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

[iancanada]

My setup:
Waveio latest firmware, Fifo+Isolator+dual XO board with 45.x and 49.x crystek clocks. LiFePO4 2x for fifo, 2x LiFePO4 with belleson 5v reg for the clock board. My DAC ist the 1794NOS from Doede, 4 decks. It is a 1794 dual mono NOS DAC, fed with i2s from a special motherboard.

DDDAC 1794 NOS DAC - Non Oversampling DAC with PCM1794 - no digital filter - modular design DIY DAC for high resolution audio 192/24 192kHz 24bit

My problem:
I´m only able to play something upsampled to 352khz but the music is completely distorted and with a lot of noise (pink noise). The jumpers on the clock board are set: tp4+5 and tp7+8. On the input side (left) is the 45.x clock, on the right side is the 49.x clock.

without the Fifo etc. everything works fine.. Have no idea where to start looking for the failure...

apoo

Hi apoo,

I got exactly the same issue when I test my PCM1794 and TDA1541A running from my PCM board at 384KHz.

I solved the problem by replacing the USB interface with other one.

Please refer the follow link for details:

http://www.diyaudio.com/forums/digi...rsal-i2s-pcm-driver-board-53.html#post3621653

Please let me know for any progress.

Regards,

Ian

 

[iancanada]

Ian,

that is a great news. Hard to believe it is still possible to improve on the set up you have. I am just wondering what is the bad news?
Regardless, a few questions. I see you have some kind of isolator after Amanero. What kind of isolator is that one, since that is a different one from the one used before the clock? Also I see you use Legato, just like I did until recently.

I have been experimenting with different I/Vs and output devices, and I went back on experimenting with transformers. After few, I settled for now on Lundahl LL1674 but used in reverse as 2:1, in order to provide a proper loading to the DAC. I hope you will try the same or similar, in my case is day / night difference to Legato. Highs completely opened, the depth and soundstage just exploded. There is nothing else, just Lundahl between DAC and my 2A3 tube amp, and when I tried for a first time, I just could not believe the difference. Imagine, I am not new to transformers in the output from DAC, but I was just astonished with the difference. Once you hear it you would never go back. It is not necessary to use the one I used, but high impedance on primary is what is needed.

Hi Vladimir,

I'm very interested in your transformer I/V stage. I also had some experience years ago. But I have to sleep for now, will get back to you tomorrow.

Have a good night.

Ian

 

[AR2]

But I have to sleep for now
Ian

He, he you cannot sleep if you want to race.

I believe I reached the final decision on my I/V stage (somehow I know I might regret this statement, ha) It will be actually my old output I used and built for my modified Behringer. After several experiments and listening I concluded the optimum to be: DAC -> balanced jFet buffer -> Lundahl LL1674 connected as 1:2. That sounds so good, it is hard to explain. With this, buffer is sonically invisible - no caps in the way of signal, and Lundahl connected that gives minimal gain, but just right amount to feed any of my amps. In the picture attached you could see how that looks like, although this was 6 channel setup I made for Behringer, that is now cut in 2 channels each. I never heard this DAC to sound as good. Instead of explaining how it sounds, you really need to hear it.

I have offer for you. In the middle of December I will go to Europe, and I will be out for about month. If you want I could send you my test set up with two channels of buffer and two Lundahls. Just, enjoy it and send it back before I return. That way you will hear for yourself... Not that I try to derail you while in the race...

 

[deanoUK]

Hi AR2, is there a thread regarding the balanced buffer you are using ?

 

[TheShaman]

Apoo, regarding L11, a quick search in this thread will return many references.
E.g. see Ian's post #2324:

For spdif board, yes, you need remove L1 if you run it from independent power supply.

But for dual xo clock board, you have to keep L11 if work with isolator board.

Ian

When it comes to using high freq clocks (i.e. 45/49MHz or higher), make sure you are aware of the complications.
E.g. quoting Ian's post #2016:

Did you read the pdf file of DIX9211. If you want to get correct spdif output, you have to feed the DIT chip with 128,256 or 512Fs MCLK. You can not get spdif output if you run MCLK at 1024*Fs (which is with 45.xxx or 49.xxx XO). That is the limitation of the spdif driver, has nothing to do with clock board or fifo.

If you want the spdif output at same time for your current configuration with 45.xxx and 49.xxx, the solution is you have to feed DIX9211 with 1/2 MCLK (can be done by a flip-flop).

