difference of philosophy > between Decca and Philips. (aka Phonogram) > Decca wanted to produce real HiFi, on the best of equipment. > Philips wanted to make it sound as well as still possible > on the crummy mass market stuff they produced. That figures. [snip] > > > In extreme cases the needle may even jump. > > > > The extreme cases are those resulting from high levels of modulation on > > pop records combined with poor playback equipment, they almost never > > occur in classical orchestral recordings intended for playback on good > > equipment. > > > > > Other problems at the high frequency end are irrelevant for this point. > > > > High frequencies are the end of the spectrum where the limitations are > > imposed by the inherent geometry of the medium, rather than by > > deficiencies in the playback equipment. > > The vinyl is no longer stiff, > and understanding what happens in detail > becomes very difficult. Hence the need for /experienced/ sound engineers. > > > > With really good studio monitor speakers and a proper stereo recording, > > > > the 'bass' can appear to be be directional, mostly because the harmonics > > > > give the position away. > > > > > > That's what I said already. > > > And (also as I said already) > > > it's the reason why a single central subwoofer > > > with good satellite speakers works nearly as well. > > > (with a crossover well below 400 Hz) > > > > The problem with that setup on real instruments is that the fundamental > > and some harmonics may be below the crossover but other harmonics may be > > above it. This 'splurges' the image of the instrument across the stereo > > stage. Whilst it can work with some instruments, it might not work with > > all of them, so it is an unnecessary limitation of the playback system > > (unless space or price constraints oblige you to use a poor quality > > set-up, where you must accept those restrictions). > > It will rarely be noticable under home listening conditions. That is merely a reflection of the fact that most home listening is done via a portable transistor radio or other low-quality signal source in a noisy environment while doing something else without any hope of there being *any* position where a stereo image can be heard. Those of us who like to sit down in a position such that the sound stage can be heard more or less as intended, and to enjoy listening to the music in peace and quite as is proper using hi fi gear - under those indeed very rare circumstances, you can't miss the quality improvements that appear when comparing a good recording with a bad one. So the fact that `whatever' will rarely be noticable under home listening conditions is a very red herring indeed - whatever this `thing' might be, it's pretty much always bloody obvious to anyone who wants to hear proper music played back on proper repro gear, sitting down to listen to it properly. The defects of duff recordings might not be immediately apparent to those without `trained ears' - but we'll notice in the end. I know I do - I notice defects, and tend to find out how to get around the defect after spotting 'em. > Even under studio conditons you would need a trained ear > and to know just what to listen for to notice it. .... and if you don't, the result tends to produce the sort of defects in the re-constructed time-varying wavefront that lead the listener to conclude that although it *seems* to sound as good as the live version, it's somehow less satisfying but they can't put their finger on it. That's why `trained ears' as you call 'em are important - not because those without the `trained ears' can't hear the defects, but because you need experience to be able to tell what causes the defects and how to correct 'em. [snip] Rowland. -- Remove the animal for email address: rowland.mcdonnell(a)dog.physics.org Sorry - the spam got to me http://www.mag-uk.org http://www.bmf.co.uk UK biker? Join MAG and the BMF and stop the Eurocrats banning biking
From: Rowland McDonnell on 29 Dec 2009 06:02 J. J. Lodder <nospam(a)de-ster.demon.nl> wrote: > Rob <patchoulianREMOVE(a)gmail.com> wrote: > > > Rowland McDonnell wrote: > > > > > It is a technical error, these days, to mix the typical audio recording > > > in a fashion optimized for vinyl discs, > > > > In what way is audio recording optimised for vinyl? That's only done when an actual groovy vinyl record thingy is the end product. > > Do you mean mixing, > > or some form of filter? Optimizing for vinyl means `making the recording bearing in mind the technical limitations of the equipment'. There are things that must be done to make it good and they're different things if you're aiming at a groovy vinyl consumer data carrier rather than a pitty CD consumer data carrier. I don't know any of the interesting details, just a few of the obvious things. > > I only ask as someone interested in recording > > *from* vinyl, and asithappens, listening to LPs. > > A better way to put it would be that the audio signal to be put on disk > is constrained by the limitations of vinyl and PU elements. The best way to put it is to point out that the time-varying wave-front experienced by the ears of the audience on playback is a product of the convolution of all the steps in the reproduction chain from microphone to ear[1]. It is therefore