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Old 10th January 2013, 08:17 PM   #2011
qusp is offline qusp  Australia
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I had a long detailed reply explaining this written out and the fuse blew outside on the electrical circuit so lost everything I was working on that wasnt saved, not much but I never remember to save long posts (its summer and everything is on) very annoying. this is hard work alright....

no Ed, you missed the point, the DIX on the fifo spdif is also likely effected. in fact its clear you didnt understand any of my post, the problem is not sample rate, it is the number of times the sample rate aka FS, is divided into the master clock frequency. to play 44.1khz with a 45.xxMhz clock, it needs to multiply 1024x aka 1024x FS, but the DIX chip which handles the spdif out and in, may be limited to 512x FS (unless the doublespeed mode Ian mentioned works) as almost nothing, including the 1794a will allow 1024x FS. ESS dacs do, maybe some others I dont know about do, but wolfson, Ti, AKM dont on any of their dacs, so the spdif chip really has no need to either.

so its actually using too LOW a samplerate with too HIGH a master clock, high samplerate will be normal, I bet you can output 96khz or 192khz just fine with the 45.xx/49MHz clocks.

is THAT clear enough?

I know now that the DDDac does the strange thing where it clocks both BCK and SCK from the same source.... in order to fool the dac, thankfully you are using the fifo because usually bck is higher jitter and the design asks it to drive 2 inputs. the flipflop on the dddac doesnt have termination either. interesting combo....

I had wondered where the clock was on that board, I did not even consider that it would be expected to be supplied by the source bck by default without any other option and mostly from 20cm or more away at the bottom of a stack of headers... that means some sources will supply the dac with pretty huge jitter. not fifo of course.

but on the upside, that means the bck and sck are the same, so wont be effected, thus why it works. similar to using ESS with the oversampling filter switched off, same deal.

its an intriguing design still, but wow... not even an optional onboard clock.

so potentially the si570 will allow this to work if it can be programmed to optionally supply a lower clock with lower samplerates, like supply 512 x fs for 44.1 so the DIX works. Until then you may have to use 22.xx/24.xx clocks if using the spdif out at lower than 88.2/96khz

Last edited by qusp; 10th January 2013 at 08:36 PM.
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Old 10th January 2013, 09:36 PM   #2012
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Quote:
Originally Posted by qusp View Post
so potentially the si570 will allow this to work if it can be programmed to optionally supply a lower clock with lower samplerates, like supply 512 x fs for 44.1 so the DIX works. Until then you may have to use 22.xx/24.xx clocks if using the spdif out at lower than 88.2/96khz
Yeah, Ian has 2 different default groups of frequencies that will suit this application.


Ed, see Ian's post here:

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Originally Posted by iancanada View Post
By taking the advantage of Si570 variable frequency output capability, I designed 4 groups of MCLK and *Fs combination in the Si570 control FW. Group is selectable according to different personal preference, or makes it suitable for different DAC chips. They are:

//Group1:Si570 frequency and *Fs combination for low mclk range
{F112896, 256*FS}, //2 44.1 KHz
{F122880, 256*FS}, //3 48 KHz
{F225792, 256*FS}, //4 88.2 KHz
{F245760, 256*FS}, //5 96 KHz
{F451584, 256*FS}, //6 176.4KHz
{F491520, 256*FS}, //7 192 KHz
{F903168, 256*FS}, //8 352.8KHz
{F983040, 256*FS} //9 384 KHz

// Group2:Si570 frequency and *Fs combination for low mid mclk range
{F225792, 512*FS}, //2 44.1 KHz
{F245760, 512*FS}, //3 48 KHz
{F225792, 256*FS}, //4 88.2 KHz
{F245760, 256*FS}, //5 96 KHz
{F451584, 256*FS}, //6 176.4KHz
{F491520, 256*FS}, //7 192 KHz
{F903168, 256*FS}, //8 352.8KHz
{F983040, 256*FS} //9 384 KHz

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Old 10th January 2013, 09:45 PM   #2013
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I had wondered where the clock was on that board, I did not even consider that it would be expected to be supplied by the source bck by default without any other option and mostly from 20cm or more away at the bottom of a stack of headers... that means some sources will supply the dac with pretty huge jitter. not fifo of course.

