Drive NOS AD1865/62,PCM1704/02/63,TDA1541 from FIFO: Universal I2S-PCM driver board - Page 51 - diyAudio
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Old 8th August 2013, 03:31 AM   #501
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Quote:
Originally Posted by apoo View Post
Hi Ian,

is it possible to use your I2S to PCM board to drive this DAC? http://www.dddac.com/documents/dddac1794_nos_ver30.pdf

The schematics of the actual board is here:
Click the image to open in full size.

apoo
Quote:
Originally Posted by iancanada View Post
Hi apoo,

Nice project!

From the spec, PCM1794 is not a traditional R-2R DAC, and it accept right justified format which is not the 'PCM' format. So, I don't think you need this I2S to PCM converter.

It's very nice you run it at NOS mode .

Ian
Quote:
Originally Posted by vzs View Post
PCM1794 is configured for Digital filter bypass - Mono (see specs Table 2.)

He has to delay both channels in order to have 24bit right justified of both: delay right channel by 7 cycles and left by 39 cycles to have the LSB bit of both data channels clocked in when right channel's latch goes low.
31-7 = 24
63-39 = 24
(31 and 63 because I2S format has data delayed by 1 cycle).

Right-channels's I2S latch signal (LR) latches both L and R DACs.

Having reviewed how that works I'm 99% sure I2S-PCM board can be used to bypass Doede's delay line.

But why on earth use PCM1794 when you can use any good old R2R DAC with this I2S-PCM board?

Zsolt
Hi Apoo,

Maybe I didn't get your point. Running PCM1794 at NOS mode is a special configuration, can your post the timing to drive it?

Here is the principle waveform of I2S to PCM board (half speed mode), you can figure out if it is working for your application.

Ian
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File Type: png Principle2013-08-07.png (54.8 KB, 587 views)
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Old 10th August 2013, 08:35 AM   #502
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Yesterday iīve got Ianīs I2S to PCM V2.0 module to do some pre testing with my Red Baron V5.0.

Click the image to open in full size.

The simultaneous (offset binary) mode runs perfect.

Big thankīs to Ian!
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Old 10th August 2013, 11:24 AM   #503
PET-240 is offline PET-240  Australia
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Quote:
Originally Posted by vzs View Post
But why on earth use PCM1794 when you can use any good old R2R DAC with this I2S-PCM board?

Zsolt
Cause I don't have one......actually I do have a TDA1541 KillerDAC (google) coming, also have a Teradak Chameleon 16 chip TDA1543 Dac as well, heavily modified. I would like to play with something computer audio related so I can fiddle with higher sampling rates. Also have a Buff III to build a tube output stage for.
Yes I'm one of those tube guys.....

Appreciate you looking into the timing thing Zsolt, much appreciated!

Cheers,

Drew.

Last edited by PET-240; 10th August 2013 at 11:25 AM. Reason: misspelled
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Old 11th August 2013, 05:10 PM   #504
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Hi Ian,

because i use two Red Baronīs parallel, i added two additional U-FL connectors for DR and DL.


Click the image to open in full size.



Now the digital input section is completed!


Click the image to open in full size.


Wave I/O for USB input --> SPDIF/AES input board --> FIFO --> Isolator board --> Dual Clock board with Crystek CCHD-957 clocks (powerd exclusive from a A123 Systems LiFePo4 cell) --> I2S to PCM V2.0 Module --> Red Baron

What i could say after 2 hours of listening, i will never go back to the I2S input!

All of you who have pre ordered the board will have MUCH fun!!!

Cheers,
Oliver

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Old 12th August 2013, 03:31 AM   #505
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Quote:
Originally Posted by dvb projekt View Post
Yesterday iīve got Ianīs I2S to PCM V2.0 module to do some pre testing with my Red Baron V5.0.

Click the image to open in full size.

The simultaneous (offset binary) mode runs perfect.

Big thankīs to Ian!
Hi Oliver,

Your system look great! Congratulations!

The jumper settings are correct. I think you solved all problem by now.

I was surprised how nice the TDA1541A can be when it's playing with the daughter board at OB mode.

vzs found even with half-speed mode, TDA1541A already been running over clock at 352KHz which I confirmed working. I'll try 384KHz to see if I'm reaching the physical limitation of TDA1541A.

Thank you so much for you efforts and your good news.

I'm very close to launch the board. It seems I still need to speed up.

Regards,

Ian
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Last edited by iancanada; 12th August 2013 at 03:34 AM.
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Old 12th August 2013, 06:04 AM   #506
qusp is offline qusp  Australia
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Oliver and Ian, wouldnt it be recommended to replace the 33Ω resistor network on DR/DL with small discrete resistors, so that you can have the correct termination on them with double the lines? am I incorrect, or should the line now be terminated with 66Ω if running 2 parallel on the same driver?
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Old 13th August 2013, 10:01 AM   #507
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Will the Verilog/VHDL code be kept proprietary for this project?

I've been looking somewhat into doing 64->32 frame and OB conversion with L/L' R/R' splitting for the 1541, but haven't got to writing more code than defining shift registers.
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Old 13th August 2013, 12:32 PM   #508
PET-240 is offline PET-240  Australia
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Just to ask a silly question and to be sure I understand as the search functions don't work so wel on an iPad, this board will be capable of running a pair of TDA1541's in dual mono? Ie one chip does left and the other right and output a balanced signal from the DL and DLn outputs for left and vice versa for right?

And Tazzz, I would assume that this will indeed remain proprietary. Personally what Ian does is quite amazing and is probably under appreciated by those not involved in the world of embedded IO control and custom programming. Not saying this is you, but I would estimate if one of us were to pay Ian an hourly rate to develop this item in work hours you wouldn't be short of a bill in the $10-15k mark with pcb design, programming and testing refining, bug resolution, manual writing, quality control and testing. Really is very involved and we get a bargain.
Bravo Ian, really is very appreciated!

Thanks,

Drew.
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Old 13th August 2013, 12:48 PM   #509
palmito is offline palmito  United States
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Quote:
Originally Posted by PET-240 View Post
Not saying this is you, but I would estimate if one of us were to pay Ian an hourly rate to develop this item in work hours you wouldn't be short of a bill in the $10-15k mark with pcb design, programming and testing refining, bug resolution, manual writing, quality control and testing. Really is very involved and we get a bargain.
Bravo Ian, really is very appreciated!
And the support!!!!! Ian's support, considering this is DIY stuff and how busy he is, is nothing short of amazing. My additional $0.02...
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Old 13th August 2013, 12:54 PM   #510
PET-240 is offline PET-240  Australia
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Yup missed the support, concur completely!
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