Funny but the internet brings up everything. I didnt know it but SRV and many others used a dummy coil to get lesser noise from the SC Position 1 3 5. Old PU without the magents.
Have to try this in Janurary.
So where exactly is the dummy coil placed : in the cavity ? How is this better than shielding the cavity ?
Sheilding is effective against RFI but not EMI. Sheilding the cavity is often only partly effective, as the pickups protrude past the shielding; sheilding the coils themselves helps with this but can have a detrimental effect on tone according to some users, may be pickup dependant.
I don't know where you'd put the coil, but pulling the magnets from a Fender pickup is dubious, as the top and bottom plates are glued directly to the magnets with no other mechanical reinforcement, so pulling the magnets could cause either damage to the inner windings or outright collapse of the coil. It's possible that using a coil with a plastic bobbin like one from a cheap, old Teisco pickup might be a substitute if coil characteristics were close enough. Using the Ilich system eliminates these problems, as their coil is attached to the underside of the pick guard or the inside of a rear cavity cover, depending on guitar type.
The use of a dummy coil in guitars was pioneered by the Alembic company in the '60s, who used a dummy coil mounted in the center position on many of their two pickup instruments.
Post by jimwilliams on Jan 7, 2018 14:54:26 GMT -6
Plenty of issues trying that out. First is it needs to be run in parallel with the active pickups. That changes/darkens tone and lowers output levels. Next, the "dummy" coil still has magnets and will pick up any ferrous induced movements. It's ALIVE!
Alembic first addressed this back in the 1970's by using a dummy coil without any magnets and a buffer opamp to blend it. Les Paul created the first "stacked" humbuckers on his Les Paul prototypes back in the 1950's. Gibson still sells those as the "P-100's", a stacked P-90 design.
My solution was a dedicated hum cancelling preamp and a dummy coil fitted internally. The preamp is two inputs, one for the active pickups and one for the dummy coil. The dummy was made from a Jap Fender strat pickup, the plastic bobbin types with the ceramic bar magnet and steel pole pieces, all of that was removed. The dummy side of the preamp has frequency response shaping (don't need anything above about 2k hz) and then feeds a trimpot for blending. I get about a -80 db hum null with that circuit, quite respectable.
My Telecasters are as quiet as the Gibson's with covered humbuckers, a joy to play out live. I once offered this design to Fender but they were not interested. I guess hum is part of Fender's appeal?