Thanks for the reply...
True, the 7808 is seeing 12V input so it has to be getting this at the PCI slot. As there are no 7812's anywhere, I have to assume 8V is the max power this board is using (OPAmps). I imagine for the power traces in the circuit, they are probably buried within the PCB and large (and not visible).
I think it would be easiest to tap external power into the board from pin 1 of the 78xx and 79xx to run it.
What do you think of the sjostrom audio regulator as seen on this forum Coris?
Set it up for 8 or 9 V -+ and run it into pins 3 of the reg's (regulators removed) and power it from the PSU 12v rail or an external PSU?
Sent from my iPhone...
I think one may do an enough good research to get as much as possible informations about the power system of this board, before starts some mods in this area. It may be that Asus has designed this board for +/- 8v on opamps to use the existent +/-12v rails from the computer PSU. Personal I think is not a good solution to use 8v on opamps witch have specified parameters for dual 12v or 15v. But they had to use the existing power rails from the computer...
I will want to try first dual 12v where is used 8v, and then 15v. This mean an external PSU which it may deliver 14-15v (17-18v) on 12v (15v) regulators. I will want use first standard 7812/7912 regulators to observe if it works well enough. Then if all it may be all right, I will think to find better regulators (lower noise).
This is an idea, but I repeat, I do not know very well this board. One may be sure that the opamps used on this sound card it work well with dual 12 or 15v. Take a look on the datasheet of these opamps. It seems to be logic to inject the new working dual tensions on the input tabs of the older 8v regulators. The 5v and 3,3v rails it may not be touched yet, I think...
I will want to try first dual 12v where is used 8v, and then 15v. This mean an external PSU which it may deliver 14-15v (17-18v) on 12v (15v) regulators. I will want use first standard 7812/7912 regulators to observe if it works well enough. Then if all it may be all right, I will think to find better regulators (lower noise).
This is an idea, but I repeat, I do not know very well this board. One may be sure that the opamps used on this sound card it work well with dual 12 or 15v. Take a look on the datasheet of these opamps. It seems to be logic to inject the new working dual tensions on the input tabs of the older 8v regulators. The 5v and 3,3v rails it may not be touched yet, I think...
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I want to rectify something wich is wrong in my previus post:
The new working dual tensions it may be injected on the output tabs of the older 8v regulators.
Doing so, the original +/-12v rails will be left open on the board and unaffected by a new power system for analogue stages...
The new working dual tensions it may be injected on the output tabs of the older 8v regulators.
Doing so, the original +/-12v rails will be left open on the board and unaffected by a new power system for analogue stages...
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Here is a labeled layout of my card...
Front channels are the only ones I'm concerned with...and being front channels, it's safe to assume the better JRC 2114's are for fronts.
Here you can see the 2114's and National L4562 buffer. The 4562 operates from 2.5 to 17V-+, so I think the analog stage is likely 8V.
Same with the JRC2114...operating voltage from 3-22V.
All OPAmps other than front and (what I assume are mic/line in 5532's) are R4508I-6CM's with R4508I-72K buffers...obviously for all channels other than front.
Here is the whole card labeled...again, I'm just interested in the front channel modifications.
Each buffer-I/V opamp has a cluster of caps, for which I'm not 100% sure of the values or which is for what opamp. However, they all have 2X22n and 4X100
I now need to take a V reading off an opamp...
Preferably anyone other than the front, in case I short it out with my probes!
Pins 4 and 8?
Sent from my iPhone...
Front channels are the only ones I'm concerned with...and being front channels, it's safe to assume the better JRC 2114's are for fronts.
Here you can see the 2114's and National L4562 buffer. The 4562 operates from 2.5 to 17V-+, so I think the analog stage is likely 8V.
Same with the JRC2114...operating voltage from 3-22V.
All OPAmps other than front and (what I assume are mic/line in 5532's) are R4508I-6CM's with R4508I-72K buffers...obviously for all channels other than front.
An externally hosted image should be here but it was not working when we last tested it.
Here is the whole card labeled...again, I'm just interested in the front channel modifications.
An externally hosted image should be here but it was not working when we last tested it.
Each buffer-I/V opamp has a cluster of caps, for which I'm not 100% sure of the values or which is for what opamp. However, they all have 2X22n and 4X100
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
I now need to take a V reading off an opamp...
Preferably anyone other than the front, in case I short it out with my probes!
Pins 4 and 8?
Sent from my iPhone...
I think it is safe to power the analogue stage with +/-12v. To use dual 15v it may be very near to max tension for some caps. But it may be safe enough too.
Anyway using 12v it will work very well. 8v it is enough low power to get the right slew rate of the opamps and another parameters, while these components are specified for 12/15v.
