Xonar ST/STX mods...

[Coris]

Originally Posted by supertron421

Hi Con, I have a bunch of questions to ask you as it seems as though you're the person to ask about this

Anyways here they are:
1. What model/size ferrite bead should be used next to the oscillator and how/where 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? Should it be insulated
4. What kind of solder should be used? I'm under the impression that 0.7mm solder is good for electronics but I'm unsure about everything else :P
5. What brand caps did you use? I have no idea which to chose from lol

Thank you very much in advance

You welcome!
1. You may find an 1Kohm/0,3ohm ferrite bead. This can be very good. (1Kohm - 100Mhz/0,3ohm DC)
2. I used a glue type one which do not get very rigid after words. A glue which can adhere very well on metal and everything else. Universal glue... Is good to have something under that oscillator. A kind of support/spacer in between the oscillator body and the board. A just little bit of glue is enough on that spacer, the board surface, and on the back of the oscillator, for have a quite solid construction. Just do this before you solder/connect the pins of the oscillator to the rest of the components.
If you will chose to lift up the processor clock pin (a very delicate operation!), then solder this to the oscillator out one just as the LAST operation to be done in this mod process.
3. Is not necessary to have isolated wires when is about very short distance wires. At everything here is to be a solid/compact construction, is no any danger that the wires will come in contact with something else around. If you can/want, you can chose to isolate the power wire, if is about few cm length. But everything is better to be very short in this area. Short (0,3 - 0,5 mm wires) connections leads to a very solid construction.
4. You have right! A thin soldering type wire is better. I prefer to use lead free soldering alloy, because this has inside some Ag, Cu, and no Pb, and I think is better for such connections. But is not quite well to blend/melange in between lead free and non lead free soldering alloy... I also use silver wires for all connections in this field... But is very well as usual way too.
5. If you refer at the SMD ceramics caps, then is not need to have a special brand one. Is good enough if they are ceramics. That's all! If is about to use ceramics in the feedback loops, then COG type (SMD) caps are best ones.
For decoupling in the analogue areas/op amps, you have to chose by the working tension (maybe 20V in op amp stages, and 6v in DAC stage). In 20v area is not very easy to find big capacity value ceramics. They can be very expensive at this tension level. But one can very well use tantalum ones. Chose the lowest ESR, and SMD type ones (no legs!), at appropriate working tension. Solder it together small caps value for get the desired capacity value. Something between 300µ and 1000µ is a very good choice.

[supertron421]

Originally Posted by Coris

You welcome!
1. You may find an 1Kohm/0,3ohm ferrite bead. This can be very good. (1Kohm - 100Mhz/0,3ohm DC)
2. I used a glue type one which do not get very rigid after words. A glue which can adhere very well on metal and everything else. Universal glue... Is good to have something under that oscillator. A kind of support/spacer in between the oscillator body and the board. A just little bit of glue is enough on that spacer, the board surface, and on the back of the oscillator, for have a quite solid construction. Just do this before you solder/connect the pins of the oscillator to the rest of the components.
If you will chose to lift up the processor clock pin (a very delicate operation!), then solder this to the oscillator out one just as the LAST operation to be done in this mod process.
3. Is not necessary to have isolated wires when is about very short distance wires. At everything here is to be a solid/compact construction, is no any danger that the wires will come in contact with something else around. If you can/want, you can chose to isolate the power wire, if is about few cm length. But everything is better to be very short in this area. Short (0,3 - 0,5 mm wires) connections leads to a very solid construction.
4. You have right! A thin soldering type wire is better. I prefer to use lead free soldering alloy, because this has inside some Ag, Cu, and no Pb, and I think is better for such connections. But is not quite well to blend/melange in between lead free and non lead free soldering alloy... I also use silver wires for all connections in this field... But is very well as usual way too.
5. If you refer at the SMD ceramics caps, then is not need to have a special brand one. Is good enough if they are ceramics. That's all! If is about to use ceramics in the feedback loops, then COG type (SMD) caps are best ones.
For decoupling in the analogue areas/op amps, you have to chose by the working tension (maybe 20V in op amp stages, and 6v in DAC stage). In 20v area is not very easy to find big capacity value ceramics. They can be very expensive at this tension level. But one can very well use tantalum ones. Chose the lowest ESR, and SMD type ones (no legs!), at appropriate working tension. Solder it together small caps value for get the desired capacity value. Something between 300µ and 1000µ is a very good choice.

Thank you very much for the helpful response

Now I'm under the impression that there is no downside to using a 25v cap where aa 16v cap used to be (there are only 2 16v nichicon caps on the whole board, everything else is 25v). So should I use 16v or 25v in that specific area? Also I've read a bit and apparently Elna Silmic II caps are very good for use on the STX and was going to get them from here:
Elna RFS Silmic II- Silk fiber and foil electrolytic audio capacitor
Would this be a good choice?

Additionally what is the diameter of the silver wire you use? And what did you replace the 2 oscons next to the molex connector with (assuming they are oscons)

[supertron421]

Hmm there's no function where I can edit my post available for me so I'll just make another.

Con I forgot to ask one thing: From what I know capacitors should be replaced with capacitors of equivalent uF value, but you are saying replace with caps of 300+ uF value?! From what I can see the output section of my STX has 5 220 uF/16v caps, 4 47uF/25v caps, 2 100uF/25v caps, and 2 22 uF/25v caps. The DAC section has 6 100uF/25v caps and 7 47uF/25v caps.

[Coris]

Originally Posted by supertron421

Hmm there's no function where I can edit my post available for me so I'll just make another.

