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#2
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Post for processing.....
On Thu, 21 Apr 2011 06:28:59 -0700, Edmund wrote
(in article ): [Moderators' note: This was actually a post by Edmund, not me. -- deb] On Wed, 20 Apr 2011 21:57:11 +0000, Audio Empire wrote: On Wed, 20 Apr 2011 07:13:16 -0700, Arny Krueger wrote (in article ): =20 "Edmund" wrote in message Hi Guys, =20 Since I now finally have a HD player I like to buy HD material. There is a possibility to buy HD tracks on line. However when I open such a file with "Audacity" I don't SEE any frequency above 20 kHz, but I must admit I did not totally analyze this data I just looked at it in the graphics of Audacity. But I still wonder if any of these tracks actually contains frequencies above 20 kHz. What do you guys make of this? Many so-called hi definition recordings are actually 24/96 or 24/192 transcriptions of analog tapes and 16/44 or 16/48 masters. Analog tapes were ususally made at 15 ips which pretty well eliminates response above 25-30 KHz. Actually, it's difficult to maintain even a pro 15 ips analog tape recorder to much above 15 kHz. Self erasure, poor head contact at ultra-short wavelengths all make analog tape "iffy" at much above 15 khz. Back in analog days, most studios only maintained their tape decks to 15Khz. More than that took too long and wasn't practical. Before I recorded the SF Symphony back in the 1970's I would carefully align both Otari MX5050s for head azimuth, bias, frequency response, and Dolby 'A' level AFTER I set up the equipment (the tape recorder was not moved after that). I never tried to get response beyond 15 Khz, but I scrupulously maintained the recorders to that level. Any of you have a source for HD which has music information above 20kHz? Not really. Let's say that the recording was made at 24 or 32- bit and 192 KHz (or perhaps DSD). The recording equipment might have that kind of bandwidth, but I'll guarantee that the microphones used don't. Most condenser mikes fall-off like a rock above the resonant frequency of their diaphragms - and that is usually 16 -18 Khz. Not much there above those frequencies. Doesn't matter, though. You likely wouldn't be able to hear it anyway. Well we can assume anything, if technicians in the past would have assumed we could not hear improvements, we would still recording music on a drum made of wax. As Jwvm correctly points out, nature abhors the creating of true hi def recordings. His list of reasons is good and relevant. Let me make clear that I don't want to start whether or not higher frequencies are audible, only that HD music should have recorded higher frequencies in the first place. Why would it? A chain is only as strong as its weakest length. In the case of recording, as elsewhere in audio, the weakest length is always the transducers - speakers, phono cartridges, microphones. In this case it's microphones. I agree that it is very nice when so-called hi def tracks are actually hi def! ;-) The hi-def doesn't refer to recordings filled with extraneous and inaudible ultra-high-frequency information, it refers to the fact that the bandwidth of the medium is wide enough that only gentle slope filters, located high above the highest audible frequency, need to be employed on either end of the the chain (recording and playback) to satisfy Nyquist. I do not think you have in fact a gentle slope filter if one use a mic that filters like a brick wall. I'm not talking about the sound-source, I'm talking about the "high-resolution" 24-bit, 88.2/96/176.4/192 Khz recording process. Many insist that this sounds better. Certainly, recording information that only small dogs can hear is of no use to most humans in and of itself. The advantage (if any) is in the process of recording and playing back with a very high sampling rate, not the information that such a sampling rate is capable of quantizing. Hint, if any part of high-resolution recording is beneficial, its the word length (24 or 32-bits) not the sampling rate. Actually both word length and sample rate interact. Actually, word length and sample rate do not "interact". Word length gives you a specific dynamic range and the longer the word, the greater the (theoretical) dynamic range. As far as I can see, somewhere around 130 dB is about the limit of current technology. But with high dynamic range comes increased recording headroom and this is high bit-rate's most important contribution. OTOH, sample rate defines the highest frequency that can be quantized. Nyquist says that this frequency is half the sampling frequency. With 192 KHz, that's a Nyquist frequency of 96 KHz which, except for the advantage that this frequency is so far out of the pass-band of human hearing that any anti-ailaising filtering would have, essentially, no affect on the signal being quantized, really is meaningless in any practical sense. Notice, I'm not saying that such a high Nyquist frequency has no sonic advantages (though some here will be quick to give that opinion), I'm just saying that any "intelligence" that lies that far above audibility, is rather pointless in and of itself. Again I do NOT want to start a discussion whether or not HD audio is audible, first I am looking for recordings that actually recorded high frequencies. Suggestions for material/recordings are appreciated. Well, Edmund. Looks as if you're out of luck. |
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#3
Posted to rec.audio.high-end
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Post for processing.....
On Thu, 21 Apr 2011 15:23:06 -0700, Audio Empire wrote
(in article ): Actually, word length and sample rate do not "interact". Word length gives you a specific dynamic range and the longer the word, the greater the (theoretical) dynamic range. As far as I can see, somewhere around 130 dB is about the limit of current technology. But with high dynamic range comes increased recording headroom and this is high bit-rate's most important contribution. I didn't mean "bit-rate" as stated above, I meant bit-depth, as in 24 or 32-bit. Sorry about that. |
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#4
Posted to rec.audio.high-end
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Post for processing.....
