My ultimate DIY stereo soundcard

Having tried pretty much every soundcard and modification out there (from X-Fi's with Black Gate's and LM4562's to Lynx's to Xonars with discrete opamps etc etc) I've finally settled on a card which does not feel like a compromise.

You need:

- an Audiotrak Prodigy HD2 ($100)
- 2 20dBm, 600ohm 1:1 transformers (I used Amplimo's)
- a bunch of caps (I used Sanyo Oscon SH, 16V)
- a fancy 5v regulator (I used a Tentlabs shunt regulator)
- some tools and soldering stuff

The result is fantastic audio!

(please ignore the rosin, it's not cleaned yet...)





A quick RMAA says <0,01% THD and >100 in s/n, dynamic range and stereo seperation. This isn't great, but it's well beyond what is audible.

The sound however, is really, really, really nice. Clarity, tone and soundstage are what set it apart. Dynamics and detail are great as well. I can't really fault it!

I'm using it in Lian Li mATX HTPC cases with Gigabyte UD motherboards (which ROCK) and passive Silverstone Phantom PSU's to great effect. You can build a pc that has the same size, price and sq as a cd player, but it's a pc with blu-ray and everything

The tricky bit is mounting the transformers. I tie-wrapped 'm to a tie-wrap-sticky-holder-thingy which I just pressed against the rear of the card. Works great, but it isn't reversible and it takes up 2 slots.

Auzentech and EMU use similar DAC chips (AK4396) and Lynx also use some voltage out ones (CS4396 I believe, not sure). I'm sure trannies can work great on those to! The great thing about AK4396 is that you don't need anything besides the transformer as long as it's the right type. The only downside on this card is that you 'kill' the line-in and hp-out. This can be avoided, but I couldn't be bothered. They both suck anyway.

I hope this doesn't get frowned upon too much and some people actually go out and try something similar. Because I promise you that if you do it right, you won't be disappointed

If anyone needs any more info I'll do my best to help.

What it comes down to is that the D/A chip, an AK4396, outputs a ready made signal with two 'issues': it's full of potential DC and it's balanced. Also, just plugging the D/A chip to the output will make the signal very prone to noise and stray capacitance and bad stuff like that.

You have an R+ (where the red wire exits the card), a R- (green wire) and a L+ and L- output. You could just use a ~5uf capacitor from the pluses to the outputs and you're done. The capacitor will block the DC and you're not using the negative outputs so it's single ended. And 5uf is enough to prevent the bass from disappearing. This works fine and sounds decent (I tried it with a 4.7uf Mundorf ZN capacitor). It's really sweet but soft and it lacks dynamics since simply put, you're only using half the power. It's also very colored because of the cap.

What I did was use a (good!) transformer that has both the plus and minus audio signal connected to it's primary winding. You tie one end of the secondary (blue) to the output, and the other (white) to signal ground. When you connect a load (at least 10kOhm ideally) to blue, the transformer sums plus and minus and sends them both flying towards your amp in a single cable strand (so it's now unbalanced). The transformer also prevents any DC from coming out and it has fantastic noise rejection. Please note that it's only this simple with an AK4396. Every other D/A chip I know of requires more stuff to be done, whether it's current -> voltage conversion or noise filtering or both.

The capacitor replacements are just a simple upgrade of what was there first. You could also use Panasonic FM, Rubycon ZA/ZL or Elna Cerafine to great effect just to name a couple. Pick 16V and you're safe. With Panasonic FM or a Rubycon ZL, I prefer to stick with at least 25V ones. They're just better, for some reason. The caps I left out were made redundant by the mod.

The new Tentlabs regulator replaces the crappy 7805A regulator that used to feed the analogue part of the AK4396. It's not the most cost effective upgrade, but I don't care. Figuring out where to put it is just a simple matter of using your multimeter and reading some spec sheets so you know which pin is what. The small blue cap is a .1uf Vishay MKP1837 I had laying around.

It's also very important you isolate the RCA plugs and the D/A output from the rest of the card! You don't want your sound leaking away through some feedback loop or cap to ground or whatever. That's why I removed some stuff near the RCA ports. Again, just use your multimeter to figure it out. Just start measuring resistance all over the place.

I hope that helped a bit!

Somebody here send me a pm about this so I thought I'd add it here.



The red circled area is the stuff you have to remove in order to isolate the RCA jacks. The red dots are where you connect the trannies. This is all that is needed to do the basic mod, but obviously you will kill the hp out doing it this way and it's not reversable.