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Old 30th January 2013, 01:55 PM   #131
Corvus5 is offline Corvus5  Poland
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I find the digital decoupling important for high frequency time resolution. With improper decoupling they are harsh, not precise, bit too loud. Now I use oscons with cermic. I may try smd ceramics and smd tantals once I buy them.

Clearing 5V path let me use oscons at the TPA +/- 12V decoupling. Normally they are artificialy harsh. Now they are clear. Using little slow but big caps at filtering stage and faster, smaller caps at decoupling works best for me. With bad filtering, the decoupling caps can't be too fast.

What about 1000uF smd tantals for 6V in one piece? 1500uF/4V are available but I'm not keen on using them with such a stress.

I plan to buy the XO Coris used. I may connect it to the 5V available on the xonar board.
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Old 30th January 2013, 05:37 PM   #132
Coris is offline Coris  Norway
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Do not forget to parallel the big decoupling capacities with 10n -100n good quality caps. I prefer SMD film as those have not long terminals/legs as the normal caps, which it may increase ESI at high frequencies. With SMD film caps one may be very carefully when solder it. To much warm, or to long time used to solder it, it may destroy those type caps.

About something else one may remember when is to decouple with large capacities.
ESR and ESI of two capacities/caps decrease (1/2) when they are paralleled. The clue here is to make an need it capacity, soldering together smaller capacities caps. Do you need 1000f, then solder you together 10x100f. or 2x500, or another combination (the many paralleled, the lower resulting ESR/ESI). Using small SMD caps this is very convenient.
Ceramic caps have not any ESI and extreme low ESR. Tantal caps have enough ESI/ESR as usually. Special tantal caps (quite expensive) have quite low ESR/ESI. _Use the described above strategy to reduce it.
The best when use decoupling caps is to not use an capacity in one piece, but many smaller soldered together.
Be carefully with the parameters of the regulators, and care to use regulators which are over current protected, when use large decoupling capacities. Do not forget that an regulator or PSU see a very large capacity at its output, when one use big capacity caps to decoupling spread in many places (many chips) on a board.

There is not only the type of dielectric or how many F one use when decoupling, but very important are ESI and ESR of the caps. So read the datasheet of those components when you chose what you want/need of caps. Chose the lowest ESR/ESI as possible for that convenient price...

Last edited by Coris; 30th January 2013 at 05:40 PM.
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Old 30th January 2013, 06:07 PM   #133
Corvus5 is offline Corvus5  Poland
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You may notice that larger caps have lesser ESR. For 1000uF it can be 15m to 50mohm while smaller can have up to 1 ohm.

The caps that was a little hot is now cold. Now the 5V filtering caps keeps getting little hot. I replaced mine with a different one and larger. The same thing happens. I wonder what it supports: the 5V analog DAC lines (there is already decoupling) or another chip? Somewhere may be the lack of power and probably I moved the buffer closer to it: from the 12V filtering to the 5V filtering.
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Old 30th January 2013, 09:02 PM   #134
Coris is offline Coris  Norway
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If you make 1000 from 10x100 SMD ceramics, then you have much lower ESR (ohm), and no ESI...
1000 may have quite low ESR comparing with lower capacities, but large ESI. And ESI is the worst when about decoupling... Big components (caps) and theirs long legs introduce parasitic impedances, and this is only bad...
But anyway, you may chose as you consider.
The filtering/decoupling caps do not have to get hot. No warm either. It is wrong functioning somewhere. There is about ripple currents which may be quite high. You may review the power of your PSU, and its delivered current.
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Old 31st January 2013, 08:21 AM   #135
Corvus5 is offline Corvus5  Poland
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I've got the feeling that the 4 FG caps to the most right when looking at the card front are little hot. I added the 1000uF cap and it's also little hot. I know the lower two are for the 5V filtering but for what are the top two? I noticed you didn't change them.

I switched to the OPA627 and then to LM6172. There's a difference. They become much clearer than before. The LM6172 in my config works at much lower gain: 1kohm||100ohm in feedback loop and is slightly to soft. When digitaly decreasing volume the sound lacks resolution and speed. Increasing this opamp gain helps this.
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Old 31st January 2013, 10:15 AM   #136
Coris is offline Coris  Norway
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Can you mark that caps on the picture? The Oscon are filtering for 12v rail coming from computer.

