audio over USB v. optical - Page 24

rsema · 12-17-2007, 11:57 AM

Ok thanks guys for your help...so if i wanted to get the best quality music from my computer as the source (better than cds) would getting music in the flac format be better? and if so would it be worth it to replace my whole library with it...according to how much better it sounds...thanks again.
Ryan

Felix509 · 12-17-2007, 01:20 PM

There is much debate if a Computer as source can sound better than the actual CD transport, In my opinion, YES..

If you have all of your music on CDs you can rip them to a lossless format, either the original CD format which is .WAV, or you can compress them into a lossless format like FLAC.

You cannot convert MP3 back to a higher quality format as some data has already been discarded during the Mp3 compression

FLAC will give you the same quality and save 20%-30% of your hard drive..

I personally use all FLAC played via Winamp. I use a M-Audio Transit to have digital optical output into my processor.

Next you will get into the debate of how to rip the music, what software is best, what hardware, etc..

Have fun

Laters...

pokki · 12-17-2007, 02:47 PM

Quote:

so if i wanted to get the best quality music from my computer as the source (better than cds) would getting music in the flac format be better?

If your source is CD then you can't get better than that. However ripping to a lossless format (FLAC etc) has the advantage that it's not a real time process so more effort can be put into correcting read errors.

Felix509 · 12-17-2007, 03:57 PM

Quote: Originally Posted by pokki

If your source is CD then you can't get better than that.

The CD being the Best it can get is a Great debate... Some people have given up $10,000 CD transports in favor of computers.. Of course you still need a DAC..

I have given up CDs and CD transports for computer as a source for the DAC, I cannot afford any CD transport that can touch my set up now.

There are many long threads debating it on different high end forums.

RedGTiVR6 · 12-27-2007, 09:25 PM

I thought I would come back in here and make note of a few things I've been reading about USB audio in some recent Stereophile magazines I've received. They've reviewed a number of USB DACs all with the same results when it comes to listening to them over USB...no good.

I'm not 100% sure why the reviews have all been like this. I've got a thread going over on the Sterophile forums to see if I can get some more detailed information. I'll post back what I find for anyone who is interested.

RedGTiVR6 · 12-28-2007, 12:16 PM

Ok - some information I've gathered, thought I would share:

I wondered why USB DACs showed such poor audio quality when the USB portions of the DAC were used. Afterall, the CD ROM connected via USB doesn't matter.

If the connection method doesn't matter for a CD-ROM, then why is it that audio over USB on a USB DAC is so bad due to jitter? What makes one ok and the other not ok?

Quote: Originally Posted by AlexO

The CD rom sends a data stream over the IDE or SATA or SCSI connection. The problem arises when sending a PCM stream to an external Digital to Analog converter. PCM protocol lacks clocking and this is what jitter is: imprecise clocking. It seems that some interfaces deal better with this issue than others.

durwood · 12-28-2007, 12:33 PM

PCM lacks clocking? Did he go into detail? Without digging to far into it, PCM or Pulse Code Modulation has to be clocked somehow. Without PCM every single CD would be useless.

http://en.wikipedia.org/wiki/Pulse-code_modulation

Found a few links discussing improvements to the CD. They may or not be relevant, but if you look at some of Werewolf's posts, he gives light to what maybe to look into.

http://forum.elitecaraudio.com/showt...hreadid=126052
http://forum.elitecaraudio.com/showt...hreadid=126082

I think one thing you have to remember is that people who spend thousands on DACs are going to have a bias against computers and less inexpensive DACs because they are under the impression cheap = poor quality and $$$ = good quality.

Links to reviews comparisons?

RedGTiVR6 · 12-28-2007, 12:52 PM

The past 2 issues in Stereophile magazine have had reviews of USB DACs.

Stereophile is generally considered unbiased as far as I've seen.

Nov. 2007 issue reviews Bel Canteo e.ONE DAC3
Jan. 2008 issue reviews Benchmark DAC1

Both by John Atkinson

I don't think its a fair assumption that those who are willing to spend a lot of money will automatically have a bias against lesser expensive products. I've read a number of reviews in the past that point to quite the opposite.

Some people claim that there is no discernible difference between running audio through the k-mixer in Windows and running bit-perfect. Do they claim this simply because they don't have the ear to be able to discern the difference? Do they claim this simply because they don't understand what's going on?

durwood · 12-28-2007, 12:55 PM

Well it's good that they give unbaised opinions sometimes.

Did they take measurements or was it purely subjective? What didn't they like about them specifically? Were they listening to them via headphones, speakers, etc.

