1. Chriscom30 Jul 2011 @ 22:38

    nice to see this new section! maybe i have something useful to share in next time!


  2. anonymous30 Jul 2011 @ 23:23

    requesting pics when posting stuff, they are helful for noobs like me :>


  3. Zeeshan Choudhry01 Aug 2011 @ 10:36

    Looking forward to some MODs 🙂


  4. adm08 Aug 2011 @ 22:34

    The best tweak I've found is replacing the op-amps in my Xonar Essence ST. Maybe someone could post recommendations and descriptions of different op-amp's "sound"?


    • Con13 Aug 2011 @ 10:50

      The best tweak is to change the oscillator/quartz with one more accurate and stable... The op-amp`s is the last tweak after many others changing are made on this audio card. I can agree that changing the op-amp`s is only the less complicated (easiest) tweak.


  5. anonymous18 Aug 2011 @ 21:50

    how expensive is a new one and where to get it from?


    • Alpha28 Aug 2011 @ 00:25

      Is there a forum thread i can follow for this mod, recall reading about this mod somewhere on Head-Fi but few were saying it made it sounded worse and isn't worth the effort.


  6. Con29 Aug 2011 @ 16:48

    Modding this Asus sound card is the right/best thing to do to have the one of the best sound out of a computer. The same really HiFI sound as from very expensive dedicated DAC devices. The hardware used on this card is very capable to do it! (I personally use Asus STX only on stereo and for music listening)
    Specially the best and easiest way to mod it with the best results, is to mod the Essence STX, or ST card. The hardware on this Asus sound card is quite good (maybe the best) in this class. It is very strange that Asus it self did not used correctly the hardware they choose it for build up this card. They are very big mistakes made by Asus designers in designing this card. At they presented afterwards their product and promoted STX/ST cards as the best HiFi card on the marked is only a big lie! They want to prove the “good” results by showing snapshots from oscilloscopes, spectrum analysers and so on. Asus only forget at ordinary consumer do not hear the sound with oscilloscopes, but with they own ears… But anyway…
    The most important one have to change/mod it on this card is the clock (oscillator), and the power supply for the respectively integrated circuits. It is essential that the clock have the lowest jitter for at this card to sound exceptional. The same essential is that the right and quiet as possible power supply feed the electronics on card.
    Unfortunately, to mod this Asus card in the right way is not easy at all. One have to have high enough skills in electronics, and the right tools too. The easiest way to do it is to change the clock/oscillator on the card with a better one. The way to do this is already describe it with pictures on the net. Just Google it. Note that the best and right way is to solder the oscillator output directly to the clock input pin of the CMI8788 processor. Desolder carefully and lift up this in clock pin of the CMI8788 processor. Then solder it directly to the oscillator output. The oscillator have to be glued on the card in one way previously. The both pins have to be positioned in right position, and then solder the pins together. Do not touch these components after, and be carefully to not change the oscillator position after soldering of the pins are made.
    More I will try here to suggest the follow:
    - remove all the “best” yellow electrolytic capacitors on this card and replace it with SMD ceramics with corresponding values. Note that near to PCM 1792 DAC on the card are 2 x 47µF capacitors (near the coper shield in the middle of the card). These have to be replaced with a equivalent value of 300µF/6v ceramic SMD. The best way to remove the yellow capacitors is not de soldering it, but broke theirs legs by moving it back and forth many times until their be separated from the legs. This take al little time, and one have to have patience to do this job…. The remaining legs on the card will help to soldering the SMD capacitors.
    - they are many passive components witch Asus use at the output of the analog signal on this card. These have to be removed. They are quite small and it have to be desolder from their places right on the output (before RCA connectors). An only 10-20 ohm resistor have to be between the op amp output leg and the RCA out connector. No capacitor to GND!
    - the analog part of the card (op amps) have to be feed it with +/-15v from a separate, dedicated hi performance power supply. The actually Asus design use +12v from ordinary computer power supply. Asus regulate and filter this +12v from the switching power supply of the computer, with an +12 regulator… There is now regulation at all in this way!
    Then they create a kind of negative power supply on the card using an local oscillator. The result is a -11v witch feeds directly the op amps and analog processing… This is the worst design one ever have seen in the audio (HiFi) field!
    - the another important change is to replace the op amps with another and better ones. Important here is the slew rate of this op amps. The highest, the better dynamics. The best way is to remove carefully all about these standard opp amps, and solder the new ones directly on the card (the same place…). The best way to remove the present component from the card is to cut it out. DO NOT DESOLDER IT! Desoldering on the card destroy the traces.
    It is important that one not touch the components of the +5v line witch came from the computer power supply. This power line and its components is used internally by the processor to control the right distribution of the power supply on the card, the relays, and so on. Else, one get error messages.
    - I will also suggest to take the output signal right from the headphone output. Just solder on this output a non inductive (SMD) 100-300 ohm resistor between the headphone connector pins on the card. Then make an adaptor for have 2 x RCA out from the headphone jack. Using in this way to output the signal will improve much the sound. The headphone circuit on the card has better performance than the opp amps from the standard analog output. Do not forget to set up in the Xonar panel the output from headphone (on a 300 ohm headphone is better). Sett your amplifier volume at the minimum one previously testing this way…

