Hi Mark and Aunty Em,
Yes, you are correct. Moreover, the vast majority of LPs had no really low frequencies below 30 Hz on them because most modest or inexpensive commercial phono cartridges wouldn't track the frequencies. It was common in the mastering of LPs to roll off lower frequencies sharply below 30 Hz. The exception were some half-speed mastered LPs and a few audiophile labels like Telarc.
Also, a subwoofer used with any turntable will tend to reproduce sub-sonic tonearm/cartridge warp frequencies, generating "woofer flap"--the woofer visibly going in and out trying to reproduce the ultra-low resonances, at 12 to 15 Hz, wasting amplifier power and creating a type of Doppler distortion.
Heavens, when I get into describing all the things that are wrong with analog vinyl playback, I can scarcely believe how we put up with it! Of course, the only alternative back then was tape, preferably open-reel. Even the cutting lathes used to master LPs had audible rumble components.
I recall a few audiophile LPs that had huge groove excursions, frequencies to 20 Hz and lower, which we used for phono cartridge tracking tests: the "1812" Overture (Tchaikovsky) on Telarc. The canon shots would literally cause most cartridges to skip out of the groove.
Cheers,
Alan
