Ampex 351 - Page 14

2-6
IVi and 15 ips CCIR Reproduce Equalization
The 7 ’ /2 and 15 ips CCIR equalization curves
are the European counter parts of the 7 ] /2 and
15 ips NAB curves. The CCIR curves and the
' NAB curves are not the same. The 71/2 ips CCIR
curve consists of a 6 db per octave decaying
slope with a 100 microsecond high end time
constant and no low end equalization. The 15
ips CCIR curve consists of a 6 db per octave
decaying slope with a 35 microsecond high end
also that the recorded signal amplitude
is increased ONLY in the 2000 to
6000 cps band, thus avoiding self 
erasure at high frequencies.
The 15 ips AME curve is intended for in 
ternal use in companies specializing in produc 
ing “ master ” recordings and is not to be con 
sidered as supplanting the NAB standard for
commercially released tapes.
89-0144
Issue A
NOTE
The CCIR specifications do not include
a low end time constant. However, the
frequency response tolerances at the
low end are broad enough that most
machines that do have a low end time
constant are still within CCIR specifi 
cations. (Most manufacturer ’ s include
the low end time constant.)
time constant and no low end equalization.
When 71/2 ips CCIR tape is played back on a
machine with 71/2 ips NAB equalization, it has
the affect of decreasing high frequency response
by approximately 6 db. When a 15 ips CCIR tape
is played back using 15 ips NAB equalization, it
has the affect of increasing high frequency re 
sponse by approximately 4 db. When NAB tapes
are played back using CCIR equalization, the
opposite affects occur.