    Here is a link with some usefully pictures: http://www.head-fi.org/t/433533/upgrading-the-cry...
    As I can see on those pictures, there is an fault in this mod process. One have to remove all the additional components and have nothing connected to the clock pin of the CM processor, but the new oscillator. Then one have to connect the new oscillator directly to the clock in pin. Best is to left up that pin as described in the text here.
    If this mod is done right, then the result is quite unbelievably.
    Is better also to mount a ferrite bead between the new oscillator power pin and the +5v supply from the card. Oscillator power pin have to be decoupled with an ceramic capacitor to the GND, right on that pin.


    • Branko Petrovski08 Sep 2011 @ 15:09

      First of all thanks for all the usefull information and your expert advice. Its obvious you have deep tehnical knolige of the subject.
      I am using Xonar ST with H6 board, using analog conection to feed denon AVC 5700 receiver. Using J river 16 as music player. I manage with friend of mine to replace only clock with 0.3ppm Vanguard and change some opamp with audio GD. . I am happy with the sound but as I can read on few forums can be much more improved.If is appropriate can I send you a private meassage.


      • Con09 Sep 2011 @ 20:00

        Hi Branko
        I`m glad to hear that you succeed to put the new oscillator in place.
        Yes, is right that are many others mods one have to make for get the most of this card. In my opinion these mods are very important to be done:
        - an separate (very good quality) power supply +/-15v for feed the I/V and output stages. This power supply can be quite small as these 3 opamps do not need more than 150-200mA. Actually less, but from this power rails are feed it too the another chips for the input signals on this card...
        I used LM2991/LM2941 adjustable to create accurate +/-15v. This separate power supply (based on a small toroid feed it from the 220vAC) have to start in the same time with the computer power. So, use an relay to control this.
        -clean an separate 3,3v & +5v power supplies for the DAC`s needs and for the clock oscillator. There are lot of dedicated chips with very good noise and stabilization parameters out there. The card use (designed by Asus you know...) the 3,3v from the computer rail/motherboard to feed the PCM1792 DAC (through PCI/PCIx connector). This is very bead! The improvement of the sound after changed this supply with a dedicated one, is huge. Personally I used small shunt regulators (based on TL431) for the oscillator (5v), another one for the analogue stage of PCM1792, and one for the 3,3v digital stage. Keep in mind that 3,3v rail on the card is used of CMI8788 processor too. I`ve used the 12v power rail from the computer (the card is also connected to +5v/+12v from main PSU).
        Remove the 7805 regulator on the card, which use 12v from the computer, and replaced with an high quality, ultra low noise 5v regulator. Use ferrite beads on the power rails/pins of the all chips involved in the sound signal processing. If one have enough high soldering skills, some adequate optical devices, and good enough (temperature control) soldering tools, then you can make the regulators using SMD components, soldering directly on the components pins (without wires), and without any PCB. This can bring the best result!
        -good decoupling/bypassing capacitates soldered right on the pins of the chips.
        I`ve used ceramic SMD 1000µF/5v on every analogue channel power pin of PCM1792 soldered directly to the chip pins. The same for the oscillator power pin. Capacitors 400-600µF (ceramic/tantalus) for decoupling the power pins of the I/V converter and the output op amps.
        -remove any capacitor from the I/V converter sound path signal. Correct set up here is very important for the finally quality and dynamics of the sound signal. The passive components have to be soldered directly on the respective chips pins. Consulting the datasheet of the op amps used is very recommended.
        -remove any ferrite bead and capacitors to the GND in the sound signal path output.

