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Author Topic: Transfer from Analog to Digital  (Read 8565 times)

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Offline Church-Audio

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Re: Transfer from Analog to Digital
« Reply #15 on: May 29, 2008, 06:15:19 PM »
Chris, I think the point that's trying to be stressed here is that going beyond 44.1/24 for an analog-based source makes NO difference what-so-ever as there is no sonic benefit from a science standard.

It may "sound" better at 192, but is it?  Scientifically, it isn't.  If the data isn't there to begin with you're just wasting space.

The initial person mentioned they wanted to burn stuff to CD, that's the other reason I stressed 44.1/24.  24 would have to be downsampled but at least it's in a better than CD format.  Nothing is gained by the larger file size; except for wasted space.
Well not everything in sound can be scientifically explained away. I have heard the difference for my own ears. I did say that it does depend on the source. But really I think that for me I have nothing to prove I know I hear a huge difference that's all that matters at the end of the day for me. Now if you give me a record with a high noise floor would I notice the difference probably not. But with some sources YES I can hear the difference and not because I am expecting it to sound better because it does at least to my ears.
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Offline Church-Audio

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Re: Transfer from Analog to Digital
« Reply #16 on: May 29, 2008, 07:03:10 PM »
I was wondering what is the best method of doing this. What equipment would best this done ? I would prefer to go CD's utilizing 44.1 redbook or  24 bit 96hz.

I know all this has to be transfered in real time, until it's in the digital format. Anyone out there making a 100 min. CD blank ?

thank you for your input on this matter.

I'm guessing here that you're transferring old analog masters (or vinyl) in hopes of preserving them in some sort of digital format. 

I've never really been able to wrap my head around why anybody would use 96KHz/24-Bit for it as, sonically, there's not enough data on that source for such a data-rate. 

What do you mean by data? Just wondering.

Chris
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Offline DSatz

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Re: Transfer from Analog to Digital
« Reply #17 on: May 29, 2008, 10:57:06 PM »
Chris, when I was in high school I took a few years of German. At one point my mother decided that she wanted to try to help me with my homework, so she picked up my textbook and started trying to read a few sentences. Not knowing any German, she came across the word "die," which is simply one form of the definite article (like our word "the," to which it is closely related). But to her, this was irrevocably the verb form of "death," and she became convinced that this had been part of the problem with Germany in the Hitler era--that they threw this terrible word around so casually, they became desensitized to it.

In German, of course, the word "die" has nothing to do with death. But my point is, you can come up with some pretty wild conclusions, as my mother did, and feel that you have clear evidence for them, if you interpret something in the wrong framework of meaning.

You are doing a similar thing by interpreting sampled audio as it was still a continuous-time, analog signal. According to the behavior of continuous-time signals, everything that you say makes sense. However, a discrete-time representation of a signal is different, and must be interpreted differently. I'd like to suggest that you read a little about Shannon's sampling theorem, because I think that otherwise we will only be able to talk in circles. As I recall, Wikipedia has a pretty good article on it.

(added the next morning): I also wanted to say that some recording equipment can indeed sound different when run at different sampling rates--but when that occurs, it isn't necessarily because of those sampling rates alone. As an example, at the end of the 1980s the Sony PCM-2500 was by far the leading studio DAT recorder; it could record at 32 kHz, 44.1 kHz and 48 kHz. For many engineers it was the first piece of digital recording equipment that allowed them to compare the three sampling rates--or so they thought.

There was general consensus that there were audible differences, and that the 48 kHz rate sounded better than the 44.1 kHz rate. However, not only the sampling rates but also three (or six, for stereo) complete, separate analog anti-aliasing filters were also being compared, since the ICs which were later introduced for digital filtering didn't exist yet. And it turns out that if you bypassed the A/D and D/A converters in the deck--effectively isolating those filters and simply listening through just them and the other analog circuitry of the deck--they sounded rather different. The 44.1 kHz filter in particular could have audible levels of a kind of hard-edged distortion when it was pushed. (Apogee, the company which is well known now for its A/D converters, got its first foothold in the studio market by offering better-sounding replacement plug-in filter modules for the PCM-2500 and other similar equipment.)

Many people formed their own, honest opinions about sampling frequencies, like I think that yours are--but those opinions weren't based on what those people thought they were based on, like I think that yours probably aren't. Similar stories could be told about "tube vs. transistor" comparisons (e.g. Neumann U 67 vs. U 87) and "CD vs. vinyl" comparisons where extrinsic factors that people didn't know about had a large, hidden influence on their decisions. It's not always easy to set up listening comparisons so that you really are testing just for the one thing that you want to test for. Unfortunately for consumers and even most studio engineers who can't get into the insides of the equipment, it is sometimes quite impossible for them to do so at all.

