LP playback curves equalizer AKEQ-2 mono

Tube in shielding case.

LP playback curves equalizer AKEQ-2 mono

Front view.

LP playback curves equalizer AKEQ-2 mono

front panel

below only ....WiKi explain what's FFRR78

78rpm playback curves

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.

Extract 78EQCurveGen.ny from the zip file downloaded from the above Forum topic.

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.

Click . You can find help inside the plug-in by choosing one of the Help options in "Select Function or Help".

Choose the curve you want from the list below.

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.

Click "OK" in the plug-in to save the .xml file to your chosen location.

Select some audio and choose .

Choose "Save/Manage Curves...".

Choose "Import...", navigate to the location where you saved the .xml file from 78EQCurveGen.ny, then "Open".

Click "OK".

Now ...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.

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.

EQ Curve List

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)	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

G.I.P Laboratory 是以復刻WE西電-勵磁式號角喇叭的公司，是在日本 YL Acoustics 復刻WE西電勵磁式號角喇叭之後才開始。全部單體的磁鐵都是勵磁式設計，也就是需要額外供應電源才能產生磁力的勵磁喇叭，號角另接。

8吋全音域喇叭原是以復刻WE755A(鈷磁Alnico)為樣本，另補高音GIP-597A。

G.I.P Laboratory 三音路設計，高音單體原廠編號是GIP-597A Model 2，它是以W. E.經典的597A高音單體為樣本復刻而成。中音則是GIP-D5015A (原WE594)，前方擁有開口頗大的號角，低音單體則是GIP-W4601A，深埋在箱體裡面，以woofer horn 設計是所謂低音號角。箱體採用美松夾板製成，兩側金屬方形外殼是額外供應電源才能產生磁力的勵磁式喇叭電源，採定電壓定電流源設計。