Description; Purpose Of The Equipment - BRUEL & KJAER 4409 Instructions And Applications

1. DESCRIPTION
1. Description
Purpose of the Equipment.
The Response Test Unit Type 4409 is intended for use with the B & K auto-
matic frequency response plotting equipment when investigating the frequency
response of sound reproducing equipment.
Fig. 1.1 shows an example in which the 4409 and a test record are involved in
the testing of a stereophonic record player.
Head under test
Mic. Amplifier
Record Player
Level recorder
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Response Test Unit
Fig. 1.1. Measuring set-up for automatic plotting of the frequency response
of a stereophonic record player.
The 4409 fulfils three different functions:
(a) channel selection in the case of stereophonic equipment either manually,
when only one channel is investigated, or automatically at a recuring fre-
quency of 1.2 Hz for automatic cross-talk or comparison measurements.
(b) equalization, by different RC filters, of the recording characteristic of the
test record.
(c) synchronization of the paper-drive of the Level Recorder Type 2305 with
the reference recordings (record or tape) under reproduction.
It is thus possible to automatically plot the frequency response of the sound
reproducing equipment. A typical experimental result is shown in Fig. 1.2.
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