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#1 Filip Plesha

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Posted 23 March 2006 - 07:32 AM

I don't know much about eletronic sound recording,
but I've noticed how sound changed over the years. All but the best music recordings in 80's, 70's and so on had a somwhat different sound than what modern digital and analog sound recordings sound.
Somehow modern sound sounds more "open" and "clean", but I can't find words how to describe older sound recordings

All this is specially present in movies.

Now can someone describe in technical terms (feel free to be technical, If I don't understand some words
I'll look it up somewhere) what makes older sound recordings sound so different?
Somehow warmer, smoother, somehow compressed, and it sounds funny when people say letters "s"

Also, how would one emulate such an old sound with either digital or analog tools?
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#2 Hal Smith

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Posted 23 March 2006 - 02:14 PM

I don't know much about eletronic sound recording,
but I've noticed how sound changed over the years. All but the best music recordings in 80's, 70's and so on had a somwhat different sound than what modern digital and analog sound recordings sound.
Somehow modern sound sounds more "open" and "clean", but I can't find words how to describe older sound recordings

All this is specially present in movies.

Now can someone describe in technical terms (feel free to be technical, If I don't understand some words
I'll look it up somewhere) what makes older sound recordings sound so different?
Somehow warmer, smoother, somehow compressed, and it sounds funny when people say letters "s"

Also, how would one emulate such an old sound with either digital or analog tools?

Transparency in reproduced sound is mostly a combination of very low noise floors and low intermodulation distortion. Purely harmonic distortion (HD) isn't a big problem in reproduction, the distortion products generated by harmonic distortion are in exactly the same mathematical relation as the natural overtones associated with timbre in musical instruments. They "hide" in the natural overtones, another way of putting it is to say that HD products are more musical. The sound will be somewhat different depending on the amount of HD, many people would describe it as being "fatter" with HD present.

The problem with an excessive noise background is obvious, the noise masks or hides the subtle characteristics of sound. But intermodulation distortion (IM) is another story entirely, in IM the distortion products are the sum and difference products of the various frequencies in the sound, as a result the new frequencies are NOT in any harmonic relationship to the original sound - they're brand new frequencies and very unnatural and unmusical.

In practice any non-linearity of amplication or mechanical transduction between sound and electrical signal will generate both HD and IM, the amount of each determined by the transfer characteristic of the non-linear stage. If you imagine a gamma curve for sound, you'll be close to the concept, perfect sound requires an absolutely straight transfer curve line.

Aphex manufactures a product called the Aural Exciter that introduces new distortion products on purpose, they've become somewhat passe' around radio stations and a little digging might find one pretty cheap. They're between $200 and $800 new depending on the exact model. There's also a TDM software Aural Exciter plug-in for Pro Tools in the $450 range.

The different character of recorded esses is somewhat due to the fact that sibilance is quite loud, it often gets clipped because it overdrives the microphone preamplifier (if not a later stage). Clipped esses basically become a white noise burst hence the distinctive sound.

One more thing, due to the higher noise and distortion product floors analog recordings usually do have a fair amount of compression added somewhere along the way. With much sound the dynamic range is great enough that without some help the sound would be in the noise one minute and overloading amplifiers the next.
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#3 Filip Plesha

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Posted 23 March 2006 - 02:54 PM

That's some great information

So let me see if I got it right..
The "warmth" of older recordings has to do with HD distortion. I assume its the same kind of distortion that makes records sound smoother and warmer than CD's, right?

I think the place where all those things I observed is pronaunced to maximum are optical soundtracks on movies. Now I have not heard an optical soundtrack in many years now, but as far as I remember it had a very textural kind of a sound, somewhat reduced in quality, but had some interesting "fatt" (as you say) qualities to it. The sharp tones used to resonate in a wery warm and unusual way, amost hypnotic.
Can you tell me, again in technical terms, what are some of the characteristics of optical soundtracks, what are their problems and what makes them sound the way they sound. Is it the same thing as for all analog sound recordings only exagerated, or is it something different..

about the "esses", just to confirm that we are talking about the same thing:
the most memorable example I can think of are some lines from SW "a new hope"
Like the one where Luke says: "I want to learn the ways of the force and become a Jedi like my father, there is nothing for me here"

his esses sound like sh, more like an s

is that the effect you described?
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#4 Hal Smith

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Posted 23 March 2006 - 03:27 PM

That's some great information

So let me see if I got it right..
The "warmth" of older recordings has to do with HD distortion. I assume its the same kind of distortion that makes records sound smoother and warmer than CD's, right?

I think the place where all those things I observed is pronaunced to maximum are optical soundtracks on movies. Now I have not heard an optical soundtrack in many years now, but as far as I remember it had a very textural kind of a sound, somewhat reduced in quality, but had some interesting "fatt" (as you say) qualities to it. The sharp tones used to resonate in a wery warm and unusual way, amost hypnotic.
Can you tell me, again in technical terms, what are some of the characteristics of optical soundtracks, what are their problems and what makes them sound the way they sound. Is it the same thing as for all analog sound recordings only exagerated, or is it something different..

about the "esses", just to confirm that we are talking about the same thing:
the most memorable example I can think of are some lines from SW "a new hope"
Like the one where Luke says: "I want to learn the ways of the force and become a Jedi like my father, there is nothing for me here" his esses sound like sh, more like an s

is that the effect you described?


