Tape Speed; Wow And Flutter - Tascam 122 Service Manual

I 122
6-8. TAPE SPEED
Use the TEAC MTT-111 test tape (containing
highly accurate 3-kHz signals) or its equivalent
to mE:asure tape speed.
1) Connect a frequency counter to the
0
UTPUT
terminals as shown in Fig. 6-8.
2) Play the test tape from the start of the tape
and check that the frequency counter reading
is within 3 kHz ±0.5 %.
3) If the reading is outside this range, clean the
tape path and check the pinch roller pressure
and takeup tension.
4) If these values are correct, adjust the resistor
of the motor so that the reading is within the
range 3000 Hz ±5 Hz.
NOT E: Adjust tape speed after the tape has run
for about 30 sec in the reproduc.e mode.
Fig. 6-7
6-9. WOW AND FLUTTER
Before measuring wow and flutter, the following
points should be read carefully. It is necessary to
decide which of the two measurement methods
should be used.
1)
Reproduce method: Measure while playing
wow & flutter test tape MT-111 or its equiv­
alent.
Record/reproduce method: Record a 3-kHz
signal on blank tape, rewind the tape and re­
produce the recorded signal.
NOTE: When measuring using the record/re­
produce method, the recorded section
should be reproduced repeatedly to
obtain the mean value . Be careful not to
read the meter for those parts of the
tape in which wow & flutter components
in record ing and reproducing cancel each
other.
2) Set the flutter meter controls to the required
standard. Select the 01 N/I EC/ ANSI peak
value or the NAB RMS value, then set the
weighting control as required.
3) Measu re at the beginning and the end of the
tape. The measured value will differ slightly
according to the measuring method and in ­
strument used. Standard values are:
1-7/8 ips:
±0.085 % peak (DIN/IEC/ANSI weighted)
±0.18
%
peak (DIN/IEC/ANSI unweighted)
0.06
%
(NAB weighted)
0.11
%
(NAB unweighted)
3-3/4 ips:
±0.055
%
peak (DIN/IEC/ANSI weighted)
±0.13 % peak (DIN/IEC/ANSI unweighted)
0.04 %
(NAB weighted)
0.07
%
(NAB unweighted)
NOTE: Measure after cleaning the tape path,
especially the capstan shaft, pinch roller
and head surfaces.
OSCI LLATOR
WOW /F LUTTER
/.IETER
UNIT
[D
und er TE S T
1"' 000i.l!PIJT"'-~---1-<>
o
0
Fig. 6-8
45