necessary to take all those steps into account, and to massage the audio signal in appropriate fashions when when possible, in order that the wavefront experienced by the ears gives as good an experience to the audience as possible - bearing in mind what's happened to the signal between the original time-varying wave-front being detected by yer mikes and the reproduced time-varying wave-front making yer ear drums jiggle. It is not merely the vinyl and the pickup elements that must be considered when massasing the signal, nor can the vinyl and pickup elements be thought of as unvarying elements for all sorts of reasons. And because the reproduction chain is too complex and subtle for pure engineering measurements to do the best job, one needs to have experienced sound engineers on the case for high quality work - people who understand the engineering/technical side thoroughly, who also have the required experience and aesthetic touch to get it spot on right when doing the mixing and cutting. Rowland. -- Remove the animal for email address: rowland.mcdonnell(a)dog.physics.org Sorry - the spam got to me http://www.mag-uk.org http://www.bmf.co.uk UK biker? Join MAG and the BMF and stop the Eurocrats banning biking
From: Rob on 29 Dec 2009 06:32 On 28/12/2009 11:07, Adrian Tuddenham wrote: > J. J. Lodder<nospam(a)de-ster.demon.nl> wrote: > >> Rob<patchoulianREMOVE(a)gmail.com> wrote: >> >>> On 26/12/2009 12:51, Rowland McDonnell wrote: >>> >>>> >>>> It is a technical error, these days, to mix the typical audio recording >>>> in a fashion optimized for vinyl discs, >>> >>> In what way is audio recording optimised for vinyl? Do you mean mixing, >>> or some form of filter? I only ask as someone interested in recording >>> *from* vinyl, and asithappens, listening to LPs. >> >> A better way to put it would be that the audio signal to be put on disk >> is constrained by the limitations of vinyl and PU elements. > > I would have said "constrained by the limitations of groove geometry and > the intended playback equipment". > > The vinyl itself does impose some limitations, but most of the problems > would still occur if they had used "Shellac" (slate dust with shellac > binder), "Acetate" (cellulose nitrate), gelatine, wax, rubber, > chocolate, thermosetting resins, catalytic resins or any of the hundreds > of other materials which have been tried over the past century. > > Ah, thanks. I suppose what I'm after is an understanding of how the sound is changed by processing (optimising) (rather than limitations of vinyl) from the master tape - would it be 'duller', 'bassier' etc.
From: Rob on 29 Dec 2009 06:36
On 29/12/2009 11:02, Rowland McDonnell wrote: > J. J. Lodder<nospam(a)de-ster.demon.nl> wrote: > >> Rob<patchoulianREMOVE(a)gmail.com> wrote: >> >>> Rowland McDonnell wrote: >>> >>>> It is a technical error, these days, to mix the typical audio recording >>>> in a fashion optimized for vinyl discs, >>> >>> In what way is audio recording optimised for vinyl? > > That's only done when an actual groovy vinyl record thingy is the end > product. > >>> Do you mean mixing, >>> or some form of filter? > > Optimizing for vinyl means `making the recording bearing in mind the > technical limitations of the equipment'. There are things that must be > done to make it good and they're different things if you're aiming at a > groovy vinyl consumer data carrier rather than a pitty CD consumer data > carrier. > > I don't know any of the interesting details, just a few of the obvious > things. > >>> I only ask as someone interested in recording >>> *from* vinyl, and asithappens, listening to LPs. >> >> A better way to put it would be that the audio signal to be put on disk >> is constrained by the limitations of vinyl and PU elements. > > The best way to put it is to point out that the time-varying wave-front > experienced by the ears of the audience on playback is a product of the > convolution of all the steps in the reproduction chain from microphone > to ear[1]. > > It is therefore necessary to take all those steps into account, and to > massage the audio signal in appropriate fashions when when possible, in > order that the wavefront experienced by the ears gives as good an > experience to the audience as possible - bearing in mind what's happened > to the signal between the original time-varying wave-front being > detected by yer mikes and the reproduced time-varying wave-front making > yer ear drums jiggle. > > It is not merely the vinyl and the pickup elements that must be > considered when massasing the signal, nor can the vinyl and pickup > elements be thought of as unvarying elements for all sorts of reasons. > > And because the reproduction chain is too complex and subtle for pure > engineering measurements to do the best job, one needs to have > experienced sound engineers on the case for high quality work - people > who understand the engineering/technical side thoroughly, who also have > the required experience and aesthetic touch to get it spot on right when > doing the mixing and cutting. > That's interesting, thanks. I'm afraid I'm of a view that the sound from decent vinyl appears more 'natural' than digital on occasion - this is a factor I hadn't considered in going some way to explaining one of the many reasons for 'difference'. |