Getting audio in and out of an iPad/iPhone/iPod Touch

[Gordon Charlton]

There are a variety of ways of getting audio in and out of iDevices. Here is a rundown of the ones I know something about. Please add to it if you can.

Via the Headset Socket

This is the cheapest way, but not the best quality audio. The iDevices expect an electret microphone and filter the signal.


Home Build

If you are going to use an electret mic then a 3.5mm TRRS Jack to 3*RCA video connector may suffice. Otherwise, without at the very least a resistor of an appropriate value across the audio in and ground the iDevice will not recognise that something is connected. A variable resistance in the audio line will also be useful to avoid clipping a hot line-level signal. This is pretty much the basis of the custom built solution I am currently using to connect my Moog Etherwave Standard theremin.

If you want to connect your theremin and are looking for a low-cost solution then I recommend consulting Thierry Frenkel, who got this working for me as well as extensively modifying my etherwave. http://theremin.tfrenkel.com/ (I note that he is a craftsman rather than a businessman, so more inclined to impress his customers with the quality of his work than the speed of his service.)


The IK Multimedia iRig

http://www.ikmultimedia.com/irig/features/

I have one of these and cannot recommend it for theremin use. The short version is - it sucks and their help desk did not respond after I told them I had already tried reducing the line level output and was still getting a hint of signal masked by a ton of noise. Guitarists seem to like it and I have seen a demo of it in use with a non-Moog synth where it worked.


The Peavey AmpKit LiNK

http://www.peavey.com/ampkitlink/

I have not tried this. It looks better than the iRig and I have read a couple of reviews that confirm this. This is a battery powered device in the same price range as the iRig.


The NSP Breakout Pedal

I have not tried this. It is more expensive than the iRig or AmpKit LiNK but looks better than either of them judging by the website and one happy user I encountered. It is designed with a gigging musician in mind, so has a metal enclosure, 1/4 inch jack sockets, true bypass, a choice of cable lengths to the iDevice and a nice big knob on top so you can adjust it to suite a mike or a guitar or a synth. Unlike the AmpKit LiNK and iRig this is mono out. They are working on a stereo out version.

http://www.newsignalprocess.com/site/nspbreakout/


Via the 30 Pin Connector

Stereo Line-in and Line-out

There was a stereo line-in and line-out option on the iDevice 30 pin connector until recently but the line-in no longer exists on the current models, so the following solutions will not work on the iPad, iPod Touch 4th generation or iPhone 4. Using this method is an improvement over the headset socket - there is no filtering and you don't have to attenuate the signal down to microphone levels for it to work. You are still using the iDevices built in A/D and D/A converters which probably aren't studio quality. I have not tried any of these.


Home Build

Here is a home build solution that gives the pinout of the 30 pin adaptor. It seems to suggest that direct wiring with no resistors or other components will work fine. As it does not include Apple's iDevice signature chip your iDevice will probably give you a warning when you try to use it but it should work anyway.

http://ipodfoo.blogspot.com/2009/06/mak ... -line.html

It will require some adapting - it offers either audio in or audio out but not both at the same time.


Sonoma Wireworks Guitar Jack Model 1

Looks good but pricey.

http://www.sonomawireworks.com/guitarjack/


Studio Six Digital iAudioInterface

Designed for professional grade audio measurement, so probably the best quality solution, but jolly expensive!

http://www.studiosixdigital.com/iphone_ ... ropho.html


USB Audio

You can do digital audio IO over USB on the iPad using the iPad USB Camera Connector, which will allow you to use your own USB Audio interface rather than a little one built into an iDevice. See here. [edit] But see posting below noting limited testing suggests this does not work with the Filtatron app. [/edit]

http://www.wired.com/gadgetlab/2010/04/ ... io-in-out/

It is possible that this will also become available for the iPod Touch 3rd and 4th generation and the iPhone 4th generation in the first quarter of 2011. See here and scroll down to the Compatibility section.

http://www.sonomawireworks.com/guitarjack/

That GuitarJack Model 2 will be USB based is not a great leap, given that it will work on the iPad.


Apogee Jam

Cheapest solution via the 30 pin connector so far at $99, due for release 31st March 2011. This is an audio-in only USB device, so you would need to get audio out via the headphone socket. Check the web-page for compatibility. At the moment it claims iPhone 4, iPad, iPad 2 and MacOS X computers. Was used by Apple to demo GarageBand on the iPad 2. The web-page only claims compatibility with GarageBand on iOS so far. Other apps are being tested.

Comes with USB to 30 pin connector cable, and also USB to USB cable for use with Macs.

http://www.apogeedigital.com/products/jam.php


Alesis iO Dock

A comprehensive iPad only solution. XLR (with phantom power) and 1/4" guitar level audio ins and stereo audio and headphone out, and also MIDI, USB and video connectivity.

https://www.alesis.com/iodock


Digital Recording Out Via FTP

For studio recording it is worth noting that the Filtatron app has a built in recorder, so you can record at full quality whist streaming audio out of either the headset socket or the 30 pin connector - so if you aren't using a USB solution the best approach (assuming the Filtatron is at the end of your effects chain and you aren't miking the amp) would be to record a scratch track from the audio out and then FTP the internally recorded version into your DAW and use it to replace the lower quality audio recording.