--best regards
« Last Edit: December 26, 2009, 08:52:38 PM by DSatz »
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Offline Church-Audio

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Re: Transfer from Analog to Digital
« Reply #18 on: May 30, 2008, 12:12:28 PM »
Chris, when I was in high school I took a few years of German. At one point my mother decided that she wanted to try to help me with my homework, so she picked up my textbook and started trying to read a few sentences. Not knowing any German, she came across the word "die," which is simply the definite article (like our word "the," to which it is closely related) for any noun in the feminine or plural. But to her, this was irrevocably the verb form of "death," and she became convinced that this had been part of the problem with Germany in the Hitler era--that they threw this terrible word around so casually, they became desensitized to it.

In German, of course, the word "die" has nothing to do with death. But my point is, you can come up with some pretty wild conclusions, as my mother did, and feel that you have clear evidence for them, if you interpret something in the wrong framework of meaning.

You are doing a similar thing by interpreting sampled audio as it was still a continuous-time, analog signal. According to the behavior of continuous-time signals, everything that you say makes sense. However, a discrete-time representation of a signal is different, and must be interpreted differently. I'd like to suggest that you read a little about Shannon's sampling theorem, because I think that otherwise we will only be able to talk in circles. As I recall, Wikipedia has a pretty good article on it.

(added the next morning): I also wanted to say that some recording equipment can indeed sound different when run at different sampling rates--but when that occurs, it isn't necessarily because of those sampling rates alone. As an example, at the end of the 1980s the Sony PCM-2500 was by far the leading studio DAT recorder; it could record at 32 kHz, 44.1 kHz and 48 kHz. For many engineers it was the first piece of digital recording equipment that allowed them to compare the three sampling rates--or so they thought.

There was general consensus that there were audible differences, and that the 48 kHz rate sounded better than the 44.1 kHz rate. However, not only the sampling rates but also three (or six, for stereo) complete, separate analog anti-aliasing filters were also being compared, since the ICs which were later introduced for digital filtering didn't exist yet. And it turns out that if you bypassed the A/D and D/A converters in the deck--effectively isolating those filters and simply listening through just them and the other analog circuitry of the deck--they sounded rather different. The 44.1 kHz filter in particular could have audible levels of a kind of hard-edged distortion when it was pushed. (Apogee, the company which is well known now for its A/D converters, got its first foothold in the studio market by offering better-sounding replacement plug-in filter modules for the PCM-2500 and other similar equipment.)

Many people formed their own, honest opinions about sampling frequencies, like I think that yours are--but those opinions weren't based on what those people thought they were based on, like I think that yours probably aren't. Similar stories could be told about "tube vs. transistor" comparisons (e.g. Neumann U 67 vs. U 87) and "CD vs. vinyl" comparisons where extrinsic factors that people didn't know about had a large, hidden influence on their decisions. It's not always easy to set up listening comparisons so that you really are testing just for the one thing that you want to test for. Unfortunately for consumers and even most studio engineers who can't get into the insides of the equipment, it is sometimes quite impossible for them to do so at all.

--best regards

I understand perfectly about sampling rates. And I also understand perfectly that when I select a higher sampling rate when I record or when I am using a digital console it simply sounds better to my ears. That's all I will say. Increased quantization  and sampling of a waveform = increased data = a more accurate representation of the waveform. I have been working with digital since the first cd player came out. I am sure you know your theory. But I know what sounds good to my ears when I mix I trust my ears first the specs/theory second.
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Re: Transfer from Analog to Digital
« Reply #19 on: May 30, 2008, 12:26:09 PM »
Honestly Chris - you sound a bit chagrined by Mr Satz sharing of his knowledge - like somehow you've been knocked off your perch.

We respect your areas of expertise. But you are starting to sound a bit self-rightgeous, if not foolish on this one.

My understanding of digital audio is...well, WAS the same as yours - but Mr Satz has highlighted a few assumptions that we seem to make.

Im not going to pretend like "I got it" as far as Satz' explanation - but his take is eye opening, and thought provoking...

Sometimes things are not what they seem...

Offline Church-Audio

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Re: Transfer from Analog to Digital
« Reply #20 on: May 30, 2008, 01:03:43 PM »
Honestly Chris - you sound a bit chagrined by Mr Satz sharing of his knowledge - like somehow you've been knocked off your perch.

We respect your areas of expertise. But you are starting to sound a bit self-rightgeous, if not foolish on this one.

My understanding of digital audio is...well, WAS the same as yours - but Mr Satz has highlighted a few assumptions that we seem to make.

Im not going to pretend like "I got it" as far as Satz' explanation - but his take is eye opening, and thought provoking...

Sometimes things are not what they seem...

