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Old 4th May 2012, 08:07 PM   #51
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Quote:
Originally Posted by Coris View Post
I can see in your design quite much capacitors and quite high capacity values. I used in my I/V converter few pF and few pF in the final opamp stage.
I'm amazed at your final mod of the card, but I've done smth as well. I use external supplies for all consumers, even +3,3V.
As for analog stage-Do you really think my values of caps are that much? Original caps in final stage were 2700 pf. Could you give the actual circuit of your output.
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Old 5th May 2012, 07:58 AM   #52
Coris is offline Coris  Norway
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You are doing right about power supplies.
About the analogue stage I will want to use like this (picture) your design (it depends a little about what opamp you will use). You will find a picture with my I/V - final stage on the 1 page of this thread.
But anyway, just experiment first as you thought and then try to use my proposal. You will hear very well the difference...
If you will build those stages compact (module) on a very little board and only connect to the rest the in, out and supplies, will be easy to take all out an modify/experiment afterwords...
They who original designed this stage, and used 2700p caps and filters, like more to hear the math not the sounds coming out of such stage...
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Old 6th May 2012, 12:23 PM   #53
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Well, I just don't know what to say, your output stage doesn't seem to filter anything, but on the other hand, it provides linear phase and good impulse response.It must sound perfect but only with a tube amp, where the transformer is like low-pass filter. And I would not connect it to a transistor amp with deep negative feedback as it might oscilate and damage or even burn down tweeters.
By the way, just noticed u are from Norway. I was there lust year. Wish I listened to your tweaked card then.
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Old 6th May 2012, 07:13 PM   #54
Coris is offline Coris  Norway
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Yes, it is not any filtering in my proposal. Do you need filtering? For what? The low pass filter after I/V convertor is meant to filter out quite high frequencies which come from the DAC chip as residual for the converting process. But a quite simple filtering will alter very much those frequencies involved in sound/music. Will also alter the phase and the response of the system... By the way, the phase accuracy is crucial for the sound stage and detailed sound of a sound system. Such DAC residual frequencies are so high and so low power at your amplifier will never succeed to amplify it. In opposite, such frequencies will be strong attenuated by the further power amplifier circuits, and first by the cables it self between source/computer and power amplifier... By the way, a such middle to high quality cable, few meters long can rich a capacity of 100 - 200pF... There are solutions to get 20 - 50pF on a similar lengh cable, but this is another story...
A deep negative feedback meaning is also to prevent oscillations... Oscillations occur when is about a positive feedback in a system...
Here is the clue I pointed in my last post about short connections, and very carefully placement of the components in making the I/V - final stages, and not at last local shielding...
I use not any filter in my modded STX after I/V stage. I have a 26 -28vpp signal swing on RCA output of the sound card. I have this signal on a 100k potmeter, and then directly in an 3886 based amplifier. By the way, my cable between computer and amplifier (a little over one meter is not shielded at all...) I have not any oscillations in my system, no any distortions or noises, and I never destroyed my tweeters, even though I`ve experimented a lot... I have for now only very clean, detailed, high dynamic, and beautiful sound out of my (computer) system... So beautiful sound as an PCM1792 can give...

You do not have to adopt my proposal, if you do not trust it... But trying it will (very much) surprise you...

You are welcome to listen my card if you will come back to Norway...

Last edited by Coris; 6th May 2012 at 07:21 PM.
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Old 21st May 2012, 07:09 PM   #55
frog993 is offline frog993  Germany
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Hello Coris

I have some questions about your external PSU.
Can you explain a little bit about yor 5V and 3.3V supply ? How much is the power consumption on the 5 and 3.3 rails ?
What traces must be cut(or desoldered) and where are the supply rails soldered on the board(3,3V,5V and ground) ?

I'am very happy about some more Pictures...
(sorry for my bad english...)

Thanks,

Frog...