Yes, HD and "warmth" are very related. Maybe with some additional high end rolloff to kill the higher frequency overtones generated by the HD.

I vaguely remember that variable area optical sound tracks (RCA/RKO system) were recorded with a moving mirror on what amounts to a d'Arsonval moving meter mechanism. There would have been all sorts of problems with mechanical resonance, overshooting, etc. in such a contraption. Who knows how many kinds of novel distortions would get introduced by that system. If they're still using that technology I'd be real surprised, there are many ways to produce a variable area optical sound track today that wouldn't use moving parts. Another thought about optical tracks, the playback system on projectors is probably still pretty much ancient technology. I suspect very little development has happen since magnetic tracks, DTS, etc. have become pretty much dominant.

I'm not certain about the SW "New Hope" esses. Given all the digital technology and toys Ben Burtt had available to him (MK I Sound Droid, etc.) that could be anything from badly overdriven sibilance fixes to a deliberately manipulating the sound to catch the viewer's ear. After all, isn't that line the overarching plot of ALL six Star Wars features?
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#5 Filip Plesha

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Posted 23 March 2006 - 03:39 PM

Well I don't know, I've heard that particular "s" performance in many films from that time, and sometimes even as late as early 90's.
To me it sounds as if the "s" gets softened somehow into an "sh"

I was just mentioning that line as an example, but the effect is present throughout that movie and many more movies from that time.

Oh and I remembered one very important fact about that, it is present only in lines which were obviously ADR-ed.
Like the lines of Aunt Beru which entire sound was recorded by another acress in the studio.
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#6 Hal Smith

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Posted 23 March 2006 - 04:09 PM

Well I don't know, I've heard that particular "s" performance in many films from that time, and sometimes even as late as early 90's.
To me it sounds as if the "s" gets softened somehow into an "sh"

I was just mentioning that line as an example, but the effect is present throughout that movie and many more movies from that time.

Oh and I remembered one very important fact about that, it is present only in lines which were obviously ADR-ed.
Like the lines of Aunt Beru which entire sound was recorded by another acress in the studio.


Aha!

Generally found in most studios, most definitely in an ADR studio, there's a magic box available called (Tah Daah!) a de-esser. Yep there's a processing function called a de-esser, it detects the excessive amount of high frequency in esses and rolls off the high end dynamically. A lot of dedicated mike processors have them, not necessarily expensive ones only. The DBX 266 mike preamp and processor has a pretty good de-esser in it, that box is my favorite bargain basement mike proc.

I suspect you've got pretty good ears - trust them. A lab full of high end audio analysis gear isn't as good as the billion dollar sound processor the good Lord installed in our heads. I've got some pretty decent audio test equipment from companies like Audio Precision and Hewlett-Packard/Agilent but I have learned to trust my clients who have golden ears and really listen to them.

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#7 Filip Plesha

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Posted 23 March 2006 - 04:32 PM

Yea, that's probably it them

thanks

by the way, what do you do, where do you work?
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#8 Dominic Case

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Posted 23 March 2006 - 05:28 PM

Now I have not heard an optical soundtrack in many years now

I suspect you have - all tracks on films played in the cinema are optical, with the exception of DTS which is played from a CD-ROM.

The distinction to make is between analogue (the Dolby SR track) and digital (Dolby SRD and Sony SDDS). Apart from the deep differences in harmonic and intermodulation distortion already mentioned, there are basic differences between analogue and digital optical tracks. Analogue has a dynamic range of under 60 dB - digital tracks can go up to 90 or 100. This isn't just a matter of how loud can the loud bits get, but what is the separation between any two levels. The SR term in Dolby SR and SRD stands for Spectral Response, where the Dolby system of noise reduction is applied differentially at different frequency bands. Prior to that, the original Dolby system was not only the first effective stereo system for optical tracks, it also extended both dynamic range (by way of noise reduction) and frequency response considerably from the old mono "Academy Curve" which started to roll off just above 1KHz.

Then the 4-2-4 method used in Dolby SR to produce centre and surround tracks as well as left and right, out of two channels in the optical track itself, is ingenious, but gives less than perfect separation. There is very much less cross-talk in the discrete digital systems, which I guess also contributes to the overall "openness" of the sound.

Analogue optical tracks are particularly susceptible to cross-modulation distortion if the printing density of the track is wrong. The characteristics of image spread introduce false tones around high frequencies leading to that "spitting" sound in "S"s. Its sound is similar to an analogue radio station just off-frequency, but that's not such a useful analogy now that most people listen to FM radio.