Not at all. Really I totally respect his knowledge. But I also respect my ears. I guess we will agree to disagree. I have no issues what so ever with being knocked off my "perch" for me its not all about who knows more its about what my ears tell me. Because at the end of the day that's all that matters to me. I totaly have nothing but respect for DSATZ! He is a very smart man. But we will simply have to agree to disagree. That's not me saying I think he is 100% wrong that's me saying I trust my ears. I am not so full of my self that I dont think there are others around here that know a thing or two more about audio then I do, because that's just silly. I really am just responding to his comments that were directed towards me. I respect his point of view but I dont share it. That does not mean I cant respect the guy who has a different point of view. I dont agree with the points of view of some professors that I know and have known. Does that make them wrong? No does it make me wrong? Maybe not maybe yes. Its all cool with me I really dont care one way or the other. I was just stating my opinion. And he was stating his. I felt in a very respectful manor. I guess that's the beauty of text it can be taken many different ways.

But rest assured I did not mean for my replies to be taken as anything but JUST MY POINT OF VIEW. I have learned alot of things here big time and continue to learn from you guys. Don't ever think that I am above being proven wrong. I am not that's how I learn. But for me in this case my ears tell me a better sampling rate sounds better so that's why I am so firm on this point at least from my perspective and the perspective of all of the engineers I know.

Chris



« Last Edit: May 30, 2008, 01:06:28 PM by Church-Audio »
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Offline DSatz

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Re: Transfer from Analog to Digital
« Reply #21 on: May 30, 2008, 11:38:33 PM »
Chris, I'm not even trying to change what you think, let alone knock you off of any perch. (Or haddock.) Your beliefs are your business, and whether you change your mind or not probably won't have much effect on my life. I'm just having a good time here, and am hoping that the same is true for you.

It's odd about science--there are conclusions that people have reached after long, hard study and research and experimentation, and meanwhile everybody else who didn't make those experiments can only judge those conclusions on whatever their general plausibility seems to be. Often, people have very little choice but to take scientific claims on faith, or else not do so. What may be perceived as "obvious" in a given time and place is extremely subject to change--sometimes drastic and rapid change. (I'll spare you the usual list of examples.)

Ultimately it comes down to the predictive ability of a theory. If you want to know whether a theory is valid, try making a squirm-proof prediction based on it. Put it all on the line. What I said earlier about THD+N is an example--I strongly agree that you have no reason to believe what I said (that adding more bits can help reduce THD+N, but that increasing the sampling rate does not help at all for frequencies below 1/2 the sampling rate) until you've actually made this experiment. Go ahead; try it yourself and see what you get. Then try to explain the result in terms of what you are so sure is the way things work ("Increased quantization  and sampling of a waveform = increased data = a more accurate representation of the waveform").

As I said early on, when you say "increased data" in this way (meaning data rate, i.e. total bits per second), you blur the distinction between sampling precision and sampling frequency. To use a single combined figure for "data rate" or "bit rate" makes some sense in the MP3 world, where the data reduction itself is the main limiting factor in sound quality. But in linear (not data-reduced or "compressed") PCM as used in CDs and DATs, etc., those two dimensions mean two different things and follow different rules. You can't sample at half the rate but use twice as many bits per sample and still get the same quality, nor vice versa. I think most people understand that very well.

Rather, the sampling needs to be precise enough to capture the full dynamic range of the signal without adding significant noise or distortion, and the sampling frequency (sampling rate) has to be more than twice the highest frequency in the signal to be recorded. Once it's high enough, though, it can't be made "higher enough" or "high enougher"--it's still just "high enough."

--best regards
« Last Edit: May 31, 2008, 10:54:55 PM by DSatz »
music > microphones > a recorder of some sort

Offline boyacrobat

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Re: Transfer from Analog to Digital
« Reply #22 on: May 30, 2008, 11:57:20 PM »
ears always the first language to the brain
theory has no sound, just thought .

both have reason to exist

g

Offline indietaperwloo

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Re: Transfer from Analog to Digital
« Reply #23 on: June 14, 2008, 03:39:08 AM »
I actually convert analog sources to digital for a living and my advice is this:

Worry about your playback source, analog stage and the quality of your ADCs more than what bit depth and sample rates you're going to use.  You can convert your old vinyl collection to DSD using a $20,000 delta-sigma ADC with analog filters for all I care but if you use a junk playback stage, the archive is going to sound like crap.