P.S. A last question, when using a external PSU, the molex connector must be used too ?
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Old 21st May 2012, 08:18 PM   #56
Coris is offline Coris  Norway
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Quote:
Originally Posted by frog993 View Post
Hello Coris

I have some questions about your external PSU.
Can you explain a little bit about yor 5V and 3.3V supply ? How much is the power consumption on the 5 and 3.3 rails ?
What traces must be cut(or desoldered) and where are the supply rails soldered on the board(3,3V,5V and ground) ?

I'am very happy about some more Pictures...
(sorry for my bad english...)

Thanks,

Frog...

P.S. A last question, when using a external PSU, the molex connector must be used too ?
Hi Frog
I`ve already published here some pictures of my dedicated PSU for the STX board. If you will go back in this thread, I think you can find those pictures and some text explanations. But I can attach here again some... One of those pictures show an 3,2W toroid transformer, so one can easy conclude that is not about important power here...
Anyway, I want to underline again that when I refer to an external PSU, I mean an PSU which will deliver power (+/-15vDC) exclusively to the final opamp stage and the I/V converter. I`ve used for this PSU LM2941/2991 regulators.
I`ve used 12vDC from the computer through Molex connector. So, yes the Molex connector have to be in place. Cut it out the 5v connection from that connector. The bords circuits need also this tension as it is, because it is controlled and used for the logic inside the board (Cmedia processor). If this tension is not seen by the processor, then error messages occur. I think that I`ve explained here (earlier posts) how is to be cut it the power on this rail so to not generate error messages from the board main processor. It is about to cut the power only for the I/V converter and the final stage on the board, to make possible to supply those stages from a better (external) PSU.
I`ve used computer`s 12v rail to create on the board 5v rail and 3,3v too. Please go back an read earlier posts where is described what about 3,3v rail and the components to be removed to isolate compleatly the board from the rest of the computer power system. I can come back to this step if you will feel the need for more explanations.
I`ve used local regulators to create both 5v and 3,3v. Keep in mind that 3,3v rail need a little more power, because the CM processor is to be feed it from this too. I did not measure the current need it by the involved stages, but I`ve used such regulators which can much more than the need of the involved chips. Here is about not more than 200-300mA (3,3v). The 5v is used only for the DAC chip (analogue part of it) and the quartz/clock stage.
Also please keep in mind that the ground plane/connections do not have to be touched or cut it ever. Keep it as it is from the Molex connector too
The aluminium cover of the original board is very good as a heat sink for the small regulators used for both 5 and 3,3v...
The 12v rail from the computer have to be used too to action an relay which will connect the main to the +/-15v PSU in the same time when the computer starts. This is very important! And please be carefully with the 220vAC inside the computer... Much care and good isolations will make everything safe here...
The picture of my final PSU published in an earlier post looks like quite complicated. Is because I`ve used the same board to build up some additional power and switching/relay circuits to supply the STX board from a battery instead for main 220vAC. I have to say that is no any difference between using a battery and an serial/analogue PSU for the resulting sound. So, I do not use now the battery anymore to supply with power my STX. So, let`s forget about battery...
I call this 15v PSU as an external PSU, but in fact is mounted inside the computer, just over the STX board (as to be seen in some pictures here). The STX board it self is not designed to support a quite heavy toroid transformer, so I had to make an supplementary support plate attached to the board, and find a way to support the whole construction quite well to avoid any mechanical tension over the STX board and the PCI Express connector in the mother board of the computer. You can also see how the whole construction look like in an earlier picture here.
I do hope those explanations help now better.

