R2R DA M1 Ultracap powered build

[bballas]

yes,little burned in yesterday,sound get better.Only 20 hours now,i like this sound so much.

nos7
-many recordings terrible
-some recordings really good-magical-so not real !!
-bass section not detailed,unclear,

8xdam1 balanced ,12rail ultracap power,Dibao output transformers
-almost all recordings great!!!
-Lifelike Sound
-all parameter balanced,good to listen

 

[abartels]

Sounds very promising Balazs

Hope I can build mine real soon!

Cheers

 

[bballas]

 

[abartels]

Looking great!

 

[abartels]

Btw, did you cut the pins from all the voltage rails between the DA-M1 modules?

If not, it is best to parallel the ultracaps and switch ground with relays too.

 

[bballas]

I cant accept bigger size dac this time.The mobility and SQ same important.I Can use 12v 20ah battery if are you afraid of ground noise.

 

[abartels]

The 8x DA-M1 modules are build with 4x 2-push-pull sets of DA-M1.
The 4 Push-Pull sets have their voltage rails connected together with long pins, so, 1x push-pull set only uses 1x 3.3V-A + 1x 3.3V-D + 1.8V-D
That is 2x 3.3V + 1x 1.8V per push-pull set (of 2 DA-M1 modules).

So, what you need is 8x 3.3V ultracap psu's, and 4x 1.8V ultracap psu's

That way you've got balanced powerrails (meaning: exactly identical Voltage level) for each DA-M1 module in push-pull set

So in total 12 psu's needed, with a total of 48 relays for the psu's.

Talking about relays, I measured mine, and I am NOT pleased with the quality of those relays.
In the beginning I had to replace one relay which had about 80 Ohms contact resistance which ruins your ESR completely.
I replaced it, and measured all other relays. The others all measured below 0.1 Ohm.

After a few weeks of burn-in I measured again, and guess????

One relay has 78 Ohms of contact resistance, and 7 others have contact resistance above 1 Ohm!!!!!

They are rubbish and unusable for this kind of design.

Please, be smart and design your own relay board. It only takes relays and NO other electronics because we do switch them ALL TOGETHER at the same time.
I investigated a lot, and it seems the Fujitsu-Takamisawa relay NA5W-K is a very good one, with bifurcated contacts and a max of 50 mOhm contact resistance.
They can handle a switching current of 2 amps, which in our design is more then needed.

https://world.taobao.com/item/531838781101.htm?spm=a312a.7700714.0.0.hUzxsO#detail


Hope this helps!


Cheers,

Alex

 

[abartels]

About ground noise, we use DC-DC converters, which in term are switching powersupplies with a switching frequency about 300kHz.

It doesn't matter how you feed the DC-DC converters, if you DON'T cut ground, there will be traveling groundnoise of about 300kHz thru ALL the psu-lines to the dac.

It isn't of any importance if you can hear it in YOUR set, it's evident that there IS a polluted 300kHz signal in your design which flows thru EVERY psu and EVERY DA-M1 module.
Maybe it is VERY noticeable on other sets, like mine. As a test I connected some groundwires from charging ucaps to running ucaps, and the result was a less musical sounding dac.

Just my 2 cents...

Cheers!

Alex

 

[rellik]

One question, Will using a bunch of low voltage caps in series to gain voltage rating eventually fail due to localized potential spikes?

I ask because I am using a similar technique for a B+ supply rail and really don't want to mess it up. Regardless, I don't like HF noise as your previous post mentioned. Sadly I cannot shunt the junctions as the whole freggin thing is now trapped in gel.

 

[abartels]

Maxwell advises if putting more than 3 ultracaps in series, you need balancing circuit.
This is because not all cells are 100% equal, and if charging at max voltage, one could die because of overvoltage.

On TaoBao or Aliexpress are many balancing boards available, or even complete ultracaps modules with 6 ultracaps in series.
They are mounted on active balancing boards.

 

[bballas]

New back panel created...

 

[abartels]

See this for some interesting facts about relays:


https://www.head-fi.org/f/threads/lks-audio-mh-da003.745032/page-48#post-13532729

https://www.head-fi.org/f/threads/lks-audio-mh-da003.745032/page-48#post-13546294

Cheers!

Alex

 

[bballas]

-transformers sound much worse than rusted relays+ultracaps
-LPS1 vs crappy relay+caps A-B tested,SQ same!
-My detonator dac sound amazing for me

Cheers!
Balazs

 

[abartels]

Hi Balazs,

Yes i know it still sounds fabulous, but it is better to use high quality relays.

You have detonator dac completely finished? Have some pics?

Cheers,
Alex

 

[bballas]

finished,but ...never finished haha
dac side stable,charge ,caps side stable.Sound also stable.
input side not so stable.gd i2s lvds with tanly usb and lks amanero don't want work.sound just shhrwrekrhr
with gd amanero works fine,but I sent outside this board yesterday.