About a year ago Dave bought a cheap Chinese resonator guitar and decided that it needed a better cone. So he ordered one but it was a bit too big for the guitar’s hole. Having taken a look at it I told him that I could make the hole bigger and so he brought it over to my workshop and we (I) ended up adding two sound holes, since he received two with the cone, remaking the bridge and sticking in a pickup between the cone and the neck.
After all that the guitar sounded definitely better, which was nice, but unfortunately has an annoying hum when amplified. Since the Dimarzio strat pickup used is hum canceling I assumed it was because the wires weren’t shielded. So after not finding any kind of wire shielding gain around town I used some aluminum tape to make a tube for the wire to go through. A bit better but… Having a layer of tape above the volume pot seemed to help so I put it in a aluminum tape coated cardboard box as a test, but the hum remained. Getting a bit fed up with removing the strings, unscrewing the screws and all I put it aside but promised Dave I’d look at it again while he was away. So yesterday I opened it up on the kitchen table took everything out, the image shows just how messy I can be when impatient, and changed the wire between the pot and output jack since the cheap wire I had put there was the weakest link so to speak.
While making sure the connections were ok, I noticed that the volume pot gave a smooth ohm progression between 0 and 6, where the resistance was at its highest, and then went pretty much all over the place on higher volume settings. Now it just so happens that the hum comes in at 6… 0 to 5.5 = no hum, 6 to 10 = hum…
um….
Wish I knew more about this stuff… Looks like I’ll need to take it apart again.