78rpm playback curves

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This page serves as a library of additional EQ curves for old disc recordings that can be used in the Equalization effect in current Audacity.
While this page deals mainly with 78rpm playback equalization curves, some detail on early (pre-1955) LP curves is also included.
 
Related article(s):


Contents


Usage

These EQ curves are presented as a table of "Bass Turnover Frequencies" and "10 kHz Gain Rolloffs". EQ Curves for Audacity can be generated from these Frequency and Rolloff values using the experimental Nyquist plug-in "78 RPM EQ Curve Generator". This plug-in is obtainable from the top of this Forum topic and requires Audacity 1.3.13 or later. Please give feedback on this plug-in, or ask for help if you need it, by replying to that Forum topic.

  1. Extract 78EQCurveGen.ny from the zip file downloaded from the above Forum topic.
  2. Place 78EQCurveGen.ny in the "Plug-ins" folder inside the Audacity installation folder, then launch or restart Audacity. For more help installing the .ny file to the correct location, click here.
  3. Click Generate > 78 RPM EQ Curve. You can find help inside the plug-in by choosing one of the Help options in "Select Function or Help".
  4. Choose the curve you want from the list below.
  5. Enter the values for your chosen curve for
    • "Bass Turnover Frequency (Hz)"
    • "10 kHz Gain Rolloff (dB)"
    • "LF Shelving Frequency (Hz)" (if a value is given)

    in the equivalent boxes in the plug-in dialogue.

  6. Click "OK" in the plug-in to save the .xml file to your chosen location.
  7. Select some audio and choose Effect > Equalization.
  8. Choose "Save/Manage Curves...".
  9. Choose "Import...", navigate to the location where you saved the .xml file from 78EQCurveGen.ny, then "Open".
  10. Click "OK".


Equalization (EQ) Curves Explained

When phonograph records are made, the sound being recorded is deliberately distorted by reducing the volume of the low frequencies and increasing the volume of the high frequencies. This process, known as 'pre-emphasis', allows the low frequencies to be accommodated in the limitations of the record groove and reduces the effect of high frequency surface noise. If pre-emphasis was not carried out, the bass notes in the music would create a groove in the record that oscillated so wildly that the stylus could jump out of it on playback, and the treble notes would be drowned out by the surface noise of the stylus in the groove.

On playback, the pre-emphasis must be reversed in order to restore the original sound. This is known as 'de-emphasis' or equalization (EQ).

Modern vinyl records use a method of pre-emphasis and de-emphasis adopted by the Record Industry Association of America (RIAA) in the 1950's, and the EQ curve used is known as the RIAA curve. However, before the RIAA curve was adopted, each record label used its own EQ curve for recording and, for these records (78rpm and early vinyl), the correct EQ curve must be used for playback.

Each 78rpm EQ curve is a combination of two filter characteristics; a bass boost curve, defined by a 'Bass Turnover' (or 3dB) frequency, and a treble cut curve, defined by a '10 kHz Gain Rolloff' parameter, i.e. a defined level of treble cut at 10 kHz.

As an example, Figure 1 below shows the characteristic of the bass boost curve defined by a 500Hz Bass Turnover, and Figure 2 shows the characteristic of the treble cut curve defined by a 10 kHz Gain Rolloff of -13.7dB. These two curves, when combined, give the characteristic shown in Figure 3.


Bass Boost curve

Figure 1. Bass Boost curve: 3dB at 500 Hz


Treble Cut curve

Figure 2. Treble Cut curve: -13.7 dB at 10 kHz


Combined Bass Boost and Treble Cut curve

Figure 3. Combined Bass Boost and Treble Cut curve


The EQ curve may also include a Low Frequency Shelving filter, (although it is absent from the definition of most 78 rpm EQ curves). This addition reduces the effect of the bass boost at very low frequencies (typically 50 or 100 Hz) in order to attenuate low-frequency noise such as turntable rumble. Figure 4 shows the effect of a 50 Hz LF shelving filter being added to the curve in Figure 3. This is in fact the RIAA standard EQ curve.


Combined Bass Boost, Treble Cut and 50 Hz LF Shelving curve

Figure 4. Combined Bass Boost, Treble Cut and 50 Hz LF Shelving curve


Acoustically recorded (pre-electric) 78rpm records have a 'flat' EQ curve, i.e. with no bass boost or treble cut and, in some early electric EQ curves, while there is a bass boost curve, the 10 kHz Gain Rolloff is zero, i.e. there is no treble cut.

