Audiophile Journeys with a PCby Rajinder Gill on December 1, 2008 1:00 PM EST
- Posted in
Outboard DAC solutions
Scouring DIY audio forums proved beneficial as I found plenty of attractively priced DAC kits based upon some of the most revered DAC chips available. The availability of USB to I2S and S/PDIF converter boards opens the doors to team commercial outboard DAC solutions as well as complete DIY kit builds to provide a high-end sound experience. DIY solutions are still confined to 16-bit 44.1KHz-48KHz resolution via USB due to hardware/software limitations in the DIY small scale market. It is expected that 2009 will see the availability of 24-bit USB to I2S and S/PDIF chips while Vista should provide native output support for these formats. For now, 16-bit resolution and two-channel playback is adequate for most audio seeing as practically all of our music is recorded with CDs in mind.
Two kits stood out from the pack and present complete solutions that are available in either a modular approach or a single PCB with all components in place to convert data from the digital realm to an audiophile grade audio output. The first is the Doede Douma USB to I2S converter. Doede's solution uses the Texas Instruments 2707 USB to I2S and audio out chip. The venerable TDA1543 is the centrepiece of this kit, favoring a purist mindset as it does not use any kind of oversampling of the digital signal. Audio output from the TDA1543 is configured to use a minimalist passive I/V approach with a final output of 0.6V, which may be a little low for power amplifiers that require higher input voltage to reach full output power. PCM2707 audio output is also available if required, although most people put its subjective abilities behind the TDA1543. Pricing options start at the €49 for the basic kit, while dropping an additional €29 will allow you to experiment with a low jitter master clock based upon a 12MHz VCXO from Tentlabs.
The best two features on this particular kit (aside from cost) are the asynchronous clocking that frees us of the sonic confines imposed by CPU and system loads at the USB end of things. Secondly, Doede does not rely on the USB bus to power any of the circuitry on the PCB. This leaves us with the chance to explore various low noise linear PSUs and batteries with relative ease. Either way, the sonic performance should be in excess of designs that rely solely on internal PC power. Also worthy of a mention here is that the I2S output allows us to try out various DAC kits in the future. For example, we could use the Doede kit solely to provide the USB to I2S conversion and proceed to add a separate I2S input DAC kit as an alternative to the TDA1543. This element of flexibility is especially important to me as I already have the outboard tube stage that I used to provide the audio zest from the Pioneer player. Most modern DAC chips available today feature balanced voltage or current outputs. In my case, a balanced voltage output DAC chip allows me to transplant the tube based audio output stage and enjoy its sonic merits at my leisure.
Doede's kit is available either pre-stuffed and ready to go, or with all of the thru-hole parts loose, leaving you to stuff the PCB and do the soldering. As the PCM2707 is an SMT device, it comes pre-mounted and pre-soldered regardless of the kit option you choose. I decided to purchase the kit without the thru-hole components soldered in, as I felt confident enough to tackle this element of construction myself. I must note that there are no part-by-part instructions supplied with the kit. However, basic instructions and pictures on the DDAC homepage are clear enough to provide a good point of reference should you wish to confirm device orientation or placement in some situations.
If you've never built or soldered a kit before you're best advised to go for the pre-built option at additional cost. Either way, you'll have to provide a suitable case to house the kit. Do make sure to buy a case large enough to house additional PCBs for discrete regulated power supplies or additional DAC boards should you get the bug to upgrade things later. Audio output from Doede's module is configurable via the TDA1543 or from the output of the PCM2707 chip itself. In either configuration, the audio performance is quite good, although the TDA1543 is clearly the better performer in most situations (there will be more subjective stuff later).
Post Your CommentPlease log in or sign up to comment.
View All Comments
Olyros - Sunday, December 21, 2008 - linkWhat about Vista's digital room correction?
I'd really like to see a comparison of the effectiveness of different DRC software on the pc, including Vista's own implementation.
Before reading this article DRC was off my radar, but now I'm really intrigued to try it out. However, reading this article one still doesn't know how he can use this specialized software with an application like Winamp or Vista Media Center. There's also no mention of all the impracticalities he might face like incompatible software, provisions for headphone use where DRC is not needed etc.
I think digital room correction on a computer could be a subject of an Anandtech article again.
Okos Bokos - Monday, December 15, 2008 - linkIf you don't care about room, don't spend money on expensive equipment.
Bass traps, diffusion panels (bookshelfs are perfect), position of speakers.
I used to play with all sort of best analyzers/equalizers, and it don't works.
In essence you can not treat time related problems (short reverbs that couses phase cancelations for eg.) with frequency related tools (equalizers).
My audio chain: CD – cables – amplifier – cables – speakers.
In 1998 I bought first pro audio soundcard, and changed CD with PC. I can not afford myself such good sounding CD player.
TV and home cinema is completily different issue.
