JOPLIN MKIII
384
k
H
z
/32bit ANALOG-TO-DIGITAL CONVERTER
REVISION P
R
A – APRIL 2019
Copyright © 2019, M2Tech Srl
40
M2Tech
www.m2tech.biz
See how low frequencies are excessively exalted due to the different turnover frequency
(50Hz for RIAA, 100Hz for FFRR), while high frequencies are attenuated more than
required due to the different roll-off (13.7dB for RIAA, 10.5dB for FFRR).
The sound of this setup would be much heavier and darker than intended by the recording
engineer, with booming low frequencies and muffled highs. A good recording would be
turned into a terrible one!
Now the need for a large collection of phono equalization curves is apparent.
9.2. List of phono equalization curves available on the
JOPLIN MKIII
and
notes on their usage
The
JOPLIN MKIII
is provided with 16 curves for microgroove LP’s and 7 curves for 78rpm’s.
A quick search on the Internet will allow you to find that the old record labels were more
than the figures above and that sometimes the same record label used different curves
during the years. Actually, it can be seen that some labels used the same curve as other
labels (e.g. Mercury used the same curve as Capitol), so the curve set provided with the
JOPLIN MKIII is the one which covers almost all the labels producing records between
1925 and 1954.
To find out more about which curve to use with a specific record, extensive literature may
be found on the Internet (for example:
http://www.shellac.org/wams/wequal.html
,
http://midimagic.sgc-hosting.com/mixcurve.htm
).
9.2.1. RIAA
It’s the standard curve of present days, used from almost all the record labels since 1954.
Its use is generally indicated on the record label and/or on the cover. It is actually the
same curve as the RCA’s “New Orthophonic”, so it can be used to play RCA records
claiming the use of that curve also.
During the years, RIAA made some amendments to the curve. The most relevant, after an
indication from IEC, was the addition of a 16Hz high pass to cope with the rumble
produced by warped records or noisy turntables. Not all cutting plants adopted this
amendment and it’s very difficult to tell whether or not it’s been adopted for a certain
pressing, as the curve is always indicated as RIAA.
The
JOPLIN MKIII
has not a specific RIAA/IEC curve, but it can be obtained by selecting
RIAA and the high-pass filter at 16Hz (see Section 8.3.7).
9.2.2. AES
