Educate me - what's this pickup cover all about

[peskywinnets]

Daeil Parts for Musical Instrument

what's the extra lump on the bottom for? (vs say the other pickup cover here .... Daeil Parts for Musical Instrument )

Also, re this bobbin...

http://www.toparts.kr/pb_05.html

available in ABS or PBT...what's the pros/cons of either?

cheers,
Pesky.

[Magnut]

That extra bit is most likely to "house" or cover the ceramic magnet.

[marku52]

Sky, it looks to me like the bulge on the bottom would be to cover up a ceramic magnet for a ceram/iron pole peice design. why you would bother to cover it up is unknown at this point.

ABS and PBT. Two different plastic materials. ABS (Acrylonitrile_butadiene_styrene) is a very common material. If you built plastic models as a kid, they were made of styrene, a subcomponent of ABS. ABS is stronger than plain styrene. Very common engineering resin. PBT (Polybutylene_terephthalate) is commonly used as the insulator in electrical housings. Why choose one over the other?

No Damn Idea. Either should be fine. Now Nylon is something I'd avoid. It is hydroscopic, means "absorbs water". Water is a polar molecule. dialectric losses can go up dramatically in a material saturated with water. Your pickups might sound great in the Sahara, but like sh*t in Florida.

But I would bet a lot of old pickups got made with nylon. It is one of the oldest molding compounds, inexpensive and easy to mold (melts at a reasonable temperature, and flows well)

[David King]

Hydroscopy notwithstanding, nylon is pretty damn tough and wear-resistant. I don't think it's dielectic properties are going to matter much at 100 mV potentials.
It can't be any worse than typical epoxies or forbon for that matter.

[big_teee]

Hydroscopy notwithstanding, nylon is pretty damn tough and wear-resistant. I don't think it's dielectic properties are going to matter much at 100 mV potentials.
It can't be any worse than typical epoxies or forbon for that matter.

Forbon is the absolute worst. Lollar did a post on how bad Forbon warps until it is potted.
I would think Potting would help any bobbin material be more moisture resistant.
Like David Said, at the small voltage and current of pickups.
Terry

[David Schwab]

Daeil Parts for Musical Instrument

what's the extra lump on the bottom for?

Those are the same as EMG covers, so the section on the bottom houses the preamp. The older EMG covers had the threaded brass inserts.