I'm looking for the time constants for the 78rpm RIAA curve. I can find several hundred pre-RIAA curves for 78rpm, and the 33.3rpm RIAA curve, but no luck on the 78rpm one.
TIA
TIA
There's only one RIAA curve. Well, two if you count the variation with the extra pole, but that's splitting hairs.
There's lots of info out there on the various EQ curves that were used back in the 78 days. Here's one place to start:
Playback equalization for 78 rpm shellacs and early 33⅓ LPs - Audacity Wiki
There's lots of info out there on the various EQ curves that were used back in the 78 days. Here's one place to start:
Playback equalization for 78 rpm shellacs and early 33⅓ LPs - Audacity Wiki
AFAIK, the nearest thing to a 'standard' on 78s (which were not all 78rpm) was the Western Electric cutting head and/or the copycats made to evade WE royalties. This is semi-documented in the RCA papers printed in AUDIO. The WE cutter was not reference-grade because the damper(s) drifted out of tune and were not cheap to re-rubber.
Here's a different analogy. WWJD? Joseph, the carpenter who raised the Christ child. Look for his joist and rafter span-table. How big a log to span 7 cubits? We don't know exactly what he would do. There was no Building Code. There was hardly the math to compute loads (just as the speakers in 78 shops were not real good). Moreover, while post-1957 cutters could be quite flat and all EQ first-order, older cutters could have complex resonances and non-minimum phase delays. IMHO most 78s can be EQed the way they did in the old days: by ear, with allowances.
Here's a different analogy. WWJD? Joseph, the carpenter who raised the Christ child. Look for his joist and rafter span-table. How big a log to span 7 cubits? We don't know exactly what he would do. There was no Building Code. There was hardly the math to compute loads (just as the speakers in 78 shops were not real good). Moreover, while post-1957 cutters could be quite flat and all EQ first-order, older cutters could have complex resonances and non-minimum phase delays. IMHO most 78s can be EQed the way they did in the old days: by ear, with allowances.
