I agree with Kev, I bought the Peterson cable but it still fails to recognise the low B and registers it as F#. Most of the time it struggles to recognise the open E. I've tried using the flat of my thumb as well as a pick and adjusted the output of my bass (Groove Tools Seven-String) without success. I've been using a Peterson VS 11 for some years and it's excellent but the iPhone software is very disappointing so far.