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Is iPod Digital Output Possible?

I've been scouring through all the ipod accessories and cannot find what I am looking for. Perhaps it does not exist. I was wondering if there is any cable or dock that will allow me to extract a digital output from my iPod video (or any iPod for that matter)? There's plenty of adapters to pull the analog out, but it seems like you always need a computer interface to get digital output. Why? Is it just a matter of software to sort out the library? More to the point; I want to connect my iPod directly to my DAC or even to my Waveterminal (requires the squareish delivery end of a USB cable) to my DAC...is this possible? Has this been discussed previously? If so, where the heck was I? No, don't answer that last part! The authorities may be listening in! Just tell me how to get a digital stream out of my iPod if it's possible.

Marco
jax2
bwhite
807 posts
 
Hi Steve - I know about MSB but I didn't realize you were doing digital out modifications to iPods - can you point me to some additional information?
redwineaudio
32 posts
 
Steve is correct... the Escient is most likely using an A/D converter and converting the analog line-out into optical and/or coax digital output. I've seen a few other docks like this, even via Bluetooth (e.g. Griffen Bluetrip). The MSB is the only one that does it properly.. that I know of.

Vinnie
audioengr
3,282 posts
 
Bwhite - The digital iPod docking station is called the iRod, for Hot-rodded iPod. It will essentially replace all of the analog circuits in the iPod with external circuits of my own design. I will bring-out the I2S interface on the docking connector. The connector will dock with my own portable box, which will have rechargable batteries, D/A, headphone amp and analog volume control (Alps). It will use the AD1853 D/A converter and be non-upsampling. I may also try to drive a low-jitter master clock back up to the iPod, locating it at the D/A chip. I am considering putting line-outs on it as well, but it may not have the space.

Steve N.
Empirical Audio
johnmhuntbch
14 posts
 
Steve

what is the latest on our project? Have you completed a product that can bring digital out of the iPod to an external dac?

Thanks
audioengr
3,282 posts
 
Johnmhuntbch - I took an iPod Video apart and mapped-out the signals. The problem in this particular unit is that the signals necessary for I2S are not present. The D/A chip is run from a 12MHz clock. It is a proprietary chip from Wolfsen, cannot find a datasheet. It also uses a half-speed bit-clock. With some effort and logic, I could generate S/PDIF from this externally, but it would be jittery.

The whole point of this was to get a low-jitter I2S out of the thing. Looks like maybe a different iPod is needed. The new ones evidently use the WM8741. This I have the data sheet for. This probably has I2S going in. Not sure which iPod to buy though. This is getting expensive. I managed to put the video iPod back together and I'm giving it to my wife for use when walking the dog...

Higher priority is getting my new Formula One DAC to market right now.

Steve N.
Empirical Audio
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