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Old 19th August 2013, 09:57 PM   #361
Coris is offline Coris  Norway
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Join Date: May 2009
Location: Norway
Hi bearpc100
Sorry for delayed answer. I have not been here in the thread for a while...

On an original board, the caps you refer too are 220/16v. These are AC/DC isolation caps, which is definitely better to not to have it there. If one have a very low DC offset or it can control this DC offset of the final opamps, then these caps are not needed.
There is a benefit to have it there big capacities caps, but one may not forget that big capacities caps in such configuration introduce a quite big impedance factor in the outputted signal path. One may parallel these with some good quality film caps. Last but not least, these caps it should be of non polarised types.

When about your measured values, it may be there 0v DC and some volts AC (signal) when is outputted signal. If you can measure 0, 00...v DC before these caps, then you can just eliminate it from the signal path (if your amplifier can accept DC coupling sources).
Anyway, these caps may not have something to do with the clicks you get some times over the signal. This fault can source from another places/stages in signal processing. It can be very well generated in streaming of the digital signal to the sound card, in the computer, it may be a latency problem, or just software problem in streaming processes, before the sound card.
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Old 1st September 2013, 08:14 AM   #362
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Quote:
Originally Posted by andreudze View Post
frog993, let me explain how power supply is arranged. Strart with molex +12V and + 5V
1.) +12V thru three 3.3 Ohm resistors feeds the 7805, that in his turn supplies analog part of DAC and auxilary consumers (ADC and relays)
2) +5V is converted by the HF invertor into +15V, that feeds the 7812 and into -12V (in fact, it would be better to have -15V and 7912 then, while there is place for 7909 on the PCB). Thus, we have splitted power supply (+/-12V) for I/U and output stage as well as for the headamp.

+3.3V comes directly from the PCI and feeds digital part of PCM as well as DSP.

The picture belows shows the power paths.
Hi I am after a bit of help.

I have read through this whole thread and with the missing pictures is difficult to ascertain the information I need.

I use an Asus Xonar ST - Purely for a spdif digital feed to a av processor - a good stereo one as part of a purely dedicated audio pc.

I am having a linear power supply designed and developed for the PC and at the moment have added an additonal 12V and 5V linear supply for the asus card.

Now the above comments states the digital section of the card gets its power from the motherboard PCI Slot - can someone please confirm if this is 100% accurate?

If so - I might as well save the additional cost of the asus feed from the linear psu and put it to other good use.

Thanks for the help

Regards
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Old 1st September 2013, 09:10 AM   #363
Coris is offline Coris  Norway
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Hi ellisdj

If you use the sound card mainly for its SPDIF out, then is no any reason to modify it very much, but only replace the standard oscillator with a better quality one.

The reasons to modify this type of sound card is to improve its analogue out. Specially when about adding an better quality power system (only for the board).
In your case, my advice is to find a better oscillator for your card, and a better filtering of the main power lines of the board.
The power the sound card get from PCI slot is 3,3v rail. this rail is used mainly for the main processor on the sound card. The rest of the power lines come through Molex connector, from the main computer switching PSU. The SPIDIF signal goes quite straight out from the board processor. The analogue to digital conversion circuits placed in the same area, gets its power from +/-12v and 5v rails on the board.

When about the power system for this sound card, I may observe again the existing confusion about the case. There is quite meaningless to try to improve the power system for whole computer. There is to much investing in this, and it will not work at last. A computer and its digital circuits are very noisy. The digital processes inside a computer system produce much noise. Adding a very clean power supply for the whole computer, and hopping that this will improve the sound of the sound card, I may say that is quite a fantasy. That clean power supply/system for whole computer will be high disturbed by the very noisy digital components, and the whole system it will be again a noisy one. To not talk more about a very inefficient task to power the whole computer from a analogue, or very sophisticated switching PSU with very low noise.
The noises in a digital system are prevented by the digital systems it self, or with help from software. Is this way the digital stages works (are made).
The whole clue with a better power system when about a sound card, is to have a very clean power for and only its analogue processing of the signal. And for its clock stage. Those stages on a sound card are very sensitive to power lines noises or other kind of noises induced from the computing system. A such mod it really improve the quality of the outputted signal. One may focus to have a very clean power for and only those stages of a sound card. This is a quite easy task, which it brings huge result.

