I want to use a Shure standard mount cartridge but my tone arm only has two wires. I plan to play 45's. Some of my records sound O.K. but some sound like I'm playing them on a stereo tuner with the balance control all the way to either the left or right. If just jumper A and B pins(and grounds) it seems to work. Is this an acceptable method? I wondered how you handle this situation where a customer purchases one of your 78 rpm (mono) stylus and plugs it into a standard mount(4 pin) cartridge. Maybe there is a more acceptable solution than my wire-the-pins-together method?
Your solution is the correct one. There will be no damage to the cartridge or your system.
All current Shure cartridges are stereo (four output pins) and if used with a monaural arm (two wires), we suggest the same wiring you employed.