Ian

Unless you really need the higher frequencies (e.g. Sabre DAC), the 22/24MHz combo is a safer choice. Same goes if you intend to use the SPDIF board's outputs.

 

[AR2]

Hi AR2, is there a thread regarding the balanced buffer you are using ?

No, I never started a thread. It was designed by ZenMod for my need based on Nelson Pass B1, but this was balanced version without caps. Cviller made circuit board design, and I did manufacturing in China. I will need to make new boards and will make some modifications to make it more useful, such as option with or without transformer, maybe more options for various Lundahl transformers and such. I will see. When I am ready I will make post for group buy, because many people asked me about it. I definitely will need to make more of it for my use.

 

[hochopeper]

ES901x IV stages ....

Having heard qusp's FIFO+AKD12+NTD1 I'd definitely encourage Ian to build his (I'm pretty sure he got one in the last GB). I think Owen (opc) mentioned he's now working on a new revision of that, based on the little details he leaked out. The teaser for you AR2 is that I suspect the new version might be more easily implemented as multichannel (compared to the 40W monster of the original) ... remains to be seen though and in a race if you're trying to plan for a component that doesn't exist, that's a risk

 

[AR2]

ES901x IV stages ....

Having heard qusp's FIFO+AKD12+NTD1 I'd definitely encourage Ian to build his (I'm pretty sure he got one in the last GB). I think Owen (opc) mentioned he's now working on a new revision of that, based on the little details he leaked out. The teaser for you AR2 is that I suspect the new version might be more easily implemented as multichannel (compared to the 40W monster of the original) ... remains to be seen though and in a race if you're trying to plan for a component that doesn't exist, that's a risk

Hochopeper, thanks for the info. Also, I do have a new I/V that seems to be the ticket, I just have to finish it. It is design by ZenMod and few other extraordinary guys for Serbian DIYAudio for a local ESS project. By concept and features it seems to be something special. I am still working on it, and when I am done I will report. Cannot talk much about it now.

It seems like we need I/V shootout

 

[TheShaman]

It's a long shot, but do we happen to have a Front Panel Express template of the SPDIF board? A DXF file would do as well.

 

[iancanada]

Ian,

that is a great news. Hard to believe it is still possible to improve on the set up you have. I am just wondering what is the bad news?
Regardless, a few questions. I see you have some kind of isolator after Amanero. What kind of isolator is that one, since that is a different one from the one used before the clock? Also I see you use Legato, just like I did until recently.

I have been experimenting with different I/Vs and output devices, and I went back on experimenting with transformers. After few, I settled for now on Lundahl LL1674 but used in reverse as 2:1, in order to provide a proper loading to the DAC. I hope you will try the same or similar, in my case is day / night difference to Legato. Highs completely opened, the depth and soundstage just exploded. There is nothing else, just Lundahl between DAC and my 2A3 tube amp, and when I tried for a first time, I just could not believe the difference. Imagine, I am not new to transformers in the output from DAC, but I was just astonished with the difference. Once you hear it you would never go back. It is not necessary to use the one I used, but high impedance on primary is what is needed.

Hi Vladimir,

The small board was a universal I2S/DSD isolator I designed a couple of months ago. Which was here: http://www.diyaudio.com/forums/digi...mate-weapon-fight-jitter-213.html#post3329364
It works perfectly with Amanero USB as well as other I2S/DSD sources. Acko has another good solution for GB, so I didn't launch this board. But I still have prototype PCBs, If you need, I'd be very glad to send some to you to make use of them.

I'm very interested in your transformer I/V. I did some testing on transformer I/V years ago, if I my memory is not wrong, it was UTC 1:1 transformer. It was good, some sweet spot at high range, but not perfect. Transformer is a native LPF and has better audible performance than capacitors. But it's also day and night difference between transformers. Just like a black magic.

Glad to know you got perfect experiencing on transformer I/V stage. I know Lundahl transformers are very good, especially for tube amplifiers, but I'v never try them. They are expensive as well . I believe your buffer + LL1674 is a much better solution than using transformer only.

He, he you cannot sleep if you want to race.