Optical digital tracks aren't affected by this particular problem.
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#9 John Pytlak RIP

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Posted 23 March 2006 - 11:15 PM

The Kodak website has a good tutorial about cross-modulation testing to optimize optical analog soundtrack performance:

http://www.kodak.com...ort/h44/h44.pdf
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#10 Hal Smith

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Posted 24 March 2006 - 12:32 AM

Yea, that's probably it them

thanks

by the way, what do you do, where do you work?

My "day" job is radio broadcast engineering, I own my own company and do all sorts of engineering for about 12 clients in OK. Degree is an MS in Teaching of Physics. I'm a contract consult to the University of Central Oklahoma's 100kW classical music FM, several radio groups around the state, and sometimes I do work for cellular and power companies performing various RF tests. I build new studios and transmitter installations now and then for clients. I do theatre lighting design here in OKC with a small Equity company, and have been getting back into film after a long layoff. I shot a bunch of 16mm B&W ethnographic film in the 70's with an ex-wife, nothing you've ever seen - it's probably all lying around the University of Chicago in some archive.

I've got to know a bunch of good actors here in OKC which got me back into thinking about film. I've got a short film in mind that in particular I'm writing for one very awesome actress who's definitely got "it". I shot some archival video of a production I lit that she was in and made of point of following her around quite a bit to see if she came off as charismatic on video as she does live on stage - she does. Ever been around an actress that has so much personal magnetism that it's hard to breathe when you're around her? Not sexual, something entirely different that has something to do with her possessing what could be understood to be a very powerful soul. Magic!

I lived and worked in New York theatre a LONG time ago and actually gaffed for Pierre Gaisseau on some avant-garde dance I had done the stage lighting for - I've never seen the footage I lit but it was for "New York - Sur Mer". That was quite a trip for me, the performances were originally in Judson Church with barely enough equipment. Pierre tried shooting there and then announced he was going to borrow a studio to re-shoot it in. The studio? The old Screen Gems studio somewhere in west midtown Manhattan. I walked into that studio and about fainted when I saw all the lighting equipment lying around and hanging off the grid. Basically I told the union types what I wanted and they rescued my way-in-over-my-head fanny.

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#11 Filip Plesha

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Posted 24 March 2006 - 07:46 AM

I suspect you have - all tracks on films played in the cinema are optical, with the exception of DTS which is played from a CD-ROM.

The distinction to make is between analogue (the Dolby SR track) and digital (Dolby SRD and Sony SDDS). Apart from the deep differences in harmonic and intermodulation distortion already mentioned, there are basic differences between analogue and digital optical tracks. Analogue has a dynamic range of under 60 dB - digital tracks can go up to 90 or 100. This isn't just a matter of how loud can the loud bits get, but what is the separation between any two levels. The SR term in Dolby SR and SRD stands for Spectral Response, where the Dolby system of noise reduction is applied differentially at different frequency bands. Prior to that, the original Dolby system was not only the first effective stereo system for optical tracks, it also extended both dynamic range (by way of noise reduction) and frequency response considerably from the old mono "Academy Curve" which started to roll off just above 1KHz.

Then the 4-2-4 method used in Dolby SR to produce centre and surround tracks as well as left and right, out of two channels in the optical track itself, is ingenious, but gives less than perfect separation. There is very much less cross-talk in the discrete digital systems, which I guess also contributes to the overall "openness" of the sound.

Analogue optical tracks are particularly susceptible to cross-modulation distortion if the printing density of the track is wrong. The characteristics of image spread introduce false tones around high frequencies leading to that "spitting" sound in "S"s. Its sound is similar to an analogue radio station just off-frequency, but that's not such a useful analogy now that most people listen to FM radio.

Optical digital tracks aren't affected by this particular problem.



yes well when I say optical I ment analog optical, since with digital sound the medium has no effect on the sound itself, it could be recorded in stone plates and wouldn't make a difference
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#12 Hal Smith

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Posted 24 March 2006 - 09:50 AM

yes well when I say optical I ment analog optical, since with digital sound the medium has no effect on the sound itself, it could be recorded in stone plates and wouldn't make a difference

I understand that John Pytlak used to work for the company that built stone plate duping equipment. :D

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#13 Matt Pacini

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Posted 26 April 2006 - 05:11 PM

That's some great information

So let me see if I got it right..
The "warmth" of older recordings has to do with HD distortion. I assume its the same kind of distortion that makes records sound smoother and warmer than CD's, right? ...


No, not really. That's not what makes CD's sound better.
Any distortion recorded digitally will result in nasty, nasty ragged edge clipping. Not musical at all.
This is the reason why some guys prefer analog, (particularly in the music recording world), because tape saturation is much preferable to digital distortion.
And of course, there are cases of actually preferring massive analog distortion, the best example being guitarists (like me) and their tube amplifiers.
Dime out a tube amp, and you get your classic rock guitar sound - nice smooth distortion, but dime out a transistor amp, and it sounds like a train wreck.

As far as the "ess" sounding like "esh", I know what you mean. I think it's all the compression going on in the crunching process of making DVD's, etc.
Much more importance is being placed on the visual than the audio in this process. In fact, I'd say it's a good chance many of the people intrusted with this job know little or nothing about audio (from the sound of it).

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