I will suggest you to cut out the in/out 8v regulators legs (not so necessary to remove it completely from the board), then inject your power +/- from an external PSU, on the out tab of the old regulators. Ground may be common and short for external PSU and the board. After you will be satisfy with the work, and have stable results, then is to be changed the resonator on AV200 with an decent quality oscillator for the same frequency. The overall result (heaving in place a better PSU for analogue stage) it may be then quite high...
Anyway using 12v it will work very well. 8v it is enough low power to get the right slew rate of the opamps and another parameters, while these components are specified for 12/15v.
I will suggest you to cut out the in/out 8v regulators legs (not so necessary to remove it completely from the board), then inject your power +/- from an external PSU, on the out tab of the old regulators. Ground may be common and short for external PSU and the board. After you will be satisfy with the work, and have stable results, then is to be changed the resonator on AV200 with an decent quality oscillator for the same frequency. The overall result (heaving in place a better PSU for analogue stage) it may be then quite high...
I was thinking the group buy -+ regulator I've seen here in another thread...running at -+8V, and then it could be easily powered by the computers 12V rail.
If I opt for 12V external regulation for the D2, I'd also have to find a quality 15-18V external power source.
I've noticed on my card that both 8V- and 8V+ run the OPAmps for an operating V of 16V.
So if I run 12, I'll be getting 24V to the OPAmps.
I think 22V was max spec on one of them.
Sent from my iPhone...
If I opt for 12V external regulation for the D2, I'd also have to find a quality 15-18V external power source.
I've noticed on my card that both 8V- and 8V+ run the OPAmps for an operating V of 16V.
So if I run 12, I'll be getting 24V to the OPAmps.
I think 22V was max spec on one of them.
Sent from my iPhone...
The reason it may be sure enough the need to use +/-12v from the computer power rails to feed these regulators for analogue stages on the board. A reasonable safe regulation from a 12v source is 9v or 8v. They chosen 8v...
At last everybody is free to take risks, to try something new, or not... So, your choice.
At last everybody is free to take risks, to try something new, or not... So, your choice.
Kinda odd then that they chose -+12V for the ST from the 12v rail.
Sent from my iPhone...
For ST/STX boards, the power system for analogue stage is quite different. Asus use on the last edition of their sound cards, an switching PSU which deliver 14,8v, then this is regulated to +12v by 7812. For the negative part is used an switching PSU which deliver-12v. I will come back to these aspects with some snap shots...
On this edition of the board, the +/-12v tensions are rigorous equal. This is good!
Else, ST/STX boards are in Asus concept a kind of high end (audiophile) sound cards... That because the designers are more respectfully for the datasheet of the components (opamps)...
So, this it may be the difference....
On this edition of the board, the +/-12v tensions are rigorous equal. This is good!
Else, ST/STX boards are in Asus concept a kind of high end (audiophile) sound cards... That because the designers are more respectfully for the datasheet of the components (opamps)...
So, this it may be the difference....
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There is the 1.00 version (ASmedia chip).
Even though the version numbering, it seems this edition is newer than others. I bought this card in the last time, while the 1.02 version is few years old now.
I have started a modifying process on this board (analogue stage including DAC, oscillator for AV100, and at last the power system). I have left untouched for moment the power system, while the DAC and analogue stage er new. Also an Crystek oscillator for AV100.
All powered by the original power system. The results are so far very good.
I will come back soon with some more infos about these mods.
Even though the version numbering, it seems this edition is newer than others. I bought this card in the last time, while the 1.02 version is few years old now.
I have started a modifying process on this board (analogue stage including DAC, oscillator for AV100, and at last the power system). I have left untouched for moment the power system, while the DAC and analogue stage er new. Also an Crystek oscillator for AV100.
All powered by the original power system. The results are so far very good.
I will come back soon with some more infos about these mods.
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I think I have to correct something about this with numbering the versions of the ST/STX boards...
After a better research, I found out that this new edition of sound cards are revision 1.00 This mean that is the first edition of a new modified design using the ASmedia chip. These boards are also marked as ASM boards.
So, the numbering of the sound cards versions it may be right at last. The old ones are 1.02 (a better design of the 1.00 revision) using PLX chip. While the last one are first edition of a design using ASM chip.
After a better research, I found out that this new edition of sound cards are revision 1.00 This mean that is the first edition of a new modified design using the ASmedia chip. These boards are also marked as ASM boards.
So, the numbering of the sound cards versions it may be right at last. The old ones are 1.02 (a better design of the 1.00 revision) using PLX chip. While the last one are first edition of a design using ASM chip.
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