        At least, something about the connection cables.One have to take care of the cables connected between the sound card and the amplifier. Short as possible is an important rule. The very good cables are unfortunately very expensive. But there is a better solution: make your own cables, using silver wires! This can be a very cheap solution, and the best result ever. Keep in mind that here is important to avoid the parasitic capacity between the output cables wires. On a usual good audio cable this parasitic capacity can rich 100pF or even 200pF. This is bead anyway, no matter how much you pay for that cable... If you can have a short distance between the computer and the amplifier, then you do not need shielded cable. The sound card can offer a very low output impedance. The present amplifiers have a quite low input impedance. Then you can just use 2 (per channel) parallel wires (GND and hot signal) to make the connection. These wires have to be parallel on the whole length. An 10-15mm distance between the wire will ensure a very low parasitic capacity. Quite thin wires will ensure too a very low parasitic capacity. The result can be something as 10-20pf per 1-2m cable. The capacity of the RCA connectors are somewhere 6-8pf.
        Buy silver wire (0,3mm/0,4mm can be a very good choice) and make your self the cables in this way. Use Teflon tube for isolation. Use something else for give to the finally cable construction a mechanical strength for that length you need. Specially in that point where have to be soldered to the RCA plugs. The silver wire it self have quite bad mechanical capabilities.

        Else, yes is OK to send me messages in private. If I can have your email address, then I can replay.
        But maybe is better to discuss here the most of the aspects. In this way everybody can contribute to the knowledge.
        It is a quite handicap on this forum the impossibility to publish pictures. Everything could be more easy in this way... These mods in this case are so many and quite complicated to be done for be described using text, That because is not quite possible to have a "tutorial" for all those mods...
        If anyone have an idea about publishing pictures, links and so on, you are welcome.
        If you have questions, just ask...


  7. Alpha08 Sep 2011 @ 05:29

    Much appreciated, bought the Vanguard XO not too long ago, still waiting for it to arrive, will get back to you after this mod.


  8. Con09 Sep 2011 @ 22:52

    Some suggestions for they who will go forward to modify (in deep) this Asus audio card, and maybe are not so aware about the way to work in this field:

    -keep the card and your self in a 0 volt environment. Take serious care about ESD when you work with the card. Best is to have a working conductive mate (ESD special made) and both the mate an you be connected to GND. Do not take the card an walk around in the place you are. Keep the card in a safe ESD place. Take the card for inserting in the motherboard by the edges. Avoid touching of chips and components if you are not connected to GND. Avoid touch the PCI/PCIEx pins on the card. Touch the GND before touch the card. Else you can have bad surprises, maybe just after you finish the hard work....

    -Be very carefully when solder the pins of the chips, and in general soldering on the card. Use that temperature for the soldering iron/pen just for an good solder on that surface you solder. The traces on the card can be destroyed at once if you insist to much soldering on it.
    Make the necessary preparation before you touch with the soldering pen the pins you are intend to solder, so the time for soldering be as short as possible. Do not keep the soldering pen to long time on the chip pin or on the SMD components. An 10 seconds soldering time is a very long time, and possible modifications in the components structure can occur. 1-2 seconds for soldering SMD components is quite OK. If you have to solder something on the GND plane of the card, solder a wire first (is nothing happen if you will still get hot that wire for quite long time...), and then solder the component to that wire (cut it previously for a length of 2-4mm as well).

    -Use adequate optical devices (if necessary) to see very well the operation and the (quite small) components.

