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1s and 0s

post #1 of 29
Thread Starter 
So far i fave heard many people comment that digital is digital, and 1s and 0s will always be ones and zeros. Many people use this logic to draw conclusions such as no cable for the transfer of digital information is better than the other and other such assumptions concerning the transfer of digital information. But i have a question about that. In order to transfer those 1s and 0s don't they have to be transmitted by elctrons, and if iam not mistaken electrons exist in the physical realm. So is it reasonable to suggest that unless the system is 100% efficient some of these electrons will not make it to its final destination? Would this suggest that a copy of a cd would indeed not be as complete as the original?(Iam not suggesting that the magnituted is appreciable to our ears, simply suggesting the presence) Any thoughts on this?
post #2 of 29
yes, in theory the transfer if information (1's & 0's) to the physical world of electrons can cause an imperfect creation of the electrical signal, but the 1's are usually represented by a change from netrual (ground) and therefore the 0's shouldn't be changed at all.

and no, since it takes many, many electrons to make up the pulse that represents the logic 1, then the information should get transmitted with integrity even if the electrons aren't a perfect representation at the receiving end of what was sent from the transmission side.

But theory is a poor standard by which to live. Reality is often perceptably different and this is such a case. Digital is very complex in execution if not in theory. It has taken almost 20yrs to get really close to executing music digitally correctly, or almost correctly. Music is also very complex and the mixing of the two has made for some interesting theories and products over the years.

So digital cables can make a difference although accourding to digital theory, they shouldn't. Also, keep in mind that we don't use redundency or check sum bits in audio, so errors are more likely to creep in than in the world of computers.

'Course, that's just my 2 bits...
post #3 of 29
SRV
the reason for using digital storage or transmission is that the transmission is less error prone (theoretically atleast).
for example going by your electron concept if we use 10 electrons to denote a 1 and 0 electrons to denote a 0 then even if only 6 electrons make it to the final destination then the signal is considered as 1 (simple majority).

theoretically it is possible to decrease the error possibilty to nil by increasing the resolution to a higher value (for ex using 100 electrons instead of 10).
But at the same time digital domain reproduction is almost always an approximation of the real world (though it can be pretty good one). Because if we use say 2 bit representation then we can have only 4 finite values 00, 01, 10, 11 and anything inbetween will be approximated to the nearest representable value.

I hope it made sense.
RawHit
post #4 of 29
I don't believe that expensive digital cables are better than cheap ones as long as the cheap ones are above a certain standard. I do believe that subjective enjoyment of music is influenced by satisfaction with the state of the system, its aesthetic appeal and a certain perverse pride at its vast cost.

So do expensive digital cables improve sound? To some listeners, sure. Which is perfectly fine because enjoyment is what it's all about. Whether or not you can see the difference on an oscilloscope doesn't really matter but if you prefer to trust that instead you can save some money.
post #5 of 29
aeberbach, I agree with you completely. I also don't believe digital cables make any difference (beyond a certain point). But if the expensive ones make you happy, then get them.

Now, my other question is why no high end digital devices use error correction. For instance, the amount of information stored in digital audio is tiny (even in SACD or DVD-A) compared to computer data, so why don't manufacturer do something like read the data several times for error checking? The price of these devices can be several thousand, so the added cost for error correction should not be terribly substantial.
post #6 of 29
All digital cables are probably well capable of transmitting the digital signal itself, so the data is not lost or changed most of the time. However, the timing of it might. So if the receiver does not reclock the signal (and reclocking is hard due to the clock imperfections, etc. some DACs recover average clock of the incoming signal but that's even harder and certainly more expensive) correctly received digital samples may be converted to analog at the wrong time. Moreover, switch from low to high and the other way around takes some time even in reclocked digital signal, and the gates in DACs would notice such switch only when a certain threshold voltage is exceeded (say 0.6v when rising/falling. they may also be different too) which also affects the timing. Same happens if slew rates on the raising and falling edges are different. Basically, what I'm trying to say is that there are tons of normally ignored variables that affect the DAC process, and cables are well capable of changing some of these variables. No magic here.

Scientifically jitter has not been proved audible, blah-blah, blah-blah-blah, blah. I don't have any opinion on that matter yet.
post #7 of 29
Quote:
I don't believe that expensive digital cables are better than cheap ones as long as the cheap ones are above a certain standard.
wow. I'm noticing more and more that you and I have VERY similar views on things.

