Should I play modern 78s?

[Wolfe]

. The earliest Columbia LPs are sometimes called "coarse groove records" because their grooves are a bit larger than regular LPs. 45s can be a bit coarser too, but I suspect that is just a volume difference since running time wasn't as much of an issue with singles. Coarse grooves and 45s generally play better with a larger stylus.

The earliest mono Columbia LP's have a 1 mil groove, the original set standard for microgroove records. 1 mil remained for mono LP's across the spectrum right up until mono LP's were phased out in the late 1960's. They do sound better with a 1 mil tip, rather than at .7 for stereo records, bass frequencies tend to be rendered better with the 1 mil, but sometimes the difference is negligible.

Not aware of any early Columbia microgroove records that deviate from that.

The early RCA Victor 33 ⅓ 'Program Transcriptions' do have slightly larger grooves, however. I think about 1.5 mil is considered ideal for those.