Columbia Vinyl LP Equalization Curve

[Craig Maier]

Columbia introduced the Vinyl LP into the market in the spring of 1948. Unlike 78's which contained only a Turnover frequency in it's EQ curve, they used a different EQ curve including both a Turnover and a Rolloff frequency. After 1954, the LP industry standardized on the RCA EQ curve which became known as the RIAA EQ curve.

The RIAA curve turnover corner frequency began at 500 Hz and it's rolloff began at 2120 Hz, with the low frequency shelf occurring at 50 Hz.

The Columbia curve turnover corner frequency began lower at 300 Hz and it's rolloff began at around 1600 Hz, with the low frequency shelf occurring at 30 Hz.

Thus, early Columbia Vinyl LP's will not sound quite correct when transferred using the RIAA system. Most noticably, they will sound too bright.

Here is the link to a preset that you can use to produce a Columbia EQ curve. If you are using a flat preamp in conjunction with pre 1954 Columbia's, just apply this curve instead of the RIAA curve Paragraphic EQ preset that you have been acoustomed to using.

If you are using an RIAA phono preamp, first you will have to apply the Reverse RIAA curve and then re-apply this Columbia curve.

Note: All of these curves and presets apply to the Diamond Cut Paragraphic EQ.

Link:

http://www.diamondcut.com/vforum/showthread.php?t=2552

[Audyossey]

Here is the link to a preset that you can use to produce a Columbia EQ curve.

Much thanks for this. I have quite a few of those LPs. I do have charts that show the appropriate corner frequency and shelf, but whether I was getting it right when I was processing those LPs is another question. I look forward to investigating this further next month.

HB

[DJBohn]

My thanks to you as well Craig. I've got 9 old single Columbia LP's as well as a few multi-disc sets (not counting the RCA Red Seal counterparts from the same era). 2 are dated 1949 and 1 from 1950. The remaining ones have no listed date - guess I'll have to do a little research on those to be sure. One must be an original 1948 release as it's in a heavy paper flapped envelope (ML-4003) instead of a cardboard sleeve.

But while I was thinking about the possible need for a 1.5 mil stylus to restore them, I found in my collection an odd ball Columbia disc. It's a 5th Anniversary Special LP (ML-4698 - Beethoven - Eroica) using their new "Automatic Electronically Controlled Variable Groove" process allowing more grooves to be squeezed into the LP for even longer playing time. lt left me wondering how well a single sized stylus would work with these...

[Craig Maier]

DJ -

Keep in mind that the RCA Red Seal records were recorded using the RIAA curve - - - even the earliest ones.

[DJBohn]

Thanks Craig, I'll remember that. Also I think it should be noted for everyone to be careful with the EQ of old LP re-issues. I have an old London LP with FFRR printed all over it, but in a tiny little box on the back it says RIAA CURVE.

[Craig Maier]

I think that London ffrr (full fidelity frequency range) was more a marketing thing than an EQ curve. It involved their claim that they captured up to 14 KHz on their 78's in the mid 1930's on forward.

[Audyossey]

...an odd ball Columbia disc. It's a 5th Anniversary Special LP (ML-4698 - Beethoven - Eroica) using their new "Automatic Electronically Controlled Variable Groove" process allowing more grooves to be squeezed into the LP for even longer playing time.

No problem. The system dynamically adjusts the pitch of the groove, not its width or depth and it's standard on all records from about that time on. What they were doing is probably being done today with a read-ahead buffer in a computer. A separate playback head read the audio before the head being used to cut the disc. It anticipated the dynamics of the program material and adjusted the spacing of the groove to avoid overcutting loud passages or to minimize wasted space on soft passages. Many carefully mastered classical 12-inch LPs can safely hold a little over 30 minutes of music on a side.

Everybody did it, but my recollection is that only Columbia advertised it.

HB

[Craig Maier]

These curves can be found and decoded via the VPP (Virtual Phono Preamp).

Craig