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1. DESCRIPTION
talk can also be made by comparison between two tests of different rotation
speeds, giving a frequency translation of the characteristic for the record
only. The recorded cross-talk, expressed in dB with reference to the modulation
level, is the separation between channels of the recording. The minimum
separation of the QR 2009 is shown on Fig. 1.13.
The tolerances of the Test Recordings Type QR 2008 are given on p. 5.
db
+1
0
-1
QR 2009
QR 2007
QR
2009~
QR 2007
~
_
4
logarithmic sweep accuracy:
~±2
.
S%±1c/s
~
...
....
100
1000
CIS
Fig.
1.12.
Curves silowing tile manufacturing tolerances wllich include both
the record itself and the equalizing filter characteristics. The accuracy is best
for lateral modulation and the tolerances are therefore narrower for the
db
-10
-20
-30
-40.,
20
Record QR 2007.
..
"'
...
100
8 = unmodulated wall
(upper limit of the
records crosstalk,
measured
in
1/3 octave
filters)
-'00
kiOO
a:JDO
sooo
10000
1000
C/S
10000
20000
~fi2333
Fig.
1.13.
Limit of cross-talk on the stereophonic recordings of Type QR 2009,
bands
1-2
and 5-6, measured in dB with respect to the recording level
(i.e .: maximum measurable channel separation).
N.B. Valid only when the playing angle does not deviate much from the
cutting angle (10°
±
5°).
12
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