Nice article... I had to make my first comment on AnandTech...
ccd - Thursday, December 11, 2008 - link
I'd love to hear from others on this issue, but my conclusions based on following thread on various forums is that the PC as a one box solution is far from perfect. The issues are as follows:
1) PC does not work as a source selector which means an external preamp if you want to use a source other than TV/cable and the CD/hard drive on the PC
2) Most solutions for volume control cumbersome at best, again requiring a preamp
3) Soundcards: the soundcards with the best DACs (ie Lynx) are not setup to act as just high fidelity soundcards. They are designed as studio mixers which makes them both expensive and hard to use for just good fidelity. Additionally, there are some formats that soundcards have not been able to decode. This is not because soundcards cannot decode, but that certain formats simply have not been available on soundcards.
4) DRC: I have not tried the software mentioned in this article, but I have tried other DRC software. My complaint is that the DRC software is not easily implemented for novices. You have to know more about using programs than I would like. Their effectiveness is a subjective evaluation, but stand alone processors are much easier to use, IMHO.
At this point in time, if I were to use a PC, I would use programs such as SoundEasy or the program available from ETFAcoustics to load a digital equalizer like the Behringer DCX 2496 for both digital crossovers and DRC. The PC is not a viable one box solution at this time as far as I'm concerned.
BTW: I should give the author the props he deserves. Most audiophiles who are into tubes and full range drivers would not touch DRC. This author not only touched it, but liked it. Hats off to you!
boredsysadmin - Wednesday, December 10, 2008 - linkI'm afraid this question will get lost in this rant war, but I'm still curios about this : How Does PC based DRC compares to ones built-in into new a/v receivers?
P.S: CSMR is right on so many levels and IMHO combining ultra Hi-End speakers with DIY usb to analog kits seems a bit silly....
Rajinder Gill - Wednesday, December 10, 2008 - linkDepends if you're looking for a one box solution (which you obviously are). I have not seen much web based edict on the technical abilities of your standard budget-mid priced reciever based DRC. If it is scaled down somehow in functionality and attenuation, a double blind test against the software would prove if it's far behind.:) Judging by all the responses here, there should be some sites out there that have covered something around that idea.
I only wanted something for my redbook playback and quick access to my tracks. Out on a limb yes, but that's just me.
egladil - Wednesday, December 10, 2008 - linkThis article is just so typical for the pseudo-audiophile scene. There people do lots of very stupid things, including stupid subjective comparisons.
For really good audiophile stuff, go to hydrogenaudio.org, there there is a rule: don't claim anything unless you have done double blind tests with significant positive results. Anything else is just too much influenced by placebo effects. Because of this reason this article is a case for a trash bin actually.
goshwan - Wednesday, December 10, 2008 - linkYup,
All musicians should not listen to their instruments at all, because it gives rise to subjective preferences. Subjective instrument choices by the individual should be outlawed. Every musician should by rights play the most scientifically perfect instrument. Subjective choices do not matter at all. We should all buy the same car based upon te pricinples of horsepower per dollar and most importantly 4 wheels touching the road. Don't you dare tell me that you have a favorite color!
We should all buy the same amps and speakers. Electronic engineers should be forced to adopt one single topology the world over. Further, no new product should enter the market place until the manufacturer can prove it's worth to the sinewave crew as offering something new and better than what's been released before. Product release shoul depend on approval by a team of government endorsed double blind testers.
Good luck in your quest!
phusg - Monday, December 15, 2008 - linkHi there,
I think you are confusing objective testing with equipment (over-rated) and subjective double-blind testing. Double-blind testing just takes out the placebo bias of knowing what hard/software set-up you are listening to. That doesn't make it objective, the assessor is still a human subject.
ccd - Wednesday, December 10, 2008 - link
What is your issue with double blind testing??? If audiophiles are unable to tell the difference between $1000 speaker cable and $25 dollar speaker cable, isn't that worth knowing??? And what has double blind testing have to do with musicians not listening to their instruments or the rest of your rant???
Double blind testing can tell what people can differentiate (my speaker wire example) or what most people prefer. Personally, I think double blind testing is best for the former, not the later. Just because most people prefer something does not mean you would prefer it.
Rajinder Gill - Wednesday, December 10, 2008 - linkWow, I never knew this stuff was going to continue on ad-infinitum when I wrote this piece. It'll please you all to know I have no plans to write another audio article. Anandtech will continue to concentrate on the computer stuff to the joy of many readers.
I'm sure someone suitable will be found to take care of the soundcard stuff the way most of you would like to see it.
The gist of this article was basically to show that even someone as knotted up as me on certain gear could adopt DRC as something special and above lesser needs in the audio chain. Some people got that, others did not. I know I'm not the greatest conveyer of things in the written word, I did my best.
For the record, I also have solid state gear, so it's not all old-age beliefs. So let it go for the sake of your own sanity folks, there really is no winning these arguments.