Computer Audio Transport, episode 2

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Hello guys.
I'd like to get some help regarding a similar problem I'm experiencing with a building computer at home.

The story first
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1. Brought in a DAC for evaluation (Red Wine Audio Isabellina)
2. Couldn't connect it to my SB3 'cause I didn't have an RCA->BNC cable.
3. I connected it to my laptop instead.
4. Listened to FLACs and WAVs on my living-room stereo, and it sounded great.
5. Bought an RCA->BNC plug & Connected the SB3 to the DAC.
7. Amazingly the sound deteriorated substantially. (i.e. CRAP!)
8. Decided to neglect the SB3 idea and dedicate a PC to it.
9. For the sake of sports, I connected a 1 y/o desktop I have at home via USB to the DAC as well, to make sure all USB outs are identical. (I played the same files via the same audio player - foobar 2000).
10. Surprisingly, the desktop was superior to the laptop.

QUESTIONS
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1. WHY O WHY WAS IT DIFFERENT? Which components degraded the sound quality? Perhaps too much magnetic field in the laptop?
2. When I buy myself a nice HTPC-like computer (FOR AUDIO ONLY), what should I pay attention to when i choose the components? (mother board, chassis, CPU).
3. Is there a quality difference between different USB controllers? If yes, which ones are the best?
4. If I buy a sound card with a USB output, will it be superior to the computer's USB?

In short - HOW DO I BUILD A COMPUTER TRANSPORT AND MAKE SURE IT'S THE BEST SOUNDING POSSIBLE FOR USB OUTPUTS?

My mind's racing on this one for 2 days now and I can't get any sleep. I WANT TO PUT THIS WHOLE SAGA BEHIND :).

HELP!

Thanks...:eek: :smash:
 
I have the similar results using the same computer. Few mohth ago I am trying to use the desktop as the musical server. But the sound from it was awful and I suggest that it has not enough perfomance for that task.
Not so long ago I have to reformat the system disc and reinstall Windows XP. Than I have install only one program - Foobar2000 and have listen a few compositions. The result is splendid!
So you have to compare the hardware if you are completely sure in the identity of software.
 
There are some people who attribute a voodoo to it. I'm not one of them. If you're the sort who believes that one resistor sounds substantially different to another, than you might want to look to into the cics cMP and cPlay projects. There's a lot of information about them over on Audio Asylum.

Well, actually, you should read that information anyway - there ARE useful pieces of advice.

Basically, you want to build a low power computer. Preferably low enough power that only the power supply fan is necessary for cooling.

For affordable performance per watt, there's no going past the Intel Core 2 Duo processors. A good choice for this sort of project is the E7300. It has enough grunt to spare that you can underclock it, and lower the core voltage to run it cooler. Put a passive cooler on it, you want to avoid fans, they're noisy both acoustically and electrically.

Now you need a motherboard to put it in. I'd suggest something based on the Intel G31 series chipset. That chipset is rock solid for normal use, and underclocking (reducing the Front Side Bus speed) will further relieve some strain, leaving it very stable. The G31, as opposed to the P31 or P35, gets you can integrated graphics controller, saving you complexity and avoiding another fan. My personal favourite is Gigabyte's G31M-S2L.

Now, for the RAM. Some people say less is more, some people have suggested that running the memory in dual channel mode is damaging to the sound, etc. To me, that falls into the category of voodoo. I would suggest 2 x 1GB sticks of RAM. You'll want 800mhz DDR2. Don't get the very cheapest no-name stuff, DDR2 is cheap enough that you can afford to buy the good stuff from Kingston or Corsair. My recommendation here goes to Kingston Hyper-X.

As to an optical drive? Don't fuss about it too much, you'll only use it for ripping music, not playback.

Hard drive: Capacity based on how much music you want to store, working on the assumption that 1 album encoded to FLAC takes about 500mb. 750GB will store well over a thousand albums. If you have, or know somebody who has, the technical know-how, buy two and run them as a RAID array, mirrored, both for data security and to increase read performance (as data can then be requested from both drives simultaneously).

Chassis? Buy one designed for sensible cooling. My personal favourite in this regard is the Antec Fusion series. These come with a good quality power supply. If you go with another case - GET A GOOD POWER SUPPLY. Cheap power supplies are a frequent contributor to poor system stability, and may also be electrically noisier.

All modern PC power supplies are switchmode PSU's.....that's not entirely good news for audio, but since your DAC's supply is separate, I'd not worry about it too much.

As for an operating system? A stripped down (nLite'd) version of XP Professional is appropriate. With the right modifications (see the projects mentioned above), it can be a very lightweight, high performance and stable operating system.

Finally - a PC transport should have no network connection. No software other than that necessary to rip and play music. Certainly no background processes like firewalls or antivirus. Correctly configuring the operating system and software will provide the greatest possible quality increase over using a multi-purpose workstation.

Ultimately, such a system should be limited by the USB DAC. USB is not an ideal protocol for audio, but it is better than having the analogue stages inside the electrically noisy PC.
 
Great info. Thanks

I've been fussing around all afternoon with cPlay and cics CMP.
While cplay was quite straightforward I was struggling with cics cmp which seemed very promising but i couldn't get it to work - it kept on returning an error message about about a CD not being present and I could never get it to integrate witih Foobar and play some music.

Have you ever dealt with these two? Do you know if it's possible to play cPlay using the cics cmp as a shell?

cPlay shows superior performance by far compared to a standard foobar.

Also, have you had personal experience with tweaking with harder, Power-wise? I'm talking about the power supplies tweaks and architecture mentioned in the cics cmp installation manual.
 
As I said, I think a lot of those "tweaks" are voodoo. If you want information on them, ask on Audio Asylum, or, on this forum, ask Peter Daniel. Some may be worthwhile, like upgrading power caps, others, like changing to 12V sourced mini power supplies fed from a linear reg, I fear may not be worthwhile at all.

No, I don't have any personal experience with CMP....It's something I've had a look at, but at the moment, I have a multi-purpose "Media Centre" rather than a dedicated "PC Transport".

http://www.audioasylum.com/forums/pcaudio/messages/2/27041.html would seem to be the relevant resource.
 
Firewire is indeed close to a perfect protocol to the job, however, I'm yet to see a chip that makes a firewire DAC as easy to implement as, for example, TI's PCM2707. The day somebody produces a chip that is designed for the purpose of Firewire -> I2S (TSB43DA42 is the closest chip that I'm aware of) will be the day we can start DIYing firewire DAC's!
 
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