A primer on Computer Audio and AN DAC Kits

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Back in the fall of 2005 Brian asked me to share my experiences on putting computer audio into my DAC 1.1 and then 2.1, so I'm well overdue and appologize for that. However, I now have a lot more experience with it and more to say, so it works out in the end.
My inspiration for trying computer audio came from Hagerman Technologies (www.hagtech.com) and Jim's HagUSB product. For about $70 I could build his device and not have to save for much more expensive units from other outfits.
The HagUSB converts the computer's USB output signal into an S/PDIF signal, which the DAC can process. No, I don't listen to MP3s (more on that later) so don't stop reading now if you think I'm into Low Fi!
On first try, I didn't like the HagUSB. However I quickly discovered that replacing the RCA S/PDIF jack recommended in the parts list with one of Brian's heavy silver plated AN parts made a HUGE improvement. I later replaced the caps in the signal path with Blackgate N series non-polar caps, and the resistors in the signal path with audio grade parts from Parts Connexion (choose your poison). These addition tweaks kept me very happy.
Used as intended, the HagUSB connects to the PC with a standard Type 1 to Type 2 connector USB cable, and then to your DAC via a digital S/PDIF cable. Right away I searched for a better USB cable and learned that there appears to be no such thing as an "audiophile" USB cable. Undeterred, I made my own.
I've tried two types so far. The firsy used a cotton insulated solid silver twisted pair, shielded with foil leftover from a disassembled coax cable. The two power wires were placed external to the silver signal wires, and were silver over copper.
This set up sounded very good, but I was concerned the shielding wasn't all it could be, so I turned to some left over DH Labs shielded interconnect I had lying around. In this case I used two lengths of the shielded-pair cable, one for signal and the other for the power connection. I should add here that the HagUSB is powered by your computer's USB bus. The DH cable sounds excellent as well and though I haven't a/b'ed the two cables yet, I don't feel any urge to go back to the solid silver at this point. I plan to try the AN/A copper cable next.
How do you get connectors for the DIY USB cables? Well, you don't. I had to take apart a cable using surgical precision to slit open the computer-end connector and then remove it from its plastic tomb. When you do so you'll see that the wires from the cable attach to the connectors on four very small pads. The DH Labs cable is a little big for these pads, but I got it to work. The smaller silver was easy to attach. A bit of heatshrink over the connector/cable interface and voila: one end of an audiophile USB cable.
The other end of the cable posed a problem because its connector does not take kindly to being taken apart and rewired. After giving it some thought, I came up with a solution in the form of the 4-pole Neutrik Speakon connector. I used one of the XLR socket openings in the DAC 2.1 chassis (which I had to enlarge a little using a Dremel tool and a cutting bit not designed for hard steel, I'm sure, but that did the trick - destroying the bit in the process, but it's a small price). On the cable I added the male connector (or is it female - these terms don't easy fit to the Speakon). I found that I needed to add some solder to keep the smaller wires in the Speakon's terminal connections, as the screw-down plate didn't quite hold them tight enough. The Speakons, by the way, are silver over copper connectors and do not hurt the sound at all. They also connect very solidly to one another and are self-cleaning. Lovely stuff.
Rather than have the HagUSB external to the DAC, I decided to move it inside, placing it over the digital board. I decided to completely eliminate the digital cable and RCA jack and instead I have the input capacitor (in my case a Jensen aluminum foil, 0.01uf) connected directly to the HagUSB, and then to the digital input transformer on the digital board. While this may violate some sacred 75 ohm digital standard, it works and I don't hear any deterioration in the sound; Quite the contrary, actually.
Now onto the PC. The best software you can use to copy CDs onto your hard drive is Exact Audio Copy (EAC) (free from http://www.exactaudiocopy.de/ ) This will make bit-perfect copies and store them in any format you wish on your hard drive. I chose to use a lossless encoder (FLAC, free from http://flac.sourceforge.net/ ) which compresses the files but does not remove information like MP3s do. For a tutorial on EAC, check out the "LINKS" page from the EAC homepage.
Playback software is also important. The best seems to be Foobar2000 (free from http://www.foobar2000.org/ and a good tutorial on setting it up is available at http://wiki.hydrogenaudio.org/index.php?title=Foobar2000 ) Foobar is pretty user unfriendly, so it's worth spending time with the tutorials that are out there.
Good news: the next version of Windows will feature audiophile-friendly sound capabilities. Remarkably, Microsoft has recognized that the inherent Windows sound capability is terrible and wants to be at the forefront of sound quality. Stay tuned).
How does PC audio sound using all the above? Well it blows away my Roksan Kandy CD player that's fitted with an aftermarket low jitter clock. Better detail, wider soundstage and a much more 'alive' sound. Once all your CD's are installed, it makes it a snap to find and play anything. I have my Foobar set to play randomly, giving me my own radio station of many hundreds of tracks that I LIKE! And commercial free too ;) It also means that all those CDs are now stored away.
My final setup uses a recently acquired Dell laptop with an 80gb hard drive. You do NOT need a powerful computer for computer audio. In fact, my PC is the lowest end model Dell offers, with a Celeron processor and 512 mb of memory. What you want to spend money on is a hard drive - the bigger, the better. I decided to start with the stock 80gb (which will hold probably something like 800 to 1000 tracks, lightly compressed) and then I added wireless networking and another 80gb into my main PC. The wireless audio from the main PC seems to sound as good as straight off the laptop's hard drive, though I'm sure that it's susceptible to interference and therefore I think having a laptop or PC close to your DAC is the best way to go. Keep in mind that you want a QUIET computer near your DAC. Even the base Dell laptop is absolutely whisper quiet.
I guess that's it in a nutshell. I'd be happy to answer any questions.

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Topic - A primer on Computer Audio and AN DAC Kits - Kamigo 11:48:39 05/20/06 (4)

Re: A primer on Computer Audio and AN DAC Kits - scarebus 12:28:31 05/20/06 (0)

USB and DAC Kit - QuadESL63 12:19:04 05/20/06 (2)

I did install it inside - Kamigo 13:29:47 05/20/06 (1)

Overlooked that in your post... - QuadESL63 17:08:52 05/20/06 (0)

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