What do I need to build a DAC for an I2S interface?

[Bricolo]

Hi all


I never build something for digital, so I don't know much about it.
I only read some topics here about dacs, and if I have correctly understood, a basical dac needs:


an optical reciever, a decoder, a dac, and a I/V stage

but I think this is for spdif, how is it for I2S (I mean something like a cdpro2), and I heard that I2S is the best way to go.


Can you also tell me wich chips are good?



thanks a lot
Alex

 

[Peter Daniel]

Philips chips accept I2S directly. All you need is a DAC chip and output stage. Here are some links:

http://home.student.utwente.nl/f.s.bouwman/audio/nonoz.html
http://www.diyaudio.com/forums/showthread.php?s=&threadid=5798&highlight=non+oversampling+dac

If you want to go with oversampling DF1704 accepts I2S directly as well. In all those cases you simply are not using the receiver.

 

[Bricolo]

Philips chips accept I2S directly. All you need is a DAC chip and output stage. Here are some links:

http://home.student.utwente.nl/f.s.bouwman/audio/nonoz.html
http://www.diyaudio.com/forums/showthread.php?s=&threadid=5798&highlight=non+oversampling+dac

If you want to go with oversampling DF1704 accepts I2S directly as well. In all those cases you simply are not using the receiver.

So, with no oversampling-> I2S directly to a PCM1704 (that's an exemple)
, then to an I/V
with oversampling-> I2S-> DS1704->PCM1704->I/V


No brickwall filter or something like this? (how does such a filter work?)



thanks Peter

 

[Peter Daniel]

So, with no oversampling-> I2S directly to a PCM1704 (that's an exemple)
, then to an I/V
with oversampling-> I2S-> DS1704->PCM1704->I/V


No brickwall filter or something like this? (how does such a filter work?)



thanks Peter

PCM1704 doesn't accept I2S format. You have to either use DF1704 (oversampling) or a sort of logic to make it compatible (non-oversampling).

 

[Bricolo]

okay


what are you using in your player (the cd pro 2 based one)? are you using the AD1865 with a tweak to use I2S?

 

[Peter Daniel]

I'm using digital out from a player and that goes to outboard DAC with CS8420 receiver, DF1704 and 4 x PCM1704K. Didn't have a chance to try I2S yet. It sounds pretty good as it's now, that's why no rush to change things.

 

[Cobra2]

I2S

Would I need any special attention to plugs or cable if I used an external DAC? (Feeding it I2S).

And if it were that easy/simple...why are manufacturers wasting money on the extra circuit for SPDIF...?

Arne K

 

[Peter Daniel]

I am not expert in that regard, but it's my understanding that I2S connection is limited to a certain safe length only, within a player itself. If the cable is longer you might need special sending and receiving circuits, like featured on Sonic Frontiers DAC, and that is more complex and expensive than SPDIF.

 

[Cobra2]

I thaugth there were a catch...

I actually tried to get hold of the SF - I2S option, when I had the SFT-1 Drive...

Time for a group-project for a universal I2S Tx/Rx..?

Arne K

 

[Peter Daniel]

It is better to built one box player, and if the box is not big enough, make power supply separate.

 

[jwb]

I2S transmitter systems have been discussed on diyaudio.com many times. Use the search engine to find them. The most popular design ideas use LVDS or PECL chipsets and twinaxial cabling.

 

[joke]

sorry of topic but...

I'm using digital out from a player and that goes to outboard DAC with CS8420 receiver, DF1704 and 4 x PCM1704K

Peter do you have any PCB extra of the DAC to sell ???
It has balanced outputs...right ?!?
Thanks
Josip

 

[DonJuan]

a dac with i2s input is probably the easiest to build. tried it here.

http://diyparadise.com/rm20dac.html

DonJuan

 

[Peter Daniel]

sorry of topic but...


Peter do you have any PCB extra of the DAC to sell ???
It has balanced outputs...right ?!?
Thanks
Josip

It has only single ended out. I bought the board from David Broadhurst. I've heard that he was hard to get in contact recantly.

 

[Bricolo]

It has only single ended out. I bought the board from David Broadhurst. I've heard that he was hard to get in contact recantly.

so you use 2 paralleled PCM1704 per channel?
why did you choose parallelling and not differential outputs?

 

[Bricolo]

I'm back


Just one more question: which cd mechanism have I2S output? Only the philips mechanisms or other ones too?

 

[Bricolo]

bump