Another Long Post
It has been long known that until the early 1950's (in the mono era), different record labels used different equalization curves. Even the same label would have different curves. So early preamps would often have multiple EQ settings. (The need for LP EQ comes from the fact that the excursions for bass frequencies are many times the size those for treble. So when a record is cut, the bass frequencies have their volume reduced, and the treble frequencies are boosted. This allows the bass excursions to fit in a record groove and the treble excursions to be large enough to not be lost in the noise of the vinyl. The EQ curve then reverses this in playback, boosting the bass and cutting the treble ideally in mirror image to the recording EQ.)
The EQ was standardized to RIAA in the early to mid 1950's, particularly led by RCA. However, it has been long commented that many (most) of the record companies, particularly those based in England and Europe (as well as the U.S. Columbia record company) used their own versions of EQ, not following the RIAA well into the stereo era until as late as the early to mid 1970's for some labels.
There is controversy about the variation of EQ in the stereo era. The conventional wisdom is that everyone used RIAA in the stereo era - after all it was the standard, and that no other EQ is necessary for stereo records.
However, there are several manufacturers of phono preamps who have put switches for different EQ curves on their equipment. They have tended to be at the high end. These include the very high end Zanden Model 1200 Mark 3 with curves for RIAA, Decca, EMI, US Columbia, and Teldec, Audio Research Reference 2 Phono Pre with curves for RIAA, Decca and Columbia, Boulder 1008 with curves for US Columbia and some monos, and mid price Graham Slee Elevator, with switches for setting bass shelf, bass turnover frequency, and treble. I currently have the Graham Slee which allows me to do RIAA, Decca, EMI and U.S. Columbia.
Just listening to my many early EMI's, Columbia's and Decca's I can heard the benefit of the non-RIAA curve. In the treble, especially, played through RIAA, the records are excessively bright. There is a 2.3db difference in the treble between RIAA and those labels - which starts in the lower treble (around 2-3kHz) so it is very easy to hear, even with my aged ears. However, some have argued that this was not a result of different EQ, just different mastering preferences.
Since actual documentation of the mastering EQ does not appear to exist and interviews with the now elderly retired mastering engineers are inconclusive, I have come up with what I think is a reasonable test of the EQ issue. There are two main tests. First is comparing an early pressing with a modern high quality reissue of an early EMI or Decca (say Speakers Corner or Testament) which both used the same master tape. The modern recording, cut within the past 5-10 years was definitely done with RIAA. I have listened to several of these comparisons and the original always sounds brighter. When I switch to the proper EQ, the two sound very similar - RIAA for reissue and old EQ for the original. The second test came from a fortuitous circumstance. The Tape Project obtained a master tape of an early Decca recording - Oistrakh playing the Bruch Scottish Fantasy and Hindemith Violin Concerto. They issued a 15ips 2 track of that master tape as part of their Series One. I have an original pressing of the London issue of that record, made in the early 60's. Paying the tape and record back to back, with the vinyl played using RIAA and the old Decca EQ, it was very clear to my ears that the old Decca EQ was the one very close to the master tape dub. The RIAA equalized record was much brighter. I have been told that originals of Beatles, Rolling Stones, etc from the '50s and '60's benefit from the other EQ curves. I don't have those to compare.
My conclusion: If you have a sizable collection of older pre 1970 vinyl, and you want to hear closer to the master tape sounded like, then try a phono preamp with variable EQ.
A note on polarity. If you have the phase resolution power in your system (my system with horns is very good for that), then having a polarity switch on your preamp can help you hear better what was recorded. Think of a trumpet - it is the difference between hearing the air blown at you and the air sucked from you. From what I have been able to hear and to learn, many (most) labels recorded with phase reversed (both channels - not just one - that would be very easy to hear). If the record was heavily multimiked, as in many pop/rock albums, then there is a good chance that some of the instruments were recorded with phase inverted and others not - in that case, it doesn't help. Also if you have dynamic speakers with complex crossovers, then there is a good chance that some of the drivers have phase inverted compared to others - so a phase switch doesn't help there either. I have found that on horns and electrostatics I can hear the phase inversions the easiest. It also helps to have the phase inversion button on your remote (as I do on my Herron VTSP-3A) so I can more easily here the differences immediately. Sounds with strong attacks - like percussion and trumpets are easiest for me to hear.
Another Note: I was speaking to Paul Stubblebine (well known mastering engineer) recently. He told me that many reissue engineers work with an oscilloscope - so they can see the absolute phase of the recording and then use that when they cut the master lacquer. He mentioned Stan Ricker as one who always does that. So Stan's polarity is always correct.
