Asynchronous I2S FIFO project, an ultimate weapon to fight the jitter

XO supply

II have designed a regulated power supply suitable for XO clock (XO on board).
I posted the schematic at http://www.diyaudio.com/forums/power-supplies/212476-well-regulated-power-supply-10.html#post3074701
Now I'm going to order parts to build all prototype: TWRPS for FIFO buffer and TWRPS-XO for XO clock.

I would like to use a Crystek oscillator, but I can't find a suitable device for 44.1 kHz (11.2896 MHz considering fixed 256* master clock on the FIFO buffer). So I'm thinking to use a 45.1584 MHz Crystek oscillator and then divide by 4 with fast flip-flop.

What do you think about?

Andrea
 
FW V3.80 will include the I2S backdoor

As all of you agree on opening the I2S input backdoor, I’m gonna include it in the GB II. The new firmware version will be V3.80. (V3.30 was for GB I, V3.50 includes 512Fs defult XO support, V3.6 has optional left justified output,V3.7 comes with optional left justified, 16/24bit right justified input supporting, V3.75 fixed a bug on switching between 44.1KHz and 48KHz with dual clock board running at dual speed mode).

I like what you got: “opening the I2S "backdoor" is all benefit and no downs”. Yes, for those who need it, it’s good news, for those who don’t, nothing changed.

Actually, the new fpga firmware just need sending a new group of instructions to DIX9211 opening the I2S input. It does not change any on the main FIFO logic. But I will still do a full set of tastings, just to make sure all functions are perfect.

Again, I’ll provide free upgrade service for all GB user within 1 year from purchases. User pay the round shipping. With a bubbled envelope, it won’t cost you much.

Thanks for DHL, giving me more 10 days upgrading the new firmware :cheeky:

Hi Ian,


2) I have rather another "issue" related to this source selection.
I'm planning to build the S/PDIF and FIFO with DAC into a Preamp, which can switch between analog line level sources and the built in DAC.
If i want to connect two digital sources to the S/PDIF input board (eg OPT and COX), the toggling functionality isn't really great and would not be compatible with the preamps input selection. For me, direct input selection would be better....
See, I'm kinda like your Boss ;-)

3) Regarding the connector, well one has to try...

Ciao, and thanks


Unforturnately, that backdoor wasn't there, my boss :).
 
[...]Unforturnately, that backdoor wasn't there, my boss :).
No no, didn't want to play your boss ;-)

In that case, toggling has to be done.
To properly isolate it from preamp logic, i think about using an optical switch.
Can you tell me whether around 30 Ohms ON resistance is low enough to toggle?

And 2Hz toggling frequency with synchronous input indicator LED querying, would that be OK, or has it to be considerably slower?
Ie toggling pulse (opto relay switch closed) 250ms, open, check LED during around 150ms, and continue toggling after another 100ms if input is not the desired one.

Thank you!
 
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Hey Ian,

Another clarity question......if I want to use a CD spinner and a computer source into the FIFO, with a TDA1541 dac or a B III, what is recommended regarding clock frequency for the dual xo board?
Just getting a little confused with all the differing values being thrown about!

Thanks Muchly!

Drew.
 
Hi qusp,

are you using a miserable 44.1 khz source!?!?!?!?!?!?!?!?!?
I think we are a jurassic example in digital audio, whereas now almost all people use PC as a source.
Which DAC chip are you using?

Andrea

haha no, but I bought a crystek that was in my cart from some time ago by mistake, I was just confirming it works and is what i'm using. my source is multichannel USB-i2s from an SSD equipped i5 mac mini and capable of 8 x 32/176.xx + 192 or 4 x 32/384 + 352; I would say its you who is in the dark ages =)

i'm running a quad mono ES9012 based AKD12P ackodac (2 actually)

most of my content is still 44.1 other than stuff i'm making myself in logic as i'm not all that keen on buying upsampled music, fine if its natively hires. since even the 45mHz clock wont cut it I decided to just leave it for now because

A. I have a beta release fifo that needs to be sent back for an update before its capable of full speed
B. I want a clock thats even better than the crystek
C. I'm waiting for the multispeed DSPLL board
D. I need multichannel for the main rig so fifo is fir now designated headphone duties. I dont have any decent speakers with passive XO
 
3, Although I left the I2S backdoor, but I didn't place a real connecter footprint on the PCB, only 4 SMT resistor’s footprints. So I have to say the backdoor is not that perfect. You have to tap a 4P PH2.0mm connecter by yourself as the picture below. Does it work for you if you really need this I2S input backdoor?

Hi Ian,

This I2S backdoor seems really interesting for me. But to be sure to add the spdif board to my wish list, I need a bit more information on how to tap this I2S input. I've seen two smd resistors which form a square shape with four pads. There is also a led near this group (like the three other groups for ttl, opt...). So I need to put a square shape connector for I2S input ?
Of course some ufl connectors would have been perfect/marvelous...
Can you give us some more specifics about the best way to tap this input in order to make the right choice ?
Thank you for your work !
 
I've seen the photos and in my message I explain what I saw, I need confirmation. I din't find the how.
So the only way I see is to solder coaxial and I don't see where to tap a ground.
That is why, since I am missing something, I post a question (after reading the posts).
 
PET-240

In your case, I recommend 45.xxx and 49.xxx. The reason is there: higher MCLK is better for ESS DAC running at SYNC mode; while, 1541 is a NOS, doesn't care about the MCLK.
Nice weekend,
Ian

Thanks Ian,

Might I ask best part supplier for crystek CCD957(I think?) just feeding youngster a bottle and the iPhone is a pita to find stuff on. Though I fear the wrath of qusp for asking.....

Thanks again!
 
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haha

actually i'm making an order at mouser tonight or tomorrow if you want me to add it
 

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Hi Ian,

This I2S backdoor seems really interesting for me. But to be sure to add the spdif board to my wish list, I need a bit more information on how to tap this I2S input. I've seen two smd resistors which form a square shape with four pads. There is also a led near this group (like the three other groups for ttl, opt...). So I need to put a square shape connector for I2S input ?
Of course some ufl connectors would have been perfect/marvelous...
Can you give us some more specifics about the best way to tap this input in order to make the right choice ?
Thank you for your work !

Hi lwif

It's not difficult for a DIYer to assemble an connector for the additional I2S port except you can not remove the 4 SMT resistors.

I'm writing the steps now, will be posted together with GB II details. Of course U.FL connecotors are the better solution for signals,so I'm highly recommended them for FIFO output, but it's not a big deal as the input of FIFO .

Good luck.

Ian