RIAA vs Columbia vs Decca

http://en.wikipedia.org/wiki/RIAA_equalization

Well find out which one sound right for each LP you are playing.
At least up to the mid 1950's the alternate curves were in use.

The Wiki aticle claims some used alternate curves as late as the 1970's..
Though most of them were basically similar. With a cut of bass, and a boost of treble in recording. with the reverse in playback.

Remastered LPs of original monos will have the RIAA curve even though the original might have used different EQ. BTW most of the alternate EQ settings (Columbia and Decca being two examples) are used for 78s and were never used for LP.

I just purchased the ARC phono stage as well. While I realize RIAA is technically correct, I've found the Columbia eq takes the edge off the bright strings on early stereo Columbia Masterworks recordings. I'm dumbfounded, but it really makes Walter and Szell much more listenable.

The problem with old records is not only RI.A.A. but in many cases also reverse/inverse phase:

"those made in the late 70's & 80's, many labels did not adopt R.I.A.A. curve in the 50's, 60's, 70's and even 80's, that was why even though I had acquired many LPs, half of them did not sound good. Yamada-san further explained to me several years ago in the tube era, big labels such as DECCA, EMI, Deustche Gramophone used their own in-house equalization curve in their recordings and all of them were in reverse/inverse phase, you can easily check this out when you play CDs with old recordings of the abovementioned labels"