Author Topic: DDDAC 1794-NOS 24-192  (Read 166526 times)

Offline kajak12

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Re: DDDAC 1794-NOS 24-192
« Reply #260 on: August 31, 2014, 09:16:17 PM »
Cheers Steve! I have 2 x 50mH choke, there seems no value smaller than 1H.
Are you keen for another visit once the DDDAC is up?
count me in with teagle
still discovering the link between electronics and audio reproduction.so much to learn and so little time

Offline Chanh

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Re: DDDAC 1794-NOS 24-192
« Reply #261 on: September 01, 2014, 06:47:49 PM »
Should not be too long now Mario! Will get you, Teagle and Vita for planning approval?! :D







Offline rhlauranna

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Re: DDDAC 1794-NOS 24-192
« Reply #262 on: September 03, 2014, 04:46:58 AM »
my deepest respect and congratulations in having finished your (so far) DDDAC1794... and with this managed to enter your admirable work as a "special project" on Doede's homepage.... wow !!!

if Bernd's controlled power supply would not be that heavy (some 20 kg) I would not hesitate to send it to you for testing purposes... when you will be testing please keep in mind that even the "best" DDDAC that we had here with us, was only half of the "complete" result without the "right" power supply...

I felt free to copy one of your pictures here on this site



can't wait for you listening report...
« Last Edit: September 03, 2014, 05:00:27 AM by rhlauranna »

Offline stevenvalve

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Re: DDDAC 1794-NOS 24-192
« Reply #263 on: September 03, 2014, 12:29:47 PM »
Its a sky scraper, Is it earthquake proof. Amazing.
« Last Edit: September 03, 2014, 12:31:33 PM by stevenvalve »

Offline Chanh

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Re: DDDAC 1794-NOS 24-192
« Reply #264 on: September 05, 2014, 12:47:27 PM »
Its a sky scraper, Is it earthquake proof. Amazing.
As current certified Structural Engineer and Owner, I can assure you that this structure is complied to all Specs, including applicable Australian Standards 2013. However, structural integrity is compromise should an event of liquidfaction ever existing. :)

Offline Greg Erskine

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Re: DDDAC 1794-NOS 24-192
« Reply #265 on: September 06, 2014, 04:55:59 PM »
Hi Chanh,

I wonder what the phase shift in the analogue output between pcb#1 and pcb#11. Has anyone tried just increasing the distance between each pcb rather than just increasing the number?

regards

Offline zenelectro

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Re: DDDAC 1794-NOS 24-192
« Reply #266 on: September 06, 2014, 06:41:08 PM »
Hi Chanh,

I wonder what the phase shift in the analogue output between pcb#1 and pcb#11. Has anyone tried just increasing the distance between each pcb rather than just increasing the number?

regards

AFAIK all the OP's are joined together, how would there be phase shift?

Z


Offline Greg Erskine

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Re: DDDAC 1794-NOS 24-192
« Reply #267 on: September 06, 2014, 07:29:48 PM »
AFAIK all the OP's are joined together, how would there be phase shift?

Z

hi zenelectro,

PCB designers concern themselves with the length of the input and output traces. When people stack the DAC pcbs they are increasing the lengths of the input and output paths. If you compare the signal paths of pcb#1 and pcb#11 it will be a few 100mm different. Significant? I am just asking. If you were doing one pcb you would never think of having the traces significantly different in length when paralleling devices.

regards

Offline zenelectro

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Re: DDDAC 1794-NOS 24-192
« Reply #268 on: September 06, 2014, 08:08:55 PM »
hi zenelectro,

PCB designers concern themselves with the length of the input and output traces. When people stack the DAC pcbs they are increasing the lengths of the input and output paths. If you compare the signal paths of pcb#1 and pcb#11 it will be a few 100mm different. Significant? I am just asking. If you were doing one pcb you would never think of having the traces significantly different in length when paralleling devices.

regards

OK I  think I understand, you are referring to RF / digital side of things? I haven't looked at the clock distribution side of things but too busy to check it out.
As far as analog OP is concerned it would be insignificant (I think).


Offline vitavoxdude

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Re: DDDAC 1794-NOS 24-192
« Reply #269 on: September 06, 2014, 10:53:33 PM »
Wow, you just have to admire the dedication to wire up all those boards with different caps and regulators; it takes an act of dedication and that in my view shows character.  Should be an interesting listen.  When is it getting booked in Chanh?
V
We all like different things so lets all agree to disagree and if any common ground is found then worship it.  Mine is the KD hence being present on this forum.

Offline Chanh

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Re: DDDAC 1794-NOS 24-192
« Reply #270 on: September 07, 2014, 09:01:18 AM »
Hi Chanh,

I wonder what the phase shift in the analogue output between pcb#1 and pcb#11. Has anyone tried just increasing the distance between each pcb rather than just increasing the number?

regards
I do not think there is a phase shift. All are well regulated on the digital front with delay clocking circuitry on mainboard. On the analog size, surely attract RFI, hence there are filter caps here. I think the formula goes 4.7nf -10nf per deck pending distance/gap between DAC board. In this 11-decks high I will apply 0.068uf as filter to reduce hf down to approx 38khz.

Wow, you just have to admire the dedication to wire up all those boards with different caps and regulators; it takes an act of dedication and that in my view shows character.  Should be an interesting listen.  When is it getting booked in Chanh?
V
many thanks for the encouragement Vita! Surely I will not repeat this exercise at this magnitude ever again. LoL! Many hours and love have been invested, not to mention the funding. An invite will definitely coming once am able to get this up and running. Right now need sourcing some Neotech pure core copper wire to finalise this DAC. Order from Brisbane can take another week or so. Would be great if I could source 1.5m locally today or tomorrow then the gtg can be as close as next weekend with sufficient burn-in period. Any one in Perth has some pls let me know.