Edit: http://forum.stereophile.com/forum/s...34&an=0&page=0

RedGTiVR6 · 12-28-2007, 09:40 PM

Quote: Originally Posted by durwood

PCM lacks clocking? Did he go into detail? Without digging to far into it, PCM or Pulse Code Modulation has to be clocked somehow. Without PCM every single CD would be useless.

http://en.wikipedia.org/wiki/Pulse-code_modulation

Quote: Originally Posted by linked Wiki article

In real systems, such a device is commonly implemented on a single integrated circuit that lacks only the clock necessary for sampling, and is generally referred to as an ADC (Analog-to-Digital converter)

From what I'm gathering PCM is the data its self.

Sitting here talking to Monte the best comparison I can come up with is this:

The clock is what actually makes PCM useful. Much like having lines of code that are uncompiled. Just because the lines of code are uncompiled doesn't mean that they are not lines of code, it just means that they don't have a useful meaning just yet. In other words, PCM data without a clock, is just PCM data...it's data that has not yet been utilized.

If the PCM protocol were to include clocking, then wouldn't it have to specify the clock timing as well? Then wouldn't that narrow down the purpose of PCM and it's protocol and make it entirely too specific for general use? Perhaps I'm getting way too ahead of myself...lol

Another comparison...Cat5 cable is designated Cat5 by a standard (protocol). A piece of Cat5 cable cannot be designated as Cat5 without being able to transfer at least X amount of data a second. So in order to specify clocking in with the PCM protocol, wouldn't you really need to specify the clock speed as well for it to be a legitimate protocol?

Quote: Originally Posted by durwood

Found a few links discussing improvements to the CD. They may or not be relevant, but if you look at some of Werewolf's posts, he gives light to what maybe to look into.

http://forum.elitecaraudio.com/showt...hreadid=126052
http://forum.elitecaraudio.com/showt...hreadid=126082

I'm reading through these now! Probably going to take me a bit though...hehe

btw - here's the thread I have going on Stereophile: http://forum.stereophile.com/forum/s...ge=0#Post32327

Felix509 · 12-28-2007, 10:54 PM

I like this stuff.. I have been wanting to get back into new stuff after a few month break..

I was always thinking that PCM was the type of data, as you say above, while SPDIF is the means of transferring the PCM data between devices. I guess something like the SPDIF is the pipeline and the PCM is the water going through the pipe.

The SPDIF has a clock embedded(Dunno if that is the right term) so that is where the DAC knows how to recover the clock the same as the device sending the data.

As for an actual spinning CD transport, If I Understand, much of the quality of the transport is in the circuit design and the quality of the oscillator that is doing the clocking prior to sending through the SPDIF.. I would think a computer cd drive has a pretty simple/cheap oscillator, making it not the best transport.

If you are not familiar with Computer Audio Asylum, here it is

a whole lot of that site is over my head, but if i read enough, i usually get the point..

RedGTiVR6 · 12-28-2007, 11:00 PM

Quote: Originally Posted by Felix509

I would think a computer cd drive has a pretty simple/cheap oscillator, making it not the best transport.

Actually, according to AlexO:

Quote: Originally Posted by AlexO

If you're connecting the drive to the computer, there isn't much to be gained from various drives or even interfaces. Some drives and interfaces are faster than others, but they're all way, way more than adequate for audio purposes. Furthermore, since the transfer from the drive will be sent as data encapsulation, at data speeds and there will be considerable buffering on the hard drive to address any error issues, the role of the CD ROM is greatly diminished.

So, unless you're connecting the CD ROM straight to the DAC, bypassing the computer, for our purposes here, the quality of the drive is irrelevant because all of them are beyond specs needed for audio streaming TO THE COMPUTER.

Hope this helps.

Quote: Originally Posted by Felix509

If you are not familiar with Computer Audio Asylum, here it is

a whole lot of that site is over my head, but if i read enough, i usually get the point..

I'll head over and check it out! Thanks for the link.

I'm like you, I can dive head first into this stuff, but I can only stay under water for so long before I must come back up for air.

I have found that each time I dive, I can stay under longer though...lol

Felix509 · 12-28-2007, 11:16 PM

Yep, that makes good sense if you are going into your computer from the CD drive.. I dunno why i was thinking you may be going directly out of the CD to the processor..

USB streaming also streams using PCM. One of the problems with USB audio is that it has no clock embedded with the PCM data. That also supports that PCM has no clock embedded.

I am searching now for the best card to output my SPDIF from, as that seems to make a big difference, but am relying on the uber experts on the Computer Audio Asylum to guide me.. <---Make sure you have Loads of time before undertaking this forum, it is full of Info and links to more info etc..... Some real experts on computer audio on here, the guy who makes Benchmark Audio, The guy who is Empirical Audio, among others..

RedGTiVR6 · 12-29-2007, 07:51 AM

I simply cannot stand the way that forum is set-up.

I've told it to display like vBulletin, but it's not doing so. No wonder they call it the asylum....:|