In order to create records in the first place, adjustments had to be made to compensate for the lack of surface space on a record. Because records rely on grooves, in order to accurately relay Bass passages on a record, the grooves would need to be so far apart that in many cases it would be impossible to fit a full song on a 78 or more than one or two on an LP. In order to compensate, records were designed minus a great deal of the Bass and manufacturers depended on the equipment that they were played on to add that bass back into the file during the listening process.
An EQ Curve is simply a preset equalizer that says, "I know you're going to be missing these frequencies...I'll just put them back in automatically."
The RIAA curve was designed for LPs and 45s. Almost all modern preamps or stereo systems add this RIAA curve in one respect or another on playback. In the heyday of turntables and stereo systems, many folks would shop for hours until they found the stereo system that sounded best. Because all stereos sounded differently, this can let you know just how well this RIAA curve was followed. Each company interpreted these EQ settings with their own style. While this was good for listening, it may not be the best for today's technology. If you are mainly transferring LPs and 45s to the computer, you may want to read about the CTP1000 Flat Phono Preamp Series. Just Click Here.
78 records were designed differently and require a different set of equalizer settings in order to play them accurately.
Verify that
you are utilizing the correct equalization curve for the particular type and
brand of record that you are about to transfer.
Turnover and sometimes Roll-off are critical breakpoint frequencies that
must be matched in a complementary manner to the recording process in order to
preserve the "flat" response of the original recording session.
Turnover frequencies for electrical recordings are between 200 to 500
Hertz, and are in the 5 KHz region of the audio spectrum.
Acoustical recordings should always be transferred "flat" and
"electricals" should be transferred with equalization that is the
correct inverse of the recording equalization that was used in the mastering
process. There are tables of values
available to determine the correct values for this. Also, it is important to have a pre-amplifier that has the
ability to adjust the turnover and Roll-off frequencies.
For more information on this topic, refer to the section entitled
"Record Transfer to Hard Drive Technical Hints."
Below is a list of common Turnover Frequencies for some of the more
common brands of lateral cut 78-RPM records:
Type,
Brand, or Process |
Turnover
Frequency |
|
|
Acoustical
Recordings |
0
Hz |
|
|
Columbia
(1925 - 1937) |
200
Hz |
Victor
(1925 - 1937) |
200
Hz |
Westrex |
200
Hz |
|
|
Decca
(1935 - 1949) |
250
Hz |
EMI |
250
Hz |
English
Columbia |
250
Hz |
HMV
(1931) |
250
Hz |
EMI
(1931) |
250
Hz |
London |
250
Hz |
Blumlein |
250
Hz |
|
|
Columbia
(1938 – End) |
300
Hz |
|
|
BSI |
350
Hz |
|
|
Capitol |
400
Hz |
Mercury |
400
Hz |
|
|
Brunswick |
500
Hz |
Decca
(1925 – 1929) |
500
Hz |
Edison
Laterals (1929) |
500
Hz |
MGM |
500
Hz |
Parlophone |
500
Hz |
Victor
(1938 – 1952) |
500
Hz |
|
|
629 |
629
Hz |