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Stuff above 20kHz

Discussion in 'Recording' started by analogue, Sep 9, 2003.

  1. analogue

    analogue Guest

    If the frequency response of DSD goes upto 100kHz, then what speakers actaully lets my brain aware of these freqs??? I.e the freq. of most monitors just dont go that high so therefore we'd be much better just have that has more bits than freqs??
     
  2. by

    by Guest

    The higher cycles do contribute to the overall sound, it adds harmonics and complexity and smoothness. On most speakers, you should be able to tell the difference between the DSD signal and the down-converter 16/44.1 version (if you got a hybrid CD like that). I think it's a much more noticable difference then the higher PCM resolutions (24/96)... DSD is an awsome technology, I can't wait till the prices go down a bit.
     
  3. jdsdj98

    jdsdj98 Active Member

    Alex, I've been asking that same question for a long time, along with questioning what mic's people are using when extolling the virtues of extended frequency response afforded with higher sampling rates, etc. I've not gotten a satisfactory answer, although I am beginning to see a few monitors offering extended response (Tannoy's latest come to mind). But realistically, there just aren't enough mic's and monitors responding FLAT way out past 20k for people to be using extended frequency response in defense of huge files and greater processing demands. I'd say the benefits of all this lie more in higher resolution offered by higher sampling rates, and more accurate dynamic range offered by higher bit depths.

    Those of us in the project studio realm rarely, if ever, get the chance to play with lots of high end toys. But just humbly asking point blank, who out there is running sessions where the vast majority of mic's employed and the entire monitoring system is capable of FLAT response significantly beyond 20k? If so, specifically who's making this stuff and what are the model numbers? Is it available to the general populace, or reserved for only the best of the best, and kept shrouded in great secrecy, as seems to be the case?

    I'm not trying to sound like a smartass at all, and certainly don't want to sound like a dumbass, but I've long been curious about this. I know there are a handful of microphones and monitors capable of FLAT response way on out there, but from what I've found, they really are just that, a handful.
     
  4. jdsdj98

    jdsdj98 Active Member

    Aw man, once again, this question falls flat on its arse.

    I have never received a make and model specific answer to this question.

    Is it because the question is idiotic, or is it because it's a perfectly legitimate one?

    I'm just curious.........
     
  5. dymaxian

    dymaxian Guest

    I think higher sampling rate's only real advantage is the transient response. The speakers will respond to a fast-attack sound (if the playback system is capable, anyway) in half the time if you double the sampling rate. However there aren't too many people who can reliably tell the difference between .0000226 seconds and .0000104 seconds. I know I can't. With the right material, and thru good speakers, you can hear the difference between 44.1 and 96. But you gotta know what you're listening for.

    I think it'd be far easier for clever engineers to use mastering tools to 'sparkle' up music and DVD soundtracks than it would to get an audible, worthwhile step forward in sound quality from a sampling rate over 96k. This will create a better sound that a clever marketing plan can attribute to the increased data-rate. I can understand that level of quality, but going over that is a little ridiculous.

    Now, if you're recording at 192k with the intention of lowering the sampling rate down to the targeted 96k once production is finished, I suppose I could see that- for the same reason as we record in 24bit when we know it'll get dithered to 16bit for standard CD use. That's still a little excessive, and personally I think I MIGHT use 88.2k in that respect... maybe...

    It's fun to play with the idea, anyway. Maybe it will make a bigger difference in your recordings than it does in mine. *shrug*

    Just thinking out loud.
     
  6. Duardo

    Duardo Guest

    The higher cycles don't add anything...they just capture higher frequencies, period. If you're hearing a difference it likely has more to do with the effects of the filters used to get rid of those higher frequencies at 44.1kHz than it does with the presence of those frequencies themselves.

    As you mentioned, Tannoy has their SuperTweeters™, and I'm sure there are a few others as well. As far as microphones are concerned, Earthworks and DPA have models that are flat past 40kHz and beyond. I'm sure that there are quite a few that, while probably not flat, do have a usable frequency response that goes up that high, but most don't bother to print it because we don't hear it and up until recently haven't really been able to cancel it. But you've got to figure that a microphone that's flat out to 20kHz can capture a lot more than that...frequency response won't drop off like a cliff.

    As for preamps, there are plenty of models from companies like Grace, Millennia, Focusrite, Earthworks, GML and others that are flat well past 100kHz and even into the mHz range.

