The silver mica is the bad (excess noisey) one. The Pease model uses an R/C ladder which would give a fractional power of f noise. The low frequency limit is just the 5G resistor rolled off by 50pF with a simple RC time constant. The lower plot conforms to this very closely.
A good question is the mechanism, a quick search of the literature does not turn up anything. The easy argument is "if it looks like a resistor it is", but DA comes from complex dielectric electromechanical interactions.
Last edited:
Scott,
You mean all of this is news to you?
Capacitor microphonics are documented for ages, as is the DA stuff.
I use Mica where the greater DA is of no concern but the Microphonics is, because PS and similar cap's are way too microphonic... I mean I have done this for a decade and a halve!
Ciao T
You mean all of this is news to you?
Capacitor microphonics are documented for ages, as is the DA stuff.
I use Mica where the greater DA is of no concern but the Microphonics is, because PS and similar cap's are way too microphonic... I mean I have done this for a decade and a halve!
Ciao T
Really? Then what is that broadband noise in Scott's measurement (which correlates with Dimitri's sim)?
Of course, it was a terrible pain, in the mastering room, to hear how your beloved mix was destroyed by the LP grooving machine. Of course, it was painful to hear how our tapes where destroyed at each passes on the magnetic heads of the multi track recorder.
While, apart some audiophile maniacs looking for i don't know what, CD copies of a master tape (analog or digital) are pretty similar to the original.
I was talking about something else related to poetry. With the research of absolute reproduction fidelity, we loose something, like hyper sharp digital color photography loose the poetry of the black and white films.
Well, I've heard recording engineers make the same complaint about CD. They'd complain how the CD didn't sound anything like what they mixed, it sounded worse.
I do very much like high quality recordings done on the SACD and Bluray formats. When comparing to the CD and SACD or even LP counterpart, it's the rare exception that I prefer the CD. I only feel I've lost something when listening to the CD format.
That's my experience and my opinion. I certainly don't discount yours which is equally valid.
John
James D. Johnston. From his time at Bell Laboratories, I believe.
Snow reflects sound just fine. If your anechoic chamber does not thwart your ability to gauge distance (not localize), then it probably only has the walls treated and not also the floors and ceilings. It's the bounce off the floor that provides echo clues to the brain about distance.
Note that I did not claim that a lack of reflections causes problems with localization. Think in terms of a polar coordinate system: you can localize a sound by detecting the angle it is coming from, but without echoes your brain cannot determine the distance. Those two parameters are completely independent.
I did not interpret Scott's remark to illustrate a case of microphonics (which is internal to the cap), but rather that thin, bouncy legs contribute to a kind of inductance modulation (in that long legs on caps have an L that is not negligeable, and that vibrations would vary the geometry of the area enclosed by the two leads).
Scott, what is your explanation?
vac
The bounciness is the reason for the spikes. But that's just a side-note, the real interesting part is illustration of the Johnson noise from DA.
First we might also wish to know what the ESR induced Johnson noise is before we can conclude the mechanisme causing it is DA.
Physically impossible to have a transparent Vinyl, John: Remember the equalizers & the compressors used by the magician/mastering engineer, to get their grooving head not going out of the rails during transients, remember the turntable head, each one sounding different from the other with all this mechanical, electrical differences, remember the RIAA curve. Mastering a CD (or Blueray, i was talking about Digital, in general) is just a matter of tuning the average volume, keeping the things flat.
Differences between a CD and a blueray is very thin don't you think, and need high level quality equipments to be noticed, agree ? I was talking for the large consumer market. For the few audiophiles, it depends so much of DA+filters stages and so on. Of course, highest sampling frequencies are best. And more thin details at low levels (bits) better it is too. Yes, a little feel of losses in CDs, but with vinyl, lot of unwanted adds + losses of dynamic, treble precision etc, when comparing to the original ;-)
Of course, i agree, but not totally.rsdio said:
Will be hard to explain with my poor English. It is very much a question of culture, i believe. If you know how is the sound of the source (a well known instrument or human voice, by example) your brain can evaluate the distance by integrating the attenuations in the the response curve ( in comparison with his memory of how was the same source when near). Those changes in the response curves are combinations of several factors. Distance in air transmission (loss of energy in the basses, damping of high frequencies) and lateral and vertical position of the sound to our ears (angles). Our ears don't have the same response curves following both horizontal and vertical angles, and our brain use all those informations to localize sounds, can estimate distance and even estimate the vertical position, front and back. We use too movements of our heads, instinctively, to help us localize the sounds, and our eyes (pretty lost in an dark anechoic chamber, i agree ;-).
Our natural environment is outside, (not so much echoes) and getting a good evaluation of the distances of our predators was a question of survey. So our brains had developed a very complex analysis program during evolution ;-) Yes i can roughly estimate distances in an anechoic chamber, may be it is different depending each of us ?
