A Loudness control wasn't intended to be scientifically accurate. It was intended to make records sound better, especially at lower volumes where the bass would sort of "disappear".

Yes, it was crude because it didn't need to be more than that. Today, you won't see loudness controls on audio equipment (except maybe on the uber low end). Instead, you have to deal with things like Audyssey, MCACC, YPAO, or other room correction software. Everything has gotten way too complicated and scientific. It's time to just sit down and enjoy some good music...

Sorry to go OT.