[MaciekN]

  I wrote that review above to check this thesis:  computer transports can compete in terms of SQ with high end CD players. Such things are claimed by poeple who own both, a properly (whatever that would mean) setup computer transport and a high end CD to compare. So I wanted to check how my PC, which can stream audio without drop-outs (so following your logic it should be at it's top as a transport) would crash an entry level hi-fi CD. Well, it didn't, as you have read. So where do these differences come from?
 
  Random, I made the effort to set up my PC transport as good as my knowledge allows me to, borrow a CD, and set up a test. I, for one, bothered to check something empirically to see if I can hear any changes, and then write it down here for open discussion. You are comfortable in saying what you do, yet I know it to be wrong since last night, simply because I CHECKED it. Sure, it can always be placebo but maybe you will at least try to make a similar test before you  discard it just by "knowing better". You are also most welcome to come to my place and hear for yourself.
 
  If things were as you describe it every single PC would sound the same, there are many variables that have to be taken into account. Jitter is surely one but I'm no good at discussing it's types and impact on SQ luckily Google can explain it. Why are there different sounding S/PDIF converters, why so many transfer types for USB, is whole computer audio just a big placebo and marketing?
 
 You seem to have some more than common knowledge about computer hardware functioning, could you please thoroughly describe what exactly is "highly problematic" in the article and why is that so?

 

[random007]

Well, I did explain a bit: 1) jitter can't cause subtle quality distortion in the audio - it will just cause loud noise. 2) jitter can't be caused by the transport because both ends buffer and retime the physical signals they get to ensure 100% accuracy all the time.
 
Have a look at the first article to turn up when Googling 'jitter': http://en.wikipedia.org/wiki/Jitter - see Mitigation: sound chips and DACs retime and buffer to remove jitter, as does every other piece of electronics in your PC. Otherwise they'd stop working.
 
Have you conducted a double blind test? You need a friend (the more the better). There's several examples around the place of people doing double blind tests and being unable to hear differences they were absolutely certain of when they knew what the components were. People have been so startled and disturbed by this that some of the more unhinged participants claim that some part of using 'scientific method' is interfering with the sound itself! Placebo works even when you suspect it's placebo - from what I've read on the subject we are all are fundamentally optimistic at a subconscious level and extremely good at finding patterns that are subconsciously expected. 
 
I've done some casual testing with Windows with nearly everything reduced to absolute minimum, tasks killed, graphics reduced to classic, and detected no change in sound quality. That's my empirical 0.01 cents worth. 
 
You can always hook up a CD drive's digital output (older CD/DVD drives had SPDIF digital out but they tend not to these days) to the sound card's aux SPDIF input and bypass the OS completely (except for using the OS to start and stop the player and select the right input on the sound card) and see what that sounds like. It used to be quite popular to do that back when Sound Blaster cards first got a digital CD header on them (partly also because Window 95's DirectX and drivers were especially dire back then).
 
I'm quite happy to be proven wrong, but certainly the reason won't be because of bit jitter.
 

 

[meyameya]

so with high end PCs, no need for this? 

 

[MaciekN]

 
Quote:

Well, I did explain a bit: 1) jitter can't cause subtle quality distortion in the audio - it will just cause loud noise. 2) jitter can't be caused by the transport because both ends buffer and retime the physical signals they get to ensure 100% accuracy all the time.
 

If jitter is causing loud noise only then I can assume my system is totally jitter-free? Why then some chips are specified to have X ns of jitter by manufacturers? Maybe we are discussing different types of jitter?
 
Quote:

Have a look at the first article to turn up when Googling 'jitter': http://en.wikipedia.org/wiki/Jitter - see Mitigation: sound chips and DACs retime and buffer to remove jitter, as does every other piece of electronics in your PC. Otherwise they'd stop working.
 

This is very unclear, as only some DACs buffer and reclock, it depends on application. Surely it improves jitter rejection but it doesn't remove it entirely. Without error signalization DAC has to work with what was sent, correct or not, it's a realtime device. In our PCs there are controle sums, repetitive sending of flawed bits and so on until everything is OK. 

 
Quote:

Originally Posted by random007 /img/forum/go_quote.gif

I've done some casual testing with Windows with nearly everything reduced to absolute minimum, tasks killed, graphics reduced to classic, and detected no change in sound quality. That's my empirical 0.01 cents worth. 
 
 

Do tell us about this test, the more the better. To what point system was stripped down, what was the accompanying equipment, etc. Could you try repeating it with some application like Fidelizer, and see if it will change anything?
 
PS. I don't understand the part about connecting CD to a soundcard, why would I use the same source twice? (I mean, why would I send signal to soundcard only to use it as a source with all it's flaws again?)
 

 

[Apalachian77]

Interesting topic, I find it difficult to beleive that this factor could be the limiting link in music fidelity/quality though.

 

[Alghazanth]

Quote:

so with high end PCs, no need for this? 

