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).
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kleshodnic - Monday, December 1, 2008 - link
Uh, just go digital out (TOS/link or HDMI) to a receiver and let ther receiver do the DAC'ing.Want a better DAC? Buy a better receiver. Not only will you get the better DAC, you will get a ton of other great features with a higher end receiver.
All this talk about computer audio is assuming that you would want to come analog out from the computer. WHY?
phusg - Tuesday, December 2, 2008 - link
It would be a lot easier I agree, but AFAIK only really expensive top-end receivers can challenge the analog out you can get from a quality consumer audio card with upgraded opamps, especially when it comes to stereo music. They are also not usually moddable. Can you link to a review of receiver with audiophile quality stereo DAC?pedobosz - Monday, December 1, 2008 - link
an interesting place to publish such an article. Have you thought of perhaps submitting to Stereophile or The Absolute Sound ? I'm sure you are just trying to raise the awareness of the PC crowd to the possibilities of great audio, but reading through the other replys, I think you are preaching to the deaf......with the exception of the Martin Logan fellow.jnmfox - Monday, December 1, 2008 - link
Computers and audio (mostly Home Theater) are my main two hobbies. I agree this article doesn't fit here at anandtech.com. I've never understood the esoteric audio crowd. If you want quality audio information go to audioholics.com or other reputable audio sites.jabber - Monday, December 1, 2008 - link
I have to say the article and lengths gone to are way over the top for what in most cases is required.The kits combined with the PC audio side is way esoteric too.
Well intentioned but sledgehammer to crack nut.......
haukionkannel - Monday, December 1, 2008 - link
Hmmm... When we talk about HiFi nothing is "bit over".For a hifi system this was relative middle range solution. The biggest consern, if you have to find one, is that the speakers will most propably have the biggest effect an the hearing experience. These type of speakers ar not meat to be the most precise in their "room" picture. And I don't say that it's a bad thing! They are good speakers. Some studio monitors would maybe be better for testing the PC as an "Hifi" sound source, because they try not to affect the sound at same way as some High end HiFi speakers, but again it's more of a matter of taste. For example Genelec speakers sound good for Vocal based music. These in here are better in music where accuracy is not so important. So it allso depends on what music you like to listen to. Just like someone above said.
I would like to see how the sound compares between good Hifi cd-player and a PC. With the same music piece and speakers. This set with those tubes can make the sound varmer, that is good for some not so good mp3 files. More accurate monitor speakers and normal amplifier, will most propably reveal the difference between good cd and not so good PC based mp3 more clearly.
Most people who are really interested in HiFi systems spent even more money than in test to their system. The real guestion is that is the PC good enough soundsource for system like that.
jabber - Monday, December 1, 2008 - link
Yes but real high end hifi is really usually bought by what Top Gear would call 'cocks'. Folks that just see money and how much they spent rather then just enjoying music. $50000 hifi systems geared to playing just 10 specialist audiophile CDs just screams "I've led a sad and lonely life!" to me.Show me a $1000 system surrounded by piles of CDs and LPs, now thats an exciting system!
The readership of this site I would say on the whole would have far more modest hifi setups.
Once you spend so much on a hi-fi you fall into the trap of listening to the equipment rather then the music itself.
Spivonious - Monday, December 1, 2008 - link
Spending that much time and effort to listen to pop music is just about the silliest thing I've ever heard.At least put something on that will work the equipment, like a Beethoven string quartet, or a Bach choral work.
And you never even touched on the issue of vinyl vs digital. To my ears, vinyl sounds so much more organic than the plasticy sound of CDs, even through a $15,000 tube-driven stereo system.
Rajinder Gill - Monday, December 1, 2008 - link
Actually, I'm just listening to some Vaughan Williams right now. Just because there's no mention in the article does not mean to say I live without classical pieces.Peace...
Hyperion1400 - Monday, December 1, 2008 - link
Amen to that. There is no set style of music for audiophiles. I personally enjoy metal and classic punk (bad religion,sex pistols etc.) as well as a mix of classical composers(I have always had a strange love for Beethoven's 9th after watching Neon Genesis Evangelion)Also, will you be doing a review of the X-fi Elite Pro or will you be primarily dealing with external hardware. I know I will most likely be shunned for mentioning such a thing in the same post as (vicariously) declaring myself an audiophile, but I absolutely love mine. Without that card and my Senhiesser HD 650s, I don't think I could listen to my music/games the same way again(no pun intended)