When using the Model 15 app, I get glitches and crackles.

This can happen when iOS is busy with other tasks or when another application takes up too much CPU resources. The easiest way to get rid of these is to quit all running apps, then restart your iPad. Then launch Model 15. It should work without any glitches.

If it doesn't work immediately, you might have to wait a while, iOS sometimes does background cleanup tasks after installing of an app that could cause this to happen also.