older LPs - different EQ?

After seeing 35,000+ LPs in one place on Sunday, including a wide variety of selections from the early years of recorded music, I suddenly remembered a foggy thing that I read a while back, and I want to confirm.

My impression is that pre-1958 or so (1955?) the record companies used a different equalization curve than the now-ubiquitous RIAA equalization. Is this true? If so, what sort of phono stages do equalization for these properly? Anything else to be aware of in this space?
i think the curve on the lp(33.33rpms) has been the same since the beginning...i wouldn't worry about it.
There are some different eq. curves in the older records. Columbia, Decca/London, another one that I can't remember, and the current RIAA. And yes there are some phono stages that have selectable curves that are built-in. Don't ask me to name one, but I know they are out there, because I have read about them.
My Marantz 7T (as did the original tube 7) had three different EQ curves on it, one if I remember well was a Columbia curve and also a different curve for '78s.

Bob P.
I know of one phono preamp that has adjustable RIAA curves, it is the FM Acoustics Resolution Series 122. I had a chance to listen to it about 2 years ago and it was one of the best I have heard tube or ss. I am not sure if they currently have a US importer but if you have a large collection of older lps it would deserve a serious audition.
The Krell KPA phono pre-amp also offered on-the-fly RIAA curve adjustment.

Greg D
KAB electroacoustics makes an audiophile grade remastering phono preamp. It covers every equalization curve ever used:


I am getting into older LPs, especially Argentinian music!
The first separate preamp that I had was a Heathkit, and it had several different equalizations. To tell the truth, the different curves were not all that much different, and judicious use of tone controls or better still, an equalizer, will solve your problem.
Some of the early eqs are really different than the RIAA eq and can sound pretty weird if some attempt is not made to get them into shape. The Hagerman Bugle can be ordered with any eq, but it is fixed, not variable, though only around $125.00. Hell, you could buy three of them, Columbia, Decca and Capitol for less than the cost of your interconnects. Gram Slee Projects makes an inexpensive phono stage with variable eq for older records, Jazz Club, I think, around 1K. The Boulder can have special eq cards ordered for it; good to know if you're the one collecting the reward for finding Sadaams two kids. The Zanden offers three choices of eq, again, lottery winners and crack dealers only need apply. Personally, this is just one more reason to own a preamp with tone controls. It may not be "right", but makes most non-standard eqed records quite listenable. Don't forget, even with correct eq, a lot of these things can use some tailoring anyway due to the mikes and recording gear used.
Hmm... where would one find out which labels require which curves? I did play one of those old LPs and it did sound weird, but the equipment was laughably unrealistic, badly configured (bass, treble whacked max, loudness turned on, big boomy Kmart speakers). I wasn't 100% sure that I was hearing a weird EQ curve or just bad reproduction. (The equipment was quite good enough, though to figure out if the LPs were in good shape, which is what I think is its intent.)
You'll be in for a surprise.
Most labels used their "own" cutting curve until 1958 - and even in 1964 the RIAA had to issue a reminder to the record producers that in fact they had agreed to use the RIAA curve and would all please use this from now on...

While they confirm they have not all curves ever used FM ACOUSTICS has researched curves of 85 different labels so far - all of which can be correctly reproduced with these phono preamps.

Once you hear the difference when the correct setting is used in comparison with the RIAA setting you will not want to listen again without correct curves. The difference can be larger than the differences in hifi systems.
chiefslave1: which phono preamps do this? Looking at the FM Acoustics web site shows two phono stages, but neither of them seem to claim anything about various equalization curves. Am I looking in the right place?