Scott's music thread got me thinking... I'm far from having a great ear when it comes to music, but –*in an automotive stereo environment –*can you true audiophile guys tell the difference between a store-bought CD and a homemade MP3 disc? All else being equal, assume that the MP3 was ripped/burned using consumer-level software at "best quality" settings.

 

From my experience MP3's just never seem to be quite as clean as a traditional CD, even when you compare a brand new source CD and rip it to MP3 and then listen to it on the same system it just seems not quite as sharp to me. This may very well be partly my imagination. I do hear a difference that is pretty apparent when listening to my mp3 player vs a CD source however even when the mp3 is ripped at 128 to 196 bit. Any imperfection seems to be magnified as well with the MP3 format /shrug


Put it this way, I would never tune a car using an mp3 source, and try to avoid "burned" CD's as well when tuning.

Fej

 

Personally, I can't tell a difference, but that's just me. The trouble with a lot of MP3's is that so many people put MP3 format files out there that the quality is just crap on.

It's been a long time, so I might be wrong, but I was under the impression that the MP3 format saves most of it's space by:

1. Eliminating any sound data that is above or below the normal human range of audible frequency.

2. Eliminating any two sound waves that would serve to cancel each other if they are played together.

By this theory the "average" human being will never distinguish a difference, no matter how much somebody tells you that they can. The only people who can really tell a difference are those that are either A full of crap, or B have a range of hearing that is outside of "normal."

There are plenty of people out there who can hear extended sound ranges, just be aware that there are just as many people out there who are full of crap. If you're setting up a brand new stereo and trying to get everything tuned properly, then yes, I would recommend using the most "pure" source that you have. Afterwards though I would challenge the average person to tell the difference between a CD and a properly encoded MP3.

 

there is definately a difference, mp3 is a compression format and there is; as a result, some lost/made up data. There are lossless codecs out there though so if your system can handle 'flac' or (i think even .wav) but the files are a lot bigger then you wont be able to hear a difference.

here is another way to rip exact copies off a cd too:
http://www.exactaudiocopy.de/

i don't think that people are full of crap though, there just seems to be a little something missing on most mp3s. i have a friend that can tell when he is listening to an mp3 vs. cd. it may not be a quality thing (though i believe it is) it may just be more of a dynamic sensation that is missing or...jeez i dont know how to explain it...but hopefully you get the point

 

Interesting thoughts. I always feel like I'm hearing a very small difference in the extereme highs and extreme lows (like the range or sound isn't quite reproducing corrrectly), but I could easily be convinced it's all in my mind.

 

I do agree, data is lost but the theory behind MP3 is that the data that is lost is not audible, at least it shouldn't be if done correctly. Again there are plenty of people out there that can hear a difference, but there are also plenty of people out there who think they can tell a difference who I promise you cannot.

The primary problem with MP3 is the overwhelming abundance of poorly converted music, either from a very poor source, or a very low encoding bitrate. If you control the codec yourself and you set it up properly when you rip it, you'll be hard pressed to tell the difference.

If you can hear a difference in a properly encoded song, congratulations, you're a better man than I am. I'm not saying that you're a liar, I'm not even trying to argue. I'm just trying to clear up some possible misunderstandings about how the format is supposed to work.

If you really want to get picky about it, CD is a terrible format. Again, I can't tell the difference, but a crisp clean record has more audio clarity than a CD. Any digital format will always be lacking over analog.

 

This would make sense. Whoever decided whatever the "normal" range is for human hearing might not quite apply to you. As such it is possible that you can hear a difference. For most of the music, or for speach, there is no difference at all. Only under the extremes of the audible range is it noticable, and even for that only for certain people.

 

Hmm, Nathan you would imply by this
that there would be no difference between a 1 bit DAC and a 24bit DAC, because basically the main difference is how much data is read from the source from a given sampling rate, and I can promise you that is not the case at all. I can give you an example, a track I have listened to literally 100's of times I have had to stop several times because I picked up guitar plucks, or string noises, or a slide of the finger that I had not heard previously due to the 24 bit DAC.

Condensed material alters the sound, no matter how small, just like "reading" more of the intended source material produces a better, more accurate sound. Just like anything in life, there are people that are enthusiasts who care about the little things

Fej

 

If you say so. The higher the sampling rate the better the reproduction of the sound as well as the higher the number of "steps" with your digital representation, the better the sound quality, as far as reproducing the original analog sound. Digital has the unfortunate drawback of being able to do yes or no, on or off, 1 or 0. A one bit DAC has ONE way to represent on or off. A 24 bit DAC is going to have the option of representing many steps between just ON and OFF, it can go so far as to try and represent how far ON or OFF something is, it can better account for magnitude, and thus the greater number of bits, the more accurate the representation of the analog signal.

