diy iphone guitar input / line output?

Hi all

I am trying different ways to get audio in and out my I-phone. Right now  I am exploring the possibilities of the combined headphones out / mic in jack on it.
This means however that I have to convert the headphone out to a line out level... and my guitar signal has to be converted to a mic level...
Any specialist out here who have thoughts on how to to that?

From what I read on the internet, peavy's ampkit link has some sort of active circuit, and that seems to work the best...

Help appreciated!

Erik

There are a number of devices that allow you to tap into the line out jack in the multi pin connector. http://www.sendstation.com/us/products/pocketdock/lineout-usb.html is one. I actually ordered a connector to try and make one myself but the pins were FAR to small for me to do a good job with.

I have been doing the same.  I wanted to use Audio Tools from studiosixdigital.com without their $400 interface.  Why buy a $400 interface to plug into a $300 phone and get something that is still more of a toy than serious test equipment. 

I actually soldered the connector for stereo line in and out.  I simply cut the unnecessary pins and spread the remaining and soldered Canare MR202 multipair to them.  There are also break-out board connectors available from Too bad the "stereo line inputs" do not really exist, even on an iPhone 3.
One thing is that there are conflicting pinouts listed for the same product, and the pinouts have changed along the different generations of iPhone and iTouch.  That takes some time.
What I determined is that there are NO line inputs on the iPhone 3 or the iPod Touch.  Pinouts list them but they are not accessible from my research.  There may be some secret manufacturer only info or other info that I did not look deeper to find.
The microphone input is heavily filtered and not really usable for audio testing or instrument recording without serious filter compensation.

The real gateway is with the digital I/O.  Alesis and others are making some interfaces that are interesting, but they hardly transcend the realm of toys at this time.  It all should be much hipper in five years.

If you want to experiment, you can get the four conductor 3.5mm jack from a few suppliers and interface to that.  It's not too hard to solder.  Use a DI to get guitar in and a simple bump box circuit to get the unbalanced stereo out up to "line level".

If you search iPod Touch and Skype there is some good info, but it did not lead to any line input joy for me.
Mike

this looks pretty good
http://www.ikmultimedia.com/irigstomp/features/
http://www.ikmultimedia.com/irig/features/

I bought the Tascam iXZ interface to play around with guitar on my iPad.  I can tell you that so far I am very disappointed with the available models for the iPad.  No comparison to the equivalent PC/Mac models.

It does indeed seem that the line ins on the iPhone 3 do not exist... Bummer... So I guess the way to go is either the jack input (3GS) or the digital (USB protocol?) via the main connector... Any ideas how to get audio in / out that way?
Pin 23, 25 and 27 of the 30 pin connector are the USB pins... Respectively power, data- and data +.
Do you guys think it would be possible to hack the cable of a simple USB 2 channel in and out interface and Connect that to these pins? And then  of course hack the interface for better quality. Is this USB actually working for iPhone 3GS? Lots of questions.... Any answers?

Edit

There seems to be an affordable USB audio interface that works with audio in and out othe iPad:
http://blog.faberacoustical.com/2010/ios/ipad/usb-audio-devices-that-work-with-ipad/

http://store.griffintechnology.com/imic

That seems like a nice starting point....

hey Brian.. appreciate your input but... I have really NO clue what you are saying Care to help me out a bit ?

Hi Erik were you able to do any progresses here?

I have Iphone 4 and Ive been thinking in building some interface for Audio in and Audio Out.

Like a box that would connect to the apple port, with 2 mic simple mic pres that  could be powered by a 9volt adapter or something similar

erikb1971 said:

It does indeed seem that the line ins on the iPhone 3 do not exist... Bummer... So I guess the way to go is either the jack input (3GS) or the digital (USB protocol?) via the main connector... Any ideas how to get audio in / out that way?
Pin 23, 25 and 27 of the 30 pin connector are the USB pins... Respectively power, data- and data +.
Do you guys think it would be possible to hack the cable of a simple USB 2 channel in and out interface and Connect that to these pins?

Click to expand...

If you want to connect a USB Audio device to the iPhone, that device must conform to the USB spec. There's a lot to connecting a device to the differential data pair D+ and D-.

There are further constraints here. While the USB Audio Class spec allows for a device to support any sampling frequency, number of channels and data word width, the class driver in the iPhone understands only 48 kHz 16 bit stereo.

Summary: if you're looking to DIY, consider looking elsewhere. I have scars from designing a USB audio device.

-a

i think the irig clone is a good project.It's simple and works great.

I use this little circuit:



easy even to build into a 1/4 jack, just had to get the 'ground on second ring' thing right.... tip is pin 1 on the 1/8 minijack. this works nicely for my bassguitar, at least for rehearsing. got this from here: http://forum.harmonicdog.com/viewtopic.php?f=2&t=6&start=50, so no credits for me beside sharing and redrawing. I remember I tweaked the values of the resistors to suit my active bass and the fet - I used a 2N3819 that was available in my toolbox.... 2N3819 are symetric, they really don't care about drain and source as many other.... gate does matter ;-)

the headphone out is ok used as a line out, no complaints here. 

- cheers, Michael