Note that in the combined EQ curve, the gains at the Bass Turnover frequency and at 10 kHz may be different from those specified by the parameters. This is not an error, but is due to fact that the gains of the bass boost and treble cut curves are simply added together.

Because 78 rpm EQ curves were non-standard and, in many cases, accurate records were not kept to show what EQ curves were used when recording 78s, there is a degree of uncertainty about what is the correct playback EQ for many record labels. The tables below have been obtained from websites which, in their turn, have compiled data from a number of sources and should prove reasonably accurate. However, the ear of the listener is the final arbiter - if it doesn't sound right, it isn't right!

According to NAB standards, the nominal speed of a 78 RPM record is precisely 78.26 RPM +/- 0.5%.


EQ Curve List

The curves in Table 1 and Table 2 below were obtained from the following publicly available sources:

1. Millennia 78 EQ chart (PDF).

2. Wilmut's World Wide Website

3. Wolverine Antique Music Society

According to the author of [2]:
Westrex (English Western Electric) should be used for HMV 78s with triangle matrix code and English Columbias with a W matrix code. Also for HMVs with diamond mark which are American Victor recordings.
Blumlein should be used for HMVs with a square by the matrix number, and English Columbias with a C , or in both cases with no code (post 1945) up to about 1953.
BSI 78 should be used for all post 1953 78s.


Table 1: 78rpm Playback Equalisation Curves

Label Series Bass Turnover
Frequency (Hz)
10 kHz Gain
Rolloff (dB)
LF Shelving
Frequency (Hz)
Source
Acoustic Recording

(such as cylinders, etc..)

0 (or as required) 0 (or as required) 1
AES standard 400 -12 1
AFRS Transcriptions 500 0 or -5 1
Allegro 750 -16 1
Allied 500 -16 1
American Recording Society 500 -12 or –13.7 1
Angel 500 -12 1
Arizona 400 -12 1
Artist 500 -16 1
Atlantic 500 -16 1
Audiophile 300 -8 1
BBC Transcriptions 1949 500 -5 1
BBC Transcriptions most 250-300 0 to -5 1
Bach Guild 501-529 500-750 -16 1
Banner adjust as required 500 -16 1
Bartok 629 -16 1
Bartok 301-304, 309, 906-920 700 -16 1
Berliner speed = 71.29 RPM 0 0 1
Blue Bird 800 -10 1
Blue Note Jazz 400 -12 1
Blumlein 250 0 50 2
Boston COL* -16 1
Brunswick rare 1000 -8.5 1
Brunswick from 1946 300 -16 1
Brunswick early 300-500 0 or -16 1
Brunswick 500 0 3
BSI 78 353 -10.5 50 [2] 1, 2
Caedmon 629 -11 1
Caedmon 1001-1022 700 -12 1
Cameo inconsistent, adjust as required 1
Canyon 400 -12 1
Capitol FDS 400 -12 1
Capitol-Telefunken 500 0 1
Capitol 500 -12 1
Capitol 1942 400 -12 3
Cetra Soria 400 -12 or -16 1
Cetra 400 -11 1
Coliseum 400 -12 1
Columbia* 1925 200 -7 1, 3
Columbia* 1926 250 -5 1
Columbia* 1938-most 300 -16 1, 3
Columbia* various COL* -16 1
Columbia* European 300 -5 1
Columbia English 250 0 3
Concert Hall 400 -12 1
Contemporary 400 -11 1
Cook Laboratories 500 -11 1
Cook Laboratories binaural inside band 500 0 1
Coral 400 or 750 -12 or -16 1
Decca early 150 or 300 0 or -6 1
Decca 78 150 -9 2
Decca 1946- 400 or 500 -12 1
Decca FFRR 1949 250 -5 1, 3
Decca FFRR 1951 300 -14 1
Decca 1934 400 -12 3
Deutsche-Grammophone 300 -5 1
Dial 500 or 750 -16 1
Disc 300 -16 1
Ducretet-Thomson 450 -11 1
EMI 1931 250 0 1, 3
EMI 33 LP 500 -12 1
EMS 375 -12 1
Edison 0 0 1
Electrola 800 -10 1
Elektra 629 -16 1
Epic thru 1954 COL* or 750 -16 1
Esoteric 400 or 500 -12 1
European 280 0 1
Festival 750 -16 1
FFRR 78 300 -5 40 2
Folkways 629 -16 1
Good Time Jazz 400 -12 1
Gramophone 300 -10 1
HMV 1925-1946 250 0 1, 3
HMV 1946 400 -10 1
HMV 1946-1954 500 or 800 -16 1
HMV American 400 -12 1
Handel Society 750 -16 or -17 1
Haydn Society 750 -16 or -17 1
Harmony Acoustics thru 8/29 300 -16 1
Hit of the Week 500 -5 1
Kapp 700 -16 1
Kendall 629 -16 1
King 500 -16 1
Linguaphone 300 0 1
L’Oiseau-Lyre 500 -10 1
London early 300 0 1
London up to LL846 500 or 750 -10.5 1
London FFRR 1949- 250 or 280 -5 1
London FFRR 1949 250 -5 3
Lyrichord early 400 or COL* -16 1
Lyrichord newer 629 -16 1
Mercury thru 10/54 400 -12 1, 3
MGM 500 0 or -12 1
MGM 500 -12 3
Montilla 500 -12 1
Musicraft 750 -14 1
NAB standard 500 -16 1
New Records 750 -16 1
Nocturne 400 -12 1
Oceanic COL* or 750 -16 1
Odeon early electricals 700 0 1
Odeon pre-1947 300 -8.5 1
Oiseau-Lyre thru 1954 COL* -8.5 1
Okeh electricals 300 0 or -8.5 1
Oriole inconsistent, adjust as required 1
Orthoacoustic Transcriptions 500 -16 1
Overtone 400 or 500 -16 1
Oxford 750 -16 1
Pacific Jazz 400 -12 1
Parlophone varies with era 300 or 500 0 or –8.5 1
Parlophone 500 0 3
Pathe inconsistent, adjust as required 1
Period 500 -16 1
Polydor 300 -8.5 1
Philharmonia 400 -12 1
Polymusic 500 -16 1
Polymusic binaural inside band 500 0 1
RCA Victor early acoustics 71.29 RPM 0 0 1
RCA Victor later acoustics 76.59 RPM 0 0 1
RCA Victor 1925 78 RPM 250 or 300 0 or -5 1
RCA Victor 1931 LP only 700 or 800 0 to –10.5 1
RCA Victor 1933 375 -8.5 1
RCA Victor 1935 300 or 500 0 1
RCA Victor 1938 500 -5 1
RCA Victor 1938 – 1948 500 0 to -12 1
RCA Victor 1938 – 1947 500 -7 3
RCA Victor 1948 500 -10.5 1
RCA Victor 1949- 500 -12 or -13 1
RCA Victor 1947 - 1952 500 -12 3
Rachmaninoff Society 750 -16 1
Radiofunken 400 0 1
Remington 500 -16 1
Renaissance 750 -12 1
RIAA standard 500 -13.7 50 1
Riverside 400 -12 1
Romeo inconsistent, adjust as required 1
Schirmer 1000 -24 1
Stradivari 750 -16 1
Supraphone 400 0 1
Technicord 800 -12 1
Telefunken 400 0 1
Transcriptions various, typical 500 -16 1
Ultraphone 400 0 1
Urania most COL* or 750 -16 1
Urania newer 400 -12 1
Vanguard 411-22, 6000-18,

