Simply put, you need an interface to route your guitar signal in and out of your iOS device.
There are many different interfaces to choose from but most of them are for desktop use, especially those sophisticated ones with multiple in/out, so be sure to choose one that's compatible with iPad / iPhone. Some interfaces are analog, such as IK Multimedia's iRig 2, and won't be able to work with iPhone 7 due to the lack of a headphone jack.
Let's take a look at what you need to use Positive Grid's apps.
1) Analog interfaces with headphone interconnect cable (NOT for iPhone 7)
- IK Multimedia iRig 2, iRig Stomp
- Peavey Ampkit Link
- Tascam iXZ
The easiest way to get your favorite guitar sounds from your iOS device. However, as we mentioned above, the analog interface is only compatible with pre-iPhone 7 models.
2) Lightning interfaces with single guitar input (NOT for iPhone 7)
- Apogee Jam
- Apogee Jam 96k
- IK Multimedia iRig HD
As long as you have an iOS device with a headphone output, you can use "input-only" interfaces and let headphone output take the duty of monitoring.
However, if you want to plug into a guitar amp, things get a little more complicated:
- If you try to plug a device with a low signal level into a device designed to take a high signal level, you will need to turn the up the amplifier volume, introducing noise.
- If you go the other way around, you will get clipping at high volumes. Turn the volume down low and you will probably be okay.
- Because of the impedance bridging principle, it is okay to plug a low impedance device into a high impedance device. It is not okay to plug a high impedance device into a low impedance device.
Examples of this principle can be found in guitar equipment: 1) Plug the instrument into effects pedal socket, but from then the signal is at line level through several pedals and the line level finally going into the high impedance instrument level amp socket. 2) Plug line out or headphone output into AUX In socket in a guitar amp. Similarly, because of the impedance bridging principle, a headphone output can generally drive a line input; but a line input generally can not drive a set of headphones.
Before you call for help, check if your guitar amp has "Aux In" (usually one socket in 1/8"). Some modern guitar amps have this as a standard feature and will happily accept the headphone signal from any consumer electronics.
If you have to connect your iPad/iPhone to a guitar amp that has only one guitar input, relax, it's not the end of the world. You just need two more tools:
A. Stereo 1/8" TRS to Mono 1/4" TS adaptor cable. Hosa and Canare are two common brands you can find easily.
B. A re-amp box to convert low impedance signal to high impedance signal and further route to guitar input of your amp.
3) Lightning interfaces with guitar input, 1 set of headphone out and/or 1 pair of outputs
- IK Multimedia iRig HD 2, iRig Pro I/O, iRig Pro DUO
- Line6 Sonic Port (VX)
- PreSonus iOne, iTwo
- Focusrite iTrack Solo
More outputs means better flexibility and, as the illustration above shows, with any of these you can either connect to your headphones, guitar amp or a pair of studio monitors (Note: to connect balanced out to a guitar amp you still need a re-amp box). Since Positive Grid software are designed with the most authentic cab simulation algorithm, we strongly suggest that you use FRFR (full range, flat response) speakers or studio monitors whenever you can to get the most out of it.
Voila! Now it's about time to fire up JamUp or BIAS and say sorry to your neighbors.