Low Rider - strange noises

[monkeyman]

Hi everybody,

I just finished a Madbean Low Rider some time ago, and every works fine excepted by some strange noises - squelch - sound when not playing notes.  In fact it is very noticeable when I rub strings from my guitar. It's very annoying because of my playing style (I play funky stuff, then I use a very percusive pick style). It happens only when using "-1 oct down". I hope you can help me. 

Thanks