Ibanez SRF705 fretless with piezo and a pair of Bart MkI for input. I had a nasty hum/buzz when I mixed in the Barts (either one) that was directly attributable to the treble pot. Full treble equals nasty hum/buzz. No treble equals no hum/buzz. I re-soldered the tabs on the treble pot to no avail. I could get it to go away slightly by repositioning the wires leading to the circuit board. I had this great idea to desolder the white plastic header and solder the wires directly to the board to make sure I had good solid connections. The problem is... I can't get the solder to stick to anything from the underside of the board as it appears that there is no metal on the back of the board for the solder to melt to. It's just the epoxy board. I see a trace on the back of the board to the middle wire, so I'm thinking this should be a double-sided PCB. My iron was set to 400C, and I backed it off to 350C, but that didn't solve the issue. I thought I'd better stop while I'm ahead (the piezo still works!) and ask for advice. Also, I noticed there was a change in parts between the 2014-early 2017 models and the later 2017 models. (search for srf705 at Ibanez parts catalog ) How would I get these parts if I need them? And if I DO need to buy a new preamp, am I stuck with the Ibby due to the piezo/active combo?