So I got a good deal on this 14 in mono coil on ebay it required a little lower rod modification. The coil seems to work fine other than it has changed the audio with that coil sounds like a old 8 bit midi video game almost like an overload on some targets but I can tell they are there. I may need to build a modified battery pack to up the voltage to the detector but coiltech makes a TDI 14 mono that looks just like mine. Wondering if anyone has any info? has anyone had luck with the 14 mono? Any idea on the audio change? I've been told I shouldn't use anything bigger than a 12 inch on this machine but I've read about others having luck.