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Old 4th February 2013, 02:56 PM   #161
Corvus5 is offline Corvus5  Poland
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This is sick. I managed to find out the 7805 working condition. 12V goes from molex to the 3*3.3ohm resistors and directly to the 7805 input pin. There's no other filtering. The first caps that seems the 7805 are the 2 FG caps. The first gets got, second father less. The 12V given to the 7805 is practically unfiltered and there is only protection with resistors. I'm moving 100nF filtering directly to the 7805 pins. Also I noticed that the 7805 and 7812 case is used as a ground. Moving the ouput filtering cap from the FG cap to the regulator ping only sligthly changed the sound in a good manner. I'll add input filtering cap. I may do the same with the 7812. I may post pictures.
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Old 4th February 2013, 04:03 PM   #162
Corvus5 is offline Corvus5  Poland
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I added some pictures. There's one small element near the 7805. Is it the cap? Stil though I moved my filtering caps to the 7805 like on pictures. Nice Caps are getting colder and the sound is slightly better.
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Old 4th February 2013, 08:39 PM   #163
Coris is offline Coris  Norway
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There is a cap there, likely on the input of 7805 to GND... It seems that is in parallel with one of yours.
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Old 5th February 2013, 05:48 PM   #164
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The current Xonar 5V voltage system for analogue stage. I wonder if the 1000uF cap may require to add diode to the 7805 between input and output, but it's still working. There's a place for another cap after the coil. The 5V regultion is now pretty good compared to other places. I may say it's now the best. The DAC 5V may need fixing. The -/+12V seems to be far behind the rest while it was the best at the begining when I took care of it. While improving 5V with addition 1000uF in its current state I noticed good bass improvement and the imaging is much better. The bass control is much better. Without proper caps it's not so good making also 3D positioning much worse. Before upgrade it was like the lower sound harmonics were somewhere else than higher. Now they are more centered
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Old 6th February 2013, 06:52 PM   #165
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I removed half caps on the card. The 5V uses 3x1000uF and it's a must. For the +/-12V it's easier and plays different role. I put attention into 7812. Using Nichicon KZ was naturally not enough (not to mention Nichicon FG). Oscons were better but KZ + MLCC was better. Oscon + MLCC in place of existing FG? Bad. Oscon + MLCC? Better. Adding MLCC o the regulator pins was a must. This 1cm makes a difference. One the distance was minimized the quality improved much. Highs are so smooth, choirs are smooth.

I noticed the difference between my 3 favourite opamps: the internal power decoupling and power noise resistance. As long as there is a difference, the power is not good enough. By improving power the difference shortens. LM6172 seems to be equal in mid and high freqs. OPA627 to be good at high and bad in mid. AD797 seems to be good but too soft on mids while highs are little worse.
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Old 8th February 2013, 07:03 PM   #166
Corvus5 is offline Corvus5  Poland
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It's not so easy. I noticed I did all I could with Muse KZ it wasn't natural and details were lost. I switched back to Silmic II to get great details and smoothness boost. Even small MLCC interfere with the Elna caps. First time I noticed in one of my reference recording turned on neon/light bulbs.

The DAC filter caps. The also play role in sound and can be improved here.

I want to add 7912 for check but I find the pins for it are probably wrong. The board gnd for it has the -12V potential. The input or output pin has the GND, the other is not connected. Is it the faulty connection so the regulator wasn't inserted?
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Old 10th February 2013, 07:38 AM   #167
Coris is offline Coris  Norway
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I found a picture with annotation about some mods on the STX board. Maybe will help...
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Old 11th February 2013, 12:59 PM   #168
Corvus5 is offline Corvus5  Poland
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Coris, have you noticed you've got the active Nichicon cap on the -15V line through the ferrite bead to the top of the 7912 place while the +15V cap is not used due to 7812 leg removed? Have you considered removing this ferrite bead for more symetrical voltages?
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Old 11th February 2013, 02:33 PM   #169
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If I ask this at head-fi, I know I get answers like "no you won't get full potential" etc.

Can the Essence drive 300ohm Sennheiser HD600's at audiophile sound quality level? I know you guys are more technical than usual audiophiles, so..
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Old 11th February 2013, 04:02 PM   #170
Coris is offline Coris  Norway
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With those cuts (output leg of 7812 and the diode beside L20) you may isolate the power rails (+/-) of the I/V stage, final opamps and some other analogue stages on SPDIF in/out).
The caps on right hand side of the regulator (my picture) may be ignored. What is on the left hand side of that regulator is important. There are the rails I named above.
There is no other better way to get symmetrical +/- rails, than using an external PSU for this purpose. The design of this card is wrong in this power stage. It works how it works, but is not right do it. More than this 12v is not just right tension level for the opamps used in I/V and finals. There may be 15v. Even the original opamps it may have +/-15v to work at the full parameters. Those are the reasons for this mod: an external, better PSU for this stage. With an transformer/toroid giving 2x18v, one may easy heave +/-15v regulated. On the picture are indicated where the 15v power rails it may be inserted.

The ferrite beads may be there where are planted, as it are used for filtering reasons. The tension drop on those ferrite beads are very low, and not important in this case.
Asymmetrical tensions on original power rails, come from bad design of the board.
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