My Super DDDAC build

[thommy]

I am just about to embark on another DDDAC build, this time a double deck with a few mods. This is for the lounge, and hopefully will stay there for years to come.

1. 4 individual sjostrom super regulators for the L & R analogue & digital supplies, involves cutting the ground plane to separate the two voltages entirely. Each part of each deck is powered in parallel with the corresponding section of the other one, so that i can easily add more layers if desired.

2. A 5th Sjostrom will regulate the WaveIO USB card and feed the DDDAC mainboard, so the decks are floating as it were and not taking power from the mainboard.

3. CCS board are added to each of the DAC chips in place of the 6k resistor

4. There are very few caps in this now because the super regulator outputs will not require a smoothing filter. The ones which remain are Silmic for the analogue side, Oscon for the larger digital ones and the new Polyphenylene Sulfide (PPS) for 0.1uF values in the mainboard. I will also be using a few of the ones supplied in the kit in less critical places.

5. Posh IV resistors seems to be an easy upgrade, so some Shinkoh or similar need to be found.

6. Sjostrom diamond buffer boards on the output to take care of impedance matching.

7. Upgraded series regulator for the spdif section.


So completely separate power supplies for each bit, high quality caps & resistors, the CCS mod and the output buffer. Should be good!

http://s2.postimg.org/xvqrlbisp/P1040762.jpg

[Ali Tait]

Shinkoh here -

http://www.hificollective.co.uk/components/shinkoh_resistors.html

Or they do Charcroft Z foils if you fancy them.

[Sovereign]

Nice one Thommy

I also have a dddac , I have made a few mods especially an unregulated power supply to ver good success. Best of luck with the build, keep the posts coming.

[thommy]

Yeh this is my second now. The first is about to get the new caps and ground plane split treatment also.

I am going to seem ridiculous here, but my plan for the power supply is an SMPS.

The preamp which contains this DAC has various power requirements. I plan to use a medical grade SMPS and some caps/resistors to get different voltages and feed all of the super regulators in parallel. There is bound to be some loss through the lack of galvanic isolation between components, but the super regulators and going to be far better than shunts so I hope that this will offset somewhat and end up being a convenient solution to an otherwise complicated power supply!

[thommy]

http://s24.postimg.org/3m79mb0th/P1040763.jpg

http://s24.postimg.org/bk1onye3p/P1040765.jpg

Managed to make a start on this, but realised that I don't have the right Elna caps. Decided to replace two 47uFs with a single 100uF in a couple of places, but then ordered 47's anyway so now I need 12 more...

[John]

Great sounding DAC I heard James a few times and be very impressed with it

[Sovereign]

Really interesting Thommy! I'm resisting reading this thread in detail as I have so much work to get through :rolleyes:

[thommy]

Cutting the ground planes seem to have worked, I no longer get a closed circuit on the DMM between the ground around the digital section and that of the analogue. It's not fully open as the ground connection runs through the chip, but nonetheless hopefully this means that the background 'digital' noise I was hearing in my previous DDDAC will not be so much of an issue here as the digital filter caps are no longer filtering off the noise straight into the analogue audio ground plane.

[Sovereign]

How is the build going tommy

[thommy]

Still quiet on the DDDAC front for now, think I have found a faulty 5v super regulator....

[thommy]

Got the single deck DDDAC working last night.

It was indeed a faulty 5v reg. Got a friend to check everything over before we powered it up with a replacement.

So this is my first implementation of the split power supply and it's a mod that hasn't cost me any money (which makes it more interesting).

The DDDAC in stock form takes 12v on the DAC board, and 5v on the WaveIO USB board. I am still using the 12v and 5v, but now the 5v feeds all of the 3v3 regulators on both the WaveIO and the DAC. Essentially the whole I2S chain has one dedicated super regulator, rather than half of that system sharing it's power supply and ground with the analogue side. The other 12v supply is now going straight to the 8v regulators on said analogue side.

Apart from the brittle sound of new caps, immediate impressions are that it is quieter; the soundstage is more robust which suggests a lower noise floor. That digital background noise has just gone so this is a recommended mod.

[djdstone]

Nice one Thommy

I also have a dddac , I have made a few mods especially an unregulated power supply to ver good success. Best of luck with the build, keep the posts coming.

What power supply did you end up using with the DDDac?