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akltam  
#1 Posted : Wednesday, September 1, 2021 6:20:44 AM(UTC)
akltam

Rank: Member

Groups: Member
Joined: 2/8/2009(UTC)
Posts: 21
Location: Hong Kong

Here is my first attempt on the Buffalo III SE project.

I think TwistedPearAudio provides the best means for DIYing a DAC. The way it was setup allow many further tweaks.

I want separate supply for each channel of the analog side. And I go for battery power supply. At first I want separate batteries for each supply and double regulation, but it proves very difficult to setup physically.

So I settle for 3 battery banks. One each for the analog supply. And then one for the whole digital supply. Unfotunately one side of the regulator for the analog side being supplied with the Buffalo board was defective. Fortunately I have some 3.3V LT30345 lying around. As LT3045 can take higher input voltage, the two 18650 batteries in series can direct go in as input.

For the digital supply I use a twin LT30435 to regulate the voltage from the twin 18650 batteries to 5V and then supply the rest of the board.

For the analog output stage, I have tried output transformer using voltage mode. (such as using Lundahl LL1684) This sounds actually quite good but not able to utilised the full 9038pro potential. So after reading further, there are output transformers designed to use current mode on 9038pro. As each 9038pro has 8 dacs, 4 to the left and 4 to the right, each channel can output high current in current mode. I have heard people using specific transformers for DACs for current output with just few mA for a very long time, which honestly I don't think provide the best analog stage implementation. But with 9038pro capable for very high current output, I think these transformer for current output mode became an excellent option.

Comparing to 9038pro in voltage mode, these transformer designed for current output mode provide excellent dynamics which is far better than the same DAC in voltage mode. It is far far better. For example, for live instrumental performances, it is so punchy that it feels like how each note is striked.

The only drawbacks of my setup is that I need to replace and charge the batteries every 5 hours. With my limited electronics knowledge and also I do not want any possible power supply contamination due to connecting chargers to the batteries, I just take out and replace the batteries when needed. I am considering using bigger battery types such as 26650 instead of 18650 which can double the usage time. 2021 9038 dac.jpg (213kb) downloaded 7 time(s).

Edited by user Wednesday, September 1, 2021 6:36:20 AM(UTC)  | Reason: Not specified

akltam  
#2 Posted : Wednesday, September 1, 2021 6:32:58 AM(UTC)
akltam

Rank: Member

Groups: Member
Joined: 2/8/2009(UTC)
Posts: 21
Location: Hong Kong

The batteries banks are mounted directly below the DAC board. These actually reduce the wiring length from the battery banks to the dac board to the minimum.

I have not experienced any hyper expensive 9038pro dacs, but this setup is much better than any other 9038 dacs I have and also the best sounding DAC I have.

2021 9038 dac top.jpg (139kb) downloaded 4 time(s).
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