Thanks, Larry
It has been long known that until the early 1950's (in the mono era), different record labels used different equalization curves. Even the same label would have different curves. So early preamps would often have multiple EQ settings. (The need for LP EQ comes from the fact that the excursions for bass frequencies are many times the size those for treble. So when a record is cut, the bass frequencies have their volume reduced, and the treble frequencies are boosted. This allows the bass excursions to fit in a record groove and the treble excursions to be large enough to not be lost in the noise of the vinyl. The EQ curve then reverses this in playback, boosting the bass and cutting the treble ideally in mirror image to the recording EQ.)
The EQ was standardized to RIAA in the early to mid 1950's, particularly led by RCA. However, it has been long commented that many (most) of the record companies, particularly those based in England and Europe (as well as the U.S. Columbia record company) used their own versions of EQ, not following the RIAA well into the stereo era until as late as the early to mid 1970's for some labels.
There is controversy about the variation of EQ in the stereo era. The conventional wisdom is that everyone used RIAA in the stereo era - after all it was the standard, and that no other EQ is necessary for stereo records.
However, there are several manufacturers of phono preamps who have put switches for different EQ curves on their equipment. They have tended to be at the high end. These include the very high end Zanden Model 1200 Mark 3 with curves for RIAA, Decca, EMI, US Columbia, and Teldec, Audio Research Reference 2 Phono Pre with curves for RIAA, Decca and Columbia, Boulder 1008 with curves for US Columbia and some monos, and mid price Graham Slee Elevator, with switches for setting bass shelf, bass turnover frequency, and treble. I currently have the Graham Slee which allows me to do RIAA, Decca, EMI and U.S. Columbia.
Just listening to my many early EMI's, Columbia's and Decca's I can heard the benefit of the non-RIAA curve. In the treble, especially, played through RIAA, the records are excessively bright. There is a 2.3db difference in the treble between RIAA and those labels - which starts in the lower treble (around 2-3kHz) so it is very easy to hear, even with my aged ears. However, some have argued that this was not a result of different EQ, just different mastering preferences.
Since actual documentation of the mastering EQ does not appear to exist and interviews with the now elderly retired mastering engineers are inconclusive, I have come up with what I think is a reasonable test of the EQ issue. There are two main tests. First is comparing an early pressing with a modern high quality reissue of an early EMI or Decca (say Speakers Corner or Testament) which both used the same master tape. The modern recording, cut within the past 5-10 years was definitely done with RIAA. I have listened to several of these comparisons and the original always sounds brighter. When I switch to the proper EQ, the two sound very similar - RIAA for reissue and old EQ for the original. The second test came from a fortuitous circumstance. The Tape Project obtained a master tape of an early Decca recording - Oistrakh playing the Bruch Scottish Fantasy and Hindemith Violin Concerto. They issued a 15ips 2 track of that master tape as part of their Series One. I have an original pressing of the London issue of that record, made in the early 60's. Paying the tape and record back to back, with the vinyl played using RIAA and the old Decca EQ, it was very clear to my ears that the old Decca EQ was the one very close to the master tape dub. The RIAA equalized record was much brighter. I have been told that originals of Beatles, Rolling Stones, etc from the '50s and '60's benefit from the other EQ curves. I don't have those to compare.
My conclusion: If you have a sizable collection of older pre 1970 vinyl, and you want to hear closer to the master tape sounded like, then try a phono preamp with variable EQ.
A note on polarity. If you have the phase resolution power in your system (my system with horns is very good for that), then having a polarity switch on your preamp can help you hear better what was recorded. Think of a trumpet - it is the difference between hearing the air blown at you and the air sucked from you. From what I have been able to hear and to learn, many (most) labels recorded with phase reversed (both channels - not just one - that would be very easy to hear). If the record was heavily multimiked, as in many pop/rock albums, then there is a good chance that some of the instruments were recorded with phase inverted and others not - in that case, it doesn't help. Also if you have dynamic speakers with complex crossovers, then there is a good chance that some of the drivers have phase inverted compared to others - so a phase switch doesn't help there either. I have found that on horns and electrostatics I can hear the phase inversions the easiest. It also helps to have the phase inversion button on your remote (as I do on my Herron VTSP-3A) so I can more easily here the differences immediately. Sounds with strong attacks - like percussion and trumpets are easiest for me to hear.
Another Note: I was speaking to Paul Stubblebine (well known mastering engineer) recently. He told me that many reissue engineers work with an oscilloscope - so they can see the absolute phase of the recording and then use that when they cut the master lacquer. He mentioned Stan Ricker as one who always does that. So Stan's polarity is always correct.
Thanks, Larry