Amber 5500 - Page 11

Amber model
5500
Owner’s Manual
Version
07
2.1.9
FILTERS
Several band
limiting
and noise
weighting
filters are
available. These
are useful
to
reduce the
effects of
extraneous noise
during
distortion
measurements or
provide
frequen-
cy
response
weighting
for
noise measure-
ments.
Four
standard filters are
provided
and four
more are
optional.
The
400 Hz
High
Pass filter
can be used to
reject
low
frequency
noise and mains
hum. It
is a
3—pole
Butterworth filter and
provides
over
40 dB
rejection
at
50 or
60
Hz. It
may
be
used
when
making
THD+N
measure-
ments of
signals
with
fundamentals of
1 kHz
or
greater.
The
filter is
selected and
deselected on a
push
on/push
off basis with
the
first filter
key.
This
filter is
independent
of
other filters
and
may
be
selected in
conjunc-
tion with
others.
The
30 kHz and
80 kHz Low Pass
filters
may
be
used to
reduce the
measurement
bandwidth in
THD+N and
other modes.
These are
3-pole
Butterworth
filters
(18
dB
per
octave
roll-off).
They
are
generally
used
in
THD+N if the
fundamental of the
signal
being
measured is less
than one third
to one
fifth of the
filter cutoff
frequency (e.g.
10
kHz
fundamental or lower for
30
kHz
filter, etc.).
The
fourth filter
(SPCL)
will be one of
3
possibilities:
Option
101
CCIR
468-3
Option
102
Psophometric
(CCI'IT
P53A)
Programmable
Audio
Measurement
System
Section 2
The choice of
which of these
three
is deter-
mined at
the
factory
at
the time
of order
and
indicated
by
a suitable
panel
label
over the
button.
In
addition to these
four
standard
filters,
four-
optional
additional
filters
may
be
provided.
The
optional
group
of four
additional filters
may
be
one of the
following
two
groups:
1)
Option
-005 Audio
contains the
following
four
filters:
a)
Audio
band
pass,
36
dB
per
octave
roll-off
at each
end.
Specify
20
Hz
to
20 kHz or 22.4
Hz to
22.4 kHz
b)
IHF
Band Pass
:
200
Hz
to
15
kHz
with
19
kHz
notch.
c)
ANSI “A”
Weighting
(also
called
NAB).
d)
CClR
468-3
weighting
(also
called
Dolby).
2)
Option
-006
Telecommunications
contains the
following
four
filters:
a)
3 kHz Flat
(Bell
41009 or
IEEE
743).
b)
15
kHz
Flat
(Bell
41009
or
IEEE
743).
c)
Program
(DIN
45405
and
Bell
41009/IEEE
743).
d)
C
Message
with notch
(Bell
41009
or
IEEE
743).
On
special order,
a mix of
filters
from
options
-005 and
-006
may
be
supplied
to a
maxi-
mum
of four
auxiliary
filters.
'
Note that
with the
exception
of the
400 Hz.
High
Pass
filter,
only
one of the
remaining up
to
seven filters
may
be
selected at
any
one
time.
2-9