A phono preamp with equalization selector

"A friend noticed me they should be played with Teldec equalization plus inverted polarity,"

Some friend you have there-encouraging unecessary audio nervosa.

ghdprentice

My Audio Research Reference 6SE has Columbia and Decca ...

That's your 3SE, George.

GHD, You say "used in the 40s and 50s".  For most of the 1940s, the 33 rpm LP as we know it today did not yet exist.  I think the very first such records were produced in 1948-49.  It was the introduction of this then new technology that necessitated the new equalization curves. 78s and whatever else was in common use through most of the 1940s were certainly not equalized according to any of these algorithms.  From there, I refer you to the article by MF that I referenced above. Whatever one might think of MF in terms of his opinions as an equipment reviewer, I do trust him to do a thorough job of research when he addresses these general subjects that apply to the hobby.  I take Ralph Karsten's (Atmasphere) word as well, that the companies that made the equipment upon which LPs were cut (Westrex, etc) who determined what equalization curve to use, and that all of these companies had adopted RIAA by the mid-50s. (Yes, I suppose there are rare exceptions, but I don't know of any, and maybe they did it differently at first, in the UK.)

@cleeds

Yes, my bad.

👍

@lewm 

Yes, you are correct the LP was introduced in 1948.

Right. I have access to every eq curve ever concocted. I only use RIAA except when playing old 78s. If you do not play old 78's it is totally unnecessary to consider other EQ curves. It is for all intents and modern purposes a marketing feature no one needs or uses.