Building Power Supply for DDE 3.0

[gto47]

I'm interested in building a custom power brick for the Audio Alchemy DDE3.0. I have read that it is dual rail 8v and 18v. It seems like the 8v must be for the decoder and the 18v must be for a high current gain stage. Does this sound correct. And in this case, does it seem rational that the rail quality supplying 8v is much less important than than the 18v rail for the amp. Does voltage stability to the dac chips make any difference?

[stephensank]

The v3.0 actually uses four supply rails, +/-18V and +/-8V duals. The 8V rails are for the digital section, yes, but only marginally less critical to the sound quality as the 18V rails. These supply inputs are regulated inside the dac to the final voltages, so it's not strictly necessary to have regulation in the outboard supply, but I prefer to do so. Although there is no benefit, you can technically feed the dac up to +/-24V on both sets of inputs, limited by the voltage rating of the input filter caps, C101-104. I have the complete schematics of the v3.0. If you send me your email address, I'd be happy to send it to you.

Personally, I find the v3.0 serverely & near irrevocably limited by the use of the PMD100 hdcd chip as digital filter, which collapses the soundstage & sucks the life out of the sound. The lovely AD1862 20bit ladder dacs used in the v3.0 sound FAR better in even a bone stock Pioneer CLD95, or a GIC-filter-deleted Denon DVD2560, which both use non-hdcd digital filter chips. Either of these betters by far even a maximally-upgraded v3.0.

[gto47]

Given that information, I wonder if the power station 4 that came with these even has separate rails. Now I understand why the monolithic upgrade was a bit expensive.

Is the PMD100 switched out when in 16 bit mode, or is it hopeless in all modes? I have the DDE1.0 and DTI1.0 and I always thought the quality was decent considering the design dates to 1994.

[stephensank]

The problem is that the PMD100 is the digital filter, period. There is no bypass route, and there is no pin for pin non-hdcd replacement. Due to the PMD100 ruining the v3 and the v1.2, the best AA dac, IMO, to upgrade is the dac in the box. A not even fully maxed out ditb utterly mopped the floor with a v3 that I maxed out. It wasn't even close, and the ditb is well down the list of best digital front end upgrade results I've gotten.
The monolithic power supply is not really very good. Just average.

[gto47]

I was able to find the schematic over on audio asylum. It does not seem to indicate the pinout for the power cable however. Am I missing something?

[stephensank]

In my schematic pdf, it's clearly laid out on page 4, the page with the primary ic voltage regulators.

[joedotcom]

Originally Posted by stephensank

I have the complete schematics of the v3.0. If you send me your email address, I'd be happy to send it to you.

I am in the same boat. Sending a PM hoping you wont mind sending me a copy as well.

-Joe
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[ihear21khz]

This German outfit has a drop in DF1704 chip module that replaces the PMD100 chip. According to their website, the module can be used in the Audio Alchemy.
ASE-Audiotuning

[stephensank]

Originally Posted by ihear21khz

This German outfit has a drop in DF1704 chip module that replaces the PMD100 chip. According to their website, the module can be used in the Audio Alchemy.
ASE-Audiotuning

That is superb info. Thanks for that.