Asynchronous I2S FIFO project, an ultimate weapon to fight the jitter - Page 77 - diyAudio
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Old 7th July 2012, 09:32 AM   #761
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Quote:
Originally Posted by qusp View Post

i've already said above it would perhaps present an advantage doing it all on one board or at least well integrated, but when there is already perfectly good solutions designed by others to use with what hes got already, the only reason would be money. I would be extremely surprised if it measured more than 1db better than what is possible already with modules. a proper and original well performing discrete analogue stage isnt a small undertaking either, I would say this is further out of Ians skillset than the USB.

Since you mention him, Lucien and Acko are already working together on a project, which could be interesting. interesting for others that is, i'm about done with dacs for quite a while I think and I cant justify building another one
If I was going to be bold enough to suggest anything to anyone I'd be suggesting that acko made a combo-board with a mounting position for the FIFO board ...
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Old 7th July 2012, 09:38 AM   #762
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ha ive had the same thought, it would only need to be the clock board too. but realistically it can just sit on the PCB close enough and neatly enough to be a non-issue

Last edited by qusp; 7th July 2012 at 09:41 AM.
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Old 7th July 2012, 09:44 AM   #763
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I wonder if everyone has recognised the significance that Ian has provided rubber mounting rings for the FIFO boards to decouple vibration from the clock circuits especially. Any integrated board that uses this decoupling technique will still be using u.fl/w.fl coax connections for moving the i2s between FIFO output and DAC input.

The value (in terms of performance gains) of an integrated DAC design over an acko combo board with FIFO is what exactly?

Last edited by hochopeper; 7th July 2012 at 09:55 AM.
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Old 7th July 2012, 10:43 AM   #764
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you sir, raise a very good point

one thing that could be cool would be a differential clock driver to get rid of the clock/ground connection as well, but any of that will add jitter, in fact pretty much any isolation technique will, so its kinda 6 one way half a dozen the other for any 'improvements' from this point on

Last edited by qusp; 7th July 2012 at 11:04 AM.
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Old 7th July 2012, 01:11 PM   #765
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Originally Posted by hochopeper View Post
If I was going to be bold enough to suggest anything to anyone I'd be suggesting that acko made a combo-board with a mounting position for the FIFO board ...
Another flashing idea! I will move the mounting holes a bit on the next version of FIFO PCB, to make a new possible option: clock board stack above the FIFO board. That will save a lot of space for a DAC project.

Nice weekend.

Ian
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Old 10th July 2012, 02:00 AM   #766
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Originally Posted by soundcheck View Post
Ian.

Why don't you built a DAC by yourself?

Instead of tweaking an average 3rd party product you should built your own DAC.

It's just a PIC and a DAC on top of your stuff. Shouldn't be such a big problem for you.
Beacuse you built it better than me .

Ian
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Old 11th July 2012, 10:10 PM   #767
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Default Steps to tap connector header to the reserved I2S input port on the S/PDIF Board

Step1: Remove R22, R23, R24, R25 from PCB. SMT soldering station is recommended tool, but normal solder iron is still OK.

Setp2: Cover the GND pads of R23, R24 and R25 with fine cut high temperature tape to avoid signals short to GND.

Setp3: Solder the 4P SMT PH2.0 header, Pin1 (WS) to R24 signal pad, Pin2 (SD) to R25 signal pad, Pin3 (SCK) to R23 signal pad and Pin4 to both R22 signal pad and GND pad,

Step4: Cut the solder mask paint beside the both GND pads of the header appearing small area of GND copper plate, please be careful no touching any other circuit route.

Step5: Solder the support pads of the header to the appeared GND copper plate. Solder iron with higher power may require. For enough support force, applying compound of strong glue (such as epoxy) is highly suggested for double support.

Step6: Make an I2S cable to introduce an additional I2S input source.

The Digikey P/Ns are:
Connector header: 455-1736-1-ND
House: 455-1164-ND
Terminal pin: 455-1127-2-ND

Ian
Attached Images
File Type: jpg I2SBackdoorPosition.JPG (528.4 KB, 595 views)
File Type: jpg CoverGNDpadsWithTape.JPG (531.0 KB, 575 views)
File Type: jpg SolderConnector.JPG (464.1 KB, 566 views)
File Type: jpg AppearGNDcopper.JPG (483.0 KB, 545 views)
File Type: jpg SolderGNDpads.JPG (468.6 KB, 515 views)
File Type: jpg PlugI2Scable.JPG (374.5 KB, 191 views)
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Last edited by iancanada; 11th July 2012 at 10:14 PM.
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Old 12th July 2012, 12:50 AM   #768
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Thanks Ian for the detailed procedures and effort. Is it possible to include the SMT header/connector in GB2 as it is difficult to just order these few parts from Digikey.
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Old 12th July 2012, 01:33 AM   #769
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Originally Posted by bigpandahk View Post
Thanks Ian for the detailed procedures and effort. Is it possible to include the SMT header/connector in GB2 as it is difficult to just order these few parts from Digikey.
Just let me think about it. I might try to supply the I2S backdoor KIT.

Ian
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Old 12th July 2012, 01:44 PM   #770
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Originally Posted by bigpandahk View Post
Thanks Ian for the detailed procedures and effort. Is it possible to include the SMT header/connector in GB2 as it is difficult to just order these few parts from Digikey.
+1 from also from me..

Well or maybe .....
We could use BIII adapter board, any chance to solder in nicely in that position...??
I2S using u.FL.... just a fought.

Rosendorfer
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