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Old 7th December 2011, 02:38 PM   #31
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Default Adding multiple computer PSUs

Quote:
Originally Posted by hollowman View Post
I've experimented with using a dedicated (external) PSU for the sound card. ...This arrangement worked fine for a while, and then (a few days hence, after power on) the HDD crashed (permanently--wouldn't spin, tho data was probably ok. I changed the driver card, and it spun up, but did not activate). The HDD was relatively new (2mos old, May 2010) and reliable (Hitachi, the most reliable brand I've encountered).
Dunno what happened, but another DIYer noted that "ground loops" discrepancy between the two PSU (native PC and external) may have caused the HDD to fry.
I researched this issue a bit more and found a possible commercial "solution" -- a device that allows one to add single computer PSUs together:

Review/description:
Add2Psu: How to combine multiple power supplies in a single computer | ExtremeTech
Manuf. site:
Add2Psu | Connect two power supplies easily and safely

Needless to say, this does not immediately address "audiophile requirements", noted in this thread, such as linear power conversion (instead of SMPS) and independent +/- rails.
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Old 8th December 2011, 08:06 AM   #32
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Originally Posted by Kuze View Post
Good lord man! lolz lolz lolz.
First words out of my own mouth to myself=Good Lord Man...that's apfoisapjsoaaspfpasaspsasa!!!
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Old 8th December 2011, 08:16 AM   #33
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Is there a link to modifications to be done on the coaxial/digital side "only" aspect of this card? I don't care about how the sound is as a dac, but do need a proper transport and if it's not too expensive to modify this card to get exceptional sound through the digital feed, would love to know of a link or two towards that path.

Thanks all!
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Old 8th December 2011, 08:22 AM   #34
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Hi hollowman

Sorry to hear that you had so big problems with your experiments.
Sorry, but it seems to me that you misunderstood quite much this about extra PSU for a mod Xonar sound card.
YOU SHOULD NEVER USE AN normal computer PSU! I realy do not know how you succed to connect a such power supply to that sound card. Is definitivelly not so easy to only connect that Molex connetor to the Xonar card...
This PSU mod presented here refere to a quite special power supply dedicated exclusivelly to the analogue stage in this audio card. This PSU is a serial one and is isolated from the main power with its own transformator (as you can see in some pictures here).
Out from your text, I understood that you`ve used an normal switching computer PSU to feed with power the sound card on that dedicated Molex connector on it, instead to connect it to the computer`s PSU (like you should). THIS IS WRONG! You should never do this...
The Molex connector which is on Xonar STX card is to be connected to the computer PSU! Not to an extra PSU. Else that card would not work at all! If one will use another dedicated serial PSU for the analogue stage of this card, then that Molex connetor have to be anyway in place to make this card to function!
A switching PSU (like a normal computer PSU) have to be connected to the main ground of the computer first. The GNDs of the wholse system have to be the same/connected. If not, quite danfgerous spikes can occur and those goes through the all system. As you already experienced, the hard disk were the first to suffer from such wrong PSU use. You were happy that only this it happenned...
It is already précised that for those mods presented here, one have to have quite large knowladge about electronics, physics and even enough advanced tools to succeed with task. If not the case, than you can ask for help some eventual specialists friends.
NEVER USE A NORMAL (extra) COMPUTER PSU FOR SUCH MODS!!!
It is not the meaning with this mods to use (another) switching PSU for this audio card. For a better sound is to be used a serial PSU, which can deliver much more quiet power to the sensitive audio stages on this card.
If one do not know what is an serial PSU, then is better to forget those mods presented here...

If one have doubts or want more informations concerning this PSU mod, then just ask your question here, before proceed by your self in a maybe/possible wrong way...
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Old 8th December 2011, 08:27 AM   #35
Coris is offline Coris  Norway
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Quote:
Originally Posted by hollowman View Post
I researched this issue a bit more and found a possible commercial "solution" -- a device that allows one to add single computer PSUs together:

