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.

Your mod is very impressive! As a complete novice starting out, what advice could you give me in regards to understanding how you modded that? I am a decent solderer but I don't know what you put where, nor do I understand why.

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!

..cool stuff.

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.

OH, Really nice..

and I will trash the opamp mania!!
How much does it costs?

ps: Please put a "Prodigy HD" in the title so it becomes searchable,

those transformers are quite pricey, and here's what Scott Wurcer(the AD797 designer) had to say about it: The best sounding audio integrated opamps - Page 166 - diyAudio

very impressive nevertheless!

If it helps, you can build a passive output for certain opamps in a circuit. Such as buffers etc. Many people say this is the prefered method as it sounds better then the opamps they have tried but the downside is th output is quite low using a passive output. I have seen passive outputs built for cards such as X-meridian's etc. I should have the circuit here somwhere very simple.. a cap and a resistor IIRC. Here is some more infomration that is ismialr to what he guy is doing above: LINK

Here is the info about using the cap and resistor for passive output, it may be applicable for your circuit also: LINK

Hope this helps.

If, he`s really a opamp designer, then you`d expect that answer,
this mod is probably the best sounding option of the HD2, considering all high end design don`t contain opamps,
unfortunately seems a bit expensive, and you cant predict results,
another point is the amplifier, this mod needs a good one,

Thanks

oh right, you haven't heard the mod..specs seem to show that SNR/THD would suck(partly due to the long wires in a noisy PC environment)...you call high end integrated opamps too expensive for you and yet, you'd consider 2 transformers that cost $100 a pop and void your warranty?

gear that doesn't use opamps uses discrete designs...anyway, the only person that can talk about this mod is the OP...he's been listening to it for a while now I guess, so he should be able to tell us about the pros/cons...against the Burson's for instance

It looks like the mods use the stock ground for the RCA jacks, have you tried something else (I dont know what) to isolate the audio ground from the computer case ground? Perhaps isolated RCA jacks, or TRS plugs. It could be worth a try

Edited/added:
Do you have loading resistors on the secondaries of the transformers?

Still the SNR maddness, have you measured the Benchmark DAC, bet the Audigy can do better in measurements,
I bought this card, just for fun, and dont want to spent a lot extra, but if I see it has potential at stock, then its a different story,
Warranty? are you kidding..

As for the external DACs being better, well I spent some money on them, keeping under 500€ for sure, but always got back to my modded EMU1212M,

Bet he`s modding

No problem. Such mods are common for soundcards or atleast I have seen them done many times with different cards.

some live unshielded wires in a PC case will pick up interferences like there's no tomorrow, sorry for the breaking news....and what's fueling all this is still the nasty ATX PSU 12V rail(that has to go through the whole mobo too )

I guess you bought the wrong 499€ DAC's then? especially if you expect a $50 soundcard to beat them.

Actually, thats one of the reason that internal soundcards can sound better..