Getting It To Work

IDevices do not always recognise the presence of an external audio input. (*) My routine is to plug everything while my iPod is awake but not running any apps, and then to run the Voice Recorder app to see if it worked. Usually it does. If not I repeat until it does. After three attempts I panic a tiny bit and reboot the iPod. Voice Recorder is convenient at gigs because it does not route sound to the audio out, so it is silent, and has a handy little volume meter so I can adjust the maximum volume of the input sound to just below clipping level. Once this is done I then run the app I intend to use and adjust the volume of the iPod to suit my amp and minimise any audio bleed from the output to the input.

(*) To be fair, this is quite seldom. Usually only after I have spoken the fatal phrase "Here, look at this. This is so neat." Expect this situation to improve with upgrades to the app and the OS.

[Thierry]

If you want to connect your theremin and are looking for a low-cost solution then I recommend consulting Thierry Frenkel, who got this working for me as well as extensively modifying my etherwave. http://theremin.tfrenkel.com/ (I note that he is a craftsman rather than a businessman, so more inclined to impress his customers with the quality of his work than the speed of his service.)

Gordon, you asked for modifications on your Etherwave which nobody had ever made before. So the notion of speed is relative, especially if you haven't seen anybody else doing the same things in the same quality...

[Gordon Charlton]

Gordon, you asked for modifications on your Etherwave which nobody had ever made before. So the notion of speed is relative, especially if you haven't seen anybody else doing the same things in the same quality...

Thierry, I was not complaining - I like that you value doing things the best way rather than saving time and effort by choosing a quicker but inferior solution. Think of my comment as my way of ensuring that you do not have to deal with impatient people.

And yes, I continue to be impressed with the quality of your work.

[rkilman]

Great post, thanks Gordon!! Just a heads up though, my understanding is that the Filtatron app does not work with USB Audio on the iPad via camera connection kit (and my limited testing reflects this). It would be interesting to find out if there are plans for this to be added in a future update (fingers crossed).

[Gordon Charlton]

Thanks for mentioning that. I have amended my post accordingly.

[MichaelA]

Gordon, Thanks for the review and links. I too have been looking for a good input device for the iPad/iPhone ever since getting Filtatron.

I just saw the iRig yesterday and my first thought was that if was designed for use with a guitar, it might not work with the hot output of a theremin. Once again, a need for an attenuator for the etherwave... But what about using the headphone jack of the etherwave and a stereo to mono adapter into the iRig?

[Kfair]

Can someone explain how to use the Ftp with the iRig? Stompbox app and amplitube are supposed to let you save and upload or download your recordings using an ftp, so you can export your recordings to your ipad, facdbook, etc. I have my server address and got the 'ftp on the go' app but am stumped as to how to sign in, username, or basically what to do at all.

[Gordon Charlton]

Added info about the forthcoming Apogee Jam interface to first post in thread.

[analoghaze]

Alesis is releasing this for ipad.

https://www.alesis.com/iodock

[Gordon Charlton]

Excellent find. Thank you.

Added to first post.

[jjjaaa]

Hello all,

I seem to be a little late to the party here...

I have an iPhone 3G and I'm looking to get stereo line in and out via the 30-pin dock connector... Has anyone successfully built a connector to do this for Filtatron? I have the soldiering chops (and basic knowledge) to do this... But I'm a little scared in case I fry my iphone!

Ideally the connection would have stereo line in and out (completely avoiding using the headphone socket and its crappy DA convertors) and be able to spilt to a charger (battery life on my 3G is not so great...). Next up would be making sure this connector would be compatible with the pinouts on iPhone4 and iPad2 (which I'm praying are the same as the iphone 3G....) as i can see me moving to both in the future.

I'm taking my knowledge on the pinouts from here: http://pinouts.ru/PortableDevices/ipod_pinout.shtml

Lastly, does the iPad1/2 and iPhone4 have the same pinouts...?

thanks for any help given!

[jjjaaa]

Oh, I forgot to ask the most important question of all- will Filtatron accept Line in via the 30-pin connector?

if not the game for my plan might be over...

Thanks!

[Gordon Charlton]

My understanding (I'm not an expert, this is just what I have read or been told) is that Filtatron should work with audio IO via the 30 pin connector. The rather wonderful Jasuto Pro - an earlier sound processing app by the author of Filtatron - certainly does, and I see no reason why a later app by him should not.

But it is worth noting that Filtatron is a mono input app. I would anticipate that it would collapse a stereo source down to mono before processing it.

I do not think a line-level to 30-pin adaptor would work with later iOS devices. Starting with iPhone 4 Apple switched from stereo line-in via the 30-pin to USB based audio IO. None of the existing line-level to 30-pin adaptors are compatible with iPhone 4 or later.

[jjjaaa]

Hi Gordon, thanks for the reply.

Bummer... So no line in via the 30-pin connector on new iDevices? I would be cool with mono in/stereo out but I really don't wanna co in via the mic IP on the top...

I figured Apple had re-assigned the line in and out pins or something on newer iDevices... Maybe they've got shot of them all together. Bummer!

Thanks again for the reply.
J

[jjjaaa]

I'm surprised there are not more people talking about this stuff... With such a great sounding app i figured more people would be looking for the best quality way in and out of iDevices...

J