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Post by flateric on Mar 18, 2010 16:23:57 GMT -5
Such a great little tuner app for the iphone/ipod touch but using a plug in mic doesn't work at a live gig. I'm a bit unhappy having to buy the special adaptor cable for it + shipping to uk, surely the wiring is simple enough to rig up a home one? Any ideas?
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Post by newey on Mar 18, 2010 17:54:35 GMT -5
Without being able to see one or test one, hard to say. From the photo, it has a TRS headphone plug at one end (not sure if the ring connection does anything here or not) and a 1/4" phono plug at the other. But then there's some sort of an in-line component sealed in a white plastic housing. My guess would be there's a resistor in there to match the input impedance of the iPhone/iPod- but that's just a guess, there could be more going on than that.
If you could find out the specs for the input, you might be able to work out what is needed.
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Post by flateric on Mar 18, 2010 18:10:27 GMT -5
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Post by newey on Mar 18, 2010 19:08:31 GMT -5
Aha! A 4 conductor plug. Didn't notice that in the photo, but of course that makes sense if the output is also an input.
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Post by ashcatlt on Mar 19, 2010 0:35:14 GMT -5
I'm not sure where you'd find the TRRS plug on its own. Seems that the earbuds that come with the iphone, as well as at least some which are sold specifically for it include that plug, though. I'm not sure what kind of wire you'll find in there if you try to hack them, though. I've run into issues with headphones that used something that looked like nylon string wrapped in foil, which was impossible to splice, let alone solder...
Once you get over this hurdle, though, the wiring is pretty straight forward. I think this must be expecting a dynamic mic, no? If so, it will probably expect a bit less input voltage than standard passive guitar will supply. Won't be enough to hurt anything, but might cause distortion of the input amplifier, which could cause issues when it comes to tuning. If this is a problem, you can pad it down with a simple voltage divider.
On the other hand, the dock connector provides 2 line-level inputs, though I guess I'm not completely sure the app you're talking about will take the input from these.
On the third hand, there are other apps which make use of the external mic input. Don't know if you'll find any of them useful, but there are Frequency Analyzers and the like. Even the "Voice Memo" app can be used to turn the iPhone into a perfectly acceptable field recorder.
Note that we're not exactly sure of impedance for these inputs. Even an extremely low-Z input should probably work okay for tuning purposes connected directly to a guitar. Unless you want to be plugging and unplugging between songs, though, you might want to use a buffered split and hang the iPhone off one side.
Also, this is an unbalanced input. Perfectly fine for guitar, but most "pro" mics have balanced output, and will require some extra consideration if you intend to connect them.
Just throwing out some thoughts here. flateric, I think you've proven you know plenty to make this happen, once you find the necessary parts.
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Post by flateric on Mar 19, 2010 12:51:45 GMT -5
I'm butchering an old lead from a Phillips mp3 player, 4-section TRRS plug on it but yes the wires are sort of wrapped in nylon and tin foil just like you mention. Anyway its in bits now so I'm going to attack it with the soldering iron. I have a series of adaptors for the other end to take it up to a standard mono guitar jack
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