With the increased number of bits also comes the increase in storage space and processing power required to handle it. If you take a given sample that was recorded, say with a 24 bit DAC and you were to truncate it and process it using only 16 bits, then yes of course you are going to lose some resolution and some sound quality, there is no arguing that point at all.

The number of bits of a DAC is to say how many "steps" there are between two values, say 0 and 1. Is there one step? or a million? That however, is not the main way that an MP3 file, at least as I understood it from years ago, saved space.

For simplification sake, say that the human ear can only hear sounds between 0 and 5 hz. Your original recording captures data from 0 to 10 hz. Since you cannot hear anything about 5 hz, you can throw that information away and there is no audible loss of quality. This has absolutely nothing to do with how many "steps" there were between 0 and 10.

Now consider a 24 bit DAC recording between 0 and 10 hz but you know you're going to throw away anything above 5. With that you could actually get a higher resolution in the area in which you will actually be able to notice it, with say a 16 bit DAC.

Again I'm making up numbers here but the point is that a large amount of recorded data might not make any difference if at all if the majority of that data is outside of the audible range. A greater resolution within the audible range will certainly result in better audio clarity, however if there is "extra" data, getting rid of it for a smaller file size does not necessarily compromise audible quality. Just because the remaining data can be composed of a lower number of bits doesn't mean that it is any less accurate for your intended purpose.

Example. Ask a simple question, what day is it. I can give you many different anwers.

1. Thursday
2. Thursday, May 18th
3. Thursday, May 18th, 2006

All three of these are technically correct, but if you only needed to know the day, there is no need to incode all the extra data.

I know I don't really have the audio background to use the technical terminology but I am not entirely wrong, I do have some knowledge of digital sampling. I never said that you can never tell the difference between an MP3 and a CD. What I said is that most people can't tell the difference because the main reason for MP3 file size is the elimination of information that is not audible, NOT the loss of resolution. Certainly you can decrease the resolution, and then you will lose quality, but you can save a lot of space and not lose anything "important" because the original source was oversampled to start with. The problem is that not everybody hears the exact same ranges of sound and not all audio equipment reproduces these sounds exactly the same way and thus there can be differences to some people under some situations. As it is though most people with most stereo equipment will never hear the difference because most people are not capable of hearing the difference or the equipment is not capable of acurately producing the sound to start with.

 

Most CD's are recorded from 20hz to 20khz, generally regarded as the normal human hearing range. Most men hear in the 17k range pretty well and it diminishes a bit from there, women hear a bit higher up near the 19k mark, these are averages. Some people hear better than others etc etc. 20hz notes are hardly heard, and anything below that is only really felt.

Taking that range, there should not be any removal of "inaudible" source material because basically there is no inaudible material in the original source. Now if you are making MP3's from records which do not have a frequency cut off, then I would understand how inaudible material could be removed without consequence to the overall sound quality and reproduction.

Compression of the original "file" size results in lost information, which affects the overall sound quality. What information gets lost? The software does not care what bits it pulls out, sometimes maybe it is something inaudible, and therefore inconsequential. Sometimes it is a pluck of a guitar string, or maybe it a breath between vocals, regardless if it is not there, it is not as high a quality recording as it could be, and therefore does not have the same level of sound quality as the original.

I do respect your explanation in the above post and do not have arguement against it.

Fej

 

simple answer......... maybe.

depends on a number of factors, one of which is the quality of the store-bought CD (yes, they DO vary) and the compression level and quality of the home-burnt MP3 CD.

Sitting still with the motor off in a quiet car I can most definitely hear a difference between a "true" CD and an MP3 CD. At times it can be a subtle difference but I can almost always hear it. Is trhe reason because the difference are just there to be obvious to anyone caring enough to listen for it or is the reason because I spent many years in the audio industry therefore I "trained" my ears to hear subtle difference, I am not sure but I can hear them none-the-less.

on the other hand, while driving down the road, with road and tire noise, exhaust noise, sounds from other traffic, etc are the differences enough to worry about? Hell no!
Most "true" audiofiles seat in a soundproofed room, with extremely expensive audio equipment placed exactly right, in a chair positioned precisely to the placement of the speakers, many times in the dark, with their eyes closed, to fully concentrate and immerse themselves in the music and the imaging of the recording. If you tied that in a car - which is impossible with the limitations in a car enviromnent amyway you would be in an accident in the first 100 ft (try driving with your eyes shut! )

