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Old 11th February 2013, 04:05 PM   #171
Corvus5 is offline Corvus5  Poland
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The Essence ST headphone amp is not the best one. The stock card requires very clean power supply. Full potential of this Essence or your HD600? I made all my DIY headphones very dependant on the amp quality due to ease of drive. Stock headphones use a lot of components which make them sound in the maker's idea way. Stock Essence is not good enough to drive stock headphones all the way. There's still some sonic trace left from the headphones. I mainly plugged in 32ohm drivers including the DIY drivers with 32ohm voice coil. The highest impedance I tried was 150ohm.

If the Xonar Essence can take the full potential of headphones then these headphones are poor ;-) If you know what I mean...

Anyway going back to the caps: I noticed oscons bypassed with ceramics can be good. I will try to capture caps impedance plot with Agilent impedance meter and do the 20Hz-110MHz plot. From what I heard with ear I can tell:
- MLCC - very low ESR, very low ESL, low capacitance
- oscon - very low ESR, medium ESL
- elna silmic II RFS - medium ESR, low ESL
- nichicon muse kz - low ESR, medium ESL
- nichicon muze fg - medium ESR, higher ESL
- nichicon HV - high ESR, low ESL

That's why I find good to use multiple Elna Silmic II or use oscons bypassed with MLCC. It makes the impedance more flat when trying to get rid of power supply noise. Silmics II have quite flat impedance but not so low. Just putting more make the sound better. Oscons however leave some unpleasant harshness in the reverberation. Adding MLCC in the 100nF-2uF range helps deal with it. Single MLCC or single oscon in my case? Not. Why? Maybe because I've got no larger MLCC than 1uF yet ;-)

Decoupling digital is a pain. Multiple oscons and MLCC when there's no room for it. The lower the overall impedance, the better.
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Old 11th February 2013, 04:08 PM   #172
Coris is offline Coris  Norway
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Quote:
Originally Posted by hedphones View Post
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..
Essence can very well drive 300 ohm headphones. Even lower and higher impedance works well. The headphone chip on this card is a very good one. But this chip alone can not do to much... There are stages before this chip which it may be improved to have a really audiophile headphone output from this card.
But anyway, the headphone output is better than RCA as it is. One may chose correctly in the software driver, the right impedance one may use for the headphones.
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Old 12th February 2013, 02:46 PM   #173
Corvus5 is offline Corvus5  Poland
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I ordered Vanguard TCXO. Is it sensitive to the given voltage? Built-in 7805 is enough or building additional one may help? Low noise voltage regulators are to hard to find. Decouple voltage? I've got no ferrite bead. I see you used ferrite bead. The 10uF tantal is however between Vdd? and some place on the board.
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Old 12th February 2013, 04:25 PM   #174
Coris is offline Coris  Norway
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It have to be only the right voltage for it`s Vdd - 5v. 7805 is not the right regulator for an oscillator.
I can not agree with your affirmation about hard to find low noise regulators... If you have access to Farnell or another electronics vendor, you may for sure find such. You may also use an shunt regulator for 5v, f. ex. T431. You may connect the regulator to the oscillator after you are sure about that regulated tension is right on it`s output.
But anyway, it may be a quite important improvement with this oscillator, than the original one.
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Old 13th February 2013, 07:28 PM   #175
Corvus5 is offline Corvus5  Poland
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I tried various xonar caps bypassing in the most important places in my system. While through-hole MLCC as electrolytic bypass gave clear high frequency, the resonance gave a little unpleasant sound. I start do a little trick the card. There are a lot of ferrite beads. The example is stock 7805 || cap 47uF || ferrite bead || cap 47uF. Or 100uF. When putting 1uF MLCC on the 7805 the best I could do is to remove first electrolytic cap and then replace second with a good sounding 1000uF.

Decoupling digital stage is a pain. I went away from the idea of oscon || MLCC. Last setup I used was 2xoscon || tantal || 2xMLCC. Maybe try (large cap + series SMD R0.27-1.00) || MLCC. Or a stack of different capacitance MLCC.

What's funny is that I noticed some in my opinion low-end opamps now are pretty good. The difference became so small and everything came mostly to the different internal power decoupling if there was any.
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Old 14th February 2013, 11:44 AM   #176
Corvus5 is offline Corvus5  Poland
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I'm still waiting for my vanguard to arrive. I bypassed ferrite bead on the 5V with 4,7ohm. Is it noise or just faster response? I don't know. I took my lying unused Panasonic FC caps (they've got higher ESR than FM) and I noticed they are very good in the digital stage. I may have to measure them with good impedance meter. The card gets to its limit in my opinion.
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Old 15th February 2013, 02:43 PM   #177
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I had to change the RCA IC to my headphones to the of the Sommer cable and decided to still try to use Amphenol plugs. I had to move from one of the Klotz cables and try lower capacitance. The sound became unpleasant but I decided to tune my Xonar for it. I had to lower opamp gains to maximize SNR, the noise floor was limiting the dynamic range of the music in the quitest parts. The added 4,7ohm resistor was really introducing noise from the regulator. Then I tried to make sound more coherent and clear. I fully removed 5V DAC decoupling caps I noticed.... almost no difference. I tried different caps and sizes and stayed with Panasonic FC as the main 5V at the filter output. Then I will go for proper decoupling. I noticed there can be a trick applied for better imaging on headphones to simulate some tube-like soundstage: make caps work more like a dual power system, less global caps, more channel decoupling. This goes away from my other the idea of using really small deceoupling caps. They seem to be slightly better at higher frequencies, probably due to little lower ESL.

Comming back to the 7912 - the potential at the 7912 ground doesn't seem right. Seems like it's not connected to anywhere. The input and ouput pins are shorted on the stock card with ferrite bead. Ok. However the ground pin is not connected to any of the -12V caps legs: should be on the positive pin.
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Old 16th February 2013, 01:05 PM   #178
Corvus5 is offline Corvus5  Poland
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Some pictures of my xonar from last 2 weeks. Comments are already in this thread. Right now I'm removing almost all +/-12V caps and building from scratch. There are 2 caps in the line in which are connected to the +/-12V and ground. Also I didn't notice the 7912 has switched input and ground legs. Now it's ok. The Silmic II caps after break in are almost non existent when filtering high freqs. I could remove them from the decoupling opamps and I noticed very, very small difference. Stock FG can go higher. I could install 7912 but I've got no smd resistor to increase voltage on the input before regulator. DAC Vcom caps are very important. I noticed Coris replaced them later. I also added larger Vishay 1845 for filtering 5V after 7805. There are already 1839 for filtering PSU 5V. I find them very good at filtering noises.
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Old 16th February 2013, 08:45 PM   #179
Corvus5 is offline Corvus5  Poland
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Coris, do you know the inductance of the CLC filter in the 5V stage? I almost completely removed 5V stage on the card. I remodeled CLC to filter to be more a C(R+L). Also used the metal cover. The sound become fresh much more detailed. More than ever on this card. Sound effects are fresh. The previous noise is non-existent. Knowing the L value would help me properly model the rest.
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Old 16th February 2013, 11:05 PM   #180
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I stripped the 5V CLC filter to the C. I now the ripple is bigger and it should be noise but... it's great! It's totally different from what I have ever heard on this card. The background sounds are very, very clean and pleasant like the dynamic range went up by 10dB and there is no added noise to it. Voices are thin and the imaging is more varied. Shouldn't it be vice-versa?
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