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

endura
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I read with great interest all the comments. So for what its worth here are my experiences.

I've been through all formats over the last 50 years, eventually ending up with PC CD/DVD ROM in a computer.
The list is long, vinyl on a Thorens/SME arm, to Micromega Classic DATA transport, with a lot of tasty items
over the years. Including 300B valve monoblocks, Monarchy Audio tube DAC, Spendor, IMF, Tannoy, BBC Monitors, etc, etc.

So the current setup.

From the CD ROM, Silver Curious USB Cables, to a Wyred For Sound, Femto Jitter Buster. From there using the Curious Link to the USB input of a Benchmark DAC, the rum in balanced mode (with Russ Andrews cable) to two Monarchy Audio SM 70 Pro amplifiers, then out to either Spendor BC1's or Kef Concertos. The Spendor had a rebuilt Crossover by Derek Hughes, whose father designed the BC1's, and he built two new air-core split transformers for them. The rest of the caps are Mundorf and Jantzen. The Kefs had new crossover built in Holland and the drive units supplied by Falcon Audio to the original specification. The cabinets have also been re-veneered.

Now here is an important bit. Inside the computer, there is fitted a USN/Sound Card, by SOtm, https://www.sotm-audio.com/sotmwp/english/portfolio-item/tx-usbexp/

It eliminates various types of noise which are blocked from the inside the digital devices. To reduce such noise, the tX-USBexp has been designed with the special filter circuits, an Ultra low-noise Voltage regulator, and an ultra-low jitter clock equipped.

There is no difference to the sound quality between whatever input to the Benchmark DAC. That's either USB, CD ROM etc.

Food for thought?

endura.

Swampbrain
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I connect my external dac (Topping D70) to my computer/digital tracks via USB and according to measurements I've seen its the preferred connection or at least A preferred means of connection. I could use an HD, spdif (optical) connection but I've been using the USB for many months now with no complaints.

I imagine the jitter problem your referring to is specific to certain dacs. Most quality hifi dacs address issues like jitter via USB I'm sure.

BTW - I listen to ALL my music via computer/digital.
Might make me not audiophile enough but I dont own a cd player, turntable, tube amp or any $100 cables but I THINK the digital music system I've been putting together kicks ass and will just keep getting better as I add a few finishing upgrade/touchs.

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