Rule of thumb; the older the record, the larger the tip size!
• 78 RPM records before 1947 use typically a tip of >65µ
• Electrical 78 RPM recordings beginning late 40-ties use a tip of 65µ
• For Mono LP’s (Microgroove) use 25µ (for late Mono’s 15µ)
• Early Stereo records (33 1/3 and/ or 45 RPM) use 15µ
• … and for all other records use whatever you like best.