Last edited by Coris; 21st May 2012 at 08:28 PM.
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Old 21st May 2012, 08:31 PM   #57
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Frog and all ...
Coris' (and similar) PSU is/are WAY more trouble than it's/they're worth (time/effort wise)... unless you like to experiment just for the "FUN" (but not necess for the PERFORMANCE) of it!
I have tried many solutions for the Xonar and am most pleased with the better COMMERCIAL "higher-end" PC PSUs, like from Antec, Seasonic, etc.
HardwareSecrets.com conducts very comprehensive OBJECTIVE tests on commercial PSU, so you can choose one with, e.g., the best ripple rejection, and linear current delivery, etc.:
Power Supples: Tests + Articles | Hardware Secrets
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Last edited by hollowman; 21st May 2012 at 08:35 PM.
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Old 21st May 2012, 09:44 PM   #58
Coris is offline Coris  Norway
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Originally Posted by hollowman View Post
Frog and all ...
Coris' (and similar) PSU is/are WAY more trouble than it's/they're worth (time/effort wise)... unless you like to experiment just for the "FUN" (but not necess for the PERFORMANCE) of it!
Sorry for you, but you do not understand what this is all about... So, be happy in your world!
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Old 21st May 2012, 10:09 PM   #59
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Default So help us understand!

Quote:
Originally Posted by Coris View Post
Sorry for you, but you do not understand what this is all about... So, be happy in your world!
So help us understand in context, manner, methodology as comprehensive is this:
Hardware Secrets Power Supply Test Methodology | Hardware Secrets
Do you conduct truly insightful and OBJECTIVE PSU load tests using scientific instruments such as:
Dongguan Sun Moon Electronics Co.,Ltd-www.sunmoonate.com

I already commented on the potential dangers of floating (or otherwise unreliable) grounds in DIY jobs -- what may have led to my HDD failure.

It's PARAMOUNT for "DIYers" to know some of the POTENTIAL hazards of pure-DIY approach. I also feel that the pure-DIY approach to PC PSU is not all that much worth the effort in ANY case (so not a whole lotta gain WRT sound compared to better comm. PSU, as noted earlier).
As far as having fun, learning, testing, building ... well, get a oscope out and test the comm PSU, read the informative articles on sites like HardwareSecrets (lotta auto didactism there)....this is "DIY" from now on as far as I'm concerned....everything else is UNSKILLED "labor".

[PS: I HATE soldering burns and fumes. LOL!!]
Oh, and ... uh ... one more thing...
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Last edited by hollowman; 21st May 2012 at 10:16 PM.
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Old 21st May 2012, 10:49 PM   #60
frog993 is offline frog993  Germany
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Hi Coris

Thanks for your explaining.

Ok, i have re-read and will try to explain what you mean.

For seperating the analog outputstage:

The +-15V comes from the external PSU with his own transformer and rectifiers etc.
For this, the output pin of the 7812 and one side from the diode between L20 will be cut/desoldered.

For seperating the 5V for the DAC and Clock:
You cut the 5V cable from the molex connector or cut the outputpin from the 7805(that a little bit unclear) ??
Then insert 5V from your own shuntregulator thats powered from the 12V molex connector, right ? Where is good point to soldering the 5V rail to the board(on the last photo it shows that it goes to small ceramic cap left from the DAC) ? My intension where on the 7805 outputpad...

For seperating the 3.3V Rail:
Desoldering the small ferritebead on the back of the card.
Then soldering the cable from 3.3V shuntregulator on one (positive)solderpad from the cap right from the DAC ?
Sorry, the final picture from yor card is a little bit crazy...

The Essence Soundcard is for my AudioPC (see picture below). At the moment i have installed a RME 9632. The 9632 comes with one (little bit old)AD1842 DAC so i will give the Asus a try because of its more modern DAC and better chances to optimate.

For +-15V rails i think the LM317/337 is a good choice(someone like this one that works for my preamp, but a little bit smaller)

Edit: What is with the extensionport for the H6 modul ? Normaly there must be 3.3V,5V and ground etc. Is this not a good place to put on the cables for 3,3 and 5V rails ?

@Hollowman

A opamp like LM49720 only works at 80% of what he really can when its driving with crappy +-12V...The -12V will create with a switching psuchip from the +12V rail. That is not the best idea...
Same is for the DAC and clock...

Greets,

Frog

Last edited by frog993; 21st May 2012 at 11:03 PM.
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