Thursday, September 18, 2014


Modding Silverstone PCIE USB card

Instead of buying an “audiophile” usb card, I decided to buy a Silverstone EC04-P PCIE to USB card and mod it.  They also make a EC01-p with two internal USB ports only, but with that one you need to figure out how to connect the USB port to your DAC.  With the EC04-P, since it has two external ports it's easy.

This mod is based on info from these threads:
xxhighend forum thread

The mod isolates the 3.3VDC from the PC, and provides a separate 3.3V generated from a linear reg I added on the board.

These pictures show where the 3.3 pins are. Two 3.3 pins to the left here.  BTW, at the point right next to these pins, I scrapped away the solder mask, and connected the 3.3V from my voltage regulator.
When you cover these pins with tape, you can cover the JTAG pin below the 3.3V, but do not cover the Power Good pin above the 3.3V, things stop working.

The other 3.3V pin is here.  This one is easy because you can cover the pins above and below with no side effects.

Initially I added a dc jack on the bracket, and then connect a little walwart to feed it about 11 VDC.  I needed at least 7VDC, and this is what I had in my stash.

Then I needed the DC jack for something else, before I had time to buy more, so I scavenged this one, and soldered the walwart leads directly to the card.  It’s like that for now, but I intend to change it soon.

I also added a Jensen 10,000 uf 4 pole cap here, it is held to the card guide with blue tak.  The walwart connects to the Jensen, and from there power goes to the regulators.

I added a LM7805 linear voltage regulator to power the molex jack on the usb card.  Without the 7805, I had to connect a molex from the PC power supply to make things work.  The 7805 provided a fixed +5VDC on the USB out.  With my DAC, the +5 from USB is not used.  I have an Amanero USB to I2S card, and it is powered from the main DAC board.

The 7805 is in the bottom left of this picture.

The rest of the mod isolates the card from the main 3.3V, and supplies power from a dedicated regulator.

I used kapton tape is isolate the 3.3V pins at the PCIE connector to the motherboard.  Now that it works, I may make etch cuts with an exacto knife so I don’t have to mess with the tape.  Then I made a little 3.3V regulator using a LM317 adjustable reg.

Scraped off some solder mask to expose copper to solder to so I could connect the 3.3V from the 317 to the USB card.  In the picture above, you can see the point right above the isolated pins where I scraped off some solder mask, and connected the 3.3V from the voltage reg.  I connected ground by my power connector, you can just see it at the top left part in the picture above.

 There is also one pin on the other side that is taped over that you can't see.

Plugged it into my PC, then plugged the DC jack into the card, and then turned on the PC.  I plugged a USB mouse into the card first to test it.  The mouse worked, so I plugged my dac in, and it works.

Future mods in consideration include a clock upgrade for the 24 MHz clock and trying a better 3.3V reg.

It sounds quite a bit better than the motherboard USB port, worthwhile mod.  Note that I did this before I added a linear 3.3V power supply, the benefit might be smaller, but I still think it is beneficial to have a separate 3.3V regulator for this card.

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