    As for who's running sessions where the microphones, preamps and converters employed run way up there...certainly a lot of classical recordings, where not so many microphones are used, are done like that. Probably more of the "purist"-type recordings in general.

    The dynamic range offered by higher bit depths isn't more accurate, it's just bigger. Each bit gives you about 6 dB. 16 bits give you a 96 dB dynamic range (potentially). 24 bits give you 144 (potentially). But the dynamic range at 16 bits is no more accurate than it is at 24.

    The transient response, as far as we can hear, is the same at higher sampling rates...if anything, it's limited by our analog amplifiers and speakers rather than the sampling rate.

    It's not the same reason at all. We record at 24-bit resolution even when dithering down to 16 at the end because some of that extra dynamic range can be retained in a properly-dithered signal. But there's no such advantage when it comes to sampling frequency. You can't retain signal above the Nyquist frequency, period...it's all gone when you downsample.

    Not that there aren't valid reasons to sample at the higher rates...certain digital processes sound better when done at higher rates, for instance, and some converters just sound better at higher rates...but you're not able to capture anything extra and keep it after downsampling as far as higher frequencies are concerned. In a best-case scenario you'll have a signal that sounds identical to the way it would have sounded if recorded at the lower rate in the first place, and in most cases it won't sound as good.
     
  7. Kurt Foster

    Kurt Foster Distinguished Member

    This topic has been discussed many times here. Check the archives.. there are comments quoted from Rupet Neve articles and pages of argument.. I have heard the difference and I believe that higher frequency response sounds better.. I have had the chance to hear 2" analog masters, against 96K and 48K and 44.1K and I think 96 is a lot better than all, except the analog..

    Even if it is not a flat response (down 10dB @25K?) it is still there contributing. More brain activity has been measured with analog vs. digital and higher rates result in the listener coming away from the listening session reporting a more "satifiying" expierence..
     
  8. Duardo

    Duardo Guest

    Sure, it's a topic that there will probably always be lots of debate on and that may never be resolved...but I still haven't heard or read anything that's convinced me that recording at 96 kHz in and of itself is superior to recording at 44.1kHz. Rupert Neve's comments pertain mostly to analog audio design, where having a flat frequency response up to 100kHz and beyond may be necessary because of the way it affects the frequencies below 20 kHz. That doesn't mean we need to capture that entire bandwidth. There has been no scientific study that has ever shown that anyone can perceive the difference...the one everyone refers to showed that our brains sense the presence of those higher frequencies on some level, but none of the subjects were able to tell which recording was which. But most importantly, the best-sounding converters I've heard sound identical at 44.1kHz and 96kHz, and until I hear something that not only sounds better, but that sounds better at higher sampling rates, I don't see any reason to believe otherwise since there's no reason, scientific or otherwise, to do so.

    The problem is, again, that this isn't something that can really be "proved"...because how do you know that the improvements you're hearing are a result of the presence of higher frequencies, and not due more to the effects of filtering and so on? Sure, if it weren't possible to design a filtering system that worked as well at 44.1kHz as it does at 96 kHz or 192 kHz that'd be one thing, but with today's oversampling converters and digital anti-aliasing filters it is possible and it is being done. But if things change, I'm all for whatever sounds best, and if I'm in a situation where I'm using a converter that clearly sounds better at 96kHz (or 88.2kHz) than it does at 44.1kHz I'll certainly run it at that frequency if I can.

    -Duardo
     
  9. Kurt Foster

    Kurt Foster Distinguished Member

    I have to respectfully disagree. As I said, I have had a chance to run an 2" analog miltitrack through a large format console with a tape send / return bus, level matched, patched through an Apogee PSX 100 at 96K.. and as I switched down from 96 to 48 and finally 44.1 the differences were obvious, not only to myself but to several other people in the room, who could not see what rate was being selected.. Switching from analog (the 2-bus) to digital (the tape send / return monitor bus) made the biggest difference but in digital, the lower the rate, the worse it sounded, with a sense of the ceiling being lowered and a perciveable loss of "air" and high end detail. I am positive to my ear, frequencies of 20K and above make a difference even though I know I don't "hear" much over 17K. To people who do hear higher than 20K (they are out there), I am sure this difference would be even more percevable. Just because you don't hear it Duardo, doesn't mean others can't either.. As I said, all of this has been gone over here before. Search the archives, there is a lot of interesting comments, arguments and opinions there. Good reading..
     