Also, consider the S/N ratio of your analog gear.  The typical noise floor of a vinyl record (12 or 7 inch at either 33 or 45 rpm) even with a decent signal chain between the turntable and the ADC it bottoms out at around anywhere from -45 to -50 dBFS at silence points with the ADCs on my system bottom out with no signal coming in at all at around -83 dBFS (faders with the connected Mackie 1402 VLZ Pro at inf and all channels muted and all master section monitoring options turned off).  So considering that, if you're transferring a vinyl record at 16/44.1 LPCM to a .wav or .aiff file, half your bits are taken up by surface noise from the vinyl and probably noise from the analog stage thus greatly reducing headroom.  Therefore, recording at 24 bit with those kinds of numbers doesn't really make much sense since you're increasing the word length with noise (from -144 to -45) and if you're sending it to CD you'd just have to trunciate the word length down to 16 anyways and add possibly more noise with a dithering process (I personally use the Apogee UV22 plugin included with Wavelab if I have to resort to such measures).

What is the point of this whole numbers argument?  Well, to me, a CD whose source is a vinyl record sounds no more different than a 24/96 wave file from the same source.  The only difference to me is that it's just a bigger file.  The numbers I think justify what my ears hear.  What I DO notice is what's happening in the analog stage.  If I don't do any kind of noise reduction or restoration of any kind, I notice the characteristics of the signal chain between the source media and the ADC (in the case of vinyl...turntable (cartridge/tonearm) > phono preamp > mixer > ADC).  These are things you really have to take into account when you're archiving audio and you want to do a decent job.
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Offline tilomagnet

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Re: Transfer from Analog to Digital
« Reply #24 on: June 14, 2008, 10:05:43 AM »
I actually convert analog sources to digital for a living and my advice is this:

Worry about your playback source, analog stage and the quality of your ADCs more than what bit depth and sample rates you're going to use. 

QFT.

And from these (PB source, preamp & ADC) the playback device is by far the most important part of the signal chain.

When using different decks for playback I do usually notice the different sound characteristics of each, however I've never been able to tell the difference between different ADCs, let alone bit depths and sample rates. And I've tried 16/44, 24/96 and DSD.

Also, when working w/ Dolby encoded tapes, the quality of Dolby decoding makes 10x the difference of an ADC upgrade.

Offline Church-Audio

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Re: Transfer from Analog to Digital
« Reply #25 on: June 16, 2008, 10:54:06 AM »
Chris, I'm not even trying to change what you think, let alone knock you off of any perch. (Or haddock.) Your beliefs are your business, and whether you change your mind or not probably won't have much effect on my life. I'm just having a good time here, and am hoping that the same is true for you.

It's odd about science--there are conclusions that people have reached after long, hard study and research and experimentation, and meanwhile everybody else who didn't make those experiments can only judge those conclusions on whatever their general plausibility seems to be. Often, people have very little choice but to take scientific claims on faith, or else not do so. What may be perceived as "obvious" in a given time and place is extremely subject to change--sometimes drastic and rapid change. (I'll spare you the usual list of examples.)

Ultimately it comes down to the predictive ability of a theory. If you want to know whether a theory is valid, try making a squirm-proof prediction based on it. Put it all on the line. What I said earlier about THD+N is an example--I strongly agree that you have no reason to believe what I said (that adding more bits can help reduce THD+N, but that increasing the sampling rate does not help at all for frequencies below 1/2 the sampling rate) until you've actually made this experiment. Go ahead; try it yourself and see what you get. Then try to explain the result in terms of what you are so sure is the way things work ("Increased quantization  and sampling of a waveform = increased data = a more accurate representation of the waveform").

As I said early on, when you say "increased data" in this way (meaning data rate, i.e. total bits per second), you blur the distinction between sampling precision and sampling frequency. To use a single combined figure for "data rate" or "bit rate" makes some sense in the MP3 world, where the data reduction itself is the main limiting factor in sound quality. But in linear (not data-reduced or "compressed") PCM as used in CDs and DATs, etc., those two dimensions mean two different things and follow different rules. You can't sample at half the rate but use twice as many bits per sample and still get the same quality, nor vice versa. I think most people understand that very well.

Rather, the sampling needs to be precise enough to capture the full dynamic range of the signal without adding significant noise or distortion, and the sampling frequency (sampling rate) has to be more than twice the highest frequency in the signal to be recorded. Once it's high enough, though, it can't be made "higher enough" or "high enougher"--it's still just "high enough."

--best regards

My perch lol... I hear the difference plain and simple. I know what I can hear and what I cant. I dont want to argue with you on this point. With certain sources I can hear the difference between lower sampling rates and higher sampling rates. I have nothing but respect for your knowledge, but that does not mean you are above being me disagreeing with you. You can have respect and still not agree on every point. My main point is when I use say a digital console and I set the converters to 44.1 and then I set them to 96k there is a world of difference for my ears. When I am using a real source like kick drum or anything else. So to my ears there is a difference between sampling rates and sound quality. That is the basis of my argument.


No perch here trust me.

Chris
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