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non-profit ver.3 TDA1541a DAC for limited budget diyers

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#1,006
hi all,

I was in china, my production line. The test sampe of the ultimate v3----sample A was funished already. this several day I will test for it. I will post the detail for this sample--A. sample ---B & C will coming, different layout, different parts & will inform to all diyers to choose which one will be the best, full balance one too.

DID anyone like me to prepare a 5687 tube output stage???

this output stage can use cap output or pre-amp out!!!!


thx

thomas
 
#1,009
Finally I got my transformer yesterday.
I got the DAC to work only without the SAA.
Turned out there was a cold soldier between the boards.

Now everything works and I have the usual problem of U4 getting too hot.

I just wanted to say that I think it is amazing and only after the first few hours of listening to it I already like it very much.

Thomas, can you please verify that the TTL input is supposed to take the higher currents from a CD-ROM?
That is the only question still open for me.

Thanks again,

Michael
 
#1,013
hi matthew2456,

kip help me a lot that post another thread in digital forum, since I did not prepare all the items such as the cd-rom fit to all the cd-rom. In my previous message said. i only test with asus 7 plextor cd-rom very good.

ASUS old model some was use philips CD-M9 but long time ago. I had a experience saw ASUS OLD CD-rom when open it was philips CD-M9.

So, as my said, Only use plextor & ASUS will be better.

If U choose another brands, amy be the hardware will not compatible.

thx


thomas
 
#1,017
Thomas, I posted some quetions for you 3 days ago but still no reply.

You have me included in the new ultimate v3 DAC with USB module right? Does the USB module include both PCM2906 and CM106L or you can only get one of the converter?

Did you shipmy 8 TDA1541A chips yet?
 
#1,018
Hello Thomas and All ,

After a month of strugglin with the Italian Postal Service I menaged to receive *my* parcel ver.3TDA1541A DAC l.b.d.
They stopped the pack for custom certificates .

I am very happy all is in perfect condition though and thank you Thomas all is like I ordered .

🙂

Jean-Charles said:

First thing I would like to see is the reduction of noise. When nothing is played and you crank up the volume control, you can hear white noise and hum at a fairly high level.

Particularly anoying is the clock module that polutes the power supply rail or may be something else. When we used the DAC without the clock the noise level goes down.
It could be wise to filter the 5 volt supply on the clock board using beads, chokes and decoupling caps on every chip on this board.
I did not conduct any advanced research on this board, but I suspect clearly the 5 volt rail to be the problem.

Jean-Charles
Click to expand...

Thank you Jean-Charles for putting at the surface the noise problem ... I confirmed myself your findings immediately . Anyway the cure for it is also very easy to implement .

1) look at the Clock little board : Disconnect the GND from J1 to J85(main board )
This immediately eliminate the noise pollution.


2) now look at the SAA7220 dig. filter board :
disconnect GND form J1 to J75 ( main board).
Disconnect GND form J5 to J24 (main board) .

Probably was a ground loop . It would be nice if you measure again the noise at the chips after this trategy .

Like somebody else reported I am pretty pleased with the dac too... over expectations must say ...
Just one thing : I prefere Tent XO for the reclock 😉

PS : the CD rom controller worked ok with Pioneer .


THANKS !!!! 🙂
 
#1,020
hi matthew2456,

ultimate ver.3 was coming.

hi mike, yes the ultimate ver.3 will follow with one piece of USB receiver. PCM2906 or CM106L. since if U use CD only. PCM2906 will better. If U play DVD audio. CM106L will better because its a real USB2.0 chips. Play USB2.0 DVD audio will more smooth than USB1.1 PCM2906.

hi fedde, sorry no S2 chips now.

hi stefanobilliani,

very thanks for your opinions.

sice jean was help me a lot to find out the weak point of the dac that i still need to modify.

For the ultimate v.3 had this improvement.

1. re-layout of the power supply, lower noise , single ground loop was erase already.
2. All the IC socket was directly fit into the PCB, not like the non-profit version , less jumper to lower the noise or said less chance to produce noise.
3. Double ( two step) voltage regulator use two step of LM317 & 337. Totally will 9 sets of power supply for the ver.3 ( ultimate version ) DAC.
more stable & the dynamic was little best than non-profit ver.


4.??????? I prefere Tent XO for the reclock ??????

I had a question was, u prefer use full version of Tent XO for the dac or only use the low jitter XO.
If U feel the low jitter XO was good. I can order from the factory.
The coming that I use was 11.2896XX, low jitter version. hope this will peerform better!!!!

I had not too much professional knowledge of the crystal. Did anyone more detail that is the best oscillator was phase oscillator??

I made a small test was if the remp was not higher over 45 degree, the TCXO, VCXO,XO will stable, Some diyers told me that if I can get the phase oscillator will good for DAC.Any information for this??????

XO or VCXO follow with the Ultimate ver.3 will <5ppm.
low jitter versions.


All the contain of the ultimate ver.3 contain 6~7 pcs of the PCB, detail will inform this several days.

thx

thomas
 
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