but on the upside, that means the bck and sck are the same, so wont be effected, thus why it works. similar to using ESS with the oversampling filter switched off, same deal.

its an intriguing design still, but wow... not even an optional onboard clock.

so potentially the si570 will allow this to work if it can be programmed to optionally supply a lower clock with lower samplerates, like supply 512 x fs for 44.1 so the DIX works. Until then you may have to use 22.xx/24.xx clocks if using the spdif out at lower than 88.2/96khz[/QUOTE]




Thank you, Qusp

I understand now.
Your talking about the influence of the ddac in my setup was confusing because it does not play a role here. The thing not even has a clock indeed, but I thought using it with the Fifo and the WavIO (which I already had in use with my III) through the backdoor it should be a golden and simple solution. And I must say, I like it's sound!
Taking into account that I already owned TP BuffIII, and the Ian offered some really nice solutions for combining the two, I did bet on two horses with choosing the higher clocks. I hoped Doede 1794 was a more simple and cheaper setup. (That's why I hooked off from the NDT1 project and gave it to Buzzforb.)
But fine, enough talking the last two days, up to listening to music now en hoping that the 570 will do everything I I have on my little list.
Cheers, Ed

Last edited by ed linssen; 10th January 2013 at 09:51 PM.
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Old 10th January 2013, 10:40 PM   #2014
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Originally Posted by hochopeper View Post
Yeah, Ian has 2 different default groups of frequencies that will suit this application.


Ed, see Ian's post here:
Hi Hocho!

Thank you for the quote. So 570 will be the answer.
I will have to add myself to the list,
Ed
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Old 10th January 2013, 10:56 PM   #2015
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No worries Ed

It was good, it gave me a chance to test out the wiki page and check that the links I put in there were correct. That quote is from the first link in the list.

For more info on the Si570 I have put an index of the important posts from Ian in the Si570 section of this wiki page.

Cheers,
Chris
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Old 11th January 2013, 12:46 AM   #2016
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Quote:
Originally Posted by ed linssen View Post
Hi Hocho!

Thank you for the quote. So 570 will be the answer.
I will have to add myself to the list,
Ed
Did you read the pdf file of DIX9211. If you want to get correct spdif output, you have to feed the DIT chip with 128,256 or 512Fs MCLK. You can not get spdif output if you run MCLK at 1024*Fs (which is with 45.xxx or 49.xxx XO). That is the limitation of the spdif driver, has nothing to do with clock board or fifo.

If you want the spdif output at same time for your current configuration with 45.xxx and 49.xxx, the solution is you have to feed DIX9211 with 1/2 MCLK (can be done by a flip-flop).

Ian
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Old 11th January 2013, 01:33 AM   #2017
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Hey Ian...
Why DIX9211 rather than PCM9211 ??
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Old 11th January 2013, 02:03 AM   #2018
qusp is offline qusp  Australia
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I guess because we didnt need an average quality ADC in our DIX.... yep only 101db DNR at 24bit/96khz worse than average, thats not much more than 16bit numbers.

I havent had a closer look, but I wouldnt be surprised if the ADC complicated the layout due to an extra analogue supply and ground.

yep just checked (couldnt help myself) complete analogue power supply section, analogue inputs and ground.. all of which would complicate the layout for no good reason. its already a mixed bag as far as layout, complicated little sucker, adding analogue on a completely digital board doesnt make any sense. I could maybe understand adding a proper ADC input to one of the 10 (yes 10!!) optical inputs or the backdoor to make a digital preamp input and clock board out of the fifo, but then you need to mess with nice low noise analogue inputs, OTT low noise regulators etc, its a whole new ballgame.

Last edited by qusp; 11th January 2013 at 02:13 AM.
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Old 11th January 2013, 02:09 AM   #2019
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Originally Posted by Adrculda View Post
Hey Ian...
Why DIX9211 rather than PCM9211 ??
DIX9211 is a dedicate digital audio interface,
PCM9211 comes with stereo DAC integrated

Ian
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Old 11th January 2013, 02:14 AM   #2020
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Quote:
Originally Posted by iancanada View Post
DIX9211 is a dedicate digital audio interface,
PCM9211 comes with stereo DAC integrated

Ian
Ti needs to fix their pages...
the DIX shows 92khz not 192 and the pcm shows 209
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