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

[ggking7]

I am joining both of you guys with this opinion. It makes all sense with internal I2S source ( USB to I2S board), but for any transportation longer than few inches benefits are lost. I2S has a clear advantage when conversions to and from S/PDIF are voided and that is where popularity stems from. But, short distance requirement, coupled with need for very particular high quality wiring and coupling, opens up I2S as a wrong choice in many situations. As for the choice of S/PDIF signal and its integrity I would always prefer balanced approach, which kind off makes it AES/EBU.

Isn't the choice of interface inconsequential when using the FIFO?

[StasioPe]

Sorry for off topic. But I did perfect tunning of Buffalo DACIII its tunning very, very, improves sound! This is related to a decrease electrical noise for ESS9018.I assembly on all in and out Trident Buffalo DACIII 18dB/oct Murata 100MHz filter.This reduces internal jitter ESS9018. Enjoy

[qusp]

you know this reduces jitter how?

ggking, no, i2s may actually be worse with fifo, because it can introduce noise on ground.

that being said, AR2 and I were talking of the interface, not fifo. think you might've missed the point of the conversation

[marce]

! Sorry but some of the mods that get shown are horrible, not neat and tidyjust look bodged.

[vzs]

Originally Posted by qusp

...I do like the idea of an isolated datastream to the clock board, to enable cutting the ground connection no matter what your source is. weve mentioned it before

I also like the idea of a separated clock board from fifo but missed where this was mentioned before.

For the I2S signals (MCK, SCK, WS, SD) a small board between fifo and clock board could comprise for e.g. some ISO150 / ISO7220 digital couplers.

Beside MCK and power what other signals are carried on the flexible molex cable? to know how many isolators are needed
What do you think?

L.E.: ISO150 might be an older part as ISO722 or alike are much cheaper

[qusp]

at marce: you said it....particularly when there is murata LC network (SMD) that would have just soldered directly across the inputs… thats if it was something really worth doing. the above is quite a contrast to the 'MODs' of the thread subject. those filters look more like noise aerials (lightning rods) connected directly to the clock power supply and ground to me.....

@ vzs: i've mentioned it a few times, last time only a few pages ago, maybe once in the GB thread too. I was thinking more an island on the PCB rather than adding another connection, but an adapter would work sure. what cable are you talking about? all we realy need to do is float ground somehow between the boards. thats easy enough for the power, just power the clock with a separate battery or transformer winding+floating reg, but the signals are another thing, there will be control signals etc, I think the only way to do this successfully would be with Ian onboard

[glt]

Originally Posted by StasioPe

Sorry for off topic. But I did perfect tunning of Buffalo DACIII its tunning very, very, improves sound! This is related to a decrease electrical noise for ESS9018.I assembly on all in and out Trident Buffalo DACIII 18dB/oct Murata 100MHz filter.This reduces internal jitter ESS9018. Enjoy

I thought the board already has ferrites on all the supply lines. This has been standard feature in all the TPA boards since way back...

[glt]

Originally Posted by vzs

I also like the idea of a separated clock board from fifo but missed where this was mentioned before.

For the I2S signals (MCK, SCK, WS, SD) a small board between fifo and clock board could comprise for e.g. some ISO150 / ISO7220 digital couplers.

Beside MCK and power what other signals are carried on the flexible molex cable? to know how many isolators are needed
What do you think?

L.E.: ISO150 might be an older part as ISO722 or alike are much cheaper

I think the NVE IL715 is a good part. It is used in other implementations to isolate I2S. I did an experiment here: Experiments with NVE IL715 Isolator H i F i D U I N O

[vzs]

Originally Posted by qusp

... I was thinking more an island on the PCB rather than adding another connection, but an adapter would work sure. what cable are you talking about? all we realy need to do is float ground somehow between the boards. thats easy enough for the power, just power the clock with a separate battery or transformer winding+floating reg, but the signals are another thing, there will be control signals etc, I think the only way to do this successfully would be with Ian onboard

Agree that would be a nice adding for a future rev. clock board.
I'm talking about the FFC cable, right to the 7pin PH2 cable. Afaik this carries the MCK from clock board to fifo and the power from fifo to clock, and probably other signals as well... Ian could tell.

This small adapter could fit/float between the FIFO and Clock-board and would have all connectors needed 2x 7pin PH2, 2x FFC conn and 2x PH2 con for power (right-angled smd version to be neat). I'm working on my multibit DAC board now and with one dirty hand I will do this as well - just to decide which digital coupler to use.

[NicMac]

Originally Posted by iancanada

Any suggestions or comments?

I love it!
But as I will have several floating supplies in my DAC I would much prefer a layout controlling 4 floating supply/battery rails.
Then I would only need 3 of these boards in my DAC