Offline Chanh

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Re: DDDAC 1794-NOS 24-192
« Reply #271 on: September 08, 2014, 09:52:20 PM »
Got my DAC wired! Hopefully no smoke come out when the power turns on later tonight.
Gota get on with fatherhood duty.... :)

Offline zenelectro

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Re: DDDAC 1794-NOS 24-192
« Reply #272 on: September 08, 2014, 10:54:42 PM »
Got my DAC wired! Hopefully no smoke come out when the power turns on later tonight.
Gota get on with fatherhood duty.... :)

Good luck!!

Offline Chanh

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Re: DDDAC 1794-NOS 24-192
« Reply #273 on: September 09, 2014, 12:44:13 AM »
Quick update - I have now tested my DAC with Doede ps for this configuration, output voltage is spot on 2.74V on left and right for both neg and pos against common. Thank God no smoke come out! :D
Will do a preliminary listening test tomorrow after work, it's 10.40pm now so have to call it the day! LoL!



Offline rhlauranna

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Re: DDDAC 1794-NOS 24-192
« Reply #274 on: September 09, 2014, 01:30:07 AM »
pressing my thumbs for you....

Offline ozmillsy

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Re: DDDAC 1794-NOS 24-192
« Reply #275 on: September 09, 2014, 07:10:13 AM »
On the analog size, surely attract RFI, hence there are filter caps here. I think the formula goes 4.7nf -10nf per deck pending distance/gap between DAC board. In this 11-decks high I will apply 0.068uf as filter to reduce hf down to approx 38khz.
Really enjoying the journey Chanh, thanks for sharing your pics.   Is there any other way the RFI can be avoided,  or is this just a by-product of the multi-board implementation? 

It seems to be a little bit of a shame to have 11 boards loaded with chips capable of serving 96k on the output,  only to drop the HF's at the last moment down to 38k.    Not a biggy in the overall scheme of things,  but was wondering if there is any other way?   (zen?)   
« Last Edit: September 09, 2014, 07:12:50 AM by ozmillsy »
It's all about the music,, not the equipment.

Offline ozmillsy

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Re: DDDAC 1794-NOS 24-192
« Reply #276 on: September 09, 2014, 08:09:50 AM »
Thinking out loud,,,,, the 1794 chips have balanced outputs IIRC.    Is the output stage on these boards balanced (in part)?   Is it relevant?

Appreciate the dac itself has single ended outputs.
« Last Edit: September 09, 2014, 08:21:49 AM by ozmillsy »
It's all about the music,, not the equipment.

Offline Chanh

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Re: DDDAC 1794-NOS 24-192
« Reply #277 on: September 09, 2014, 09:11:18 AM »
Hi Ozmillsy,

There are in total 22x 1794 DAC chips in this configuration. Each DAC chip is serving mono hence fully balance capable.

As for hf filter, I can bring it down to 50khz without compromising the SQ, but really can we actually capable hearing beyond 32khz? Perhaps Zen or the designer can provide a more competent inputs? :)

Btw, this DAC can do upto 384khz @24bit. Not limiting to 96khz like you said. Doede?
« Last Edit: September 09, 2014, 09:14:38 AM by Chanh »

Offline zenelectro

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Re: DDDAC 1794-NOS 24-192
« Reply #278 on: September 09, 2014, 11:47:53 AM »
Thinking out loud,,,,, the 1794 chips have balanced outputs IIRC.    Is the output stage on these boards balanced (in part)?   Is it relevant?

Appreciate the dac itself has single ended outputs.

Oz,

Just about every modern DAC chip has balanced OP architecture, that's part of how they get big numbers, by cancellation
of even order distortion and whatever other common mode noise etc.

Using a transformer on the OP is a great idea, but optimizing the transformer to suit the particular DAC is the trick.


Offline ozmillsy

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Re: DDDAC 1794-NOS 24-192
« Reply #279 on: September 09, 2014, 07:38:01 PM »
There are in total 22x 1794 DAC chips in this configuration. Each DAC chip is serving mono hence fully balance capable.

Yeah, but that doesnt tell me the output circuit is a balanced circuit.  Not likely.     

Quote
Btw, this DAC can do upto 384khz @24bit. Not limiting to 96khz like you said. Doede?
The chips are 24/192 native digital resolution.   192k digital format allows us to store up to a maximum of 96k analog (following nyquist),  and this is what we hope to get on the analog output for 192k data (96k in/96k out).

What is not clear from the datasheet for the 1794 chip,  is what we can feed it when used in mono mode, and more importantly how it will process the data?   
eg:  you may be able to feed in 384k,  but the chip could be decimating the data stream down to what it can handle (192k?).
So, it's possible to feed in 24/384k, and get lovely sounding music on the output,   but that doesnt mean the chip is actually using all the data.     

The whole 384k thing and what chips actually do with it,  is not easy for consumers like us to understand.  I feel like there is alot of smoke and mirrors going on by chip and dac vendors.

Quote
As for hf filter, I can bring it down to 50khz without compromising the SQ, but really can we actually capable hearing beyond 32khz? Perhaps Zen or the designer can provide a more competent inputs? :)

Well, this is a debate that is had time and again on many audio forums.   As a user of redbook cd format, I can hardly argue with you.  haha  :)

« Last Edit: September 09, 2014, 10:05:30 PM by ozmillsy »
It's all about the music,, not the equipment.