I'd like to know this as well.

 

[MaciekN]

What do you mean by high end PC? A high end digital transport? As I understand it such PC would not benefit from apps like Fidelizer or Game Booster simply becuase it has already these things disabled. Such PC is theoretically described in "The Art of Building Computer Transports" and it's stripped down as much as it can possibly be without loosing system stability.

 

[Willakan]

Yes, but the "Art of Building Computer Transports" is simply wrong in a great many areas.

 

[MaciekN]

I think it's puristic rather than wrong, just a guess though as I haven't heard such a PC. I doubt someone would hear a difference between 256 colours and 32 bit or with explorer.exe on or off but it's an all-or-nothing approach. And I must say that I did hear improvements from going this way, even if test conditions were less than perfect. It would be great if you too ran some empirical test, the more opinions the better.
Could you write down some of the points where and why do you disagree with it?

 

[sterling1]

I'm a layman in computer audio discussions. A few years ago I discovered iTunes and downloaded it to my PC. Thereafter, I thought it would be neat to listen to my iTunes library from my home theatre. I bought an X-FI HD to get digital from PC to S/PDIF input on my home theatre preamp. I'm pleased with what I hear, more so than when using X-FI as a DAC, or when using analog output from computer to home theatre. However, to get to where I am now, required too much research and experimentation. Jeepers Creepers, I thought the operating manual for my preamp was tough. Getting iTunes to the home theatre system was much harder, as I had virtually  no understanding or instructions on how to do it.  I'm still confused, I don't know if my process and procedure has yielded the best result, although, so far, everything sounds great. What is particularly interesting is, in my haphazard experimentation, I discovered I can up-sample everything from iTunes to 24/96. I don't know where this up-sampling is taking place; but, I perceive it is enhancing my pleasure. Yet, this makes me think maybe there's some other tweak out there that has eluded me. Also I wonder why there are add-on programs for iTunes available for Macs but not available for PC. Are Macs deficient with their own iTunes program?

 

[Alghazanth]

Quote:

What do you mean by high end PC? A high end digital transport? As I understand it such PC would not benefit from apps like Fidelizer or Game Booster simply becuase it has already these things disabled. Such PC is theoretically described in "The Art of Building Computer Transports" and it's stripped down as much as it can possibly be without loosing system stability.

A high end PC as in one with ample resources to dedicate to the media playback,
 
 

 

[MaciekN]

What is your system resources usage with only foobar open? I have around 2-5% with 600-700MB RAM in use yet I found sonic improvements after using app that reduces background processes. Looks like pure processing power is not the key here, "ample resources" would mean anything that allows you to smoothly run OS + your music player of choice, and that would only be the first step in setting up a "high end PC".

 

[MaciekN]

Today I've edited boot.ini file partially as described in "The Art... " by adding "/timeres=9800" and made a short comparison with Harman HD750. Game Booster was on, resampler was off, and I killed soundcard process (RTHDCPL.exe) along with java scheduler, anti-virus, and... explorer.exe , so it looked like this:

It was funny because sometimes it showed 0% CPU usage.
 
Again I used Ultrasone Reference CD, especially tracks 2 (drums imaging test), 7- Also Sprach Zarathustra, for depth and left to right soundstage, and 8 played on Chakraphon whatever it is.
 
Now, transports were nearly indiscernable, Harman had only slighly deeper soundstage, or maybe it had the same soundstage but placed a little further from head. Left to right it was very similar. In terms of tonality, detail, and instrument placement I could not tell any difference.
 
 
EDIT: Random, I've re-read some materials on jitter and you are right if we are discussing it's impact on the first bit (so called most significant bit), if it was read as 0 instead of 1 or the other way around then there would be drop/rise equal to half the amplitude of the signal. I think that materials on http://www.tnt-audio.com/clinica/jitter1_e.html can close our discussion on this subject.
 

 

[Bill1202]

I thought apps like Game Booster are used to free up resources mostly for video?  Computer audio used very little audio and with a good soundcard, the audio is shielded and should not be an issue?  School me?  I don't get the point of this discussion yet?  Can you hear the difference when you have apps running and your system in full run mode?

 

[MaciekN]

 On the previous page you can find my comparison between my PC and Harman Kardon HD750 CD player. Also, reading a few posts back should help you understand what's this thread about.
 
I know that Game Booster, unlike Fidelizer, was not designed with audio performance in mind but it can "boost" any application, so I checked it and described my impressions in that comparison.
 
Good soundcard probably helps a lot but doesn't do it all, at least that's what I've read. Even if it's external and not subject to EMI inside computer case it's still connected to the system. If you are interested in the highest possible fidelity from your PC you must optimize the system too. Check on google "The Art of Building Computer Transports", it's an interesting reading and I can assure you that at least some of the things presented there are audible (like ediiting system file boot.ini, as described in my previous post)