    -If you will lift up pins of the chips, do not bend it many times in opposite directions. Do the operation in one movement and let it as it is at least. Prepare the position of the pins - components before you touch it with the soldering pen for soldering operation. Do not touch it afterwords. Do not try to change the positions of the soldered components, even could be possible by bending terminals/pins/wires. Take the right decision before the soldering operation occur in such cases.
    If you have to desolder something, do not think to use again that desoldered SMD component. Desoldering process is in most of the cases destructive for SMD components. Specially for the SMD film capacitors.

    Good luck!


  9. Alpha10 Sep 2011 @ 05:13

    Con... i just did the ox mod a few hours ago running along with some 49710HA's and I'm impress, what a difference.

    Now on to the caps mod, where's the best place to purchase these? thanks.


    • Con10 Sep 2011 @ 13:53

      Glad to hear you have a better sound. Just give it a try to this: LM6172. In this case you have to modify the feedback resistor in I/V converter, and the same in output stage.
      Anyway is best to remove the feedback capacitors which is are parallel with the feedback resistors (I/V & final stages)

      About capacitors: the easiest way is to buy it from Farnell in your area. But than you must be registered there and buy as a company. If you can do this, is the best way. If not, you can try Digikey or any other component retailer in your area. Most important in this case is the quality of the components. After a quick research you can find for sure what is best for you as price and quality. For the low level tensions (3,3v/5v) and bypassing I will suggest the 100µF/6v ceramic SMD. You can easily solder together those capacitors for make the capacity you want. Just do it quick and care to not warm to much and to long time those components. Hold together 3 of such capacitors with a adequate tool and solder all in one movement. Wait for cooling. Touch the soldered area with a metal something for help a faster cooling and remove the thermal energy. Solder the other side in the same way and repeat the earlier procedure. Then put together as many as need it the 3 capacitors entities and solder all together in the same way as before. You will have a pack of capacitors which can be soldered now nearest as possible to the corresponding pins of the chips. You can also use very short adequate wires in this respect.
      I will suggest too, that you replace first the filtering capacitors for the power rails on the card and the decoupling/bypass capacitors for the DAC, I/V, and output stage op amps. It is not necessary to remove all the capacitors from the card in this moment. Maybe later on...


      • Alpha22 Sep 2011 @ 03:16

        Con wish you could post a pic tutorial on these mods cause right now you're speaking Greek! something similar to the XO mods pics i see floating around. Provide some links to the ceramic SMD's you recommend, all this would be greatly appreciated.


  10. Con22 Sep 2011 @ 22:46

    Please watch this in the future: http://www.diyaudio.com/forums/pc-based/197116-xo...

    Pictures will come soon, as my time will permit... It have to be prepared for publishing... This is a quite time consuming work...

    For the components providers I can suggest Digikey, Mouser, Farnell


    • Michael Reed13 Oct 2011 @ 00:12

      Con I have a couple questions as I'm going to mod my Essence STX soon:

      1. What model/size ferrite bead should be used next to the oscillator and how should it be mounted?

      2. What type of glue should be used on the oscillator and approximately how much?

      3. What wire should I use between the oscillator?


  11. guillermo30 Nov 2011 @ 20:26

    Con, is these the Vanguard model for the Asus xonnar ST?: http://www.ebay.com/itm/Vanguard-Ultra-precision-...


  12. Thunderbolt19 Feb 2012 @ 21:18

    I'd like to do some modifications in order to have better sound quality. atm only the exchange of the clock, but later on maybe other stuff as well.

    however, are there any kind of modifications recommended to do along with the exchange of the clock, because otherwise it might be hard to reach certain areas on the card once the clock is exchanged or maybe parts that cannot be accessed without removing the clock again? or stuff which is simply recommended to change as well while Im already working at the clock?

    if so what kind of stuff, which additional parts would I need to buy in such a case and approx. how much more would that cost me?

    btw Con, which opamps do you specifically recommend for the STX?


  13. BobD24 Jun 2013 @ 18:57

    I just picked up a Xonar DSX. I have seen a lot of talk on various forums of replacing the stock op-amp on it with a LME49720NA op-amp. Does anyone have any feedback on swapping op-amps, and if so, which one(s) do you like?



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