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

[TirNaOg]

May be Send a P.M to Ian.

Ian seems to be offline lately...

 

[TirNaOg]

Something happened to my McFIFO/McDualXO setup today. After changing album/playlist, it went silent. All LEDs are correct, but somhow there is no voltage on McDualXO LRCK and SD output. Did some measurements:

McDualXO u.fl output (going to Curryman DAC ES9023).

MCLK - 1,08V

SCK - 1,51V

LR & SD - 0



on McFIFO J8 input connector I get:

SCK - 1,55V

LRCK - 1,61V

SD - 1,20V

McDualXO LDO in and out are normal (5,11V and 3,26v)

Clock's LED lit and changes over to other one during bitrate change.



Please help me, what should be the next step to check.

What are you using as a source? Hardware and software ..?

 

[nielsek]

For software I use Volumio. Hardware options are:
Rpi3 with Ian's I2S adapter
Odroid C1+ with Ian's Isolator
Software versions of Volumio are different (but latest) for both.

The setup was working correctly, with no problems at all. Strange that it just went silent on chaning the playlist. Music source change was from 48KHz 32bit to 44,1KHz 16bit. No errors in software, keeps playing, just no audio.

 

[nielsek]

Check the outputs of the mcfifo board( the unpopulated connector). Maybe the ribbon cable went bad somehow...

I checked the outputs of McFIFO (J15) and the story is the same. There is voltage for SCK, but none for LRCK and SD.
At the same time there is voltage on the McFIFO input (J8). All three are OK: SCK, LRCK, SD.
Does this mean that the fault is on McFIFO board?

 

[TirNaOg]

Don’t suppose you have another SBC to switch over and try?

 

[nielsek]

Don’t suppose you have another SBC to switch over and try?

Yes I do and checked both Raspberry3 and Odroid. The outcome is the same.

 

[wealas]

Well, you can try and check the isolator chip, if there is voltage on the input but not the output of the chip then that's probably gone bad.

 

[TirNaOg]

Ah ...did you switch the ribbon cable, sorry if you have been asked all this already. Also any voltage regs such as LT3045s before your DC inputs? Just discovered a fault in one of mine giving intermittent current.

 

[TirNaOg]

I Does this mean that the fault is on McFIFO board?

Beginning to look like that....

 

[nielsek]

Well, you can try and check the isolator chip, if there is voltage on the input but not the output of the chip then that's probably gone bad.

Thanks for the hint. Which pins should I check?

 

[nielsek]

Ah ...did you switch the ribbon cable, sorry if you have been asked all this already. Also any voltage regs such as LT3045s before your DC inputs? Just discovered a fault in one of mine giving intermittent current.

Yes I did switch the ribbon cable and have tried different DC inputs.

 

[wealas]

Thanks for the hint. Which pins should I check?

No clue, maybe you can trace the board from the output connector.

 

[hellokitty123]

This is going to be a really stupid question but where do I connect this fifo buffer into an existing DAC?

 

[gvl]

This is going to be a really stupid question but where do I connect this fifo buffer into an existing DAC?

Surgery required.

 

[hellokitty123]

Where exactly? My dac anatomy knowledge is not as good as I want it to be.

 

[gvl]

Where exactly? My dac anatomy knowledge is not as good as I want it to be.

Conceptually you want to add it just before the DAC chip, however depending on a DAC it may not be a simple bolt-on mod.

 

[hellokitty123]

Can you help me figure out where I would need to connect it on my Audio-GD NFB-1 module?



sorry I know those aren't the best pictures, my phone is crappy.

 

[gvl]

I'm afraid it's not that simple. You generally need to have access to the schematics or reverse engineer the design to know where to tap in, if that's even possible.

 

[hellokitty123]

That sucks, they refused to send me schematics last time I asked.
Reverse engineering shouldn't be too terrible difficult. What is it that I am looking for in the design?

 

[gvl]

That sucks, they refused to send me schematics last time I asked.
Reverse engineering shouldn't be too terrible difficult. What is it that I am looking for in the design?

Easier said than done but this board needs to be inserted on the I2S serial bus, considering the DAC chip operates in I2S mode anyway. I don't have a real hands on experience with it, so this is just from a theoretical perspective.