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

[iancanada]

Originally Posted by 1audio

Attached is a zip of he expresspcb file I used to test the design concepts. It incorporates an input regulator to handle short circuit protection etc. the regulator circuit supporting two dip oscillators and the transformer coupled output to prevent the system grounds from undoing all the work.

I won't have a chance to create a schematic for it but by careful inspection that should not be necessary. Its offered as a starting point, not as an end in itself.

The basic regulator was first published by someone else (I have lost the reference) and my addition is the TL431 servo.

Don't trust this, study and verify (I may well have made mistakes) and build on it.

Thanks Demian, get a new job

Ian

[iancanada]

Just a kindly reminder that the Ian asynchronous I2S and S/PDIF FIFO KIT group buy is running. Please go the group buy area for details:

http://www.diyaudio.com/forums/group-buys/207438-ian-asynchronous-i2s-s-pdif-fifo-kit-group-buy.html

I will continue this thread for technical issues, new progress may include:

1.Trying suitable low noise power supply for oscillators and FIFO project.

2.New Si570 based clock board.

3.I2S and S/PDIF FIFO applications.

4.Possible battery based power supply with charging management.

5.Technical supplort

…….

Have a nice week.

Ian

[qusp]

looking out for that Si570

[zinsula]

Hi Ian, I'm still reluctant to buy the otherwise very impressive FIFO kit as I'm unsure about how easy it is to leave out the LDO and to power the clock(s) with a very low noise regulator.
- Do you supply a schematic with the kit?
- Does the dual clock board have one LDO per clock?

I see in your previous post that you are investigating a low noise power supply. Would that mean having it on (newly designed) boards or add on?

[zinsula]

Does someone enlighten me about the performance of the Si570 down to 10Hz offset and at clock rates we need in this project (i.e. around 25 MHz)?

I can find phase noise spec for clock frequencies above 100MHz and down to an offset of 100Hz.
However those values are significantly less good than eg. the Crystek CCHD-957 Model or a Tentlabs clock at 100Hz offset and lower (i.e. suitable for this project) clock frequencies.

[iancanada]

Originally Posted by zinsula

Hi Ian, I'm still reluctant to buy the otherwise very impressive FIFO kit as I'm unsure about how easy it is to leave out the LDO and to power the clock(s) with a very low noise regulator.
- Do you supply a schematic with the kit?
- Does the dual clock board have one LDO per clock?

I see in your previous post that you are investigating a low noise power supply. Would that mean having it on (newly designed) boards or add on?

Hi zinsula,

The easiest way to evaluate and connect an external low noise power supply is using the IC socket as an adapter, just as what I did before to evaluate the battery power supply.
http://www.diyaudio.com/forums/digital-line-level/192465-asynchronous-i2s-fifo-project-ultimate-weapon-fight-jitter-24.html
After you making sure the external power supply is good enough, you can connect them to the dual XO board by just removing the filters or the LDOs. It’s not a difficult job, especially for you J.

For a very skilled DIYer like you, what I recommended is configuring a FIFO with external clock, (please see the user guide for detailed) which is not suggested for the normal users. So that, you can design your own power supply and clock and do not have to be limited by my board. Although I couldn’t guarantee my clock board is the best, but it truly based on long time testing and optimizing. You could keep it as a reference, by comparing with it, you will know by how much your improvement is achieving.

Once I have time, I’ll design a prototype PCB for Demian’s reg. I could send a couple of that PCB to you for free to make some evaluation if you like.

Ian

[zinsula]

Thank you Ian. This could well be an option, but if using an external clock, the "comfortable" automatic clock switching is lost.
Primarily, I'd plan to connect the FIFO to a multi format DVD player, which puts out both the 44.1 and the 48kHz - Family of sample rates.
But I'll take one...

[qusp]

it will be interesting to put Demians regulator up against Jung's AD797 based circuit from the old Electronic Design article from analogue devices 'how to build an ulra-low noise reference' which has noise estimated at 1.25nV/(2^root)Hz (not sure how to make the square root symbol with normal text)

[nattonrice]

Most people will write sqrt(*).

[GOR3]

Egad! Intra-Oz flaming.