Uncle Fiesta wrote:Having read the review, someone is going to have to sit me down and explain very slowly how changes in the insulation of the wire on a pickup over time, can make its sound change.
Deterioration of the (very thin) varnish coating on pickup winding wire (or any winding wire*) will reduce its insulating properties, causing an effect similar to a short circuit by allowing a certain amount of leakage between adjacent turns in the coil. The number of turns wound onto the bobbin will have been "reduced" because some of them are no longer doing anything, or at least, not doing as much. If a coil is supposed to have (say) 1,000 turns**, reduction in the insulation properties of the varnish might have the effect of effectively reducing the number of turns around the magnets to (say) 900. That would change the tonal response and will reduce the output.
[* I served an apprenticeship rewinding electric motors. The memory of winding wire and its various types of insulation coating still gives me nightmares.]
[** I don't know how many turns are actually wound onto a pickup. I once watched Roberto Pistolesi re-wind an open-circuit early 1960s Fender Jazz Bass pickup, but definitely can't remember how many revolutions of the pickup were recorded on the digital read-out he had on the winding lathe.]