BRUEL & KJAER 2305 - Response Test Unit Type 4409

Response Test Unit Type 4409.
Mono- and stereophonic recording and reproducing systems such as gramo-
phone systems*), tape recorders, motion picture sound systems etc. can be
automatically examined when the B & K Response Test Unit Type 4409 is
Fig. 4.8. Response Test Unit Type 4409.
combined with the Level Recorder in a suitable measuring arrangement. The
whole system, including the transducer (pick-up, recording/reproducing
head etc.) can be examined automatically, which is a great asset in both
development and production .
The Test Unit Type 4409 has three independent functions, which can he
made use of separately or combined:
Synchro-starter. This starts the paper drive on the Level Recorder auto-
matically so that the frequency calibrated recording paper will run in
synchronism with the frequency sweep of a special pre-recorded test
(reference)
record. The start demand to the Level Recorder is given at the
instant a 1000 Hz (c/s) synchronizing signal ceases. This 1000 Hz (cis) signal
is
on the gliding frequency test record and immediately preceeds the
frequency sweep.
Two Channel Seleetor. A built-in automatic selector makes it possible to
record two separate signal levels "simultaneously" on the Level Recorder.
It consists of a free-running multivibrator which drives a switching arrange-
ment. The multi vibrator is fully transistorized and has a frequency of
a
pproximately 1.2 Hz (c/s).
*) For investigation of gramophone systems the B & K Frequency Records Type QR 2007
(monophonic) and Type QR 2009 (stereophonic) can be used.
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