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-   -   DAC with Four PCM 1704, PMD100, CS8412 (http://www.diyaudio.com/forums/digital-line-level/183478-dac-four-pcm-1704-pmd100-cs8412.html)

gabrielbecheanu 19th February 2011 11:32 AM

DAC with Four PCM 1704, PMD100, CS8412
 
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Hi
A few days ago a friend of mine bring me a DAC with four PCM1704, PMD100 HDCD decoder and CS8412 receiver to listen. This DAC was bought from Analog metric..
The DAC have one S/PDIF and one AES.EBU input,
I made two power transformers but the DAC doesn’t work.
Any one has experience with this DAC?
Any suggestion?
Best regards

pionik 19th February 2011 04:11 PM

Quote:

Originally Posted by gabrielbecheanu (Post 2474879)
I made two power transformers but the DAC doesn’t work.

Hi, check schematics of PSU part for this DAC. I have another model of DAC from this firm and found that they made very strange shematics in PSU - they use the same type of regulators chip to obtain (-) and (+) voltage. Thus, (-) voltage they derived with regulator placed in path to common "earth" on PCB. You need separate second windings (not common earth connection between them) on transformers for EACH voltage on PCB connector, even with eaqual values. After your previous attempt and before new connection, you need check all diods in PSU - some of them already could be broken.

gabrielbecheanu 20th February 2011 08:17 PM

Thanks pionik
I just received the schematic diagram and i will check everything from power supply to output stage.
If some one made an improvement to this DAC i would like to know more about it.
I think that this DAC has more to show me after I will make him to work again
I have a DAC with CS4398 from Ebay, i will compare him with this four PCM1704 digital analog converter . I am so curios to see who will win the contest.
Best regards

zerotohero 29th March 2011 01:32 PM

How did you get on Gabriel?

Would be interesting to see how it compared with your dac.

qusp 29th March 2011 03:15 PM

its not such a strange way to use floating regulators, as long as they inform the customer. in fact myself and a friend are utilizing the same technique with our dac psu. we are doing it for reasons 2 fold. the very high quality linear tech lt1764a regulator does not have a negative pole counterpart of the same extreme high quality, low noise and current capability and we can buy in bulk all the same chip to use throughout all 10 regulated voltages, simplifying layout and allowing bulk pricing on the regs

gabrielbecheanu 20th August 2012 09:25 PM

Hi
Finally i manage to fix this DAC with the help of a friend of mine but i am disappointed. A lot of components for nothing.
Will be better to make another one with this good quality parts.
I have the service manual for Nakamichi Dragon and I intend to inspire from them to make another DAC with 4x pcm1704 with HDCD decoding and 192khz support.
Best regards

bear 21st August 2012 03:57 AM

what is the I/V converter and the output buffer?

Your sound may be limited there, not in the digital end - depending on what they really did on the digital side...

_-_-bear

abraxalito 21st August 2012 04:02 AM

As its Analogmetric I doubt the problem's in the parts, the layouts are what suck. As well as some of the dubious design decisions in some instances (like on my TDA1541A version).

gabrielbecheanu 22nd August 2012 07:18 PM

Hi
I made more tests to this DAC and none with good results
24\96 don`t play well ,after a few seconds he start to loose digital signal
and the output stage is awful. I will try another time with another output stage.
I found something interesting in Romania with 1704. It is made by a company from Iasi, i will talk with them to make some test if is possible.
Here is the product Audiobyte OEM
This is not advertising

ihear21khz 23rd August 2012 03:16 AM

The CS8412 is not a true 24bit/96 receiver. Try using an 8414. I am not familiar with the dac you have but if I recall correctly the 1704 needs to be configured differently to process 24bit. You can do this in hardware mode. Check the 1704 datasheet.


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