In a car, good sound, with decent staging and imaging, and good tonal balance is the best you can achieve. Don't worry about subtle differences in recordings of CD because when your actually driving it's useless anyway.
keep in mind that no matter how good and how expensive a car audio sytstem can be, even the extreme very best one is EASILY blown away by even the lower end of the hi-end audiophile home system. (sorry, but your $5,000 or even $10,000 home theater system that sounds good is not even remotely close to a true audiophile system. The same $10k wouldn't even buy a single component in a real hi-end system)

 

this was kind of cool:
http://www.audioboxinc.com/quality.html

At Audio Box, there is a very specific level of "quality" that is referred to as the first level of compression. The first level of compression is defined as "the first level of audio compression that allows at least one percent of the listening audience to hear the difference between a CD player source audio and computer source audio."

Ideally, when switching between computer source audio, and other audio sources, the listener(s) should NOT be able to distinguish a difference. If any difference is perceivable, the computer should sound better.

Audio Box has conducted numerous tests with a wide variety of audiences, rooms, music types, and equipment configurations. With a given audience of twenty or more people, the following results have been observed:

* Statistically, at least one listener will be present who can distinguish the difference between CD source audio and computer source audio AT ANY COMPRESSION LEVEL HIGHER THAN 3:1.
* Statistically, two or more listeners will be present who can distinguish the difference between CD source audio and computer source audio AT ANY COMPRESSION LEVEL HIGHER THAN 6:1.
* A majority of listeners can distinguish the difference between an MP3 audio file, at any compression level, and an uncompressed audio file.
* A majority of listeners can hear quality loss from a TAPE RECORDING of an MP3 file at any compression level higher than 10:1.

In summary, the first level of compression is 3:1 or 6:1 compression, depending upon how sensitive your listening group is. This definition presumes a "perfect" listening environment. Obviously, a less-than-perfect listening environment introduces other factors that can lower audio quality.

While reviewing listener comments, groups of listeners had common things to say about different audio compression levels. The written feedback about each compression format was usually consistent about what audio traits listeners heard or could not hear. These comments include:

ADPCM (4:1)
-The music sounds flat, like someone took the detail out of it.

MPEG Layer 2 (12:1)
-The high frequencies are muddy.
-The music has lost important details.

MPEG Layer 3 (12:1)
-The highs are very sharp...
-The mid-range is missing, but the highs are reproduced well.

MPEG Layer 3 (24:1)
-The music sounds like a transistor radio.

 

Cool info, will have to check that site out later tonight.

Fej

 

256 mp3 vs cd... you won't hear a difference on a great set of headphones, let alone a car stereo.

People can argue all they want, but look at the damn waveforms..

 

it goes up that high?

 

heh..doing more research:

two testers in blind tests of both tracks were able to tell that the CD was slightly better sounding than 192Kbps MP3. The differences were very suble, however. There was slightly more distortion of drum cymbals in the Mary J. Blige track, and the highs sounded slightly more emphasized - surprising, since the cutoff of the MP3 was 16KHz vs the CD's 20KHz. The Rachmaninov track sounded surprisingly similar - the piano sounded almost identical to the original, but the strings seemed a little subdued. When comparing CD vs 256Kbps and 320Kbps MP3, however, one listener actually preferred the MP3 - it sounded brighter, while the other found no difference. Neither listener could tell the difference between 256Kbps and 320Kbps MP3.

http://www.lincomatic.com/mp3/mp3quality.html

 

Hardly any mp3's that are "readily available" (read shared) are recorded at 256. Most are lucky to be at 128, some you may find 192. If you burned and converted all of your own mp3's with software that allowed the 256 conversion I could totally understand how there would be hardly any, if not zero, difference between the two sources.

In my arguement I am debating the difference between your normally converted 128kpbs mp3 vs your traditional (non sacd) CD. There is a difference in the sound quality, one that I would be willing to bet that most people would hear. I compare it to listening to a song on tape. But to each their own. I am comfortable knowing that I can tell the difference between the two, and is the reason I do not have any of my mp3's on anything but my ipod.

Fej

 

i only have my mp3's on my ipod, my laptop, a removable hardrive and my car's hardrive

 

in my post I as "assuming" a "standard" MP3 with a compression at a higher level MP3's level such as 128.

once you get into the 256 MP3's you are never going to hear the slightest difference in a car and probably 99 44/100% of the people wouldn't hear it at all even on an excellent home system

 

very interesting. I knew there was a difference between cds and mp3s, didnt know how close and how far apart they can be at the same time 128-256 and up. Very good read. Only problem i have is keeping original cds from getting scratched all the time