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In Reply to: RE: "It is debatable whether 192/24 can capture the output of a high quality master tape" posted by Chris from Lafayette on October 09, 2015 at 19:32:40
It's quite simple: you listen to the output of the tape recorder directly and you listen to the output of the digital playback of a recording made previously from the tape recorder. If you hear a difference, then higher resolution digital gear is needed.
It could be that the resolution from a 30 IPS wide track tape master isn't good enough to show up problems with the digital gear. In this case, the test is a live microphone feed. This is a simple A - B test that compares apples to apples. The goal is to see whether or not digital recording is "perfect sound" or not.
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
Follow Ups:
i.e., take the output of a digital recorder, record it onto an analogue tape machine, and see if you notice a difference. I'd lay odds that you might notice MORE of a difference with his kind of a test! ;-)I also read of a test some years ago where LP's were recorded onto CD-quality digital recorders (i.e., not hi-rez), and listeners were unable to tell which were the LP's and which were the digital recordings of those same LP's.
Edits: 10/09/15
"i.e., take the output of a digital recorder, record it onto an analogue tape machine, and see if you notice a difference. I'd lay odds that you might notice MORE of a difference with his kind of a test! ;-)"
I've yet to own or use a tape recorder that was audibly transparent as to its input. At the very least, recording at low levels will produce obvious amounts of tape hiss, while recording at high levels will produce audible dynamic compression and audible harmonic and IM distortion. However, I've not used anything better than 1/4" 15 IPS two track recorders with standard tape and low bias frequencies. My understanding is that there are recorders that get much better performance, among other things by burning lots of expensive new-technology tape under their heads.
As to whether a differences is larger or smaller, this assumes that differences can be ordered, i.e. they are one dimensional. Different media have different potential and actual distortions and these come in a great variety, making it impossible to linearly rank distortions. Some listeners tolerate certain types of distortion much better than others. Thus, for example, when I was recording to magnetic tape I liked to keep the levels low to avoid compression and distortion. Other people hated tape hiss and didn't want their work to have an obvious defect that even untrained listeners could hear. They recorded at higher levels. Thus started the loudness wars...
Taking your statement as an argument (and ignoring the smiley) your argument is at best an argument from mediocrity. My mother taught me, "Every everyone else jumps off the bridge, does that mean it's safe?". More likely, your argument relates to the phrase, "Two wrongs don't make a right." Poor quality sources are not an excuse for poor quality equipment downstream in the record playback chain that starts at the microphones and recording venue and ends at the speakers and listening room.
It matters not what the source is, an LP, a live microphone feed, a master tape, or an off the air FM broadcast, if the digital record - playback process can not achieve transparency there is a fault. The fault is in one or more of the three places: the ADC, the mathematical limitations of the format, the DAC. People interested in perfection struggle to make each piece of the chain under their control as high quality as they possibly can within the limitations of their resources.
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
Mainly, the part about folks being more or less sensitive to different kinds of distortions (e.g., Todd with his RFI sensitivity).
I also agree that "Poor quality sources are not an excuse for poor quality equipment downstream in the record playback chain that starts at the microphones and recording venue and ends at the speakers and listening room."
I also agree that two wrongs don't make a right.
I suppose it all comes down to what crosses the threshold into "poor" quality for a given listener with a particular set of sensitivities. I'd say that, in general during my lifetime, sound quality has improved A LOT - and improvements in digital recording are a large factor in this overall improvement. I've owned (analogue) open reel tape decks myself and, although they can sound wonderful on occasion, I don't want to go back to them. I'm not necessarily looking for perfection, so perhaps you could say that that's an argument from mediocrity. However, I AM interested in the raising of the general standard of audio, and, as I say, I think that I've observed this improvement during my lifetime.
Hey Tony,
There are too many variables to boil it down to that.
Still, you're on a good thought track about this. Continue on!
:)
I am aware of more variables. They become apparent if one spends time thinking and running these kinds of tests. However, going into detail won't convince anyone about the subject we are discussing. I'd rather people get off their butts and get their hands dirty doing actual conversion and listening tests. They can reach their own conclusions, or not, as the case may be.
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
and what type of analog equipment would be necessary to capture them?For example, surely dynamics are bordered by the resilience of the atmosphere at the loud end, and the insensitivity of the human cochlea at the quiet end. You can only go so loud before the atmosphere loses its elasticity and you go from wave forms to concussions. Further, surely it is possible to be so quiet that a healthy human ear cannot detect the sound.
Any idea what this dynamic range is? Any idea of what sort of analog equipment would be needed in order to capture it?
How about for frequency range. Let's set 1 Hz as our lower limit. What is the highest frequency we need to worry about and what type of analog equipment would be necessary to capture that?
We can ask similar questions about frequency response, that is how sensitive the ear is to flatness of frequency response and what we need to build to equal that, and timing response, that is how sensitive the ear is to wow and flutter and what we need to do to match that.
Could an analog recording and playback device ever be built that could satisfy these issues? We can always say that we could keep building tape recorders that throw more ips at the problem, but surely there is an upper limit to the speed at which the spindles can rotate and the bulk of the tape they can handle? I may be wrong, but I suspect the physical limitations of the recording and playback equipment will be met long before we reach the theoretical limitations of "analog."
Now here's my question: we could draft a "curve" showing the theoretical limits of analog. We could also draft a "curve" showing the practical limitations of analog equipment. I think all would agree that the practical limitations curve would have much less area under it than the theoretical limits curve. However, what would the curve of the practical limitations of digital equipment look like compared to the curve of the practical limitations of analog equipment?
I'm sure the digital and analog curves would differ, that is, each would have benefits the other lacks, but how much area would each curve have under them? Further, how much would it cost to implement the analog curve and the digital curve?
Just curious.
JE
Edit: no sooner did I hit "Post Message" than another thought occurred to me: are there areas under the curve that are "tastier" than others? That is, is a boomy bass preferable to a bright treble? If so, why? Discuss.
je
Edits: 10/10/15
The low limit comes from Brownian motion of the air. The amplitude measured will depend on the size of the detector (eardrum or microphone) and the bandwidth used for hearing an individual sound. The high limit comes from the limits of atmospheric pressure and the speed of sound. A little Googling showed these physical limits as -24 dB and +194 dB. Higher levels are possible in the form of shock waves (e.g. explosions).
There have been studies showing the peak SPLs at an orchestral concert reaching SPLs of 122 dB (e.g. Mahler's 8th symphony). Human hearing can hear sounds down to about -9 dB at some frequencies.
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
are capable of processing greater musical dynamic ranges than are possible on the Earth's surface?That's pretty cool when you think about it.
JE
Edit: I knew this reminded me of something! See link.
je
Edits: 10/11/15
Actually, 64 bit DAWs use floating point. Range amounts to roughly 1000 bits.
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
Yes. This has been analyzed six ways to Sunday.
See Knudson & Harris's "Acoustical Designing in Architecture", Olson's "Music, Physics and Engineering", and Eric Heller's recent "Why You Hear What You Hear". Your topic is addressed and defined in all three, among numerous others.
:)
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