Review/description:
Add2Psu: How to combine multiple power supplies in a single computer | ExtremeTech
Manuf. site:
Add2Psu | Connect two power supplies easily and safely
I will suggest to just forget those things and those links you found about PSUs...
Is a wrong direction and have nothing to do with the subject in this thread! Sorry, but It seems to me that you misunderstood completely the meaning of the mods in this thread...
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Old 8th December 2011, 07:07 PM   #36
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Quote:
Originally Posted by Coris View Post
I will suggest to just forget those things and those links you found about PSUs...
Is a wrong direction and have nothing to do with the subject in this thread! Sorry, but It seems to me that you misunderstood completely the meaning of the mods in this thread...
It has a LOT to to do with this thread if some of the mods pose a potential risk to PC components. The misunderstanding is yours.
I wanted to relay a personal account with using an outboard/ext. PSU (similar to the intent to your DIY PSU approach). Both the computer PSU I used WERE connected to SAME computer ground (I tested this with DMM). The only diff. was independent power up. I don't know the topology of your mods/PS so I don't know if/how you addressed this (do you have schematics?)
IAC, and TTBOMK, the Xonar card only obtains part of its pwr from the Molex (3.3v from PCI bus, maybe. Correct me if I'm wrong). Hence, I don't feel comfortable using externals.
I noted my account and relayed what other modders have suggested regarding grounding issues (and independent power-ups) leading to surges. I think this is what may have killed my HDD (no way to be sure, tho, but I'd rather be safe).

On an different issue, in the brainbit blog, you noted:
"- the another important change is to replace the op amps with another and better ones. Important here is the slew rate of this op amps. The highest [sic], the better dynamics. "
This is mostly incorrect. Dynamic range of an OPA is tied to several other parameters -- not just slew rate.

Last edited by hollowman; 8th December 2011 at 07:15 PM.
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Old 8th December 2011, 08:36 PM   #37
Coris is offline Coris  Norway
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The mods in this thread do not have any potential risk for the PC components, if the moders knows what to do and how to do it... As I specified in many of the previous posts, one must have enough knowledge in the field to succeed in to this.
Else, here is a general presentation of some mods as inspiration propose and not as "how have to be done".
Is up to everybody themselvs to decide if is able to proceed to those mods or not, and take self the risks.

As you can see in the presented pictures here and in the texts too, is nothing about using an another/extra conventional computer power supply for the Xonar audio card. If one decide to try something like this, then is on the own risk, not because it followed the indications here. In this thread is nothing about like this!

By the way, it is special mentioned in the post about an dedicated PSU for the analogue stage of Xonar, that one have to use a reley to control (by the computer power system) this external PSU at power on/off.
One should not mess around with those things, and afterwords if the things goes wrong, write it here that the thread "pose a potential risk to PC components".... Let`s be fair! Right?

Slew rate in an amplifier have a radical contribution to its dynamic range. Higher the slew rate, better the dynamics in the system...

Last edited by Coris; 8th December 2011 at 08:42 PM.
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Old 8th December 2011, 08:39 PM   #38
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Quote:
Originally Posted by Coris View Post
It is already précised that for those mods presented here, one have to have quite large knowladge about electronics, physics and even enough advanced tools to succeed with task. If not the case, than you can ask for help some eventual specialists friends.
Ahh ... and your "advanced knowledge about electronics, physics and even enough advanced tools to succeed with task..." makes you expert enough to suggest the following:
Quote:
More I will try here to suggest the follow:
- remove all the “best” yellow electrolytic capacitors on this card and replace it with SMD ceramics with corresponding values.
From your brainbit post.
Epic, bitbrain moment, dude! You should be in stand-up ! IAC, You've got an audience here:
http://www.youtube.com/watch?v=IDDEpnjgTyw

Last edited by hollowman; 8th December 2011 at 08:49 PM.
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Old 9th December 2011, 12:44 AM   #39
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Quote:
Originally Posted by hollowman View Post
On an different issue, in the brainbit blog, you noted:
"- the another important change is to replace the op amps with another and better ones. Important here is the slew rate of this op amps. The highest [sic], the better dynamics. "
This is mostly incorrect. Dynamic range of an OPA is tied to several other parameters -- not just slew rate.
Your interpretation is mostly incorrect. 'The dynamics' is a subjective (sound) impression, not directly related to a measurement of dynamic range.
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Old 9th December 2011, 07:09 AM   #40
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Quote:
Originally Posted by abraxalito View Post
Your interpretation is mostly incorrect. 'The dynamics' is a subjective (sound) impression, not directly related to a measurement of dynamic range.
Yes, if we want to get anally quixotic about things, "dynamics" does not necessarily mean DR.
Going back to Coris' orig remark about slew rate being prop. to "dynamics" ... I think "speed" or "PRaT" may have been more what he had in mind. Even then, "slew rate" (the electrical qty and parameter) is, by itself, pretty hard to nail down on specific sonic subjectives.
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