7001-7011, 8000-8004

COL* or 750 -16 1
Velvet Tone acoustics to 8/29 300 -16 1
Victor 1925 (see RCA Victor for 1929-) 200 to 500 -7 3
Vitaphone 950 -18.5 1
Vitaphone motion picture 300 0 1
Vocalion electricals 300 0 1
VOX 500 or 750 -16 1
War Department 12” Special Services 700 -5 1
Western Electric early transcriptions 300 0 1
Westminster pre-1956 500 or 750 -16 1
Westminster “AES” printed on jacket 400 -12 1
Westrex 200 0 1, 2
Westrex (later) 300 or 500 0 2
Zonophone early 71.29 RPM 0 0 1
Zonophone most 300 0 1
  • COL - Some recordings require a Bass Turnover of 300 Hz or 500 Hz, a 10 kHz rolloff of -16 dB and a LF Shelving filter at 100Hz.
This is often referred to as a "Columbia curve".



Table 2: Pre-1955 LP Playback Equalisation Curves

Label Series Bass Turnover
Frequency (Hz)
10 kHz Gain
Rolloff (dB)
LF Shelving
Frequency (Hz)
Source
Angel 500 -12 3
Audio Fidelity 500 -16 3
Bach Guild 501-529 500 -16 3
Bartok 301-304, 309, 906-920 629 -16 3
Boston 500 -16 3
Caedmon 1001-1022 629 -16 3
Capitol 400 -12 3
Capitol-Cetra 400 -12 3
Cetra-Storia (a)500 or (b)400 (a)-16 or (b)-12 3
Colosseum (a)400 or (b)500 (a)-12 or (b)-16 3
More to be added
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