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2. OPERATION
In the case of stereophonic systems, simultaneous plot of the responses of the
two channels is feasible by means of the 4409's 2-channel selector in the same
way as for record players.
In Fig. 2.17 is finally shown an example of a test including the microphone
and loudspeaker used with a tape recorder. For automatic distortion measure-
ments, a Spectrometer Type 2112 (or the Band Pass Filter Set Type 1612)
should be added.
Synchro-start of a Continuous Recording.
When the automatic stop function of the Level Recorder used in conjunction
with the synchro-starter of Type 4409 is not desired, the Gear Lever X of the
2305 should be pushed in and the stop-start switch should be in "stop" posi-
tion. A 1ooo Hz signal sent to the 4409 will then start the recorder, and the
stopping is obtained manually by switching to
"Start"
and coming back to
"Stop" immediately afterwards.
BF.O.
1022
Record
Artificial
Voice
r-----.
<;5
@
@
~
Control
Amplifier
~
I
Dictating
Machine
under test
Replay
to Level
Recorder 230 5
and Synchro
Starter 4409
<;5
@
@
~
.
4,2347
Fig. 2.17. Complete testing of a tape recorder including acoustical input and
output (microphone and loudspeaker). A servo-regulating amplifier in the
B.F.O. maintains a constant acoustical input levei up to
8-
10 kHz by means
of the regulating microphone Type 4132 mounted on the
Artificial
Voice
Type 4215.
33
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