When and why did the term "HiFi" become associated with Lps

[mmilovan]

to me, hi fi is 15khz and above - stereo OR mono -

Well, I have one studio lacquer from 1946. that goes above 15 KHz, and is recorded wonderfully.

I think that major improvement was around end 1930s begin 1940s when newest cutting head were introduced, and also some other equipment (f.e. limiters). Studio equipment for cutting sound master lacquers then produced trully hi-fi sound.

[Shrdlu]

to me, hi fi is 15khz and above - stereo OR mono -

So it's something neither of us can hear anymore...

"All the highest notes, neither sharp nor flat / The ear can't hear as high as that / Still, I thought I'd please any passing bat / With my High Fidelitee ..." (Flanders and Swann, "A Song of Reproduction", from "At The Drop of a Hat", ca. 1959)