[bellsprout]

After reading several guides on how to do a diy iMod, I was thinking about taking the digital signal and adding optical out or something. Surely it can't be that hard. Worth a try?

 

[krmathis]

"Anything" is possible!
It would be great if you went on with this, succeeded, and then posted your steps.

 

[bellsprout]

I am no DIYer at all tho. I'm just guessing that all it would involve is finding the output cable from the DAP, cutting it and soldering it onto an optical jack.

I'm not even sure if that'll do anything tho. I don't even know if it tehre is such a cable. It could just be small strip of PCB track. Can someone shed some light on this?

 

[MASantos]

I don't think that the ipod has an spdif digital output. Probably IS2. You would need to design a is2 to spdif converter based on some IC, have a board, someway to power it. It is certainly feasible, but easy? I don't know.

Wadia has the itransport which outputs digital out, but I remember reading that it uses a IC from apple only available to companies.

Alpine (the car audio brand) suposedly also extracts digital out from the ipod to use the DAC in the car receiver unit, in their ipod specific car radios.


It would be awesome to be able to do this with the ipods battery or an external battery pack!

 

[joneeboi]

You can follow my exploration of the topic in this thread,

http://www.head-fi.org/forums/f6/diy...al-out-288449/

Basically, you'd take the I2S straight from the DAC by soldering wires straight to the chip, send it out of the iPod somehow, whether by drilling a hole somewhere or soldering to unused pins in the dock, and then convert it with any number of I2S converters like this one,

S/PDIF output extension for Portable MiniDisc Devices

We figured that is what MSB did with their iLink.

OR

You can do what a lot of iPod-capable car stereos do and stream the USB data and do your own D/A conversion. I'm not entirely sure how that works, but I know there is more programming than I care to learn. If anything, you could just hook up one of those decks to a car battery and carry that around. Open it up and mess around with the DAC and amplifier for extra points.

 

[cobaltmute]

The car stereo guys are just treating the iPod as a USB drive and reading the data. Problem is that you have a limitation then of what the DAC can do in the car stereo and if you run Apple Lossless you are foobar (from what I've seen)

 

[The Monkey]

Quote:

Originally Posted by MASantos /img/forum/go_quote.gif Alpine (the car audio brand) suposedly also extracts digital out from the ipod to use the DAC in the car receiver unit, in their ipod specific car radios.

I've read about this, too. Do you think the extraction is done through the USB/dock cable that comes with the head unit, or is it done in the head unit itself?

 

[FallenAngel]

I'm guessing it's done through the serial interface. Doesn't look like there are digital output pins on an iPod.

 

[joneeboi]

Quote:

Originally Posted by FallenAngel /img/forum/go_quote.gif I'm guessing it's done through the serial interface. Doesn't look like there are digital output pins on an iPod.

The serial interface isn't being used. The only pins used in my Apple USB cable are pins 21, 23, 25, 27 and 29. I have a Pioneer DEH-P4000UB, and my DIY iPod USB cables don't work. I tried a bunch of resistor values from pin 21 to ground, but it didn't seem to help. Sadly, I have to shell out the 25 odd bucks for a USB cable from the Apple Store unless someone can hook up some info on what's going on in the Apple-provided USB cable.