I believe I reached the final decision on my I/V stage (somehow I know I might regret this statement, ha) It will be actually my old output I used and built for my modified Behringer. After several experiments and listening I concluded the optimum to be: DAC -> balanced jFet buffer -> Lundahl LL1674 connected as 1:2. That sounds so good, it is hard to explain. With this, buffer is sonically invisible - no caps in the way of signal, and Lundahl connected that gives minimal gain, but just right amount to feed any of my amps. In the picture attached you could see how that looks like, although this was 6 channel setup I made for Behringer, that is now cut in 2 channels each. I never heard this DAC to sound as good. Instead of explaining how it sounds, you really need to hear it.

I have offer for you. In the middle of December I will go to Europe, and I will be out for about month. If you want I could send you my test set up with two channels of buffer and two Lundahls. Just, enjoy it and send it back before I return. That way you will hear for yourself... Not that I try to derail you while in the race...

Good to know your are very happy with this I/V stage. Your offer sounds very nice, I couldn't wait to listen to them . Legato was good, but I know there is still space to improve IV stage. I bought an OPC NTD1 stage KIY, but I still have no time to build it . Thanks for your finished board . Wish I have good time with it, and then will be returned to you just before you get back. My shipping address will be follow up.

Race is still going on

Have a good night.

Ian

 

[Zen Mod]

that isn't I/V stage ( in any way or measure ) , as AR2 is using xformer right now
Sabre's output is looking into DC coupled balanced Jfet buffer ( sky high input impedance ) so it's working in pure voltage mode ;
after that , Lundahl xformer connected as 1:2 .

xformer for any sort of I/V is simply impractical there , tnx to sissy nature of Sabre output - halfway between voltage and current output realms

(I'm feeling all the time as riding that ship , while sitting in Heechee chair )

I'm not even going to comment approach of resistive loading of Sabre's output , translating it to voltage strong as fly's fart , then amplifying it again zillion times

it's either pure voltage route .... or non-compromised active I/V conversion route , last one with I/V input impedance lesser than 2R

 

[TNT]

But isn't actually:

"resistive loading of Sabre's output , translating it to voltage strong as fly's fart , then amplifying it again zillion times"

=

"non-compromised active I/V conversion route , last one with I/V input impedance lesser than 2R"

where fly's fart is what You get at 2R

?

 

[Zen Mod]

nope

one thing is if you load it with few ohms (in form of plain resistor) to convert current to (tiny) voltage, then introduce voltage amplification of zillion db

other thing is if you load it with active I/V ,having few ohms (0 as wishful hope) of input impedance ..... which role is exact and linear transfer of DAC output current to I/V stage output node - which is exact place of I/V conversion

 

[apoo]

The i2s output voltage at the WaveIO isolator is 2,6V and the i2s voltage after the dualXO board is 1,6v. Does this mean anything!?! Might this be the problem for my distorting DAC?!? I didn´t try the PCM board yet!

Hi apoo,

I got exactly the same issue when I test my PCM1794 and TDA1541A running from my PCM board at 384KHz.

I solved the problem by replacing the USB interface with other one.

Please refer the follow link for details:

http://www.diyaudio.com/forums/digi...rsal-i2s-pcm-driver-board-53.html#post3621653

Please let me know for any progress.

Regards,

Ian

 

[TNT]

If a 2 pole sees an impedance (resistance), does it matter how it was achieved from the source point of view, and can the source know?

//

nope

one thing is if you load it with few ohms (in form of plain resistor) to convert current to (tiny) voltage, then introduce voltage amplification of zillion db

other thing is if you load it with active I/V ,having few ohms (0 as wishful hope) of input impedance ..... which role is exact and linear transfer of DAC output current to I/V stage output node - which is exact place of I/V conversion

 

[Zen Mod]

imagine this :

case 1 : DAC - resistor - 40db voltage gain stage - buffer , to have 1Vrms per leg

case 2: DAC - I/V stage without active voltage gain - buffer , to have 1Vrms per leg

which one is better , from signal energy preservation point of view ?

 

[TNT]

Buffer = 1:1 ?

 

[Zen Mod]

roughly , yes ; voltage gain slightly under 1 , current gain - as you manage it

though , I/V stage , when properly done , is having current buffer role ; to clarify more - it's relocating position of I/V resistor away from DAC chip itself , while not contributing at all in output current

so , you can see it also as voltage gain stage

 

[TNT]

So into almost 0 ohm, the chip outputs 1 volt?

 

[Zen Mod]

yes , and no ;
if you say - chip outputs through I/V stage , then yes

my last iteration , still waiting for proper tests , is having 1.15R differential dynamic input impedance (so 0R575 per leg) ; output swing set to 2Vrms differential