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Red GTi VR6
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audio via a computer...best cd-rom?

While I know that many individuals here are not into audio via a computer, I'm hoping that some individuals will have some valuable insight in this regard.

I'm of the understanding that audio over USB is not desirable due to jitter. So, to have an external CD-rom drive that is connected to the computer via a USB cable is not exactly ideal. Understood and appreciated.

However, I'm curious to know if anyone has any recommendations on a rom drive and the best method of connection for highest quality? IDE, SATA, Firewire?

On a side note, I would love to see more reviews of high end solutions based on the computer...but alas, it seems that I'm one of the few who wishes to see this field explored more.

bifcake
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Re: audio via a computer...best cd-rom?

It doesn't really matter how you connect your CD rom drive to your computer. CD requires 150kps throughput and all of these interfaces can do much, much better than that.

The thing to do is to connect the computer to an external DAC via the sPDIF output on your sound card. That would probably be the best method.

linden518
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Re: audio via a computer...best cd-rom?

Has anyone heard Peachtree Audio's Decca integrated amp yet? Supposedly it's a $800 hybrid tube/solid state 50 Wpc with a built-in DAC designed by Scott Nixon. I hear it even has a direct slot for a Sonos amp in the back. It sounds like a pretty good solution to beginners getting into hi-fi audio, at least, from the computer angle. I'm intrigued...

Red GTi VR6
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Re: audio via a computer...best cd-rom?

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?

I'm still curious to know what CD-Rom everyone would recomend.

bifcake
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Re: audio via a computer...best cd-rom?

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.

Red GTi VR6
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Re: audio via a computer...best cd-rom?

I think there's been a disconnect somewhere. You are assuming that all CD-rom drives are to be 'internal' CD-roms and that they are all connected as such (via IDE, SATA, etc). As I mentioned in my first post...external drives.

I think there's been a drastic turning of the point of this thread...I'm interested in finding out A) what the best CD-ROM drive is B) what is the best method of connecting an external drive....because I understand that USB is not a good idea.

I do appreciate the help, I just would rather keep on topic.

bifcake
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Re: audio via a computer...best cd-rom?

Sorry, didn't realize we were talking about an external drives since you mentioned IDE and SATA. Are you talking about connecting the external drive directly to a DAC or are you talking about connecting the drive to the computer and then to a DAC?

Red GTi VR6
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Re: audio via a computer...best cd-rom?

Connecting an external drive to a computer.

Where the audio signal goes after it exits the computer is really of no concern at this point. I'm just trying to figure out one step of the equation at a time....

I do appreciate your help here. I've tried to find information about a good drive but it seems that most people immediately dismiss me thinking that all drives are created equal.

Any drive can be made into an external drive, so it doesn't have to be designated as an external drive...cases are available out there for them.

bifcake
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Re: audio via a computer...best cd-rom?

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.

Red GTi VR6
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Re: audio via a computer...best cd-rom?

Thank you! That's the explanation I was looking for!

Everyone else just dismissed me.

Now, the connection between the computer and the drive its self shouldn't matter either I take it based on what you've said.

Red GTi VR6
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Re: audio via a computer...best cd-rom?

Sitting here talking to my husband we had some more questions.

We're gathering then that the actual transport mechanism in a standalone CD player for home audio use isn't what matters. It's everything after that point that matters. What takes that data stream and changes it to analog that makes up the difference between a $150 CD player and a $5000 CD player?

Is there really any difference between the optical eye in a $150 and a $5000 CD player?

bifcake
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Re: audio via a computer...best cd-rom?


Quote:
Sitting here talking to my husband we had some more questions.

We're gathering then that the actual transport mechanism in a standalone CD player for home audio use isn't what matters. It's everything after that point that matters. What takes that data stream and changes it to analog that makes up the difference between a $150 CD player and a $5000 CD player?

Is there really any difference between the optical eye in a $150 and a $5000 CD player?

Hi,

The transport mechanism in a standalone CD player matters because it's not encapsulating the audio as data packets and feeding it to the computer. It's feeding an audio stream via a PCM protocol to the internal Digital to Analog converter. So, the transport mechanism matters, but the shorter your pathway to the DA converter, the less prominent role the transport plays, but I wouldn't say that it doesn't matter at all unless it's feeding the data to the COMPUTER and encapsulates the audio stream as data packets.

Red GTi VR6
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Re: audio via a computer...best cd-rom?


Quote:
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.

I'm discussing this with another individual and we're a bit confused by your comment that the PCM protocol lacks clocking...

After reading up on the Wiki article (http://en.wikipedia.org/wiki/Pulse-code_modulation), I can see where PCM is PCM. 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.

Does that make sense? Is this the correct way to think about PCM data and your comment about the PCM protocol lacking clocking? If the PCM protocol were to include clocking, then wouldn't it have to specify the clock timing? 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

bifcake
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Re: audio via a computer...best cd-rom?

Hmmm... do you really want to get into the nitty gritty of the inner workings of transport protocols?

I am not sure how to answer your questions without writing a white paper on the subject. Suffice it to say that if you feed PCM stream to the DAC without buffering, then you will get small timing errors. These errors are called jitter and they adversely affect sound quality.

When the CD Rom feeds the data to the computer, it doesn't stream time sensitive data. Rather, it sends packets to the computer which are then buffered and assembled in proper order. The CD Rom does not use PCM to send data to the computer. Once the computer assembles the packets, it sends the data to the DAC via PCM and THIS is where we get into the timing issues.

u320
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cdrom audio explained

Whats hes trying to say is that in a computer cd audio drive or cdrom etc doesn't convert the audio itself as the pc and software handle that task. A unit type cd aduio player type has some seperate means to take the .cda format of the disc and render it to sound. cda is compact digital audio.

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