CDP vs DAC connected to computer

[philodox]

Quote:

Originally Posted by tfarney /img/forum/go_quote.gif If the DACs are equal, and the files on the computer are lossless, the computer will be technically better. The computer feeds chunks into RAM, varifies that they are a bit-perfect match to what's on the hard drive, them plays them from RAM. No moving parts. No stability issues. No contest. No matter how good the cdp is. With that said, I don't know if you'll ever hear the difference, but theoretically the computer is superior if the DACs are the same.

Actually, I would think quite the opposite. Most of what you are describing has very little sonic impact, and considerations for these design issues are made when the CD player is built. Not sure where you got the idea that CD players aren't bit perfect, but it is computers that are such a hassle to get bit perfect, not the other way around. There are two big negatives that computers have going for them over a single box CD player. The first being power supply noise, the second being the SPDIF format. Even if you are talking a squeezebox with an aftermarket power supply, the signal is still going through SPDIF and as such a CD player with the same DAC and output stage as the external DAC the squeezebox is feeding still has the sonic advantage.

 

[HeadLover]

Quote:

Originally Posted by philodox /img/forum/go_quote.gif Actually, I would think quite the opposite. Most of what you are describing has very little sonic impact, and considerations for these design issues are made when the CD player is built. Not sure where you got the idea that CD players aren't bit perfect, but it is computers that are such a hassle to get bit perfect, not the other way around. There are two big negatives that computers have going for them over a single box CD player. The first being power supply noise, the second being the SPDIF format. Even if you are talking a squeezebox with an aftermarket power supply, the signal is still going through SPDIF and as such a CD player with the same DAC and output stage as the external DAC the squeezebox is feeding still has the sonic advantage.

Didn't understand you

So
Why isn't a DAC good as or even better when connecting to a PC rather than a CDP ?
What is the problem with SPDIF ?

 

[philodox]

Most CD players read the disc and send the digital signal directly to the DAC chip, which converts it and sends it to the analog output stage and from there to your preamp or headphone amp. A high end CD player will have seperate power supplies for the analog and digital sections which should help them operate as they are intended.

A computer uses a low quality [by comparison] switching power supply. These PSU's are very efficient and work quite well to power a computer, but are not ideal for powering an audio circuit. It is very easy for the digital signal to pick up noise in such an environment. By moving to an externally powered USB device or a wireless system [squeezebox], you can overcome this.

However, In order for the computer [or squeezebox, etc] to be able to send a digital signal to an external DAC, it first needs to convert it to the SPDIF format. It then travels over a coax RCA cable or an optical cable [both of which have their issues and may not be of good quality/design]. The DAC then recieves this SPDIF signal and converts it back. Either or both of the SPDIF conversions may not be ideal. Problems in these conversions, or in the digital cable, or with PSU noise can cause issues such as timing errors. Sonically, this can translate to collapsed soundstage, harshness, etc. Some DACs try to correct this by reclocking, but in my experience this either does not completely fix the problem or introduces problems of its own. Someone mentioned slaving the clock, or using a master clock, which would correct most issues of this nature as far as I know. A CD player will have these same issues when sending a digital signal to an external DAC, though the SPDIF circuit will likely be properly implemented.

These issues can be very hard to get around, and it is often quite the battle to perfect a computer as source setup once you are aware of them [have heard them]. The issues that tfarney attributes to CD players are both less impactful and easier to resolve. Error correction in most CD players can more than handle these slight variations.

I'd like to point out that I have nothing against computer as source setups, nor do I think they can't sound good. I do think it is a LOT easier and potentially cheaper to get a good setup with a single box CD player.

EDIT: A computer as source setup also requires a fair bit of setup/knowledge to perfect. You have to worry about getting perfect rips through EAC and encoding to FLAC, you have to setup ASIO, kernel streaming or some other form of quality output, you have to setup your playback software properly, etc. Much easier to just pop in a CD.

 

[HeadLover]

so
After all I have read here, still did not get the answer as for what is better

 

[HeadLover]

Quote:

Originally Posted by philodox /img/forum/go_quote.gif Most CD players read the disc and send the digital signal directly to the DAC chip, which converts it and sends it to the analog output stage and from there to your preamp or headphone amp. A high end CD player will have seperate power supplies for the analog and digital sections which should help them operate as they are intended. A computer uses a low quality [by comparison] switching power supply. These PSU's are very efficient and work quite well to power a computer, but are not ideal for powering an audio circuit. It is very easy for the digital signal to pick up noise in such an environment. By moving to an externally powered USB device or a wireless system [squeezebox], you can overcome this. However, In order for the computer [or squeezebox, etc] to be able to send a digital signal to an external DAC, it first needs to convert it to the SPDIF format. It then travels over a coax RCA cable or an optical cable [both of which have their issues and may not be of good quality/design]. The DAC then recieves this SPDIF signal and converts it back. Either or both of the SPDIF conversions may not be ideal. Problems in these conversions, or in the digital cable, or with PSU noise can cause issues such as timing errors. Sonically, this can translate to collapsed soundstage, harshness, etc. Some DACs try to correct this by reclocking, but in my experience this either does not completely fix the problem or introduces problems of its own. Someone mentioned slaving the clock, or using a master clock, which would correct most issues of this nature as far as I know. A CD player will have these same issues when sending a digital signal to an external DAC, though the SPDIF circuit will likely be properly implemented. These issues can be very hard to get around, and it is often quite the battle to perfect a computer as source setup once you are aware of them [have heard them]. The issues that tfarney attributes to CD players are both less impactful and easier to resolve. Error correction in most CD players can more than handle these slight variations. I'd like to point out that I have nothing against computer as source setups, nor do I think they can't sound good. I do think it is a LOT easier and potentially cheaper to get a good setup with a single box CD player.

I agree with all that you say
But
What about a CD transporter and a DAC ? they are still connected with Digital (like the PC) and can have some jittering and so on, right ?
But a lot of top high end audio brands use this style

and the same for PSU, some brands use PSU outside the box, and some inside the CDP

So I still don't get the answer I want

 

[proglife]

Quote:

Originally Posted by HeadLover /img/forum/go_quote.gif So I still don't get the answer I want

I have no answer for you and I enjoy reading these nit-picky technical arguments for the sake of entertainment.

BUT, if you're asking because you're trying to decide on a purchase, the better question is "which is more convenient for my life style?". The chances that you'll be able to tell a difference between the computer and cd based transport running into the same DAC is unlikely. Even if it is discernible to you, it will be such a minor difference that the question of convenience is probably a more important thing to consider.

If popping a cd in a drive makes more sense for your lifestyle, that's probably what you should go for. If you have the room and ability to set up a computer based system, that's probably the better option for you.

 

[philodox]

Quote:

Originally Posted by HeadLover /img/forum/go_quote.gif I agree with all that you say But What about a CD transporter and a DAC ? they are still connected with Digital (like the PC) and can have some jittering and so on, right ? But a lot of top high end audio brands use this style

That is correct, I said much the same here: "A CD player will have these same issues when sending a digital signal to an external DAC, though the SPDIF circuit will likely be properly implemented."

If you are talking about two box devices, they usually have specialized connections that send the digital signal and the clock signal seperately and do not use SPDIF.

Unless I read the OP wrong though, the question was CDP vs. Computer+DAC, not CDP+DAC vs. Computer+DAC. Quote:

Originally Posted by HeadLover /img/forum/go_quote.gif and the same for PSU, some brands use PSU outside the box, and some inside the CDP

There is nothing wrong with having the PSU inside the CDP. The quality and type [linear vs. switching] of the power supply is what is really important. Quote:

Originally Posted by proglife /img/forum/go_quote.gif I have no answer for you and I enjoy reading these nit-picky technical arguments for the sake of entertainment.

I responded as I did based on what was being said, but I definately trust my ears over any technical explination. I have had multiple computer as source setups in the past, as well as CD player setups. All of what I am, poorly, trying to explain technically I have experienced first hand. Quote:

Originally Posted by proglife /img/forum/go_quote.gif BUT, if you're asking because you're trying to decide on a purchase, the better question is "which is more convenient for my life style?". The chances that you'll be able to tell a difference between the computer and cd based transport running into the same DAC is unlikely. Even if it is discernible to you, it will be such a minor difference that the question of convenience is probably a more important thing to consider. If popping a cd in a drive makes more sense for your lifestyle, that's probably what you should go for. If you have the room and ability to set up a computer based system, that's probably the better option for you.

Very good advice here. That should really be the first thing you think about.

 

[infinitesymphony]

Quote:

Originally Posted by HeadLover /img/forum/go_quote.gif So I still don't get the answer I want

All setups have strengths and weaknesses. None are inherently 'better.' It is impossible to completely eliminate jitter, and it's not guaranteed that a sound card's digital output will have less jitter than a CD player (and vice-versa). Every device is different.

 

[tfarney]

Quote:

Originally Posted by philodox /img/forum/go_quote.gif Actually, I would think quite the opposite. Most of what you are describing has very little sonic impact, and considerations for these design issues are made when the CD player is built. Not sure where you got the idea that CD players aren't bit perfect, but it is computers that are such a hassle to get bit perfect, not the other way around. There are two big negatives that computers have going for them over a single box CD player. The first being power supply noise, the second being the SPDIF format. Even if you are talking a squeezebox with an aftermarket power supply, the signal is still going through SPDIF and as such a CD player with the same DAC and output stage as the external DAC the squeezebox is feeding still has the sonic advantage.

