What is the proper name or description for the pickup pictured on top and for the one on the bottom?
And (other than appearance) what are the differences between the two?
Kris, yes I know they're both humbuckers.
Why do some have covers and others don't?
Why does the top show six "dots" and the bottom show twelve?
Is there a difference in sound?
Etc.
the cover is purely cosmetic. some people claim a smotoher high end with covers on (load of bollox) other than that, it's all visual.
traditionaly gibby humbuckers have 6 adjustable poles, and 6 slugs. when you place covers on pickups, the adjustable ones are left visible, except on EMG's and Tony Iommi pickups that have bar magnets.
Potting helps eliminate microphonic feedback, or squeeling when the pickup is pushed into higher gain. Original HUmbucker (From the 50's), and burstbucker pro's are NOT waxed potted, and offer a really great overdriven tone, than you can sorta force into a controlled feedback (like Clapton when he played Crossroads live (he only does it on one note))
IF you're looking for replacement humbuckers that ARE NOT wax potted... I LOVED the Burstbuckers that come in the Vintage Mahogany Les Paul.
if you want Wax potted, try Seymour DUncan 59, or JB, or Custom Custom... assuming you want the sound that I like!
The cover, if it is made of a magnetic metal WILL affect the inductance of the pickup, which affects the sound and power output level. Case in point, the Epiphone humbuckers use a brass cover and a vintage PAF uses a nickel silver cover. Brass is non-magnetic, and the highs and lows are more pronounced and the pickup tends to sound less natural. Wax potting helps to avoid feedback problems, but it also reduces the touch response of a pickup. Someone in the crowd would never notice any difference, but the player sure notices.