Xonar ST/STX mods...

[Corvus5]

Originally Posted by Joel Wesseling

I'm Planning to use the Xonar Card..

I havent read the thread in detail..

How important is the PC power supply for the overall sound???

I was thinking of getting a Horizontal case to build my new pc but I have a Large empty tower that could hold just about anything..

Thanks, Joel

Joel, the bad power supply for the xonar may lower the sound quality. I think noone has taken any xonar essence measurements for different PC PSUs.

Take a look at the first image: the headphone out noise. The only change is added filtering near the molex line. The noise goes down. The PC PSU is not able to handle it. It's not the cheapest psu available, it's the OCX modxstream 500W as seen on my previous image.

The second is the THD. Third and fourth is the the noise and THD one the line out without buffer opamp.

[bambadoo]

I have 2 different Xonar stx in 2 different computers. One with internal smps and one with external and picopsu connected to the mainboard.

Only looking at det spectrum from the line in the one with external PSU seems a bit better but that might just be small differences in the cards themself.

I also have a Xonar essence one (havent testet it yet) and will buy Creatives newest ZXR which looks very promising. Especially the ADC part.

Will maybe change the psu in one of the computers to this
http://www.techpowerup.com/reviews/S...S-520FL/9.html
Seasonic platinium s-520.
Fanless (I like it silent )

[Corvus5]

The eagle has landed

[Corvus5]

I tried for over an hour to desolder old quartz. I the end its all pads came out. Now I've got to find the place to solder the oscillator ouput. Any ideas?

[Corvus5]

By taking a look at the Xonar Essence drivers source code, I see that in my case the main chip controls the CS2000 and then the CS2000 clock ouput is given to the PCM1792. In the case of first release of STX the AV100 has the direct control the the DAC clock and internally does the clock multiplication. Also the CS2000 clock aux output is available on the third top pin on the large pin connector.

The AV100 uses I2C to control CS2000. Other inputs are: CLK_IN, XTO and XTI/REF_CLK. I guess the CLK_IN comes from the AV100 and XTI/XTO are connected to the quartz as in application note. I wonder how it works.

There's a delta-sigma fractional-n frequency synthesizer and Hybrid analog-digital phase locked loop.

5.1.3 External Reference Clock (REF_CLK)
For operation with an externally generated REF_CLK signal, XTI/REF_CLK should be connected to the reference clock source and XTO should be left unconnected or pulled low through a 47 kΩ resistor to GND.

I think I get it. the CLK_IN is used as a base, but the PLL uses the clock or quartz for better resolution and stability. I will connect REF_CLK to the oscillation ouput and leave the XTO as it was.

[Corvus5]

The direct clock pin is available near the old quartz. There are two liner, the pin with lower is ok. Now I've got to fix the pin I've chosen incorectly - 65 and maybe nearby 66. They go the U10. It's probably ATMLH924 or similar - maybe small uc or memory.

[Corvus5]

How it is possible the clock gives tens of volts on the output when being fed with 5V? The average voltage on the clock output is the 28V. Isn't it a bit too much?

[Corvus5]

Almost everything is fixed. First, the card wasn't recognized. The device ID was ok. Then the card device ID switched to the universal CMI8788 driver. No sound, the sound and movies were slowed down to 60%. I ran the eeprom fix utility which recognized the card as Xonar Essence ST. I selected to rewrite the eeprom anyway. After reboot the was recognized by the Windows as a Xonar Essence ST and sound was playing The only problem is with the slowown. Everything is slow. Recently I moved the ground for the oscillator to the ground of the 7805.

[Coris]

Originally Posted by Corvus5

How it is possible the clock gives tens of volts on the output when being fed with 5V? The average voltage on the clock output is the 28V. Isn't it a bit too much?

You may have a wrong measurement method.... Of course is not possible to have 28v at the output of an oscillator powered at 5v... The output level should be a little bit under 5v.
Or you got something else in the box of an Vanguard oscillator...

[Coris]

Originally Posted by Corvus5

Almost everything is fixed. First, the card wasn't recognized. The device ID was ok. Then the card device ID switched to the universal CMI8788 driver. No sound, the sound and movies were slowed down to 60%. I ran the eeprom fix utility which recognized the card as Xonar Essence ST. I selected to rewrite the eeprom anyway. After reboot the was recognized by the Windows as a Xonar Essence ST and sound was playing The only problem is with the slowown. Everything is slow. Recently I moved the ground for the oscillator to the ground of the 7805.

Something got wrong with your mod... At least you have wrong frequency out from that oscillator, or very wrong level of the clock signal. If you`ve got problem with the identification of the board in your computer, then it may happen something with the main processor of the board, or it is not working as it should... or its clock is very bad.
Power the board out of your computer (12v/5v on Molex), on your bench, and do some measurements on the oscillator power, frequency out, or so...
At least you may not trust very much what to be bought on ebay... Just do some measurements on that oscillator, and be sure that is working as it should, before connecting it to the STX processor.