G.R.A.S. AL0010, Instruction Manual

Page: 5 / 10

Actuator Calibration Stand Type AL0010 - Page 4
G.R.A.S. Sound & Vibration
Fig. 2 Showing places for parking electro-static actuators and microphone
protection grids and the grub screw for securing the preamplier
3) Signal generator capable of generating logarithmically swept tones within the frequency
range of interest. This signal is fed to the actuator supply.
4) Measurement amplier.
This receives, via the Type 12AK, the signal picked up by the microphone and measures
the response of the microphone to the swept tone.
Items 3 and 4 could be combined in the same unit, e.g. a computer tted with suitable hardware
and software for A/D and D/A conversions in order to simulate both a signal generator and
measurement amplier.
Test Procedure
General
The basic stages in the test procedure are:
1) Setting up the microphone on the AL0010, see Fig. 3 or Fig. 4.
2) Applying a signal via the actuator supply to the electro-static actuator and measuring the
output from the microphone.
The following deals in more detail with each stage of the test procedure.
Plug
Place plug in hole provided before
parking the 1⁄2-inch electro-static
actuator here
Recesses for parking elec-
tro-static actuators and micro-
phone protection grids