  10. Kurt,
    I like that your test was conducted using quality converters. Lower quality converters might even make it more obvious. I am content to stay at 24/48 until such time as I feel a significant upgrade is available to me at an attractive price. David
     
  11. Duardo

    Duardo Guest

    But how do you know that the difference you're hearing has anything to do with the presence of higher frequencies? How do you know that it doesn't have more to do with the design of that particular converter than the higher sampling rate itself? Again, I've participated in tests like this myself, and with some converters there is a clear difference to my ear. But that only means that that particular converter sounds better at 96kHz, and it certainly doesn't mean that it sounds better because it's captured higher frequencies.

    -Duardo
     
  12. Kurt Foster

    Kurt Foster Distinguished Member

    The converters I was using was an Apogee AD 8000. I am pretty sure we could agree this particular A/D/A is a benchmark piece..
     
  13. Duardo

    Duardo Guest

    Actually, we can't agree on that...it's an Apogee piece, not a Benchmark...

    Seriously, though, now I'm confused...were you comparing a PSX100 to an AD8000?

    -Duardo
     
  14. Kurt Foster

    Kurt Foster Distinguished Member

    Opps! You're right it was a PSX 100 not the AD 8000 I keep making that mistake.. I made it before in some of those other threads I refered you to... sorry , silly me. I have rented both units before from Jarvis, David Denny is SF... I get soooo confused! K. :confused:
     
  15. Duardo

    Duardo Guest

    Yeah, I'd agree that the PSX100 is a benchmark piece, although there are certainly better units out there...and also, the design of the PSX has changed over the years, so a new PSX will sound better than one that's two years old, which will sound better than one that's four years old...

    In any case, despite the fact that it's a great converter, it's not perfect...nothing is...just that even though it sounded different to you at the different sampling rates, how do you know that the differences you were hearing had anything to do with the presence of higher frequencies?

    -Duardo
     
  16. Kurt Foster

    Kurt Foster Distinguished Member

    Duardo,
    "A sense of the ceiling being lowered and a perciveable loss of "air" and high end detail." These artifacts were not present in the analog play back and even at 96K there was some , albeit slight loss.. as the sample rate was decreased, these artifacts imposed themselves increasingly. What else would you attribute this to? The only thing I can think of is the loss of frequenceis above 20K (the 2" tape machine was specd out to 24K.. ).
     
  17. Duardo

    Duardo Guest

    I would think the more likely thing would be the effects of the antialiasing filters.

    -Duardo
     
  18. Kurt Foster

    Kurt Foster Distinguished Member

    Aren't those the things that roll off the high end above a certian frequency? :s:
    @20K for 48K and @40K for 96K?

    I think that's what I'm saying ....

    The absence of higher frequencies is detrimental.
    There was a time when a lot of people thought that we didn't need anything over 6K because that's all AM would do... then it was 15K for FM ... but thank Gawd the engineers of those days still shot for 20K... (and higher).. this is why vinyl still sounds better to some of us..
     
  19. AudioGaff

    AudioGaff Well-Known Member

    Well, Vinyl and it's related electronics are far from ideal, neutral or being natural and had so many issues that it requires a special RIAA eq curve to try to compensate for it's non linearaties.

    Increased bit depth and higher sampling rates do offer many advantages but it is much harder to work with to obtain the higher quality recordings it is capable of capturing as it no longer allows you to ignore, bury or hide the flaws and other negative nuances in the recording process that many took for granted. At the same time, the postive things in those flaws are now hard to almost impossible to recreate without using yet another layer of hardware/software processing, or rather some sort of emulation processing that is not the same and has it's own artifacts.

    In every piece of analog gear I've used that has a much extended bandwidth over the normal 20khz, has sounded better to me. However, I don't believe that the extended bandwidth it has is the main reason or is even as important as many other factors.
     
  20. I could see the "sounds better" factor coming from:
    1. Higher sampling rates allowing a smoother curved anti-aliasing filter.
    2. The presence of higher, inaudible frequencies having an effect on lower, audible frequencies that results in a more "realistic" sound.
    3. Higher sampling rates more "realistically" capturing audible frequencies (and amplitude).
    Guess I'm a fence sitter. David
     
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