A phono preamp with equalization selector

@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.  

I'll Take You Down Memory Lane.

My Uncle's 1958 Fisher President II, EQ had not yet been Standardized

Very Unique 'Stereo Radio' (Live Binaural Broadcasts)

Look up the Harmon Kardon Festival monaural receiver. That’s what my parents had as of the early 50s, even predates the unit shown above. As I mentioned, it provided a choice of EQ curves including RIAA, Columbia, Decca, and maybe one other. I’m guessing that this is because the industry was just settling on RIAA during the period 1948-55(?). I do recall fiddling with the EQ in order to hear the differences. So maybe if you own very early production mono LPs, there might be a marginal benefit; the different EQs did not seem to make much difference to tonal balance, to my pre-teen ears.

Here is the HK Festival monaural tube tuner from early 1950s.  My memory of its built in equalization curves was faulty; the photos show "Eur", "RIAA", and "LP", not Columbia or Decca.  I wonder what were the differences between Eur or LP vs RIAA.