Con I forgot to ask one thing: From what I know capacitors should be replaced with capacitors of equivalent uF value, but you are saying replace with caps of 300+ uF value?! From what I can see the output section of my STX has 5 220 uF/16v caps, 4 47uF/25v caps, 2 100uF/25v caps, and 2 22 uF/25v caps. The DAC section has 6 100uF/25v caps and 7 47uF/25v caps.

There is an EDIT function/button (down right corner on the site/side) which is active 30 min after you send your post. So it is possible to edit the post.

First there is no problem to replace low tension caps with high one. Opposite is bad... The only problem could be their physical dimensions. Higher the working tension, bigger the cap... On the STX board is about 12v. If you will want to use a dedicated PSU +/-15v will be this the highest level. So you can very safe use 16v caps everywhere. I do actually so... But if is about 5v or 3,3v then is more rational not to use 16v ones, but using lower tension ones, because they are smaller so...
The caps on this board have different functions. Is better to identify those functions/caps placement on the board, for customize the replacement accordingly by their function. Some are there as decoupling ones (connected on the power in pin of some components/op amps/DAC). Some are there for filtering (connected on power out pin of the regulators or in the power path). Some are there also as a filter function for the DAC different stages (internally). And some are in the SPDIF/optic in area of this board. Those last specified will not be an priority for the actual mods. So you can very well ignore/forget it an let they in their place.
One meaning of the mods on this board is also replacing of some caps with another ones with another (bigger) value. My previous suggestion about 300µ/1000µ caps was about they used in decoupling area in the analogue stage of the board (op amps).
There is a place (market on few pictures) where is about bigger value filter caps used by the DAC. Originally there was 47µ. Better to replace with 300µ ones. But is important that specially those caps used in DAC filtering internally stages be a ceramics type. As shown in pictures you can solder 3 of such caps (100µ/6v) together for replace that original 47µ value.
I replaced that Oscon caps on power in place, not because they were bad, but because in my opinion they were to small. Replaced with 1000µ very low ESR caps on the same place.
You can very well invest in that kind of caps you mention in your post. I do not know how big they are comparing with the existing ones. As a principle, I not agree with the idea to use any kind of electrolytic in this mods for this board. Well, one can use such caps for filtering power path on input. Like I actually did (because need it a large capacity with quite high working tension, difficult to find or very expensive as tantalum or ceramics).
So, I still recommend using of ceramics or/and tantalum caps for replacing the original ones. There are many companies which produce caps, and they have their own interest to recommend so an so their products, with so and so capabilities... You can very well experiment in this... I did it, and my result was better as I did on my board, and as recommended here. That kind of caps can be very good in another kind of devices... Another problem with those electrolytic`s is that they have legs/terminals. In some places those long legs mean parasitic impedance... It is not possible to cut those legs very short because they have to be soldered in place... SMD components have not those problems...
The another advantage of those ceramics tantalum SMD is that they are very small in dimensions and can be soldered very close to the target point. They have very good specifications in ESR and a quality than electrolytic never can rich... So, your choice.
I can suggest you to hear on a sound file played using the caps so as they are mounted on the board. Then replace some on one stage with another ones. Hear again the same sound file and note the changes. Do the same for the rest of the caps you intend to replace. So you will have in the end a very good impression about what is happen and what is the best component to replace it with. If you can find enough patience for this processing mode...

I use for interconnections silver wires between 0,2mm and 2mm. Now depends what to connect with and where... On this board could be very well to use 0.2 - 0.3mm. If is about interconnections on caps on power path, or to GND, or in between, then you can use a quite bigger diameter (0.5 - 1mm).

[adamlau]

Looking to replace only the caps along the DAC-to-analogue-to-output path. Can someone point me to a diagram, image overlay, or board numbering layout (e.g. CE8) for the various caps and their functions (filtering, decoupling)? Card is not here yet, but I want to get a head start on picking up some caps. And is their a reason why folks here are recapping with Silmic II and not Cerafine?

[lduarte1973]

@CORIS

Just out of curiosity , if you had to sell your modded board how much would you ask for it ?

[Coris]

Originally Posted by lduarte1973

@CORIS

Just out of curiosity , if you had to sell your modded board how much would you ask for it ?

Yes, good question... You know, I have only one so far, and I use it... So, will be quite difficult for me to decide to sell it. Else, if is to think about a price, it will be for sure enough high. Many times the original price of the card...
I`ve used quite long time on this card and the all necessary mods are to many now. But one can try to DIY the most of those mods. It is a reward at least: an incredible sound out of it.

[lduarte1973]

Originally Posted by Coris

an incredible sound out of it.

about that i have no doubts

[Coris]

Originally Posted by adamlau

Looking to replace only the caps along the DAC-to-analogue-to-output path. Can someone point me to a diagram, image overlay, or board numbering layout (e.g. CE8) for the various caps and their functions (filtering, decoupling)? Card is not here yet, but I want to get a head start on picking up some caps. And is their a reason why folks here are recapping with Silmic II and not Cerafine?

The answer here (STX)...

[hollowman]

I've experimented with using a dedicated (external) PSU for the sound card. I tested and measured it several times prior to plugging it in to the installed audio card.
This arrangement worked fine for a while, and then (a few days hence, after power on) the HDD crashed (permanently--wouldn't spin, tho data was probably ok. I changed the driver card, and it spun up, but did not activate). The HDD was relatively new (2mos old, May 2010) and reliable (Hitachi, the most reliable brand I've encountered).
Dunno what happened, but another DIYer noted that "ground loops" discrepancy between the two PSU (native PC and external) may have caused the HDD to fry.
That said, I know several DIYers that successfully build and use external PSUs -- I don't know whether they ran into issues like mine.
Hence, I prefer to play it safe and use an internal (native) HQ computer PSU, like the Seasonic noted below.

Note: The external PSU was a Seasonic computer PSU that was "high rated" here:
Seasonic X-Series 650 W Power Supply Review