When about the missing pictures in thread, I will try to find some of my old pictures, and publish it here for inspiration reasons...
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Old 1st September 2013, 10:11 AM   #364
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Hi Coris - thank you for the reply you have written.

So from what you have said the Asus Spdif Digital out takes no power from the 12 or 5 Volt supply from the psu as it comes direct of the main processor.
It therefore only takes its power from the PCI slot i.e. 3.3V for that duty?


12v and 5v only power the analogue side of the board / headphone amp .

Can you please confirm the above statements 100%


In terms of power to the pc improving sound - I know its debated however if providing clean linear power direct to certain components i.e. cpu , mobo - 5v for USB its supposed to increase sound quality dramatically.

I will know soon and report back
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Old 1st September 2013, 12:05 PM   #365
Coris is offline Coris  Norway
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The SPDIF out circuitry use of course 5v from the main computer PSU. The 5v rail is used on all the card circuits (which need this power... DAC digital stage, ADC stage, relays, and so on). The main processor on the STX sound card use 3,3v from PCIe slot. I`m not very sure if ST board take this power through PCI slot, but the STX version does. I worked most on STX version (PCIe slot). Googling on this it may bring some more informations...

Providing so called clean power to a main computer processor and motherboard is quite a challenge. This is highly inefficient. The power system designed on motherboard it self is a high performance one and provide that "clean power" needed by the processor for its digital working processes. The audio improvements it may definitely not come from this.
The main processor in the computer stream out the digital signals to the main digital processor on the sound card. Here is decoded, and sent it further to the DAC on the board. DAC transform the digital stream in audio signal (human perceptible). In this stage is very important to have a clean power, A BEST AS POSSIBLE CLOCK SYSTEM, and zero noises. These three "parameters" have big impact in reconstruction of an analogue signal from the digital streamed informations. The same is about ADC stage. The rest of digital processing is corrected and cleaned up for noises by internal correction stages, or by the software processes. In digital processing, a "clean analogue power" have very little impact for quality. The digital world is about switching signals, which by definition generate huge harmonics, spikes and many electrical noises in very large spectre. A large part of digital processing is directed to take care to remove all these to prevent altering of informations.

Seeing this problem from another angle, think that around 100W of a provided analogue power have to feed alone only an usual computer processor... But is not only about 100w for the processor, is about much many Watts to be provided to the motherboard itself, video card and so on... Such task to provide to a whole computer analogue power, it may be s quite surrealist scenario... That for it was invented the switching power supply/system...

But providing clean analogue power for some crucial circuitry in whole this digital system is very possible, is very reasonable, and bring important improvements for the final results...

Last edited by Coris; 1st September 2013 at 12:10 PM.
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Old 25th September 2013, 05:33 PM   #366
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Join Date: Aug 2013
Quote:
Originally Posted by Coris View Post
Hi bearpc100
Sorry for delayed answer. I have not been here in the thread for a while...

On an original board, the caps you refer too are 220/16v. These are AC/DC isolation caps, which is definitely better to not to have it there. If one have a very low DC offset or it can control this DC offset of the final opamps, then these caps are not needed.
There is a benefit to have it there big capacities caps, but one may not forget that big capacities caps in such configuration introduce a quite big impedance factor in the outputted signal path. One may parallel these with some good quality film caps. Last but not least, these caps it should be of non polarised types.

When about your measured values, it may be there 0v DC and some volts AC (signal) when is outputted signal. If you can measure 0, 00...v DC before these caps, then you can just eliminate it from the signal path (if your amplifier can accept DC coupling sources).
Anyway, these caps may not have something to do with the clicks you get some times over the signal. This fault can source from another places/stages in signal processing. It can be very well generated in streaming of the digital signal to the sound card, in the computer, it may be a latency problem, or just software problem in streaming processes, before the sound card.
WOW! Thank you so much for your answer. It is really helpful.
I thought just "BIG" is "BETTER", so I expected something "BIG".

