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

[Fridrik]

Ian, if a Over or Under buffer condition is detected will the LED stay on until a reset?

[andrea_mori]

Originally Posted by qusp

due to fifo memory buffer it is asyncronous with the source, it has to be...

not really, the FIFO buffer operates anyway asynchronously, since it stores data and releases them after a certain delay, so starting from the FIFO buffer we have a new sinchronized system, isolated from the source but linked by the MCLK.
If the same MCLK is used to feed directly the DAC BCK... BINGO
The FIFO buffer isolates the source jitter and the DAC chip receives a very clean BCK, that's the way to minimize the jitter in digital to analog conversion.

[iancanada]

Originally Posted by Fridrik

Ian, if a Over or Under buffer condition is detected will the LED stay on until a reset?

What do you think it gonna be happened?

Ian

[ed linssen]

Hi,

After using the Fifi/Spdif combo for several hundreds of hours now, feeding from Wave I/O, Sqeezebox touch, and a dreambox sattuner, going into the DDDAC1794 Nosdac, or the BIII, I never suffered from any bufferproblem whatsoever!
The message I can bring is of a vast and unexpected overall gain in playback Quality, yes capital Q! You guys do the talking while I luckily fancy an overwhelming music experience in the meantime. I never expected this gain was possible using better clocks (Crystek 957/44+49) in this way......
Ed

[1audio]

I have encountered a Computer source that was more like .5% slow and several DAC's had trouble locking to it. Its not common and the AES standard is pretty tight, something like .5 ppm but not many consumer sources maintain to this tolerance.

[Fridrik]

Originally Posted by iancanada

What do you think it gonna be happened?

Ian

If it was my code I would design them as warning flags...

LED Over= one or many overrun
LED Under= one or many underrun

because it's hard to look and focus on 2 LED for more than 15 minutes I would require a soft or hard reset to remove the warning flags. But hey it's not my project

[iancanada]

Originally Posted by Fridrik

If it was my code I would design them as warning flags...

LED Over= one or many overrun
LED Under= one or many underrun

because it's hard to look and focus on 2 LED for more than 15 minutes I would require a soft or hard reset to remove the warning flags. But hey it's not my project

Fridrik,

Do you think fifo really need to be reset when empty or full?

Actually fifo designed with depth indicator with which you can clearly know what the clock tolerances and quality it is of you digital audio sources. But I didn't public it, because I believe focus on the music is more important than keep monitoring and predict the moment going full or empty. Though the indicator is much better than 2 LED.

Regards,

Ian

[Fridrik]

Hi! just to give you folks a brief FIFO review:

Hardware :
FIFO in SPDIF buffer mode
CCHD-957 oscillators with Dual Clock Board
DAC : Anedio D1 ( with integrated headphones amplifier)
Headphones : Beyer DT880 600 ohms ( modded cable)
Sources: Various:
Players: Jriver 18 and Foobar
BNC cable : 6 inch 75 ohms
Fifo opticaly linked to the source: Various cables used ( I'm using a 25 feets toslink cable now!!!) As expected the optical cable is irrelevant to resulting sound performance


Fifo powered by 4 Energizer 2300mah NIMH Batt, also tried 2 LiPeFO4 @6.4Volt sound was on par or maybe less fluide (not sure on this).

With 44.1khz material the sound is better ( definition increased) on the FIFO that with the USB interface of my DAC.

I've tried 3 transfo:

Newava S22083 (Don't like...)
Newava S22160 (softer but the sound is less precise than with the Pulse transformer)
DA101C (sound cheap)

The stock Pulse 65612 give the best image and 3D sensation on my setup. Voices are more recessed (ei: toward back).

[Fridrik]

Originally Posted by iancanada

Fridrik,

Do you think fifo really need to be reset when empty or full?

Actually fifo designed with depth indicator with which you can clearly know what the clock tolerances and quality it is of you digital audio sources. But I didn't public it, because I believe focus on the music is more important than keep monitoring and predict the moment going full or empty. Though the indicator is much better than 2 LED.

Regards,

Ian

Reset : was talking of resetting the EMPTY or FULL LED on the board not the fifo itself.

My point was only that since we don't acces to your debug port the LEDs are the only info the enduser have. Unless you send morse code thru them of course

[iancanada]

Originally Posted by Fridrik

Hi! just to give you folks a brief FIFO review:

Hardware :
FIFO in SPDIF buffer mode
DAC : Anedio D1 ( with integrated headphones amplifier)
Headphones : Beyer DT880 600 ohms ( modded cable)
Sources: Various:
Players: Jriver 18 and Foobar
BNC cable : 6 inch 75 ohms
Fifo opticaly linked to the source: Various cables used ( I'm using a 25 feets toslink cable now!!!) As expected the optical cable is irrelevant to resulting sound performance


Fifo powered by 4 Energizer 2300mah NIMH Batt, also tried 2 LiPeFO4 @6.4Volt sound was on par or maybe less fluide (not sure on this).

With 44.1khz material the sound is better ( definition increased) on the FIFO that with the USB interface of my DAC.

I've tried 3 transfo:

Newava S22083 (Don't like...)
Newava S22160 (softer but the sound is less precise than with the Pulse transformer)
DA101C (sound cheap)

The stock Pulse 65612 give the best image and 3D sensation on my setup. Voices are more recessed (ei: toward back).

Good to know that Fridrik, nice system.

What clocks are you using right now?

Actually I did S/PDIF FIFO (similar to your configuration) evaluation on my SONY-PCM7040 DAT (working as DAC), Which was retired from a local studio because of mechanical problem. With FIFO, sound quality got big progressed, very impressive. Even compare with it quite decent internal pll clock.

Different digital transformer sounds different, but no as much as changing clocks. You can try both, I'm interested in your result.

Have fun!

Ian

BTW, I'm glad you like my pulse . Actually it not that bad, it was selected as standard setup from a couple of candidates.