Unfiltered, directly from standard I2S source:
64-Bit word (2x32 Bit == 1 LRCK cycle (1/fs) is constructed from 64 BCK cycles (64fs)) ... you can modify the input logic also for "not standard" 48-Bit word (like CP2615 outputs), but better use the standard source.
Cheapest USB-I2S device is based on CM108, available from aliexpress (you need solder wires on I2S data pins, not simple). Better option is PCM2706, available on aliexpress (PCM2706 USB to I2S).
Advanced USB-I2S devices are based on XMOS, amanero, .... Or another devices are available like bluetooth-i2s, sdcard-i2s, etc.
Thanks for the info Miro, I'll remove C31/36. Should I also leave R10/11 uninstalled or install them ?rev 1.3 has no RC filter on the output (that is why the C37/C38 are missing).
C27 and C33 (100u - 330u) are for opamps power supply, you need these on the PCB !!!
C31 and C36 (47p) are for the I/V, better to let it empty because some CFA opamps hate this capacitor.
... so for you: Remove the C31/36 from the PCB ... but the C27/C33 must stay on the PCB
Potentially its the best source - but as ever, implementation is king. Its best because there's no clock on an SDcard so you have complete flexibility over clocking - you could put the clock right next to the DAC and then feed it back to the SDplayer if you want to gild the lily. And it has the potential for being the lowest power asynchronous source which means lower RFI and also the possibility to use battery for extreme isolation.
SD Card player, properly done, has one data processor running on the same clock as (at) the DAC, which is where the clock should be.
It collects data from a solid-state memory, rather than from another computer runnning at a completely different frequency, via some interface like USB.
So no need for things like FIFO to solve all those issues.
And it does nothing else other than output WAV data in I2S.
I don't know of anything simpler.
Mine has only a single dsPIC, a 2x16 LCD, some keys, and a clock.
https://www.diyaudio.com/community/threads/ultimate-source.90725/post-1068005
I do not need anything else other than 44.1/16.
If you need fancy formats, go and have a look at the SDTrans384.
https://www.diyaudio.com/community/threads/microsd-memory-card-transport-project.142562/post-2788130
Cheers,
Patrick
It collects data from a solid-state memory, rather than from another computer runnning at a completely different frequency, via some interface like USB.
So no need for things like FIFO to solve all those issues.
And it does nothing else other than output WAV data in I2S.
I don't know of anything simpler.
Mine has only a single dsPIC, a 2x16 LCD, some keys, and a clock.
https://www.diyaudio.com/community/threads/ultimate-source.90725/post-1068005
I do not need anything else other than 44.1/16.
If you need fancy formats, go and have a look at the SDTrans384.
https://www.diyaudio.com/community/threads/microsd-memory-card-transport-project.142562/post-2788130
Cheers,
Patrick
Thanks guys,
Yep, I believe I can understand that and that is why I droped a "lot of cash" around Iancanada masterclocks and fifos side to side to async Xmos Usb.
But whatever the clock domain is isolated I didn t found the differences nigth and day and power supplies before the fifos can still be heard. And some claims those SD card is better than diy fifos ?! So indeed the lack of standalone ARM like with its own clock should matter.
Does that mean actual cd players work the same than SD card ?
Ok off topic here, sorry for that...
Yep, I believe I can understand that and that is why I droped a "lot of cash" around Iancanada masterclocks and fifos side to side to async Xmos Usb.
But whatever the clock domain is isolated I didn t found the differences nigth and day and power supplies before the fifos can still be heard. And some claims those SD card is better than diy fifos ?! So indeed the lack of standalone ARM like with its own clock should matter.
Does that mean actual cd players work the same than SD card ?
Ok off topic here, sorry for that...
"So anything at the FIFO side does not count, right?"
Right, with regards to the DAC.
"The data will come by itself without a clock anywhere upstream the DAC ?"
Partially correct; there is no MCLK input to the FIFO, there are only the I2S-requisite SLCK, LRCK and SD inputs... and their timing matters only in relation to the I2S data structure, the determinative timing for the DAC comes from the synchronous MCLK - same as Koon's, minus the uP/LCD... but this is all old hat and probably just apples and oranges; I agree that there is an economy in using an ASIC to generate the I2S stream but in this case I see a concrete benefit to a circuit which is "less" as it regards the D/A conversion circuit even if it is "more" overall.
I thought the topic was relevant because Miro's boards are capable of a wide range of input possibilities given the "I2S-NOS-R2R" hardware, but since the focus is "Unfiltered, directly from standard I2S source" the SD-Card player looks like a great solution.
Right, with regards to the DAC.
"The data will come by itself without a clock anywhere upstream the DAC ?"
Partially correct; there is no MCLK input to the FIFO, there are only the I2S-requisite SLCK, LRCK and SD inputs... and their timing matters only in relation to the I2S data structure, the determinative timing for the DAC comes from the synchronous MCLK - same as Koon's, minus the uP/LCD... but this is all old hat and probably just apples and oranges; I agree that there is an economy in using an ASIC to generate the I2S stream but in this case I see a concrete benefit to a circuit which is "less" as it regards the D/A conversion circuit even if it is "more" overall.
I thought the topic was relevant because Miro's boards are capable of a wide range of input possibilities given the "I2S-NOS-R2R" hardware, but since the focus is "Unfiltered, directly from standard I2S source" the SD-Card player looks like a great solution.
Here's a boxed up version : https://www.aliexpress.com/item/225...216573777609395918e0438!12000027100082331!sea
As I have explained before in this thread with USB audio class2 asynchronous (or adaptive) mode the source (i.e. computer) clock domain is totally isolated from the dac. If the USBI2S bridge is properly implemented there is no need for FIFO. I2S timings are generated from the same MCK that DAC uses.
On SD card players....
A friend has the one linked below (warning you need their matching 10mHz clock, or provide your own). As with all of these, the interface is a bit funky, but usually works well. The sound quality from this one is very good indeed.
https://www.aliexpress.com/item/100...916573961592842641e0756!12000025805593687!sea
The thing to search for is "SD digital turntable".
I wouldn't buy one of the ones in a case - the power supplies are usually inferior and ultimately you are better to supply your own power.
this one is the new version of the old "yellow" SD card player which myself and several friends have used. I don't know anything about it.
https://www.aliexpress.com/item/100...b16573962813973051eb70d!12000020404988269!sea
A friend has the one linked below (warning you need their matching 10mHz clock, or provide your own). As with all of these, the interface is a bit funky, but usually works well. The sound quality from this one is very good indeed.
https://www.aliexpress.com/item/100...916573961592842641e0756!12000025805593687!sea
The thing to search for is "SD digital turntable".
I wouldn't buy one of the ones in a case - the power supplies are usually inferior and ultimately you are better to supply your own power.
this one is the new version of the old "yellow" SD card player which myself and several friends have used. I don't know anything about it.
https://www.aliexpress.com/item/100...b16573962813973051eb70d!12000020404988269!sea