I believe that when you get above a certain point in digital interconnects, its not worth it. Now, I'm really not sure if there's no difference in what's being recieved/transmitted, or if there's no audible difference. I haven't had enough time with really expensive cables (read: none. )
post #8 of 29
CDs, DVD-A, and SACD do use error correction, a type of reed-solomon coding. I think this coding takes up about 1/3 of the capacity of the disc. Its also why you should never wipe Cd's in a circular motion, as that will damage too many bits in a row for the coding to correct.

QUOTE]For instance, the amount of information stored in digital audio is tiny (even in SACD or DVD-A) compared to computer data[/QUOTE]

Actually, digital audio requires a huge amount of data, each second of DVD-A (highest resolution, stereo) needs over 9 megabits of data. Adding additional error correction, especailly in the early days of CD, would have reduced capacity too much.

There is no error correction once the data is read off the disc, but its very unlikely that any bits will be dropped.

Bit errors, ie mistaking a 1 for a 0 is very uncommon in digital electronics, and is not a concern in audio. Much more important is jitter, ie the timing of the bits. This timing is an analog process, not digital...
post #9 of 29
I guess I was not very clear by slower than data used in computers, I was refering to hard drivers/RAID/ram/high speed DVD-ROMs/etc. These are all common place today (my RAID setup is capable of 50+ MB/s sustained, and I bought the computer a year ago new for less than $500).

Jitter is a matter for the DAC (assuming it reclocks) correct? Since this stage involves analog signals, I was not refering to this stage, but rather just the transport. But if you're saying that all (higher end) transports read CDs/DVDs with near 100% accuracy, and is only the DAC that ultimately affects the sound, then I guess I am misinformed about the situation, and retract my statement.
post #10 of 29
My new Plextor CDR has an interesting option. You can, through software, manually adjust the angle of the laser. You can do this to 1) increase compatibility with other players or 2) change the sonics of an audio CD.

Bits is bits. Yeah sure.
post #11 of 29
Thomas: Is that also for audio cds? I know computers use a sort of correction where it sees the data, and if its incomplete, tries to complete it. Ex: computer sees la_b. It guesses lamb. But if it sees la__, it doesn't know, since it could also be lake. Do audio cds do the same?
post #12 of 29
Hirsch,

By changing he angle, is this ONLY when burning CDs? If so, than this is probably for better compatibility with other (lower quality) CDPs or CD-Roms.
post #13 of 29
Quote:
Jitter is a matter for the DAC (assuming it reclocks) correct? Since this stage involves analog signals, I was not refering to this stage, but rather just the transport. But if you're saying that all (higher end) transports read CDs/DVDs with near 100% accuracy, and is only the DAC that ultimately affects the sound, then I guess I am misinformed about the situation, and retract my statement.
Well, the master clock is set by the transport when it reads the data, and everything downstream is based on that clock. Good DACs will clean up the clock signal with advanced PLL's, and some people are developing DACs that completely recock the incomming data, but those are very rare. (i'm not even sure if there are any commercially available) For most DACs, jitter in the transport will make its way to the output.


This is the reason that people claim transports and even digital cables affect sound quality, though i agree that its much better to deal with it in the DAC design rather than spend $$$ to ensure everything before it is perfect.

Quote:
: Is that also for audio cds? I know computers use a sort of correction where it sees the data, and if its incomplete, tries to complete it.
All Cd's have the basic error correction; there is lots of redundant data written in that will correct a certain number of read errors. A mathematical formula uses this extra redundent information to fill in missing data, up to a certain point. I believe its somewhere around 140 errors per second, but its been a while since i've looked at this stuff. Anything below that will be corrected to 100% accuracy, once you go above that, different transports will do different things-i believe some will round it off, others will simply drop the sample.

Data CD's have additional layers of error correction. In fact, i think almost half of the capacity of a CD is used just for error correction with data. Again, they use complex mathematical algorithims and the extra redundant data to correct errors. Data CD's definately don't guess data (if it encounters too many errors, it'll give you an error message) , while audio likely will try and guess the damaged data...
post #14 of 29
Bits isn't always bits. Frustrating, but true.

Digital cables do make a difference... it's small but audible when listening carefully.
post #15 of 29
Quote:
Originally posted by Nick Dangerous
Bits isn't always bits. Frustrating, but true.

Digital cables do make a difference... it's small but audible when listening carefully.
When I switched to the Elco's, I didn't need to listen carefully, and IMO the difference wasn't small. I had listened to several digital cables and heard no difference, but when I found one that mattered, it really mattered.

Markjia,

The angle change is only for use during recording. As I said, Plextor gives two reasons to use it. One is compatibility. The other is altering sonics. Mind you, they don't say what altering the laser angle will actually DO to the sonics, but they do say the sound will change.
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