Thanks again.
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Old 29th September 2013, 04:08 AM   #367
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Join Date: Sep 2013
Could someone(Coris) summarize the mods? Rank it by difficult? What gains? How?


Change Opamps;
DC Coupling;
New Oscillator; powered by battery;
Filter/New Power supply; 3.3V; 5V; 12V;
Change a pletora os caps.
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Old 29th September 2013, 08:13 AM   #368
Coris is offline Coris  Norway
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Changing the op amps without having a better power supply for the audio board is quite nonsense. The same is about a better clock...
Having a better oscillator with a bad power system is not very logic too...
So... The first step one may take, is to provide a better power for the board. This is not very easy mod! A serial PSU for the analogue stage of the board is recommended first. The same PSU it may be used to get 5v and 3,3v, for some stages on the board. Do not forget that the driver software of the sound card it need to see 5v and 12v from the computer, to not generate errors...
The second enhancement is to put in place a better oscillator. Powering this oscillator from a battery is the best one can get in this area. Moderate difficultly.
Having those mods in place, one may try further to experiment with another op amps, caps, and so on.
But, the most important, before one may proceed to modifying the sound card, is to be ensured that the sound card run on a quite good computer system, tweaked for audio use. Here is about having in place a good motherboard, processor, an efficient OS and the rest of the audio software installed.
This my last remark is based on my last (quite surprising) experience.
I have bought a bran new sound card (STX) to modify it in a more professional way than the old one were made. I listened this new stock card on a win8 system also hardware updated, and I have to say that I`m impressed by the sound quality of the sound card as it is out from Asus. I know very well how bad my old STX stock sound card sounded on my previous system. But it were then about win XP, win7, an old motherboard/processor.
They made something with win8, so the audio processing is much improved in this last OS. The way the last motherboards improvements are made leads too to a higher audio quality. Not to say more about 64bit processing, Xonar last driver, ASIO improvements, Foobar improvements. When I say about sound improvements, I refer to improvements in sound stage definition, sound details, and fidelity.
The conclusion is that a stock audio board (we talk about Xonar) it sounds much better in a last updated/upgraded computer system. I have remarked an also big audio improvement of my modified STX, after using this card in a updated computer system...
I will suggest to all who think to get better sound out of a computer, to upgrade both hardware and software in the system, before proceed to modifications of the sound card. If one have a dedicated audio computer, then this computer it can be tweaked hardly to preform best for audio use. If one may use that computer for another tasks too, then a moderate tweaking is needed to get good performances in audio playback.
I will suggest to fix first the computer with the sound card as it is, get the best one can get in this stage, then start to modify/improve the sound card. This sequence will work best to get the most out of a computer audio system.

Last edited by Coris; 29th September 2013 at 08:37 AM.
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Old 14th October 2013, 02:37 PM   #369
Wungun is offline Wungun  Canada
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Hard to imagine how a mainboard could effect the sound quality of an add-in audio card, apart from maybe CPU power, signal noise in the board itself, and/or power regulation.
I like my Gigabyte boards, with quality Japanese caps, /V regulation, 2oz copper PCB layout, etc.
If you are using Windows as your media server/player, you HAVE to bypass Windows audio by using ASIO or WASAPI and stream hardware direct.


Sent from my iPhone...
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Old 14th October 2013, 09:27 PM   #370
Coris is offline Coris  Norway
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I use of course ASIO and WASAPI to by pass the Winows audio. But anyway it is better quality in my opinion on win8 than older OS. Why? I do not know so far...
BTW, there is not only using ASIO/WASAPI to by pass the windows audio processing, but are necessary many other tweaks in OS itself to prepare it for higher quality audio...

Last edited by Coris; 14th October 2013 at 09:50 PM.
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