[ I fumbled the formatting on the last message here. The
corrected attribution appears on the next three lines. -- dsr ] In Message-ID: Edmund wrote: On Wed, 20 Apr 2011 21:57:11 +0000, Audio Empire wrote: On Wed, 20 Apr 2011 07:13:16 -0700, Arny Krueger wrote (in article ): =20 "Edmund" wrote in message Hi Guys, =20 Since I now finally have a HD player I like to buy HD material. There is a possibility to buy HD tracks on line. However when I open such a file with "Audacity" I don't SEE any frequency above 20 kHz, but I must admit I did not totally analyze this data I just looked at it in the graphics of Audacity. But I still wonder if any of these track= s actually contains frequencies above 20 kHz. What do you guys make of this? =20 Many so-called hi definition recordings are actually 24/96 or 24/192 transcriptions of analog tapes and 16/44 or 16/48 masters. Analog tape= s were ususally made at 15 ips which pretty well eliminates response above 25-30 KHz. =20 Actually, it's difficult to maintain even a pro 15 ips analog tape recorder to much above 15 kHz. Self erasure, poor head contact at ultra-short wavelengths all make analog tape "iffy" at much above 15 khz. Back in analog days, most studios only maintained their tape decks to 15Khz. More than that took too long and wasn't practical. Before I recorded the SF Symphony back in the 1970's I would carefully align bot= h Otari MX5050s for head azimuth, bias, frequency response, and Dolby 'A' level AFTER I set up the equipment (the tape recorder was not moved after that). I never tried to get response beyond 15 Khz, but I scrupulously maintained the recorders to that level. =20 Any of you have a source for HD which has music information above 20kHz? =20 Not really. Let's say that the recording was made at 24 or 32- bit and 192 KHz (or perhaps DSD). The recording equipment might have that kind of bandwidth, but I'll guarantee that the microphones used don't. Most condenser mikes fall-off like a rock above the resonant frequency of their diaphragms - and that is usually 16 -18 Khz. Not much there above those frequencies. Doesn't matter, though. You likely wouldn't be able to hear it anyway. Well we can assume anything, if technicians in the past would have assume= d we could not hear improvements, we would still recording music on a drum=20 made of wax. =20 =20 As Jwvm correctly points out, nature abhors the creating of true hi de= f recordings. His list of reasons is good and relevant. =20 Let me make clear that I don't want to start whether or not higher frequencies are audible, only that HD music should have recorded higher frequencies in the first place. =20 Why would it? A chain is only as strong as its weakest length. In the case of recording, as elsewhere in audio, the weakest length is always the transducers - speakers, phono cartridges, microphones. In this case it's microphones. =20 I agree that it is very nice when so-called hi def tracks are actually hi def! ;-) =20 The hi-def doesn't refer to recordings filled with extraneous and inaudible ultra-high-frequency information, it refers to the fact that the bandwidth of the medium is wide enough that only gentle slope filters, located high above the highest audible frequency, need to be employed on either end of the the chain (recording and playback) to satisfy Nyquist.=20 I do not think you have in fact a gentle slope filter if one use a mic that filters like a brick wall. I was talking about the recording process not the signal source. And mikes don't filter at all, they roll-off after reaching their moving mass's resonant peak like all transducers. Many insist that this sounds better. Certainly, recording information that only small dogs can hear is of no use to mos= t humans in and of itself. The advantage (if any) is in the process of recording and playing back with a very high sampling rate, not the information that such a sampling rate is capable of quantizing. Hint, i= f any part of high-resolution recording is beneficial, its the word lengt= h (24 or 32-bits) not the sampling rate. Actually both word length and sample rate interact. Actually, word length and sample rate do not "interact". Word length gives you a specific dynamic range and the longer the word, the greater the (theoretical) dynamic range. As far as I can see, somewhere around 130 dB is about the limit of current technology. But with high dynamic range comes increased recording headroom and this is high bit-rate's most important contribution. OTOH, sample rate defines the highest frequency that can be quantized. Nyquist says that this frequency is half the sampling frequency. With 192 KHz, that's a Nyquist frequency of 96 KHz which, except for the advantage that this frequency is so far out of the pass-band of human hearing that any anti-ailaising filtering would have, essentially, no affect on the signal being quantized, really is meaningless in any practical sense. Notice, I'm not saying that such a high Nyquist frequency has no sonic advantages (though some here will be quick to give that opinion), I'm just saying that any "intelligence" that lies that far above audibility, is rather pointless in and of itself. Again I do NOT want to start a discussion whether or not HD audio is=20 audible, first I am looking for recordings that actually recorded=20 high frequencies. Suggestions for material/recordings are appreciated. Well, Edmund, it looks like you are pretty-much out of luck. I doubt seriously, if any high-resolution recordings have anything on them much above 30 KHz, if that. And I'll guarantee you there's certainly nothing at all above 50 KHz on ANY recording. If the master was analog, like I said yesterday, you can figure that 15-16 KHz is about the uppermost limit. |
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