Sorry if I wasn't clear. My statement about the computer as source being theoretically superior assumed that the DAC and/or soundcard was outside of the computer, with it's own power supply. I have heard really clean, quiet audio coming straight out of a computer, but it is the exception, not the rule.

As far as S/PDIF is concerned, many high-end cdp set-ups use a separate DAC. The cdp itself is just a transport. The link between them is S/PDIF. The disadvantage, as I understand it, of S/PDIF is jitter. At levels well below the threshold of human hearing. Much of what we're talking about probably is. The advice to use what is most convenient is probably the best.

Tim

 

[Ragonix]

Quote:

Originally Posted by HeadLover /img/forum/go_quote.gif so If that the case, why do people spend like 10,000$ or more for a CDP, when they can buy a good DAC for like 2000$ ? A good DAC may cost you even 5000$ or 10,000$ but still some CDP cost 5x times more So, what and where is the "trick" ?

People also spend $10k or more on dacs while other people can get good a cdp for $2k.

 

[LeonvB]

Quote:

so how can you make sure the sound from your computer get completely "clean" from the sound card digital exit to the DAC ? What sound card do you need and what drivers and software so you can play FLAC and let the DAC do the rest of the process ?

In theory, it's simple: don't use a sound card in the PC. Skip the software player part, most of the OS problems, etc.: use a network equipped DAC to play the sound. As long as the PC or NAS is able to pump data onto the network, it'll remain playing the most perfect stream of data money can buy. Networks have error detection, re-send ability, etc. And all for a sum of money few would believe.

Unfortunately most current network equipped DACs are either extremely high end (fi. Linn), or pretty low end devices (fi. Squeezebox). The middleground simply isn't as well developed and/or balanced a design (Transporter) as it should be, and even high end devices have their problems (Linn: no remote?? Even a Logitech Duet has one). But we're only at the beginning of this change, and I'm sure we'll see more practical designs in the future.

 

[philodox]

Tim - Seems we're on the same page though slightly on either side as far as preference.

As I said before though, most two box CD players have a proprietary link and don't use SPDIF. I'd also like to point out that SPDIF isn't always evil, but that it has the potential to be, and as such should be avoided if possible. I use a whole whack of optical and coaxial connections to route my 'home theatre' setup and it sounds fine, but that is not my critical listening rig.

 

[22906]

Quote:

Originally Posted by tfarney /img/forum/go_quote.gif If the DACs are equal, and the files on the computer are lossless, the computer will be technically better.

I think this is a bit misleading. The only real theoretical advantage to the computer-transport is the convenience of storing music on a computer. Using USB to connect a PC to a DAC is not a straightforward, jitter-free affair. The widespread TI PCM270x USB receiver chips have far from perfect jitter performance, and only very recent (and expensive) USB DACs utilize asynchronous mode to transmit the audio data, which is a big leap forward in jitter reduction.

It is definitely not a clear-cut issue looking at it from this side of the DAC chip. When comparing to integrated CDP, master clock integration and signal routing is greatly simplified in the one-box solution as opposed to transport-DAC duets. A computer-transport is not really any better than CD-transports in this regard, so it's hard to put computer-transport performance on par with high end one-box CDPs.

 

[number1sixerfan]

I think in the real world with the same dac chip, and computer dac and cd player would sound pretty much the same. Please inform me if anyone has done an experiment and found one to sound *better* (and not by technical measurements), but I speculate that not much of these small technical differences amount to much in an audible sense.

 

[philodox]

I don't think anyone has ever gone as far as you are suggesting [unless I misread you], but I've gone half way there.

My lavry da-10 sounded noticably different when using my old Archos MP3 player [playing WAVs], my Chaintech sound card, my Squeezebox and my Eastsound CD-E5. If I had to rank them, it would be as follows: Eastsound > Squeezebox > Archos > Chaintech. I also found that on the Squeezebox, WAV's sounded better than FLAC... which doesn't really make any sense. I asked about this on the forums at the time and the best theory was that the built in FLAC decoder had issues. In the end, I changed the settings so that it decoded the FLAC on my computer and sent it to the Squeezebox in WAV format. I used an optical cable on the Chaintech as it sounded better, but on all of the other sources [the Archos only has coax] sounded better with coaxial cables. I also compared a bunch of coaxial cables and found one that was clearly superior. Luckily, it was also the cheapest.

It is hard to say what exactly it was that caused these differences, but they were there. Most of these listening sessions were with a group of 3-4 people and our preferences were nearly identical. We didn't bother with any sort of rigorous scientific testing, but I still value the results.