M2TECH JOPLIN MKIII, Руководство пользователя

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JOPLIN MKIII
384
k
H
z
/32bit ANALOG-TO-DIGITAL CONVERTER
REVISION P
R
A – APRIL 2019
Copyright © 2019, M2Tech Srl
43
M2Tech
www.m2tech.biz
9.2.16. Brunswick
Brunswick is a very old record company who mainly produced 78rpm’s. The curve offered
with the
JOPLIN MKIII
is the one used for the 78rpm’s.
9.2.17. Columbia 1925, Columbia 1938 and Columbia England (CO25, CO38
and COLE)
Columbia was very active cutting 78rpm’s before introducing the microgroove LP. She
used different curves in different years: one between 1925 and 1938 and one from 1938
on. Not only: her English branch, Columbia England, developed her own curve for 78rpm’s
cut in Great Britain.
9.2.18. Decca FFRR 78rpm (DEC)
This is the equalization curve for 78rpm used by Decca, from which the LP FFRR was later
developed.
9.2.19. MGM 78rpm (MGM7)
Before cutting LP’s, MGM produced 78rpm’s, which were cut using MGM proprietary curve
for 78rpm.
9.2.20. Victor 1938-47 and Victor 1947-52 (VIC3 and VIC4)
Victor is an old company, later purchased by RCA, who produced 78rpm since 1925. The
curve adopted between 1925 and 1938 is same as Columbia type 1925 (See 9.2.16), later
curves are offered with specific choices.
9.3. Equalizing tapes: why and when
Recording and playback heads used in tape recorders have a frequency response which is
strongly non linear and heavily dependent on the magnetic flux in the tape. Moreover, the
tape hiss increases with frequency. For this reason, also tapes are equalized. Two
equalization standards exist: NAB, mainly used in USA and Japan, and CCIR (later IEC),
mainly used in Europe. To make things more complicated, each standard has different
curves for different tape speeds, as flux changes with speed.
The main difference between records and tapes is that almost no turntable is provided with
a built-in phono amplifier/equalizer, while almost all reel-to-reel tape recorders are. Thus,
providing tape equalizations could seem to be useless.