To appreciate more objective the sound quality in connection with different opamps, I suggest you to find a better oscillator and do this mod first. The oscillator it may have its own regulator. It works very well an 3,3v oscillator (own regulator). You will be very surprising by the resulting sound with a quality oscillator in place. Then you can prove some different opamps...
I will also suggest to cut the 3,3v coming from motherboard, and create this tension from f. ex. 5v rail on the board. Isolate this 3,3v rail from the computer power system it improve much too, the sound.
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Old 31st January 2013, 01:34 PM   #137
Corvus5 is offline Corvus5  Poland
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The lower oscon was hot first. Now these 4 FG caps are little hot with the one on the back side no matter the size or brand. I'm not sure if all 4 were hot. It may be that the stress went from the 12V filter caps to the 5V filtering caps by added larger caps to the 5V. I wonder where try to touch the next element. Is it the 5V analog DAC decoupling which I already try to improve or maybe some next regulator? I wonder if by proper filtering I can decrease caps stress and improve quality in the same time.

I marked these caps on the image below.
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Old 31st January 2013, 02:10 PM   #138
Corvus5 is offline Corvus5  Poland
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I looked for your Crystek oscillator. They say it is 25ppm still it may be better than Vanguard? Maybe it's due to better voltage regulators?
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Old 31st January 2013, 02:54 PM   #139
Corvus5 is offline Corvus5  Poland
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I replaced most 100uF silmic II with freshly bought 220uF. There was an improvement on AD797. Then switching to LM6172 was easier. I started replacing all elna 12V caps with a Nichion Muse KZ 100uF I just bought. They are a bit expensive. I used 47uF before and now 100uF. With LM6172 it's much clearer. There are 2x100uF KZ for TPA and 2x100uF for LM6172 plus 2x47uF KZ on rail-rail on opamp. Clear. Some instruments sounds 3D in the terms the sound comming from it is not a flat sound played in the space but some are more round. It's quite fast and has a lot more presence. Too bad I couldn't play the 5V line. I fought I could find SMD ceramics and SMD tantals in local stores as I bought SMD resistors. No way, I have to order them online too.
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Old 31st January 2013, 06:10 PM   #140
Coris is offline Coris  Norway
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Quote:
Originally Posted by Corvus5 View Post
The lower oscon was hot first. Now these 4 FG caps are little hot with the one on the back side no matter the size or brand. I'm not sure if all 4 were hot. It may be that the stress went from the 12V filter caps to the 5V filtering caps by added larger caps to the 5V. I wonder where try to touch the next element. Is it the 5V analog DAC decoupling which I already try to improve or maybe some next regulator? I wonder if by proper filtering I can decrease caps stress and improve quality in the same time.

I marked these caps on the image below.
The uper caps in the picture are filtering for +/-12v rails. The lower ones are 5v filtering for DAC analogue stage, clock and others stages on the board.
You still use the board`s power system, and I`m personally quite sceptic for the results you may have... It is possible you have some high frequency oscillations, because the added caps, or something, and this may cause the heating of that caps. Else it may be few other causes to got this faults in functioning.
I will want to remove the original caps completely (as I did my self) and replacing with some better quality ones.
You may also try to see what happen when powering the board from another 12v/5v PSUs plugged in to the Molex. Find some 12v/5v PSUs you trust and power the board this way on your bench (out of the computer). Watch if any changing in heating of that caps. If is not happen, then it may be something wrong with the power in your computer (not about the DC tensions, but some pulses or some HF AC component). If is happen again with another PSUs, then it may be some inaudible oscillations in that area of the board. Is good to use an oscilloscope to find out more. Or just do some measurements anyway, with an multimeter, on few important points on power rails on that area.
I suspect that by adding some more caps on the back side of the board, you have created some loops and positive feedback somewhere. Do not forget that the switching PSU for the -12v rail is still working on your board...
Anyway, is something which goes wrong when you get hot caps... I will even do not think at all to appreciate the output sound in such conditions...

Else, yes, Crystek is the best solution. Vanguard is much better than that cheap original oscillator, but Crystek is much better than that Vanguard...
I use right now this last edition of Crystek oscillators, and the results are very good. There is not only about how many/less ppm is about, but how low is the jitter, phase noise and so on. Crystek is one of the best in quality for theirs oscillators. But it may be quite expensive... Anyway, I think is worth.

Last edited by Coris; 31st January 2013 at 06:16 PM.
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