AL1201G based DAC - looking for input

[b-square]

it would be great if this board had an option for i2s input instead of just spdif.


thanks,
bb

 

[Russ White]

Just that I am atively working on it still. I will post some more details very soon. I have actually decided to go very "modular" with this design with a seperate PCB for output filtering/buffering if desired.

Glad someone other than just me is still interested.

 

[ezkcdude]

Thanks, Russ. I'm in the (very) early planning stages of designing my first DAC, hence, the interest.

 

[Russ White]

it would be great if this board had an option for i2s input instead of just spdif.


thanks,
bb

I would be glad to include I2S but I am not sure if the AL1201G can accept I2S or if I would have to convert it.

 

[Russ White]

A request for help.

I asked WaveFront about making the AL1201 accept I2C and here is the response I got:

Hi Russ,

The AL1201G cannot directly accept I2S input, as it is exepcting left justified input. However, since I2S is just left justified data shifted to the right by 1 bit, you can undo the shift by shifting the wordclock to the right by 1 bit.

By feeding a DFF's data input with wordclock, and the clock input with bitclock (64xFs) whose rising edge is aligned with the edges of wordclock, the output will be a properly shifted wordclock that can be fed to the AL1201G without having to do anything to the audio datastream. You can do this with something like a 74HC74.

Now please understand I am no digital expert in the least, and a few of those terms in there have me scratching my head. I would be so grateful if someone could show me a diagram or schematic of how this might work. Or even just point me to a good place where I could go read about it.

Cheers!
Russ

 

[chris719]

Hmm, that may work, but you also are inverting left and right channels since I2S uses word clock low for left and not right channel data, not really a big problem.

 

[b-square]

here's a vote for using a different dac. lack of i2s input and lack of support for sampling rates above 55kHz are pretty weak.


bb

 

[rfbrw]

here's a vote for using a different dac. lack of i2s input and lack of support for sampling rates above 55kHz are pretty weak.


bb

Consider it an impetus to start your own design.

 

[Russ White]

here's a vote for using a different dac. lack of i2s input and lack of support for sampling rates above 55kHz are pretty weak.


bb

I am going forward with this DAC for several reasons.

1) I have heard a professional example of a DAC using this chip and it sounds very good.

2) I love that it needs no I/V stage.

3) Balanced output.

4) Monolithlic design which requires no external clock or PLL.

5) Very good dynamic range.

6) Convenient easy to DIY solder SOIC package.

7) Easy to obtain and at a low cost (about $4.50).

I2S input was never a huge priority for me, but I still think it would be very possible to add it. In fact one could easily make a stakable PCB which used something like a PCM2707 and a DFF or two to get what we need for I2S into the AL1201.

Do you know a balanced output SOIC or DIP standalone DAC chip? I don't want to do anything smaller then SOIC and I don't want a uC on the PCB nor an oscillator. I would be very happy to consider it if you do.

For now I am quite happy with 48KHz as I plan on just using this with CD transport or soundcard SPDIF out.

This is not the only DAC I plan to design, just the first. So I will keep it simple (yet modular) , and relatively cheap.

Cheers!
Russ

 

[b-square]

Consider it an impetus to start your own design.

i thought we were just supposed to sit around waiting for people to design stuff and then get all excited and say we wanted in on the group buy!


bb

 

[rfbrw]

i thought we were just supposed to sit around waiting for people to design stuff and then get all excited and say we wanted in on the group buy!


bb

Especially when it annoys Ulas.

 

[Jocko Homo]

Making me break radio silence..........

Wow........2 posts in row that I agree with. When was the last time that happened?

Back to lurking. Remember.......I may be away, but never far enough away that I can't keep my eyes on the troublemakers.

Just what you needed: one more reason to be paranoid. Just because you imagine that someone is out to get you does not mean that they really aren't.

Jocko

 

[ezkcdude]

I for one would love if there was a sticky thread where people put their finished and working designs. It would be a great resource for newbs like myself who keep resurrecting old threads in search of ideas.

 

[Russ White]

I have shelved this design in favor of a new one which can be found here:

http://www.diyaudio.com/forums/showthread.php?postid=914368#post914368