IK multimedia iRig diy cable ?

[mat]

The Amplitube iRig http://www.ikmultimedia.com/irig/features/ seems like a great practise tool. The basic app for iPhone is free, and the iRig connector seems to be reasonably priced also but we have to wait for them for quite a while to come to the music stores (at least where I live). I was thinking how to make one. Here is what Peter from IK multimedia wrote:

There's impedance matching going on, yes, and it is possible for DIY but not a super simple thing to be honest. It will get the right signal into the iPhone/iPad/iPod Touch and the latency will be minimal (just like the PC/Mac AmpliTube products). This isn't a 1:1 port of AmpliTube 3 of course, due to platform requirements and such but it does sound really great.

Thanks for the kind words and questions and I really do hope people enjoy this.
_________________
Peter Toriello
Community Support
IK Multimedia

I can build the cable (the iPhone miniplug connectors are towards the tip: mic,ground,left and right) but would like to know how to match the guitar to iPhone impedance ? Some kind of transformer might be needed. Someone also wrote that the guitar signal should be padded down for it being too hot for the iPhone.

One user video:http://www.youtube.com/watch?v=VnOUQNm2zQA

Mat

[Cliff Schecht]

You need to figure out the input impedance of the iPhone jack. I would assume it's high enough that it doesn't care what's driving it. Even though guitar pickups are relatively high impedance (lets say 10k to make it easy), the iPhone input impedance is going to be at least 100x larger than this and shouldn't cause any impedance mismatching. Remember, for optimum transfer of voltage you want the source to be as low impedance possible and the destination to be as high impedance as possible. That's why guitar pedals use at minimum a 1 Meg input resistor, otherwise you start loading down the guitar signal and lose both amplitude and overall fidelity.

[mat]

You need to figure out the input impedance of the iPhone jack. I would assume it's high enough that it doesn't care what's driving it. Even though guitar pickups are relatively high impedance (lets say 10k to make it easy), the iPhone input impedance is going to be at least 100x larger than this and shouldn't cause any impedance mismatching. Remember, for optimum transfer of voltage you want the source to be as low impedance possible and the destination to be as high impedance as possible. That's why guitar pedals use at minimum a 1 Meg input resistor, otherwise you start loading down the guitar signal and lose both amplitude and overall fidelity.

Thanks Cliff for the answer. Some people has tried the PRS's Guitar Bud cable http://prscables.com/blog/category/prs-guitar-bud/ with iRig with poor results. It seems to be a cable and nothing more.

Maybe we have to wait until someone actually opens the iRig and deqoops it

I just ordered mine. Now I just have to wait.

Someone mentioned to make the iPhone/iRig a backup system for the gigs but one must be sure to put the iPhone to aeroplane mode. Nobody wants to be called by wife in the middle of the song and hear from the PA 'where the ***l are You ?!!! - get some milk and tampoons from the market when You come home, will You !' ....