I'm trying to adapt a phono cartridge to replace a crystal one. The newer cartridge is a flip one, actually a sliding switch from 78 to MG. What would MG stand for?

It also has 3 prongs, one being ground?
:I'm trying to adapt a phono cartridge to replace a crystal one. The newer cartridge is a flip one, actually a sliding switch from 78 to MG. What would MG stand for?

MICROGROOVE. 3 prongs would likely be for stereo. One would be the neutral. The other two should be connected together and then to the wire that goes to the high end of the volume control. The neutral lead should be connected to the outer shield of the phono wire.

A note about 78s vs. microgroove records. 78 rpm records have approximately (standard) a 3 mil groove. Long playing records (microgroove) have a 1 mil groove. Most replacement needles for flip cartridges do not come fitted with 3 mil needles with the stupid assumption that noone plays 78s anymore. Unless your 78 needle is fitted with a properly ground 3 mil needle, your 78s will hiss and sound poor. If you push the needle to one side of the groove and then the hiss goes away somewhat, then you know you have the wrong sized needle. A proper needle will fit the groove properly and won't bounce around the bottom. Properly played 78s in good condition are a treat to listen to. They are velvety smooth and like a dream (especially when the Modernaires or Helen Forrest are singing).

Thomas