When you need to create a distance in a movie outside scene (no echo available), on a studio recorded voice, you had to work on the response curve (reducing basses and treble) to create realistic dialogs or effects. Here too image helps, and culture too with our eyes: we can integrate the lens angle (tele-photo or wide angle) as well
Our listening experience is a very complex thing, and can be different between people, may-be that explain all those lines, during all these years, in this forum ?
Last edited:
Discussions of vinyl vs. CD are apples-and-oranges if comparing commercial releases. In the case of American popular music of the boomer generation, it's now very difficult to find (in America) good transfers of major acts because they've been "remastered" by deaf but well-meaning yoyos.
If you want to hear a clean American transfer of Van Morrison, Emmylou Harris, or the Grateful Dead, you'll need to find a used version made before about 1995. It will sound like the vinyl record, but without the wear. A newer transfer and "mastering", even if it's by Rhino or someone like that, stinks on ice. There's no excuse either - the technology is improved close enough to perfect that it doesn't matter. It's a *choice* to make it worse. Bah, humbug.
Personally, I quit worrying about the *technical* quality of CD's when I found I could burn a CD-R copy of a vinyl record that I couldn't tell from the original. Good enough is good enough.
Thanks,
Chris
If you want to hear a clean American transfer of Van Morrison, Emmylou Harris, or the Grateful Dead, you'll need to find a used version made before about 1995. It will sound like the vinyl record, but without the wear. A newer transfer and "mastering", even if it's by Rhino or someone like that, stinks on ice. There's no excuse either - the technology is improved close enough to perfect that it doesn't matter. It's a *choice* to make it worse. Bah, humbug.
Personally, I quit worrying about the *technical* quality of CD's when I found I could burn a CD-R copy of a vinyl record that I couldn't tell from the original. Good enough is good enough.
Thanks,
Chris
Calm down Thorsten, obviously? I'm afraid you are mistaken. If a capacitor with DA behaves from its terminals like an R-C network then it has Johnson noise.
It's a distraction, just that I tacked the cap in and left the leads long. At 5G Ohms any movement makes for some charge induced. SY is right the mica cap has several KOhms of real impedance midband due to DA loss and this is what is important.
ESR/DA I'm not sure they are distinguishable except that an ESR would act like a fixed resistance not a distributed RC with a frational f dependence. An ESR would be a flat vs f noise floor just like in the plot where the amplifier noise floor is about 3nV/rt-Hz.
Please don't be distracted by these details because I can't help trying to explain every one of them.
Last edited:
> may-be that explain all those lines, during all these years, in this forum ?
May-be 🙂? .... 🙂
May-be 🙂? .... 🙂
The example I cited referred to human voice only, which does not have significant bass or high frequency. Within the confines of an anechoic chamber, there doesn't seem to be enough distance possible for air transmission to affect voice to any significant degree. I'm sure that a violin playing near or far would have some high frequency loss, but not voice.
All of the HRTF effects that you list above affect position perception in terms of angle only. None of these effects allow calculation of distance.
I beg to differ that there are not many echoes outside. We're certainly less conscious of the echoes, but leaves and snow and ground cover all reflect sound and enter the calculations of our brains. It takes very careful artificial constructions to eliminate echoes completely. It's not enough to reach "not so much echoes" - it's necessary to completely remove them before the effect I'm citing can be perceived (or not perceived, as it were). The reason that I am excited about psychoacoustics research is that we can often only learn how we perceive something like the distance of a sound source when eliminating a major contributing factor such as echos.
Actually, I'd say that the real differences are in the anechoic chamber. Very few actually remove echoes due to bounce off the floor and the ceiling. Bell Laboratories specifically dealt with these echoes and that's when distance perception disappeared. I suspect that your anechoic chamber just wasn't built with the same high budget.
Yes, in film and video games it is common practice to exaggerate such effects so that they are noticed. But in real life there is no exaggeration, and in a true anechoic chamber there's practically no distance perception for human voice.When you need to create a distance in a movie outside scene (no echo available), on a studio recorded voice, you had to work on the response curve (reducing basses and treble) to create realistic dialogs or effects. Here too image helps, and culture too with our eyes: we can integrate the lens angle (tele-photo or wide angle) as well
There are minor differences from person to person, but all sound is affected by the same laws of physics for everyone. So, the challenge is to distinguish between effects that are largely or completely controlled by the laws of physics, and therefore will be perceived the same by every listener, versus effects that are dependent upon the shape of the pinnae, size of the head, and condition of the hearing system, e.g. training (Nelson's 10,000 hours) or age/abuse (too many hours of rock concerts), and thus might vary greatly from one listener to the next.
- Status
- Not open for further replies.