Det er godt vi er i den lyse tiden av året, der det er hyggelig å sitte oppe og lytte til musikk mens man setter seg inn i ulikt.
Mye feilinformasjon på nettet omkring dette med merkespesifikke EQ-kurver - og da i begge retninger. Alle gikk ikke over på RIAA i 1954/55, men tilsvarende ser det ut som om de store selskapene rettet seg inn etter denne kurven innen utgangen av 50-tallet. Det avhenger litt av hvem man velger å tro.
Tror vi AMR-Audio er det bare å gå til innkjøp av sofistikert multi-kurvesjalter:
The original Mercury Living Presence series (Decca FFSS, Decca FFRR EQ)
The original Deutsche Grammophon Classical records (Decca FFSS, Decca FFRR, CCIR EQ)
The original Miles Davis records (Columbia EQ)
Verve Jazz records, with performers like Charlie Parker, Count Basie, Ella Fitzgerald, Nina Simone and The Righteous Brothers etc. (Columbia & AES EQ)
The original Dave Brubeck Quartet records (Columbia EQ)
A significant number of the original stereo Decca (Europe) records (Decca FFSS, Decca FFRR EQ)
Rectify high frequency roll-off and excessive phase shift of all, including Neumann and Western Electric vinyl cutting lathes (Enhanced RIAA EQ)
Tror vi det tyske HiFi-museet, så er bildet slett ikke så ille -- men typisk nok var det også Tyskland som forsøkte å innføre en egen standard, fremfor å følge RIAA. På denne linken er det mer informasjon enn jeg noensinne trodde jeg hadde lyst til å ha innabords, men den er interessant. Skrevet av en som arbeider med arkivering av plater over på andre formater, og som er meget opptatt av at man bruker riktige innstillinger for å gjengi opptakene korrekt. Han har gjort utstrakte lyttetester, og gått så langt som til å få fatt i ulike utgivelser i forskjellige land, for å sammenligne dem.
http://www.hifimuseum.de/sound-restoration-teil-6.html
For mono og stereo fra 50-tallet og tidligere (mono) er sjalting høyst relevant; for opptak utover 60-tallet mindre relevant, selv om det dukker opp unntakstilfeller. HiFi-museets link dekker ikke opptak i Østblokken, der man visstnok fortsatte å bruke CCIR eller andre RIAA-avvikende kurver.
Ulike nettsted (og produsenter) gir inntrykk av at DGG fortsatte å bruke RIAA-avvikende EQ langt ut på 60- og 70-tall, men det står ikke hogd i stein noe sted jeg har funnet hittil. Engasjerende emne, og jeg har lært mye nyttig om vinyl ved å lese meg gjennom HiFi-museumets usedvanlig seriøse og hakesleppdetaljerte gjennomgang.
Den som har skrevet HiFi-museums gjennomgang er meget avvisende til digital korreksjon, og mener dette gir misvisende resultat.
Et lite sitat fra sistnevnte omkring EQ-anbefalinger fra produsentene, som viser hvor uoversiktlig dette er:
Many early LPs were packed in sleeves with equalisation details; but I know cases where sleeves were reissued without the details, or records were re-mastered but packed in old sleeves. I have also met cases where the sleeves were printed in one country and the records pressed in another, with consequent mismatches in the documentation; and second-hand record shops have proved unhelpful, because proprietors (or their customers) swap sleeves and discs to get a complete set in good condition. I can think of only one way to solve these difficulties - collect a number of records of the same make, and of the relevant age and country of origin, and study the sleeves as well as the discs to work out the originals (which is what Ive tried to do here).
Some manufacturers consistently advocated the same standard curves, even when they pressed records from imported metalwork (or even their own old metalwork) made to other characteristics; and of course there were always black sheep who never said anything at all on the subject! There is considerable aural evidence that users of each of the standards converged to reduce the differences between them, although they never admitted it.
HiFi-museets skribent mener det er helt feil å ta utgangspunkt i etikett på LP, siden det er hvor den ble kuttet som er avgjørende, og viser også til avvik innenfor samme merkenavn, som hos Decca:
My own research shows there were actually three different curves (komm. hos Decca). I did listening tests, comparing ancient LP issues with more-modern versions (assumed to be RIAA), or with original 78s (assumed to be 25 and 531 microseconds). Before I can give the results, I must describe Deccas LP matrix numbers. Prefixes were ARL for 12" and DRL for 10". Next came the matrix number, allocated in numerical order as far as I can tell; and then the take number (signifying the attempts to make a satisfactory metal negative). Then a letter to indicate the disc cutting engineer, and sometimes a W which (I believe) indicates a master-disc cut in wax rather than nitrate. On British versions, an R may follow. This means Remastered, after which the take numbers go back to 1; unfortunately these may be any of the three equalisation curves. However, if the matrix number is engraved rather than punched, this proves RIAA, because the engraving machine was purchased some months after RIAA was adopted.
The three curves are:
(1) Blumlein 500Hz (318 microseconds), used for (Take 1s of) matrix numbers up to ARL1170-2B (and of course many higher take-numbers of these).
(2) 50 microseconds and 318 microseconds, used for (Take 1s of) matrixes ARL1177-1B to ARL2520-2A (and of course many lower numbers with higher take-numbers than 1). It is only fair to say that comparisons sometimes sound better using 40 microseconds instead of 50, but there is no consistency about this. During this period, UK Decca and Telefunken introduced the MP format (meaning Medium Play, ten-inch discs roughly paralleling what had been issued on 45rpm EPs). These matrixes were numbered in the TRL series.
(3) RIAA (75, 318 and 3180 microseconds), used for ARL2539-2A onwards. Deccas RIAA engineering test disc is LXT5346, with matrix number ARL3466-2. MP discs switched to RIAA at about matrix TRL392.
Unfortunately, by the time Decca switched to the new International Standards the company had changed to a new internal procedure for its single records. They called it a Sub-Matrix Number. Each track was given a sub-matrix number when the tape master was made, and this number would be transferred to the 78rpm or 45rpm matrix when the disc was cut, which might be anything up to a year later. Thus we cannot use such a matrix number to tell us when the master disc was cut.
The only possible way of breaking this hiatus is to assume that the matrix engraving-machine was introduced simultaneously for both LPs and singles (and EPs and other media), and thus that everything with an engraved matrix number must be RIAA.
